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<H1> 6. Database Packages </H1>
<!--docid::SEC140::-->
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC141">6.1 Relational Database</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'relational-database</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC165">6.2 Relational Infrastructure</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC178">6.3 Weight-Balanced Trees</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'wt-tree</TD></TR>
</TABLE>
<P>
<A NAME="Relational Database"></A>
<HR SIZE="6">
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<H2> 6.1 Relational Database </H2>
<!--docid::SEC141::-->
<P>
<CODE>(require 'relational-database)</CODE>
<A NAME="IDX917"></A>
</P>
<P>
This package implements a database system inspired by the Relational
Model (<CITE>E. F. Codd, A Relational Model of Data for Large Shared
Data Banks</CITE>). An SLIB relational database implementation can be created
from any <A HREF="slib_6.html#SEC166">6.2.1 Base Table</A> implementation.
</P>
<P>
Why relational database? For motivations and design issues see<BR>
<A HREF="http://swissnet.ai.mit.edu/~jaffer/DBManifesto.html">http://swissnet.ai.mit.edu/~jaffer/DBManifesto.html</A>.
</P>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC142">6.1.1 Using Databases</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'databases</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC147">6.1.2 Table Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC154">6.1.3 Database Interpolation</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'database-interpolate</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC155">6.1.4 Embedded Commands</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'database-commands</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC162">6.1.5 Database Macros</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'within-database</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC164">6.1.6 Database Browser</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">'database-browse</TD></TR>
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<A NAME="Using Databases"></A>
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<H3> 6.1.1 Using Databases </H3>
<!--docid::SEC142::-->
<P>
<CODE>(require 'databases)</CODE>
<A NAME="IDX918"></A>
</P>
<P>
This enhancement wraps a utility layer on <CODE>relational-database</CODE>
which provides:
</P>
<P>
<UL>
<LI>
Identification of open databases by filename.
<LI>
Automatic sharing of open (immutable) databases.
<LI>
Automatic loading of base-table package when creating a database.
<LI>
Detection and automatic loading of the appropriate base-table package
when opening a database.
<LI>
Table and data definition from Scheme lists.
</UL>
<P>
<A NAME="SEC143"></A>
<H4> Database Sharing </H4>
<!--docid::SEC143::-->
<P>
<EM>Auto-sharing</EM> refers to a call to the procedure
<A NAME="IDX919"></A>
<CODE>open-database</CODE> returning an already open database (procedure),
rather than opening the database file a second time.
</P>
<P>
<BLOCKQUOTE>
<EM>Note:</EM> Databases returned by <CODE>open-database</CODE> do not include
wrappers applied by packages like <A HREF="slib_6.html#SEC155">6.1.4 Embedded Commands</A>. But
wrapped databases do work as arguments to these functions.
</BLOCKQUOTE>
<P>
When a database is created, it is mutable by the creator and not
auto-sharable. A database opened mutably is also not auto-sharable.
But any number of readers can (open) share a non-mutable database file.
</P>
<P>
This next set of procedures mirror the whole-database methods in
<A HREF="slib_6.html#SEC177">6.2.4 Database Operations</A>. Except for <CODE>create-database</CODE>, each
procedure will accept either a filename or database procedure for its
first argument.
</P>
<P>
<A NAME="IDX920"></A>
</P>
<DL>
<DT><U>Function:</U> <B>create-database</B> <I>filename base-table-type</I>
<DD><P>
<VAR>filename</VAR> should be a string naming a file; or <CODE>#f</CODE>. <VAR>base-table-type</VAR> must be a
symbol naming a feature which can be passed to <CODE>require</CODE>. <CODE>create-database</CODE>
returns a new, open relational database (with base-table type <VAR>base-table-type</VAR>)
associated with <VAR>filename</VAR>, or a new ephemeral database if <VAR>filename</VAR> is <CODE>#f</CODE>.
</P>
<P>
<CODE>create-database</CODE> is the only run-time use of require in SLIB
which crosses module boundaries. When <VAR>base-table-type</VAR> is <CODE>require</CODE>d by <CODE>create-database</CODE>; it
adds an association of <VAR>base-table-type</VAR> with its <EM>relational-system</EM> procedure
<A NAME="IDX921"></A>
to <VAR>mdbm:*databases*</VAR>.
</P>
<P>
alist-table is the default base-table type:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'databases)
(define my-rdb (create-database "my.db" 'alist-table))
</pre></td></tr></table></DL>
Only <CODE>alist-table</CODE> and base-table modules which have been
<CODE>require</CODE>d will dispatch correctly from the
<CODE>open-database</CODE> procedures. Therefore, either pass two
arguments to <CODE>open-database</CODE>, or require the base-table of your
database file uses before calling <CODE>open-database</CODE> with one
argument.
<P>
<A NAME="IDX922"></A>
</P>
<DL>
<DT><U>Procedure:</U> <B>open-database!</B> <I>rdb base-table-type</I>
<DD><P>
Returns <EM>mutable</EM> open relational database or #f.
</P>
</DL>
<P>
<A NAME="IDX923"></A>
</P>
<DL>
<DT><U>Function:</U> <B>open-database</B> <I>rdb base-table-type</I>
<DD><P>
Returns an open relational database associated with <VAR>rdb</VAR>. The
database will be opened with base-table type <VAR>base-table-type</VAR>).
</P>
<P>
<A NAME="IDX924"></A>
<DT><U>Function:</U> <B>open-database</B> <I>rdb</I>
<DD>Returns an open relational database associated with <VAR>rdb</VAR>.
<CODE>open-database</CODE> will attempt to deduce the correct base-table-type.
</P>
</DL>
<P>
<A NAME="IDX925"></A>
</P>
<DL>
<DT><U>Function:</U> <B>write-database</B> <I>rdb filename</I>
<DD><P>
Writes the mutable relational-database <VAR>rdb</VAR> to <VAR>filename</VAR>.
</P>
</DL>
<P>
<A NAME="IDX926"></A>
</P>
<DL>
<DT><U>Function:</U> <B>sync-database</B> <I>rdb</I>
<DD><P>
Writes the mutable relational-database <VAR>rdb</VAR> to the filename it was
opened with.
</P>
</DL>
<P>
<A NAME="IDX927"></A>
</P>
<DL>
<DT><U>Function:</U> <B>solidify-database</B> <I>rdb</I>
<DD><P>
Syncs <VAR>rdb</VAR> and makes it immutable.
</P>
</DL>
<P>
<A NAME="IDX928"></A>
</P>
<DL>
<DT><U>Function:</U> <B>close-database</B> <I>rdb</I>
<DD><P>
<VAR>rdb</VAR> will only be closed when the count of <CODE>open-database</CODE> - <CODE>close-database</CODE>
calls for <VAR>rdb</VAR> (and its filename) is 0. <CODE>close-database</CODE> returns #t if successful;
and #f otherwise.
</P>
</DL>
<P>
<A NAME="IDX929"></A>
</P>
<DL>
<DT><U>Function:</U> <B>mdbm:report</B>
<DD><P>
Prints a table of open database files. The columns are the
base-table type, number of opens, `<SAMP>!</SAMP>' for mutable, the
filename, and the lock certificate (if locked).
</P>
</DL>
<TABLE><tr><td> </td><td class=example><pre>(mdbm:report)
-|
alist-table 003 /usr/local/lib/slib/clrnamdb.scm
alist-table 001 ! sdram.db jaffer@aubrey.jaffer.3166:1038628199
</pre></td></tr></table><P>
<A NAME="SEC144"></A>
<H4> Opening Tables </H4>
<!--docid::SEC144::-->
<P>
<A NAME="IDX930"></A>
</P>
<DL>
<DT><U>Function:</U> <B>open-table</B> <I>rdb table-name</I>
<DD><P>
<VAR>rdb</VAR> must be a relational database and <VAR>table-name</VAR> a symbol.
</P>
<P>
<CODE>open-table</CODE> returns a "methods" procedure for an existing relational table in
<VAR>rdb</VAR> if it exists and can be opened for reading, otherwise returns
<CODE>#f</CODE>.
</P>
</DL>
<P>
<A NAME="IDX931"></A>
</P>
<DL>
<DT><U>Procedure:</U> <B>open-table!</B> <I>rdb table-name</I>
<DD><P>
<VAR>rdb</VAR> must be a relational database and <VAR>table-name</VAR> a symbol.
</P>
<P>
<CODE>open-table!</CODE> returns a "methods" procedure for an existing relational table in
<VAR>rdb</VAR> if it exists and can be opened in mutable mode, otherwise returns
<CODE>#f</CODE>.
</P>
</DL>
<A NAME="SEC145"></A>
<H4> Defining Tables </H4>
<!--docid::SEC145::-->
<P>
<A NAME="IDX932"></A>
</P>
<DL>
<DT><U>Function:</U> <B>define-domains</B> <I>rdb row5 <small>...</small></I>
<DD><P>
Adds the domain rows <VAR>row5</VAR> <small>...</small> to the `<SAMP>*domains-data*</SAMP>' table
in <VAR>rdb</VAR>. The format of the row is given in <A HREF="slib_6.html#SEC175">6.2.2 Catalog Representation</A>.
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(define-domains rdb '(permittivity #f complex? c64 #f))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX933"></A>
</P>
<DL>
<DT><U>Function:</U> <B>add-domain</B> <I>rdb row5</I>
<DD><P>
Use <CODE>define-domains</CODE> instead.
</P>
</DL>
<P>
<A NAME="IDX934"></A>
</P>
<DL>
<DT><U>Function:</U> <B>define-tables</B> <I>rdb spec-0 <small>...</small></I>
<DD><P>
Adds tables as specified in <VAR>spec-0</VAR> <small>...</small> to the open
relational-database <VAR>rdb</VAR>. Each <VAR>spec</VAR> has the form:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(<name> <descriptor-name> <descriptor-name> <rows>)
</pre></td></tr></table>or
<TABLE><tr><td> </td><td class=example><pre>(<name> <primary-key-fields> <other-fields> <rows>)
</pre></td></tr></table><P>
where <name> is the table name, <descriptor-name> is the symbol
name of a descriptor table, <primary-key-fields> and
<other-fields> describe the primary keys and other fields
respectively, and <rows> is a list of data rows to be added to the
table.
</P>
<P>
<primary-key-fields> and <other-fields> are lists of field
descriptors of the form:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(<column-name> <domain>)
</pre></td></tr></table>or
<TABLE><tr><td> </td><td class=example><pre>(<column-name> <domain> <column-integrity-rule>)
</pre></td></tr></table><P>
where <column-name> is the column name, <domain> is the domain
of the column, and <column-integrity-rule> is an expression whose
value is a procedure of one argument (which returns <CODE>#f</CODE> to signal
an error).
</P>
<P>
If <domain> is not a defined domain name and it matches the name of
this table or an already defined (in one of <VAR>spec-0</VAR> <small>...</small>) single
key field table, a foreign-key domain will be created for it.
</P>
</DL>
<A NAME="SEC146"></A>
<H4> Listing Tables </H4>
<!--docid::SEC146::-->
<P>
<A NAME="IDX935"></A>
</P>
<DL>
<DT><U>Function:</U> <B>list-table-definition</B> <I>rdb table-name</I>
<DD><P>
If symbol <VAR>table-name</VAR> exists in the open relational-database
<VAR>rdb</VAR>, then returns a list of the table-name, its primary key names
and domains, its other key names and domains, and the table's records
(as lists). Otherwise, returns #f.
</P>
<P>
The list returned by <CODE>list-table-definition</CODE>, when passed as an
argument to <CODE>define-tables</CODE>, will recreate the table.
</P>
</DL>
<P>
<A NAME="Table Operations"></A>
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</TR></TABLE>
<H3> 6.1.2 Table Operations </H3>
<!--docid::SEC147::-->
<P>
These are the descriptions of the methods available from an open
relational table. A method is retrieved from a table by calling
the table with the symbol name of the operation. For example:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>((plat 'get 'processor) 'djgpp) => i386
</pre></td></tr></table><P>
Some operations described below require primary key arguments. Primary
keys arguments are denoted <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small>. It is an
error to call an operation for a table which takes primary key arguments
with the wrong number of primary keys for that table.
</P>
<P>
<A NAME="IDX936"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>get</B> <I>column-name</I>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the value for the <VAR>column-name</VAR> column of the row associated
with primary keys <VAR>key1</VAR>, <VAR>key2</VAR> <small>...</small> if that row exists in
the table, or <CODE>#f</CODE> otherwise.
<P>
<TABLE><tr><td> </td><td class=example><pre>((plat 'get 'processor) 'djgpp) => i386
((plat 'get 'processor) 'be-os) => #f
</pre></td></tr></table></DL>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC148">6.1.2.1 Single Row Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC149">6.1.2.2 Match-Keys</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC150">6.1.2.3 Multi-Row Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC151">6.1.2.4 Indexed Sequential Access Methods</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC152">6.1.2.5 Sequential Index Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC153">6.1.2.6 Table Administration</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Single Row Operations"></A>
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</TR></TABLE>
<H4> 6.1.2.1 Single Row Operations </H4>
<!--docid::SEC148::-->
<P>
The term <EM>row</EM> used below refers to a Scheme list of values (one for
each column) in the order specified in the descriptor (table) for this
table. Missing values appear as <CODE>#f</CODE>. Primary keys must not
be missing.
</P>
<P>
<A NAME="IDX937"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:insert</B>
<DD>Adds the row <VAR>row</VAR> to this table. If a row for the primary key(s)
specified by <VAR>row</VAR> already exists in this table an error is
signaled. The value returned is unspecified.
</DL>
<P>
<TABLE><tr><td> </td><td class=example><pre>(define telephone-table-desc
((my-database 'create-table) 'telephone-table-desc))
(define ndrp (telephone-table-desc 'row:insert))
(ndrp '(1 #t name #f string))
(ndrp '(2 #f telephone
(lambda (d)
(and (string? d) (> (string-length d) 2)
(every
(lambda (c)
(memv c '(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
#\+ #\( #\ #\) #\-)))
(string->list d))))
string))
</pre></td></tr></table><P>
<A NAME="IDX938"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:update</B>
<DD>Returns a procedure of one argument, <VAR>row</VAR>, which adds the row,
<VAR>row</VAR>, to this table. If a row for the primary key(s) specified by
<VAR>row</VAR> already exists in this table, it will be overwritten. The
value returned is unspecified.
</DL>
<P>
<A NAME="IDX939"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:retrieve</B>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the row associated with primary keys <VAR>key1</VAR>, <VAR>key2</VAR>
<small>...</small> if it exists, or <CODE>#f</CODE> otherwise.
</DL>
<P>
<TABLE><tr><td> </td><td class=example><pre>((plat 'row:retrieve) 'linux) => (linux i386 linux gcc)
((plat 'row:retrieve) 'multics) => #f
</pre></td></tr></table><P>
<A NAME="IDX940"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:remove</B>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
removes and returns the row associated with primary keys <VAR>key1</VAR>,
<VAR>key2</VAR> <small>...</small> if it exists, or <CODE>#f</CODE> otherwise.
</DL>
<P>
<A NAME="IDX941"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:delete</B>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
deletes the row associated with primary keys <VAR>key1</VAR>, <VAR>key2</VAR>
<small>...</small> if it exists. The value returned is unspecified.
</DL>
<P>
<A NAME="Match-Keys"></A>
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</TR></TABLE>
<H4> 6.1.2.2 Match-Keys </H4>
<!--docid::SEC149::-->
<P>
<A NAME="IDX942"></A>
The (optional) <VAR>match-key1</VAR> <small>...</small> arguments are used to restrict
actions of a whole-table operation to a subset of that table. Those
procedures (returned by methods) which accept match-key arguments will
accept any number of match-key arguments between zero and the number of
primary keys in the table. Any unspecified <VAR>match-key</VAR> arguments
default to <CODE>#f</CODE>.
</P>
<P>
The <VAR>match-key1</VAR> <small>...</small> restrict the actions of the table command
to those records whose primary keys each satisfy the corresponding
<VAR>match-key</VAR> argument. The arguments and their actions are:
</P>
<P>
<BLOCKQUOTE>
<DL COMPACT>
<DT><CODE>#f</CODE>
<DD>The false value matches any key in the corresponding position.
<DT>an object of type procedure
<DD>This procedure must take a single argument, the key in the corresponding
position. Any key for which the procedure returns a non-false value is
a match; Any key for which the procedure returns a <CODE>#f</CODE> is not.
<DT>other values
<DD>Any other value matches only those keys <CODE>equal?</CODE> to it.
</DL>
</BLOCKQUOTE>
<P>
<A NAME="IDX943"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>get*</B> <I>column-name</I>
<DD>Returns a procedure of optional arguments <VAR>match-key1</VAR> <small>...</small> which
returns a list of the values for the specified column for all rows in
this table. The optional <VAR>match-key1</VAR> <small>...</small> arguments restrict
actions to a subset of the table.
<P>
<TABLE><tr><td> </td><td class=example><pre>((plat 'get* 'processor)) =>
(i386 i8086 i386 i8086 i386 i386 i8086 m68000
m68000 m68000 m68000 m68000 powerpc)
((plat 'get* 'processor) #f) =>
(i386 i8086 i386 i8086 i386 i386 i8086 m68000
m68000 m68000 m68000 m68000 powerpc)
(define (a-key? key)
(char=? #\a (string-ref (symbol->string key) 0)))
((plat 'get* 'processor) a-key?) =>
(m68000 m68000 m68000 m68000 m68000 powerpc)
((plat 'get* 'name) a-key?) =>
(atari-st-turbo-c atari-st-gcc amiga-sas/c-5.10
amiga-aztec amiga-dice-c aix)
</pre></td></tr></table></DL>
<P>
<A NAME="Multi-Row Operations"></A>
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<H4> 6.1.2.3 Multi-Row Operations </H4>
<!--docid::SEC150::-->
<P>
<A NAME="IDX944"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:retrieve*</B>
<DD>Returns a procedure of optional arguments <VAR>match-key1</VAR> <small>...</small>
which returns a list of all rows in this table. The optional
<VAR>match-key1</VAR> <small>...</small> arguments restrict actions to a subset of the
table. For details see See section <A HREF="slib_6.html#SEC149">6.1.2.2 Match-Keys</A>.
</DL>
<P>
<TABLE><tr><td> </td><td class=example><pre>((plat 'row:retrieve*) a-key?) =>
((atari-st-turbo-c m68000 atari turbo-c)
(atari-st-gcc m68000 atari gcc)
(amiga-sas/c-5.10 m68000 amiga sas/c)
(amiga-aztec m68000 amiga aztec)
(amiga-dice-c m68000 amiga dice-c)
(aix powerpc aix -))
</pre></td></tr></table><P>
<A NAME="IDX945"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:remove*</B>
<DD>Returns a procedure of optional arguments <VAR>match-key1</VAR> <small>...</small> which
removes and returns a list of all rows in this table. The optional
<VAR>match-key1</VAR> <small>...</small> arguments restrict actions to a subset of the
table.
</DL>
<P>
<A NAME="IDX946"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:delete*</B>
<DD>Returns a procedure of optional arguments <VAR>match-key1</VAR> <small>...</small>
which Deletes all rows from this table. The optional <VAR>match-key1</VAR>
<small>...</small> arguments restrict deletions to a subset of the table. The
value returned is unspecified. The descriptor table and catalog entry
for this table are not affected.
</DL>
<P>
<A NAME="IDX947"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>for-each-row</B>
<DD>Returns a procedure of arguments <VAR>proc</VAR> <VAR>match-key1</VAR> <small>...</small>
which calls <VAR>proc</VAR> with each <VAR>row</VAR> in this table. The
optional <VAR>match-key1</VAR> <small>...</small> arguments restrict actions to a
subset of the table. For details see See section <A HREF="slib_6.html#SEC149">6.1.2.2 Match-Keys</A>.
</DL>
<P>
Note that <CODE>row:insert*</CODE> and <CODE>row:update*</CODE> do <EM>not</EM> use
match-keys.
</P>
<P>
<A NAME="IDX948"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:insert*</B>
<DD>Returns a procedure of one argument, <VAR>rows</VAR>, which adds each row in
the list of rows, <VAR>rows</VAR>, to this table. If a row for the primary
key specified by an element of <VAR>rows</VAR> already exists in this table,
an error is signaled. The value returned is unspecified.
</DL>
<P>
<A NAME="IDX949"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>row:update*</B>
<DD>Returns a procedure of one argument, <VAR>rows</VAR>, which adds each row in
the list of rows, <VAR>rows</VAR>, to this table. If a row for the primary
key specified by an element of <VAR>rows</VAR> already exists in this table,
it will be overwritten. The value returned is unspecified.
</DL>
<P>
<A NAME="Indexed Sequential Access Methods"></A>
<HR SIZE="6">
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H4> 6.1.2.4 Indexed Sequential Access Methods </H4>
<!--docid::SEC151::-->
<P>
<A NAME="IDX950"></A>
<EM>Indexed Sequential Access Methods</EM> are a way of arranging
database information so that records can be accessed both by key and
by key sequence (ordering). <EM>ISAM</EM> is not part of Codd's
relational model. Hardcore relational programmers might use some
least-upper-bound join for every row to get them into an order.
</P>
<P>
Associative memory in B-Trees is an example of a database
implementation which can support a native key ordering. SLIB's
<CODE>alist-table</CODE> implementation uses <CODE>sort</CODE> to implement
<CODE>for-each-row-in-order</CODE>, but does not support <CODE>isam-next</CODE>
and <CODE>isam-prev</CODE>.
</P>
<P>
The multi-primary-key ordering employed by these operations is the
lexicographic collation of those primary-key fields in their given
order. For example:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(12 a 34) < (12 a 36) < (12 b 1) < (13 a 0)
</pre></td></tr></table><P>
<A NAME="Sequential Index Operations"></A>
<HR SIZE="6">
<A NAME="SEC152"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H4> 6.1.2.5 Sequential Index Operations </H4>
<!--docid::SEC152::-->
<P>
The following procedures are individually optional depending on the
base-table implememtation. If an operation is <EM>not</EM> supported,
then calling the table with that operation symbol will return false.
</P>
<P>
<A NAME="IDX951"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>for-each-row-in-order</B>
<DD>Returns a procedure of arguments <VAR>proc</VAR> <VAR>match-key1</VAR> <small>...</small>
which calls <VAR>proc</VAR> with each <VAR>row</VAR> in this table in the
(implementation-dependent) natural, repeatable ordering for rows. The
optional <VAR>match-key1</VAR> <small>...</small> arguments restrict actions to a
subset of the table. For details see See section <A HREF="slib_6.html#SEC149">6.1.2.2 Match-Keys</A>.
</DL>
<P>
<A NAME="IDX952"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>isam-next</B>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the key-list identifying the lowest record higher than
<VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which is stored in the relational-table;
or false if no higher record is present.
<P>
<A NAME="IDX953"></A>
<DT><U>Operation:</U> relational-table <B>isam-next</B> <I>column-name</I>
<DD>The symbol <VAR>column-name</VAR> names a key field. In the list returned
by <CODE>isam-next</CODE>, that field, or a field to its left, will be
changed. This allows one to skip over less significant key fields.
</P>
</DL>
<P>
<A NAME="IDX954"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>isam-prev</B>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the key-list identifying the highest record less than
<VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which is stored in the relational-table;
or false if no lower record is present.
<P>
<A NAME="IDX955"></A>
<DT><U>Operation:</U> relational-table <B>isam-prev</B> <I>index</I>
<DD>The symbol <VAR>column-name</VAR> names a key field. In the list returned
by <CODE>isam-next</CODE>, that field, or a field to its left, will be
changed. This allows one to skip over less significant key fields.
</P>
</DL>
<P>
For example, if a table has key fields:
<TABLE><tr><td> </td><td class=example><pre>(col1 col2)
(9 5)
(9 6)
(9 7)
(9 8)
(12 5)
(12 6)
(12 7)
</pre></td></tr></table><P>
Then:
<TABLE><tr><td> </td><td class=example><pre>((table 'isam-next) '(9 5)) => (9 6)
((table 'isam-next 'col2) '(9 5)) => (9 6)
((table 'isam-next 'col1) '(9 5)) => (12 5)
((table 'isam-prev) '(12 7)) => (12 6)
((table 'isam-prev 'col2) '(12 7)) => (12 6)
((table 'isam-prev 'col1) '(12 7)) => (9 8)
</pre></td></tr></table><P>
<A NAME="Table Administration"></A>
<HR SIZE="6">
<A NAME="SEC153"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H4> 6.1.2.6 Table Administration </H4>
<!--docid::SEC153::-->
<P>
<A NAME="IDX956"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>column-names</B>
<DD><A NAME="IDX957"></A>
<DT><U>Operation:</U> relational-table <B>column-foreigns</B>
<DD><A NAME="IDX958"></A>
<DT><U>Operation:</U> relational-table <B>column-domains</B>
<DD><A NAME="IDX959"></A>
<DT><U>Operation:</U> relational-table <B>column-types</B>
<DD>Return a list of the column names, foreign-key table names, domain
names, or type names respectively for this table. These 4 methods are
different from the others in that the list is returned, rather than a
procedure to obtain the list.
<P>
<A NAME="IDX960"></A>
<DT><U>Operation:</U> relational-table <B>primary-limit</B>
<DD>Returns the number of primary keys fields in the relations in this
table.
</P>
</DL>
<P>
<A NAME="IDX961"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-table <B>close-table</B>
<DD>Subsequent operations to this table will signal an error.
</DL>
<P>
<A NAME="Database Interpolation"></A>
<HR SIZE="6">
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</TR></TABLE>
<H3> 6.1.3 Database Interpolation </H3>
<!--docid::SEC154::-->
<P>
<CODE>(require 'database-interpolate)</CODE>
</P>
<P>
Indexed sequential access methods allow finding the keys (having
associations) closest to a given value. This facilitates the
interpolation of associations between those in the table.
</P>
<P>
<A NAME="IDX962"></A>
</P>
<DL>
<DT><U>Function:</U> <B>interpolate-from-table</B> <I>table column</I>
<DD><VAR>Table</VAR> should be a relational table with one numeric primary key
field which supports the <CODE>isam-prev</CODE> and <CODE>isam-next</CODE>
operations. <VAR>column</VAR> should be a symbol or exact positive integer
designating a numerically valued column of <VAR>table</VAR>.
<P>
<CODE>interpolate-from-table</CODE> calculates and returns a value
proportionally intermediate between its values in the next and
previous key records contained in <VAR>table</VAR>. For keys larger than
all the stored keys the value associated with the largest stored key
is used. For keys smaller than all the stored keys the value
associated with the smallest stored key is used.
</P>
</DL>
<P>
<A NAME="Embedded Commands"></A>
<HR SIZE="6">
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</TR></TABLE>
<H3> 6.1.4 Embedded Commands </H3>
<!--docid::SEC155::-->
<P>
<CODE>(require 'database-commands)</CODE>
</P>
<P>
This enhancement wraps a utility layer on <CODE>relational-database</CODE>
which provides:
</P>
<P>
<UL>
<LI>
Automatic execution of initialization commands stored in database.
<LI>
Transparent execution of database commands stored in <CODE>*commands*</CODE>
table in database.
</UL>
<P>
When an enhanced relational-database is called with a symbol which
matches a <VAR>name</VAR> in the <CODE>*commands*</CODE> table, the associated
procedure expression is evaluated and applied to the enhanced
relational-database. A procedure should then be returned which the user
can invoke on (optional) arguments.
</P>
<P>
The command <CODE>*initialize*</CODE> is special. If present in the
<CODE>*commands*</CODE> table, <CODE>open-database</CODE> or <CODE>open-database!</CODE>
will return the value of the <CODE>*initialize*</CODE> command. Notice that
arbitrary code can be run when the <CODE>*initialize*</CODE> procedure is
automatically applied to the enhanced relational-database.
</P>
<P>
Note also that if you wish to shadow or hide from the user
relational-database methods described in <A HREF="slib_6.html#SEC177">6.2.4 Database Operations</A>, this
can be done by a dispatch in the closure returned by the
<CODE>*initialize*</CODE> expression rather than by entries in the
<CODE>*commands*</CODE> table if it is desired that the underlying methods
remain accessible to code in the <CODE>*commands*</CODE> table.
</P>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC156">6.1.4.1 Database Extension</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC157">6.1.4.2 Command Intrinsics</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC158">6.1.4.3 Define-tables Example</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC159">6.1.4.4 The *commands* Table</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC160">6.1.4.5 Command Service</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC161">6.1.4.6 Command Example</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Database Extension"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H4> 6.1.4.1 Database Extension </H4>
<!--docid::SEC156::-->
<P>
<A NAME="IDX963"></A>
</P>
<DL>
<DT><U>Function:</U> <B>wrap-command-interface</B> <I>rdb</I>
<DD>Returns relational database <VAR>rdb</VAR> wrapped with additional commands
defined in its *commands* table.
</DL>
<P>
<A NAME="IDX964"></A>
</P>
<DL>
<DT><U>Function:</U> <B>add-command-tables</B> <I>rdb</I>
<DD>The relational database <VAR>rdb</VAR> must be mutable.
<VAR>add-command-tables</VAR> adds a *command* table to <VAR>rdb</VAR>; then
returns <CODE>(wrap-command-interface <VAR>rdb</VAR>)</CODE>.
</DL>
<P>
<A NAME="IDX965"></A>
</P>
<DL>
<DT><U>Function:</U> <B>define-*commands*</B> <I>rdb spec-0 <small>...</small></I>
<DD><P>
Adds commands to the <CODE>*commands*</CODE> table as specified in
<VAR>spec-0</VAR> <small>...</small> to the open relational-database <VAR>rdb</VAR>. Each
<VAR>spec</VAR> has the form:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>((<name> <rdb>) "comment" <expression1> <expression2> <small>...</small>)
</pre></td></tr></table>or
<TABLE><tr><td> </td><td class=example><pre>((<name> <rdb>) <expression1> <expression2> <small>...</small>)
</pre></td></tr></table><P>
where <name> is the command name, <rdb> is a formal passed the
calling relational database, "comment" describes the
command, and <expression1>, <expression1>, <small>...</small> are the
body of the procedure.
</P>
<P>
<CODE>define-*commands*</CODE> adds to the <CODE>*commands*</CODE> table a command
<name>:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(lambda (<name> <rdb>) <expression1> <expression2> <small>...</small>)
</pre></td></tr></table><P>
</P>
</DL>
<P>
<A NAME="IDX966"></A>
</P>
<DL>
<DT><U>Function:</U> <B>open-command-database</B> <I>filename</I>
<DD><A NAME="IDX967"></A>
<DT><U>Function:</U> <B>open-command-database</B> <I>filename base-table-type</I>
<DD>Returns an open enhanced relational database associated with
<VAR>filename</VAR>. The database will be opened with base-table type
<VAR>base-table-type</VAR>) if supplied. If <VAR>base-table-type</VAR> is not
supplied, <CODE>open-command-database</CODE> will attempt to deduce the correct
base-table-type. If the database can not be opened or if it lacks the
<CODE>*commands*</CODE> table, <CODE>#f</CODE> is returned.
<P>
<A NAME="IDX968"></A>
<DT><U>Function:</U> <B>open-command-database!</B> <I>filename</I>
<DD><A NAME="IDX969"></A>
<DT><U>Function:</U> <B>open-command-database!</B> <I>filename base-table-type</I>
<DD>Returns <EM>mutable</EM> open enhanced relational database <small>...</small>
</P>
<P>
<A NAME="IDX970"></A>
<DT><U>Function:</U> <B>open-command-database</B> <I>database</I>
<DD>Returns <VAR>database</VAR> if it is an immutable relational database; #f
otherwise.
</P>
<P>
<A NAME="IDX971"></A>
<DT><U>Function:</U> <B>open-command-database!</B> <I>database</I>
<DD>Returns <VAR>database</VAR> if it is a mutable relational database; #f
otherwise.
</P>
</DL>
<P>
<A NAME="Command Intrinsics"></A>
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<H4> 6.1.4.2 Command Intrinsics </H4>
<!--docid::SEC157::-->
<P>
Some commands are defined in all extended relational-databases. The are
called just like <A HREF="slib_6.html#SEC177">6.2.4 Database Operations</A>.
</P>
<P>
<A NAME="IDX972"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>add-domain</B> <I>domain-row</I>
<DD>Adds <VAR>domain-row</VAR> to the <EM>domains</EM> table if there is no row in
the domains table associated with key <CODE>(car <VAR>domain-row</VAR>)</CODE> and
returns <CODE>#t</CODE>. Otherwise returns <CODE>#f</CODE>.
<P>
For the fields and layout of the domain table, See section <A HREF="slib_6.html#SEC175">6.2.2 Catalog Representation</A>. Currently, these fields are
<UL>
<LI>
domain-name
<LI>
foreign-table
<LI>
domain-integrity-rule
<LI>
type-id
<LI>
type-param
</UL>
<P>
The following example adds 3 domains to the `<SAMP>build</SAMP>' database.
`<SAMP>Optstring</SAMP>' is either a string or <CODE>#f</CODE>. <CODE>filename</CODE> is a
string and <CODE>build-whats</CODE> is a symbol.
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(for-each (build 'add-domain)
'((optstring #f
(lambda (x) (or (not x) (string? x)))
string
#f)
(filename #f #f string #f)
(build-whats #f #f symbol #f)))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX973"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>delete-domain</B> <I>domain-name</I>
<DD>Removes and returns the <VAR>domain-name</VAR> row from the <EM>domains</EM>
table.
</DL>
<P>
<A NAME="IDX974"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>domain-checker</B> <I>domain</I>
<DD>Returns a procedure to check an argument for conformance to domain
<VAR>domain</VAR>.
</DL>
<P>
<A NAME="Define-tables Example"></A>
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<H4> 6.1.4.3 Define-tables Example </H4>
<!--docid::SEC158::-->
<P>
The following example shows a new database with the name of
`<TT>foo.db</TT>' being created with tables describing processor families
and processor/os/compiler combinations. The database is then
solidified; saved and changed to immutable.
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'databases)
<A NAME="IDX975"></A>(define my-rdb (create-database "foo.db" 'alist-table))
(define-tables my-rdb
'(processor-family
((family atom))
((also-ran processor-family))
((m68000 #f)
(m68030 m68000)
(i386 i8086)
(i8086 #f)
(powerpc #f)))
'(platform
((name symbol))
((processor processor-family)
(os symbol)
(compiler symbol))
((aix powerpc aix -)
(amiga-dice-c m68000 amiga dice-c)
(amiga-aztec m68000 amiga aztec)
(amiga-sas/c-5.10 m68000 amiga sas/c)
(atari-st-gcc m68000 atari gcc)
(atari-st-turbo-c m68000 atari turbo-c)
(borland-c-3.1 i8086 ms-dos borland-c)
(djgpp i386 ms-dos gcc)
(linux i386 linux gcc)
(microsoft-c i8086 ms-dos microsoft-c)
(os/2-emx i386 os/2 gcc)
(turbo-c-2 i8086 ms-dos turbo-c)
(watcom-9.0 i386 ms-dos watcom))))
(solidify-database my-rdb)
</pre></td></tr></table><P>
<A NAME="The *commands* Table"></A>
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<H4> 6.1.4.4 The *commands* Table </H4>
<!--docid::SEC159::-->
<P>
The table <CODE>*commands*</CODE> in an <EM>enhanced</EM> relational-database has
the fields (with domains):
<TABLE><tr><td> </td><td class=example><pre>PRI name symbol
parameters parameter-list
procedure expression
documentation string
</pre></td></tr></table><P>
The <CODE>parameters</CODE> field is a foreign key (domain
<CODE>parameter-list</CODE>) of the <CODE>*catalog-data*</CODE> table and should
have the value of a table described by <CODE>*parameter-columns*</CODE>. This
<CODE>parameter-list</CODE> table describes the arguments suitable for passing
to the associated command. The intent of this table is to be of a form
such that different user-interfaces (for instance, pull-down menus or
plain-text queries) can operate from the same table. A
<CODE>parameter-list</CODE> table has the following fields:
<TABLE><tr><td> </td><td class=example><pre>PRI index ordinal
name symbol
arity parameter-arity
domain domain
defaulter expression
expander expression
documentation string
</pre></td></tr></table><P>
The <CODE>arity</CODE> field can take the values:
</P>
<P>
</P>
<DL COMPACT>
<DT><CODE>single</CODE>
<DD>Requires a single parameter of the specified domain.
<DT><CODE>optional</CODE>
<DD>A single parameter of the specified domain or zero parameters is
acceptable.
<DT><CODE>boolean</CODE>
<DD>A single boolean parameter or zero parameters (in which case <CODE>#f</CODE>
is substituted) is acceptable.
<DT><CODE>nary</CODE>
<DD>Any number of parameters of the specified domain are acceptable. The
argument passed to the command function is always a list of the
parameters.
<DT><CODE>nary1</CODE>
<DD>One or more of parameters of the specified domain are acceptable. The
argument passed to the command function is always a list of the
parameters.
</DL>
<P>
The <CODE>domain</CODE> field specifies the domain which a parameter or
parameters in the <CODE>index</CODE>th field must satisfy.
</P>
<P>
The <CODE>defaulter</CODE> field is an expression whose value is either
<CODE>#f</CODE> or a procedure of one argument (the parameter-list) which
returns a <EM>list</EM> of the default value or values as appropriate.
Note that since the <CODE>defaulter</CODE> procedure is called every time a
default parameter is needed for this column, <EM>sticky</EM> defaults can
be implemented using shared state with the domain-integrity-rule.
</P>
<P>
<A NAME="Command Service"></A>
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</TR></TABLE>
<H4> 6.1.4.5 Command Service </H4>
<!--docid::SEC160::-->
<P>
<A NAME="IDX976"></A>
</P>
<DL>
<DT><U>Function:</U> <B>make-command-server</B> <I>rdb table-name</I>
<DD>Returns a procedure of 2 arguments, a (symbol) command and a call-back
procedure. When this returned procedure is called, it looks up
<VAR>command</VAR> in table <VAR>table-name</VAR> and calls the call-back
procedure with arguments:
<DL COMPACT>
<DT><VAR>command</VAR>
<DD>The <VAR>command</VAR>
<DT><VAR>command-value</VAR>
<DD>The result of evaluating the expression in the <VAR>procedure</VAR> field of
<VAR>table-name</VAR> and calling it with <VAR>rdb</VAR>.
<DT><VAR>parameter-name</VAR>
<DD>A list of the <EM>official</EM> name of each parameter. Corresponds to the
<CODE>name</CODE> field of the <VAR>command</VAR>'s parameter-table.
<DT><VAR>positions</VAR>
<DD>A list of the positive integer index of each parameter. Corresponds to
the <CODE>index</CODE> field of the <VAR>command</VAR>'s parameter-table.
<DT><VAR>arities</VAR>
<DD>A list of the arities of each parameter. Corresponds to the
<CODE>arity</CODE> field of the <VAR>command</VAR>'s parameter-table. For a
description of <CODE>arity</CODE> see table above.
<DT><VAR>types</VAR>
<DD>A list of the type name of each parameter. Correspnds to the
<CODE>type-id</CODE> field of the contents of the <CODE>domain</CODE> of the
<VAR>command</VAR>'s parameter-table.
<DT><VAR>defaulters</VAR>
<DD>A list of the defaulters for each parameter. Corresponds to
the <CODE>defaulters</CODE> field of the <VAR>command</VAR>'s parameter-table.
<DT><VAR>domain-integrity-rules</VAR>
<DD>A list of procedures (one for each parameter) which tests whether a
value for a parameter is acceptable for that parameter. The procedure
should be called with each datum in the list for <CODE>nary</CODE> arity
parameters.
<DT><VAR>aliases</VAR>
<DD>A list of lists of <CODE>(alias parameter-name)</CODE>. There can be
more than one alias per <VAR>parameter-name</VAR>.
</DL>
</DL>
<P>
For information about parameters, See section <A HREF="slib_4.html#SEC65">4.4.4 Parameter lists</A>.
</P>
<P>
<A NAME="Command Example"></A>
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</TR></TABLE>
<H4> 6.1.4.6 Command Example </H4>
<!--docid::SEC161::-->
<P>
Here is an example of setting up a command with arguments and parsing
those arguments from a <CODE>getopt</CODE> style argument list
(see section <A HREF="slib_4.html#SEC62">4.4.1 Getopt</A>).
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'database-commands)
<A NAME="IDX977"></A>(require 'databases)
<A NAME="IDX978"></A>(require 'getopt-parameters)
<A NAME="IDX979"></A>(require 'parameters)
<A NAME="IDX980"></A>(require 'getopt)
<A NAME="IDX981"></A>(require 'fluid-let)
(require 'printf)
(define my-rdb (add-command-tables (create-database #f 'alist-table)))
(define-tables my-rdb
'(foo-params
*parameter-columns*
*parameter-columns*
((1 single-string single string
(lambda (pl) '("str")) #f "single string")
(2 nary-symbols nary symbol
(lambda (pl) '()) #f "zero or more symbols")
(3 nary1-symbols nary1 symbol
(lambda (pl) '(symb)) #f "one or more symbols")
(4 optional-number optional ordinal
(lambda (pl) '()) #f "zero or one number")
(5 flag boolean boolean
(lambda (pl) '(#f)) #f "a boolean flag")))
'(foo-pnames
((name string))
((parameter-index ordinal))
(("s" 1)
("single-string" 1)
("n" 2)
("nary-symbols" 2)
("N" 3)
("nary1-symbols" 3)
("o" 4)
("optional-number" 4)
("f" 5)
("flag" 5)))
'(my-commands
((name symbol))
((parameters parameter-list)
(parameter-names parameter-name-translation)
(procedure expression)
(documentation string))
((foo
foo-params
foo-pnames
(lambda (rdb) (lambda args (print args)))
"test command arguments"))))
(define (dbutil:serve-command-line rdb command-table command argv)
(set! *argv* (if (vector? argv) (vector->list argv) argv))
((make-command-server rdb command-table)
command
(lambda (comname comval options positions
arities types defaulters dirs aliases)
(apply comval (getopt->arglist options positions
arities types defaulters dirs aliases)))))
(define (cmd . opts)
(fluid-let ((*optind* 1))
(printf "%-34s => "
(call-with-output-string
(lambda (pt) (write (cons 'cmd opts) pt))))
(set! opts (cons "cmd" opts))
(force-output)
(dbutil:serve-command-line
my-rdb 'my-commands 'foo (length opts) opts)))
(cmd) => ("str" () (symb) () #f)
(cmd "-f") => ("str" () (symb) () #t)
(cmd "--flag") => ("str" () (symb) () #t)
(cmd "-o177") => ("str" () (symb) (177) #f)
(cmd "-o" "177") => ("str" () (symb) (177) #f)
(cmd "--optional" "621") => ("str" () (symb) (621) #f)
(cmd "--optional=621") => ("str" () (symb) (621) #f)
(cmd "-s" "speciality") => ("speciality" () (symb) () #f)
(cmd "-sspeciality") => ("speciality" () (symb) () #f)
(cmd "--single" "serendipity") => ("serendipity" () (symb) () #f)
(cmd "--single=serendipity") => ("serendipity" () (symb) () #f)
(cmd "-n" "gravity" "piety") => ("str" () (piety gravity) () #f)
(cmd "-ngravity" "piety") => ("str" () (piety gravity) () #f)
(cmd "--nary" "chastity") => ("str" () (chastity) () #f)
(cmd "--nary=chastity" "") => ("str" () ( chastity) () #f)
(cmd "-N" "calamity") => ("str" () (calamity) () #f)
(cmd "-Ncalamity") => ("str" () (calamity) () #f)
(cmd "--nary1" "surety") => ("str" () (surety) () #f)
(cmd "--nary1=surety") => ("str" () (surety) () #f)
(cmd "-N" "levity" "fealty") => ("str" () (fealty levity) () #f)
(cmd "-Nlevity" "fealty") => ("str" () (fealty levity) () #f)
(cmd "--nary1" "surety" "brevity") => ("str" () (brevity surety) () #f)
(cmd "--nary1=surety" "brevity") => ("str" () (brevity surety) () #f)
(cmd "-?")
-|
Usage: cmd [OPTION ARGUMENT ...] ...
-f, --flag
-o, --optional[=]<number>
-n, --nary[=]<symbols> ...
-N, --nary1[=]<symbols> ...
-s, --single[=]<string>
ERROR: getopt->parameter-list "unrecognized option" "-?"
</pre></td></tr></table><P>
<A NAME="Database Macros"></A>
<HR SIZE="6">
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</TR></TABLE>
<H3> 6.1.5 Database Macros </H3>
<!--docid::SEC162::-->
<P>
<CODE>(require 'within-database)</CODE>
</P>
<P>
The object-oriented programming interface to SLIB relational databases
has failed to support clear, understandable, and modular code-writing
for database applications.
</P>
<P>
This seems to be a failure of the object-oriented paradigm where the
type of an object is not manifest (or even traceable) in source code.
</P>
<P>
<CODE>within-database</CODE>, along with the `<SAMP>databases</SAMP>' package,
reorganizes high-level database functions toward a more declarative
style. Using this package, one can tag database table and command
declarations for emacs:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>etags -lscheme -r'/ *(define-\(command\|table\) (\([^; \t]+\)/\2/' \
source1.scm ...
</pre></td></tr></table><P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC163">6.1.5.1 Within-database Example</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="IDX982"></A>
</P>
<DL>
<DT><U>Function:</U> <B>within-database</B> <I>database statement-1 <small>...</small></I>
<DD><P>
<CODE>within-database</CODE> creates a lexical scope in which the commands
<CODE>define-table</CODE> and <CODE>define-command</CODE> create tables and
<CODE>*commands*</CODE>-table entries respectively in open relational
database <VAR>database</VAR>.
</P>
<P>
<CODE>within-database</CODE> Returns <VAR>database</VAR>.
</P>
</DL>
<P>
<A NAME="IDX983"></A>
</P>
<DL>
<DT><U>Syntax:</U> <B>define-command</B> <I>(<name> <rdb>) "comment" <expression1> <expression2> <small>...</small></I>
<DD><A NAME="IDX984"></A>
<DT><U>Syntax:</U> <B>define-command</B> <I>(<name> <rdb>) <expression1> <expression2> <small>...</small></I>
<DD><P>
Adds to the <CODE>*commands*</CODE> table a command
<name>:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(lambda (<name> <rdb>) <expression1> <expression2> <small>...</small>)
</pre></td></tr></table><P>
</P>
</DL>
<P>
<A NAME="IDX985"></A>
</P>
<DL>
<DT><U>Syntax:</U> <B>define-table</B> <I><name> <descriptor-name> <descriptor-name> <rows></I>
<DD><A NAME="IDX986"></A>
<DT><U>Syntax:</U> <B>define-table</B> <I><name> <primary-key-fields> <other-fields> <rows></I>
<DD><P>
where <name> is the table name, <descriptor-name> is the symbol
name of a descriptor table, <primary-key-fields> and
<other-fields> describe the primary keys and other fields
respectively, and <rows> is a list of data rows to be added to the
table.
</P>
<P>
<primary-key-fields> and <other-fields> are lists of field
descriptors of the form:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(<column-name> <domain>)
</pre></td></tr></table>or
<TABLE><tr><td> </td><td class=example><pre>(<column-name> <domain> <column-integrity-rule>)
</pre></td></tr></table><P>
where <column-name> is the column name, <domain> is the domain
of the column, and <column-integrity-rule> is an expression whose
value is a procedure of one argument (which returns <CODE>#f</CODE> to signal
an error).
</P>
<P>
If <domain> is not a defined domain name and it matches the name of
this table or an already defined (in one of <VAR>spec-0</VAR> <small>...</small>) single
key field table, a foreign-key domain will be created for it.
</P>
<P>
</P>
</DL>
<P>
<A NAME="Within-database Example"></A>
<HR SIZE="6">
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<H4> 6.1.5.1 Within-database Example </H4>
<!--docid::SEC163::-->
<P>
Here is an example of <CODE>within-database</CODE> macros:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'within-database)
(define my-rdb
(add-command-tables
(create-database "foo.db" 'alist-table)))
(within-database my-rdb
(define-command (*initialize* rdb)
"Print Welcome"
(display "Welcome")
(newline)
rdb)
(define-command (without-documentation rdb)
(display "without-documentation called")
(newline))
(define-table (processor-family
((family atom))
((also-ran processor-family)))
(m68000 #f)
(m68030 m68000)
(i386 i8086)
(i8086 #f)
(powerpc #f))
(define-table (platform
((name symbol))
((processor processor-family)
(os symbol)
(compiler symbol)))
(aix powerpc aix -)
;; ...
(amiga-aztec m68000 amiga aztec)
(amiga-sas/c-5.10 m68000 amiga sas/c)
(atari-st-gcc m68000 atari gcc)
;; ...
(watcom-9.0 i386 ms-dos watcom))
(define-command (get-processor rdb)
"Get processor for given platform."
(((rdb 'open-table) 'platform #f) 'get 'processor)))
(close-database my-rdb)
(set! my-rdb (open-command-database! "foo.db"))
-|
Welcome
(my-rdb 'without-documentation)
-|
without-documentation called
((my-rdb 'get-processor) 'amiga-sas/c-5.10)
=> m68000
(close-database my-rdb)
</pre></td></tr></table><P>
<A NAME="Database Browser"></A>
<HR SIZE="6">
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</TR></TABLE>
<H3> 6.1.6 Database Browser </H3>
<!--docid::SEC164::-->
<P>
(require 'database-browse)
</P>
<P>
<A NAME="IDX987"></A>
</P>
<DL>
<DT><U>Procedure:</U> <B>browse</B> <I>database</I>
<DD><P>
Prints the names of all the tables in <VAR>database</VAR> and sets browse's
default to <VAR>database</VAR>.
</P>
<P>
<A NAME="IDX988"></A>
<DT><U>Procedure:</U> <B>browse</B>
<DD></P>
<P>
Prints the names of all the tables in the default database.
</P>
<P>
<A NAME="IDX989"></A>
<DT><U>Procedure:</U> <B>browse</B> <I>table-name</I>
<DD></P>
<P>
For each record of the table named by the symbol <VAR>table-name</VAR>,
prints a line composed of all the field values.
</P>
<P>
<A NAME="IDX990"></A>
<DT><U>Procedure:</U> <B>browse</B> <I>pathname</I>
<DD></P>
<P>
Opens the database named by the string <VAR>pathname</VAR>, prints the names
of all its tables, and sets browse's default to the database.
</P>
<P>
<A NAME="IDX991"></A>
<DT><U>Procedure:</U> <B>browse</B> <I>database table-name</I>
<DD></P>
<P>
Sets browse's default to <VAR>database</VAR> and prints the records of the
table named by the symbol <VAR>table-name</VAR>.
</P>
<P>
<A NAME="IDX992"></A>
<DT><U>Procedure:</U> <B>browse</B> <I>pathname table-name</I>
<DD></P>
<P>
Opens the database named by the string <VAR>pathname</VAR> and sets browse's
default to it; <CODE>browse</CODE> prints the records of the table named by
the symbol <VAR>table-name</VAR>.
</P>
<P>
</P>
</DL>
<P>
<A NAME="Relational Infrastructure"></A>
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</TR></TABLE>
<H2> 6.2 Relational Infrastructure </H2>
<!--docid::SEC165::-->
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC166">6.2.1 Base Table</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC175">6.2.2 Catalog Representation</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC176">6.2.3 Relational Database Objects</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC177">6.2.4 Database Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Base Table"></A>
<HR SIZE="6">
<A NAME="SEC166"></A>
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</TR></TABLE>
<H3> 6.2.1 Base Table </H3>
<!--docid::SEC166::-->
<P>
<A NAME="IDX993"></A>
A <EM>base-table</EM> is the primitive database layer upon which SLIB
relational databases are built. At the minimum, it must support the
types integer, symbol, string, and boolean. The base-table may restrict
the size of integers, symbols, and strings it supports.
</P>
<P>
A base table implementation is available as the value of the identifier
naming it (eg. <VAR>alist-table</VAR>) after requiring the symbol of that
name.
</P>
<P>
<A NAME="IDX994"></A>
</P>
<DL>
<DT><U>Feature:</U> <B>alist-table</B>
<DD><CODE>(require 'alist-table)</CODE>
<A NAME="IDX995"></A>
<P>
Association-list base tables support all Scheme types and are suitable
for small databases. In order to be retrieved after being written to a
file, the data stored should include only objects which are readable and
writeable in the Scheme implementation.
</P>
<P>
The <EM>alist-table</EM> base-table implementation is included in the
SLIB distribution.
</P>
</DL>
<P>
<EM>WB</EM> is a B-tree database package with SCM interfaces. Being
disk-based, WB databases readily store and access hundreds of
megabytes of data. WB comes with two base-table embeddings.
</P>
<P>
<A NAME="IDX996"></A>
</P>
<DL>
<DT><U>Feature:</U> <B>wb-table</B>
<DD><CODE>(require 'wb-table)</CODE>
<A NAME="IDX997"></A>
<P>
<A NAME="IDX998"></A>
<CODE>wb-table</CODE> supports scheme expressions for keys and values whose
text representations are less than 255 characters in length.
See section `wb-table' in <CITE>WB</CITE>.
</P>
</DL>
<P>
<A NAME="IDX999"></A>
</P>
<DL>
<DT><U>Feature:</U> <B>rwb-isam</B>
<DD><CODE>(require 'rwb-isam)</CODE>
<A NAME="IDX1000"></A>
<P>
<EM>rwb-isam</EM> is a sophisticated base-table implementation built on
WB and SCM which uses binary numerical formats for key and non-key
fields. It supports IEEE floating-point and fixed-precision integer
keys with the correct numerical collation order.
</P>
</DL>
<P>
This rest of this section documents the interface for a base table
implementation from which the <A HREF="slib_6.html#SEC141">6.1 Relational Database</A> package
constructs a Relational system. It will be of interest primarily to
those wishing to port or write new base-table implementations.
</P>
<P>
<A NAME="IDX1001"></A>
</P>
<DL>
<DT><U>Variable:</U> <B>*base-table-implementations*</B>
<DD>To support automatic dispatch for <CODE>open-database</CODE>, each base-table
module adds an association to <VAR>*base-table-implementations*</VAR> when
loaded. This association is the list of the base-table symbol and the
value returned by <CODE>(make-relational-system <VAR>base-table</VAR>)</CODE>.
</DL>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC167">6.2.1.1 The Base</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC168">6.2.1.2 Base Tables</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC169">6.2.1.3 Base Field Types</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC170">6.2.1.4 Composite Keys</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC171">6.2.1.5 Base Record Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC172">6.2.1.6 Match Keys</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC173">6.2.1.7 Aggregate Base Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC174">6.2.1.8 Base ISAM Operations</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="The Base"></A>
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<H4> 6.2.1.1 The Base </H4>
<!--docid::SEC167::-->
<P>
All of these functions are accessed through a single procedure by
calling that procedure with the symbol name of the operation. A
procedure will be returned if that operation is supported and <CODE>#f</CODE>
otherwise. For example:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'alist-table)
<A NAME="IDX1002"></A><A NAME="IDX1003"></A>(define my-base (alist-table 'make-base))
my-base => *a procedure*
(define foo (alist-table 'foo))
foo => #f
</pre></td></tr></table><P>
<A NAME="IDX1004"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-base</B> <I>filename key-dimension column-types</I>
<DD>Returns a new, open, low-level database (collection of tables)
associated with <VAR>filename</VAR>. This returned database has an empty
table associated with <VAR>catalog-id</VAR>. The positive integer
<VAR>key-dimension</VAR> is the number of keys composed to make a
<VAR>primary-key</VAR> for the catalog table. The list of symbols
<VAR>column-types</VAR> describes the types of each column for that table.
If the database cannot be created as specified, <CODE>#f</CODE> is returned.
<P>
Calling the <CODE>close-base</CODE> method on this database and possibly other
operations will cause <VAR>filename</VAR> to be written to. If
<VAR>filename</VAR> is <CODE>#f</CODE> a temporary, non-disk based database will be
created if such can be supported by the base table implelentation.
</P>
</DL>
<P>
<A NAME="IDX1005"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>open-base</B> <I>filename mutable</I>
<DD>Returns an open low-level database associated with <VAR>filename</VAR>. If
<VAR>mutable</VAR> is <CODE>#t</CODE>, this database will have methods capable of
effecting change to the database. If <VAR>mutable</VAR> is <CODE>#f</CODE>, only
methods for inquiring the database will be available. If the database
cannot be opened as specified <CODE>#f</CODE> is returned.
<P>
Calling the <CODE>close-base</CODE> (and possibly other) method on a
<VAR>mutable</VAR> database will cause <VAR>filename</VAR> to be written to.
</P>
</DL>
<P>
<A NAME="IDX1006"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>write-base</B> <I>lldb filename</I>
<DD>Causes the low-level database <VAR>lldb</VAR> to be written to
<VAR>filename</VAR>. If the write is successful, also causes <VAR>lldb</VAR> to
henceforth be associated with <VAR>filename</VAR>. Calling the
<CODE>close-database</CODE> (and possibly other) method on <VAR>lldb</VAR> may
cause <VAR>filename</VAR> to be written to. If <VAR>filename</VAR> is <CODE>#f</CODE>
this database will be changed to a temporary, non-disk based database if
such can be supported by the underlying base table implelentation. If
the operations completed successfully, <CODE>#t</CODE> is returned.
Otherwise, <CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="IDX1007"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>sync-base</B> <I>lldb</I>
<DD>Causes the file associated with the low-level database <VAR>lldb</VAR> to be
updated to reflect its current state. If the associated filename is
<CODE>#f</CODE>, no action is taken and <CODE>#f</CODE> is returned. If this
operation completes successfully, <CODE>#t</CODE> is returned. Otherwise,
<CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="IDX1008"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>close-base</B> <I>lldb</I>
<DD>Causes the low-level database <VAR>lldb</VAR> to be written to its associated
file (if any). If the write is successful, subsequent operations to
<VAR>lldb</VAR> will signal an error. If the operations complete
successfully, <CODE>#t</CODE> is returned. Otherwise, <CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="Base Tables"></A>
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<H4> 6.2.1.2 Base Tables </H4>
<!--docid::SEC168::-->
<P>
<A NAME="IDX1009"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-table</B> <I>lldb key-dimension column-types</I>
<DD>Returns the ordinal <VAR>base-id</VAR> for a new base table, otherwise
returns <CODE>#f</CODE>. The base table can then be opened using
<CODE>(open-table <VAR>lldb</VAR> <VAR>base-id</VAR>)</CODE>. The positive integer
<VAR>key-dimension</VAR> is the number of keys composed to make a
<VAR>primary-key</VAR> for this table. The list of symbols
<VAR>column-types</VAR> describes the types of each column.
</DL>
<P>
<A NAME="IDX1010"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>open-table</B> <I>lldb base-id key-dimension column-types</I>
<DD>Returns a <VAR>handle</VAR> for an existing base table in the low-level
database <VAR>lldb</VAR> if that table exists and can be opened in the mode
indicated by <VAR>mutable</VAR>, otherwise returns <CODE>#f</CODE>.
<P>
As with <CODE>make-table</CODE>, the positive integer <VAR>key-dimension</VAR> is
the number of keys composed to make a <VAR>primary-key</VAR> for this table.
The list of symbols <VAR>column-types</VAR> describes the types of each
column.
</P>
</DL>
<P>
<A NAME="IDX1011"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>kill-table</B> <I>lldb base-id key-dimension column-types</I>
<DD>Returns <CODE>#t</CODE> if the base table associated with <VAR>base-id</VAR> was
removed from the low level database <VAR>lldb</VAR>, and <CODE>#f</CODE> otherwise.
</DL>
<P>
<A NAME="IDX1012"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>catalog-id</B>
<DD>A constant <VAR>base-id</VAR> ordinal suitable for passing as a parameter to
<CODE>open-table</CODE>. <VAR>catalog-id</VAR> will be used as the base table for
the system catalog.
</DL>
<P>
<A NAME="Base Field Types"></A>
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<H4> 6.2.1.3 Base Field Types </H4>
<!--docid::SEC169::-->
<P>
<A NAME="IDX1013"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>supported-type?</B> <I>symbol</I>
<DD>Returns <CODE>#t</CODE> if <VAR>symbol</VAR> names a type allowed as a column
value by the implementation, and <CODE>#f</CODE> otherwise. At a minimum,
an implementation must support the types <CODE>integer</CODE>,
<CODE>ordinal</CODE>, <CODE>symbol</CODE>, <CODE>string</CODE>, and <CODE>boolean</CODE>.
</DL>
<P>
<A NAME="IDX1014"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>supported-key-type?</B> <I>symbol</I>
<DD>Returns <CODE>#t</CODE> if <VAR>symbol</VAR> names a type allowed as a key value
by the implementation, and <CODE>#f</CODE> otherwise. At a minimum, an
implementation must support the types <CODE>ordinal</CODE>, and
<CODE>symbol</CODE>.
</DL>
<P>
An <EM>ordinal</EM> is an exact positive integer. The other types are
standard Scheme.
</P>
<P>
<A NAME="Composite Keys"></A>
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<H4> 6.2.1.4 Composite Keys </H4>
<!--docid::SEC170::-->
<P>
<A NAME="IDX1015"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-keyifier-1</B> <I>type</I>
<DD>Returns a procedure which accepts a single argument which must be of
type <VAR>type</VAR>. This returned procedure returns an object suitable for
being a <VAR>key</VAR> argument in the functions whose descriptions follow.
<P>
Any 2 arguments of the supported type passed to the returned function
which are not <CODE>equal?</CODE> must result in returned values which are not
<CODE>equal?</CODE>.
</P>
</DL>
<P>
<A NAME="IDX1016"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-list-keyifier</B> <I>key-dimension types</I>
<DD>The list of symbols <VAR>types</VAR> must have at least <VAR>key-dimension</VAR>
elements. Returns a procedure which accepts a list of length
<VAR>key-dimension</VAR> and whose types must corresopond to the types named
by <VAR>types</VAR>. This returned procedure combines the elements of its
list argument into an object suitable for being a <VAR>key</VAR> argument in
the functions whose descriptions follow.
<P>
Any 2 lists of supported types (which must at least include symbols and
non-negative integers) passed to the returned function which are not
<CODE>equal?</CODE> must result in returned values which are not
<CODE>equal?</CODE>.
</P>
</DL>
<P>
<A NAME="IDX1017"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-key-extractor</B> <I>key-dimension types column-number</I>
<DD>Returns a procedure which accepts objects produced by application of the
result of <CODE>(make-list-keyifier <VAR>key-dimension</VAR> <VAR>types</VAR>)</CODE>.
This procedure returns a <VAR>key</VAR> which is <CODE>equal?</CODE> to the
<VAR>column-number</VAR>th element of the list which was passed to create
<VAR>composite-key</VAR>. The list <VAR>types</VAR> must have at least
<VAR>key-dimension</VAR> elements.
</DL>
<P>
<A NAME="IDX1018"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-key->list</B> <I>key-dimension types</I>
<DD>Returns a procedure which accepts objects produced by application of
the result of <CODE>(make-list-keyifier <VAR>key-dimension</VAR>
<VAR>types</VAR>)</CODE>. This procedure returns a list of <VAR>key</VAR>s which are
elementwise <CODE>equal?</CODE> to the list which was passed to create
<VAR>composite-key</VAR>.
</DL>
<P>
<A NAME="Base Record Operations"></A>
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<H4> 6.2.1.5 Base Record Operations </H4>
<!--docid::SEC171::-->
<P>
In the following functions, the <VAR>key</VAR> argument can always be assumed
to be the value returned by a call to a <EM>keyify</EM> routine.
</P>
<P>
<A NAME="IDX1019"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>present?</B> <I>handle key</I>
<DD>Returns a non-<CODE>#f</CODE> value if there is a row associated with
<VAR>key</VAR> in the table opened in <VAR>handle</VAR> and <CODE>#f</CODE> otherwise.
</DL>
<P>
<A NAME="IDX1020"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-getter</B> <I>key-dimension types</I>
<DD>Returns a procedure which takes arguments <VAR>handle</VAR> and <VAR>key</VAR>.
This procedure returns a list of the non-primary values of the relation
(in the base table opened in <VAR>handle</VAR>) whose primary key is
<VAR>key</VAR> if it exists, and <CODE>#f</CODE> otherwise.
</DL>
<P>
<CODE>make-getter-1</CODE> is a new operation. The relational-database
module works with older base-table implementations by using
<CODE>make-getter</CODE>.
</P>
<P>
<A NAME="IDX1021"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-getter-1</B> <I>key-dimension types index</I>
<DD>Returns a procedure which takes arguments <VAR>handle</VAR> and <VAR>key</VAR>.
This procedure returns the value of the <VAR>index</VAR>th field (in the
base table opened in <VAR>handle</VAR>) whose primary key is <VAR>key</VAR> if
it exists, and <CODE>#f</CODE> otherwise.
<P>
<VAR>index</VAR> must be larger than <VAR>key-dimension</VAR>.
</P>
</DL>
<P>
<A NAME="IDX1022"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-putter</B> <I>key-dimension types</I>
<DD>Returns a procedure which takes arguments <VAR>handle</VAR> and <VAR>key</VAR> and
<VAR>value-list</VAR>. This procedure associates the primary key <VAR>key</VAR>
with the values in <VAR>value-list</VAR> (in the base table opened in
<VAR>handle</VAR>) and returns an unspecified value.
</DL>
<P>
<A NAME="IDX1023"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>delete</B> <I>handle key</I>
<DD>Removes the row associated with <VAR>key</VAR> from the table opened in
<VAR>handle</VAR>. An unspecified value is returned.
</DL>
<P>
<A NAME="Match Keys"></A>
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<H4> 6.2.1.6 Match Keys </H4>
<!--docid::SEC172::-->
<P>
<A NAME="IDX1024"></A>
<A NAME="IDX1025"></A>
<A NAME="IDX1026"></A>
A <VAR>match-keys</VAR> argument is a list of length equal to
the number of primary keys. The <VAR>match-keys</VAR> restrict the actions
of the table command to those records whose primary keys all satisfy the
corresponding element of the <VAR>match-keys</VAR> list. The elements and
their actions are:
</P>
<P>
<BLOCKQUOTE>
<DL COMPACT>
<DT><CODE>#f</CODE>
<DD>The false value matches any key in the corresponding position.
<DT>an object of type procedure
<DD>This procedure must take a single argument, the key in the corresponding
position. Any key for which the procedure returns a non-false value is
a match; Any key for which the procedure returns a <CODE>#f</CODE> is not.
<DT>other values
<DD>Any other value matches only those keys <CODE>equal?</CODE> to it.
</DL>
</BLOCKQUOTE>
<P>
<A NAME="Aggregate Base Operations"></A>
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<H4> 6.2.1.7 Aggregate Base Operations </H4>
<!--docid::SEC173::-->
<P>
The <VAR>key-dimension</VAR> and <VAR>column-types</VAR> arguments are needed to
decode the composite-keys for matching with <VAR>match-keys</VAR>.
</P>
<P>
<A NAME="IDX1027"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>delete*</B> <I>handle key-dimension column-types match-keys</I>
<DD>Removes all rows which satisfy <VAR>match-keys</VAR> from the table opened in
<VAR>handle</VAR>. An unspecified value is returned.
</DL>
<P>
<A NAME="IDX1028"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>for-each-key</B> <I>handle procedure key-dimension column-types match-keys</I>
<DD>Calls <VAR>procedure</VAR> once with each <VAR>key</VAR> in the table opened in
<VAR>handle</VAR> which satisfy <VAR>match-keys</VAR> in an unspecified order.
An unspecified value is returned.
</DL>
<P>
<A NAME="IDX1029"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>map-key</B> <I>handle procedure key-dimension column-types match-keys</I>
<DD>Returns a list of the values returned by calling <VAR>procedure</VAR> once
with each <VAR>key</VAR> in the table opened in <VAR>handle</VAR> which satisfy
<VAR>match-keys</VAR> in an unspecified order.
</DL>
<P>
<A NAME="Base ISAM Operations"></A>
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<H4> 6.2.1.8 Base ISAM Operations </H4>
<!--docid::SEC174::-->
<P>
These operations are optional for a Base-Table implementation.
</P>
<P>
<A NAME="IDX1030"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>ordered-for-each-key</B> <I>handle procedure key-dimension column-types match-keys</I>
<DD>Calls <VAR>procedure</VAR> once with each <VAR>key</VAR> in the table opened in
<VAR>handle</VAR> which satisfy <VAR>match-keys</VAR> in the natural order for
the types of the primary key fields of that table. An unspecified value
is returned.
</DL>
<P>
<A NAME="IDX1031"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-nexter</B> <I>handle key-dimension column-types index</I>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the key-list identifying the lowest record higher than
<VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which is stored in the base-table and
which differs in column <VAR>index</VAR> or a lower indexed key; or false
if no higher record is present.
</DL>
<P>
<A NAME="IDX1032"></A>
</P>
<DL>
<DT><U>Operation:</U> base-table <B>make-prever</B> <I>handle key-dimension column-types index</I>
<DD>Returns a procedure of arguments <VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which
returns the key-list identifying the highest record less than
<VAR>key1</VAR> <VAR>key2</VAR> <small>...</small> which is stored in the base-table and
which differs in column <VAR>index</VAR> or a lower indexed key; or false
if no higher record is present.
</DL>
<P>
<A NAME="Catalog Representation"></A>
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<H3> 6.2.2 Catalog Representation </H3>
<!--docid::SEC175::-->
<P>
Each database (in an implementation) has a <EM>system catalog</EM> which
describes all the user accessible tables in that database (including
itself).
</P>
<P>
The system catalog base table has the following fields. <CODE>PRI</CODE>
indicates a primary key for that table.
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>PRI table-name
column-limit the highest column number
coltab-name descriptor table name
bastab-id data base table identifier
user-integrity-rule
view-procedure A scheme thunk which, when called,
produces a handle for the view. coltab
and bastab are specified if and only if
view-procedure is not.
</pre></td></tr></table><P>
Descriptors for base tables (not views) are tables (pointed to by
system catalog). Descriptor (base) tables have the fields:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>PRI column-number sequential integers from 1
primary-key? boolean TRUE for primary key components
column-name
column-integrity-rule
domain-name
</pre></td></tr></table><P>
A <EM>primary key</EM> is any column marked as <CODE>primary-key?</CODE> in the
corresponding descriptor table. All the <CODE>primary-key?</CODE> columns
must have lower column numbers than any non-<CODE>primary-key?</CODE> columns.
Every table must have at least one primary key. Primary keys must be
sufficient to distinguish all rows from each other in the table. All of
the system defined tables have a single primary key.
</P>
<P>
A <EM>domain</EM> is a category describing the allowable values to occur in
a column. It is described by a (base) table with the fields:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>PRI domain-name
foreign-table
domain-integrity-rule
type-id
type-param
</pre></td></tr></table><P>
The <EM>type-id</EM> field value is a symbol. This symbol may be used by
the underlying base table implementation in storing that field.
</P>
<P>
If the <CODE>foreign-table</CODE> field is non-<CODE>#f</CODE> then that field names
a table from the catalog. The values for that domain must match a
primary key of the table referenced by the <VAR>type-param</VAR> (or
<CODE>#f</CODE>, if allowed). This package currently does not support
composite foreign-keys.
</P>
<P>
The types for which support is planned are:
<TABLE><tr><td> </td><td class=example><pre> atom
symbol
string [<length>]
number [<base>]
money <currency>
date-time
boolean
foreign-key <table-name>
expression
virtual <expression>
</pre></td></tr></table><P>
<A NAME="Relational Database Objects"></A>
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<H3> 6.2.3 Relational Database Objects </H3>
<!--docid::SEC176::-->
<P>
This object-oriented interface is deprecated for typical database
applications; <A HREF="slib_6.html#SEC142">6.1.1 Using Databases</A> provides an application programmer
interface which is easier to understand and use.
</P>
<P>
<A NAME="IDX1033"></A>
</P>
<DL>
<DT><U>Function:</U> <B>make-relational-system</B> <I>base-table-implementation</I>
<DD><P>
Returns a procedure implementing a relational database using the
<VAR>base-table-implementation</VAR>.
</P>
<P>
All of the operations of a base table implementation are accessed
through a procedure defined by <CODE>require</CODE>ing that implementation.
Similarly, all of the operations of the relational database
implementation are accessed through the procedure returned by
<CODE>make-relational-system</CODE>. For instance, a new relational database
could be created from the procedure returned by
<CODE>make-relational-system</CODE> by:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(require 'alist-table)
<A NAME="IDX1034"></A>(define relational-alist-system
(make-relational-system alist-table))
(define create-alist-database
(relational-alist-system 'create-database))
(define my-database
(create-alist-database "mydata.db"))
</pre></td></tr></table></DL>
<P>
What follows are the descriptions of the methods available from
relational system returned by a call to <CODE>make-relational-system</CODE>.
</P>
<P>
<A NAME="IDX1035"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-system <B>create-database</B> <I>filename</I>
<DD><P>
Returns an open, nearly empty relational database associated with
<VAR>filename</VAR>. The only tables defined are the system catalog and
domain table. Calling the <CODE>close-database</CODE> method on this database
and possibly other operations will cause <VAR>filename</VAR> to be written
to. If <VAR>filename</VAR> is <CODE>#f</CODE> a temporary, non-disk based database
will be created if such can be supported by the underlying base table
implelentation. If the database cannot be created as specified
<CODE>#f</CODE> is returned. For the fields and layout of descriptor tables,
<A HREF="slib_6.html#SEC175">6.2.2 Catalog Representation</A>
</P>
</DL>
<P>
<A NAME="IDX1036"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-system <B>open-database</B> <I>filename mutable?</I>
<DD><P>
Returns an open relational database associated with <VAR>filename</VAR>. If
<VAR>mutable?</VAR> is <CODE>#t</CODE>, this database will have methods capable of
effecting change to the database. If <VAR>mutable?</VAR> is <CODE>#f</CODE>, only
methods for inquiring the database will be available. Calling the
<CODE>close-database</CODE> (and possibly other) method on a <VAR>mutable?</VAR>
database will cause <VAR>filename</VAR> to be written to. If the database
cannot be opened as specified <CODE>#f</CODE> is returned.
</P>
</DL>
<P>
<A NAME="Database Operations"></A>
<HR SIZE="6">
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<H3> 6.2.4 Database Operations </H3>
<!--docid::SEC177::-->
<P>
This object-oriented interface is deprecated for typical database
applications; <A HREF="slib_6.html#SEC142">6.1.1 Using Databases</A> provides an application programmer
interface which is easier to understand and use.
</P>
<P>
These are the descriptions of the methods available from an open
relational database. A method is retrieved from a database by calling
the database with the symbol name of the operation. For example:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(define my-database
(create-alist-database "mydata.db"))
(define telephone-table-desc
((my-database 'create-table) 'telephone-table-desc))
</pre></td></tr></table><P>
<A NAME="IDX1037"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>close-database</B>
<DD>Causes the relational database to be written to its associated file (if
any). If the write is successful, subsequent operations to this
database will signal an error. If the operations completed
successfully, <CODE>#t</CODE> is returned. Otherwise, <CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="IDX1038"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>write-database</B> <I>filename</I>
<DD>Causes the relational database to be written to <VAR>filename</VAR>. If the
write is successful, also causes the database to henceforth be
associated with <VAR>filename</VAR>. Calling the <CODE>close-database</CODE> (and
possibly other) method on this database will cause <VAR>filename</VAR> to be
written to. If <VAR>filename</VAR> is <CODE>#f</CODE> this database will be
changed to a temporary, non-disk based database if such can be supported
by the underlying base table implelentation. If the operations
completed successfully, <CODE>#t</CODE> is returned. Otherwise, <CODE>#f</CODE> is
returned.
</DL>
<P>
<A NAME="IDX1039"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>sync-database</B>
<DD>Causes any pending updates to the database file to be written out. If
the operations completed successfully, <CODE>#t</CODE> is returned.
Otherwise, <CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="IDX1040"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>solidify-database</B>
<DD>Causes any pending updates to the database file to be written out. If
the writes completed successfully, then the database is changed to be
immutable and <CODE>#t</CODE> is returned. Otherwise, <CODE>#f</CODE> is returned.
</DL>
<P>
<A NAME="IDX1041"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>table-exists?</B> <I>table-name</I>
<DD>Returns <CODE>#t</CODE> if <VAR>table-name</VAR> exists in the system catalog,
otherwise returns <CODE>#f</CODE>.
</DL>
<P>
<A NAME="IDX1042"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>open-table</B> <I>table-name mutable?</I>
<DD>Returns a <EM>methods</EM> procedure for an existing relational table in
this database if it exists and can be opened in the mode indicated by
<VAR>mutable?</VAR>, otherwise returns <CODE>#f</CODE>.
</DL>
<P>
These methods will be present only in mutable databases.
</P>
<P>
<A NAME="IDX1043"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>delete-table</B> <I>table-name</I>
<DD>Removes and returns the <VAR>table-name</VAR> row from the system catalog if
the table or view associated with <VAR>table-name</VAR> gets removed from the
database, and <CODE>#f</CODE> otherwise.
</DL>
<P>
<A NAME="IDX1044"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>create-table</B> <I>table-desc-name</I>
<DD>Returns a methods procedure for a new (open) relational table for
describing the columns of a new base table in this database, otherwise
returns <CODE>#f</CODE>. For the fields and layout of descriptor tables,
See section <A HREF="slib_6.html#SEC175">6.2.2 Catalog Representation</A>.
<P>
<A NAME="IDX1045"></A>
<DT><U>Operation:</U> relational-database <B>create-table</B> <I>table-name table-desc-name</I>
<DD>Returns a methods procedure for a new (open) relational table with
columns as described by <VAR>table-desc-name</VAR>, otherwise returns
<CODE>#f</CODE>.
</P>
</DL>
<P>
<A NAME="IDX1046"></A>
</P>
<DL>
<DT><U>Operation:</U> relational-database <B>create-view</B> <I>??</I>
<DD><A NAME="IDX1047"></A>
<DT><U>Operation:</U> relational-database <B>project-table</B> <I>??</I>
<DD><A NAME="IDX1048"></A>
<DT><U>Operation:</U> relational-database <B>restrict-table</B> <I>??</I>
<DD><A NAME="IDX1049"></A>
<DT><U>Operation:</U> relational-database <B>cart-prod-tables</B> <I>??</I>
<DD>Not yet implemented.
</DL>
<P>
<A NAME="Weight-Balanced Trees"></A>
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<H2> 6.3 Weight-Balanced Trees </H2>
<!--docid::SEC178::-->
<P>
<CODE>(require 'wt-tree)</CODE>
<A NAME="IDX1050"></A>
</P>
<P>
<A NAME="IDX1051"></A>
<A NAME="IDX1052"></A>
<A NAME="IDX1053"></A>
<A NAME="IDX1054"></A>
Balanced binary trees are a useful data structure for maintaining large
sets of ordered objects or sets of associations whose keys are ordered.
MIT Scheme has an comprehensive implementation of weight-balanced binary
trees which has several advantages over the other data structures for
large aggregates:
</P>
<P>
<UL>
<LI>
In addition to the usual element-level operations like insertion,
deletion and lookup, there is a full complement of collection-level
operations, like set intersection, set union and subset test, all of
which are implemented with good orders of growth in time and space.
This makes weight balanced trees ideal for rapid prototyping of
functionally derived specifications.
<P>
</P>
<LI>
An element in a tree may be indexed by its position under the ordering
of the keys, and the ordinal position of an element may be determined,
both with reasonable efficiency.
<P>
</P>
<LI>
Operations to find and remove minimum element make weight balanced trees
simple to use for priority queues.
<P>
</P>
<LI>
The implementation is <EM>functional</EM> rather than <EM>imperative</EM>.
This means that operations like `inserting' an association in a tree do
not destroy the old tree, in much the same way that <CODE>(+ 1 x)</CODE>
modifies neither the constant 1 nor the value bound to <CODE>x</CODE>. The
trees are referentially transparent thus the programmer need not worry
about copying the trees. Referential transparency allows space
efficiency to be achieved by sharing subtrees.
<P>
</UL>
<P>
These features make weight-balanced trees suitable for a wide range of
applications, especially those that
require large numbers of sets or discrete maps. Applications that have
a few global databases and/or concentrate on element-level operations like
insertion and lookup are probably better off using hash-tables or
red-black trees.
</P>
<P>
The <EM>size</EM> of a tree is the number of associations that it
contains. Weight balanced binary trees are balanced to keep the sizes
of the subtrees of each node within a constant factor of each other.
This ensures logarithmic times for single-path operations (like lookup
and insertion). A weight balanced tree takes space that is proportional
to the number of associations in the tree. For the current
implementation, the constant of proportionality is six words per
association.
</P>
<P>
<A NAME="IDX1055"></A>
<A NAME="IDX1056"></A>
<A NAME="IDX1057"></A>
<A NAME="IDX1058"></A>
Weight balanced trees can be used as an implementation for either
discrete sets or discrete maps (associations). Sets are implemented by
ignoring the datum that is associated with the key. Under this scheme
if an associations exists in the tree this indicates that the key of the
association is a member of the set. Typically a value such as
<CODE>()</CODE>, <CODE>#t</CODE> or <CODE>#f</CODE> is associated with the key.
</P>
<P>
Many operations can be viewed as computing a result that, depending on
whether the tree arguments are thought of as sets or maps, is known by
two different names. An example is <CODE>wt-tree/member?</CODE>, which, when
regarding the tree argument as a set, computes the set membership
operation, but, when regarding the tree as a discrete map,
<CODE>wt-tree/member?</CODE> is the predicate testing if the map is defined at
an element in its domain. Most names in this package have been chosen
based on interpreting the trees as sets, hence the name
<CODE>wt-tree/member?</CODE> rather than <CODE>wt-tree/defined-at?</CODE>.
</P>
<P>
<A NAME="IDX1059"></A>
<A NAME="IDX1060"></A>
The weight balanced tree implementation is a run-time-loadable option.
To use weight balanced trees, execute
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(load-option 'wt-tree)
</pre></td></tr></table><A NAME="IDX1061"></A>
<P>
once before calling any of the procedures defined here.
</P>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC179">6.3.1 Construction of Weight-Balanced Trees</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC180">6.3.2 Basic Operations on Weight-Balanced Trees</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC181">6.3.3 Advanced Operations on Weight-Balanced Trees</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_6.html#SEC182">6.3.4 Indexing Operations on Weight-Balanced Trees</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Construction of Weight-Balanced Trees"></A>
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<H3> 6.3.1 Construction of Weight-Balanced Trees </H3>
<!--docid::SEC179::-->
<P>
Binary trees require there to be a total order on the keys used to
arrange the elements in the tree. Weight balanced trees are organized
by <EM>types</EM>, where the type is an object encapsulating the ordering
relation. Creating a tree is a two-stage process. First a tree type
must be created from the predicate which gives the ordering. The tree
type is then used for making trees, either empty or singleton trees or
trees from other aggregate structures like association lists. Once
created, a tree `knows' its type and the type is used to test
compatibility between trees in operations taking two trees. Usually a
small number of tree types are created at the beginning of a program and
used many times throughout the program's execution.
</P>
<P>
<A NAME="IDX1062"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>make-wt-tree-type</B> <I>key<?</I>
<DD>This procedure creates and returns a new tree type based on the ordering
predicate <VAR>key<?</VAR>.
<VAR>Key<?</VAR> must be a total ordering, having the property that for all
key values <CODE>a</CODE>, <CODE>b</CODE> and <CODE>c</CODE>:
<P>
<TABLE><tr><td> </td><td class=example><pre>(key<? a a) => #f
(and (key<? a b) (key<? b a)) => #f
(if (and (key<? a b) (key<? b c))
(key<? a c)
#t) => #t
</pre></td></tr></table><P>
Two key values are assumed to be equal if neither is less than the other
by <VAR>key<?</VAR>.
</P>
<P>
Each call to <CODE>make-wt-tree-type</CODE> returns a distinct value, and
trees are only compatible if their tree types are <CODE>eq?</CODE>. A
consequence is that trees that are intended to be used in binary tree
operations must all be created with a tree type originating from the
same call to <CODE>make-wt-tree-type</CODE>.
</P>
</DL>
<P>
<A NAME="IDX1063"></A>
</P>
<DL>
<DT><U>variable+:</U> <B>number-wt-type</B>
<DD>A standard tree type for trees with numeric keys. <CODE>Number-wt-type</CODE>
could have been defined by
<P>
<TABLE><tr><td> </td><td class=example><pre>(define number-wt-type (make-wt-tree-type <))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX1064"></A>
</P>
<DL>
<DT><U>variable+:</U> <B>string-wt-type</B>
<DD>A standard tree type for trees with string keys. <CODE>String-wt-type</CODE>
could have been defined by
<P>
<TABLE><tr><td> </td><td class=example><pre>(define string-wt-type (make-wt-tree-type string<?))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX1065"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>make-wt-tree</B> <I>wt-tree-type</I>
<DD>This procedure creates and returns a newly allocated weight balanced
tree. The tree is empty, i.e. it contains no associations.
<VAR>Wt-tree-type</VAR> is a weight balanced tree type obtained by calling
<CODE>make-wt-tree-type</CODE>; the returned tree has this type.
</DL>
<P>
<A NAME="IDX1066"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>singleton-wt-tree</B> <I>wt-tree-type key datum</I>
<DD>This procedure creates and returns a newly allocated weight balanced
tree. The tree contains a single association, that of <VAR>datum</VAR> with
<VAR>key</VAR>. <VAR>Wt-tree-type</VAR> is a weight balanced tree type obtained
by calling <CODE>make-wt-tree-type</CODE>; the returned tree has this type.
</DL>
<P>
<A NAME="IDX1067"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>alist->wt-tree</B> <I>tree-type alist</I>
<DD>Returns a newly allocated weight-balanced tree that contains the same
associations as <VAR>alist</VAR>. This procedure is equivalent to:
<P>
<TABLE><tr><td> </td><td class=example><pre>(lambda (type alist)
(let ((tree (make-wt-tree type)))
(for-each (lambda (association)
(wt-tree/add! tree
(car association)
(cdr association)))
alist)
tree))
</pre></td></tr></table></DL>
<P>
<A NAME="Basic Operations on Weight-Balanced Trees"></A>
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<H3> 6.3.2 Basic Operations on Weight-Balanced Trees </H3>
<!--docid::SEC180::-->
<P>
This section describes the basic tree operations on weight balanced
trees. These operations are the usual tree operations for insertion,
deletion and lookup, some predicates and a procedure for determining the
number of associations in a tree.
</P>
<P>
<A NAME="IDX1068"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/empty?</B> <I>wt-tree</I>
<DD>Returns <CODE>#t</CODE> if <VAR>wt-tree</VAR> contains no associations, otherwise
returns <CODE>#f</CODE>.
</DL>
<P>
<A NAME="IDX1069"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/size</B> <I>wt-tree</I>
<DD>Returns the number of associations in <VAR>wt-tree</VAR>, an exact
non-negative integer. This operation takes constant time.
</DL>
<P>
<A NAME="IDX1070"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/add</B> <I>wt-tree key datum</I>
<DD>Returns a new tree containing all the associations in <VAR>wt-tree</VAR> and
the association of <VAR>datum</VAR> with <VAR>key</VAR>. If <VAR>wt-tree</VAR> already
had an association for <VAR>key</VAR>, the new association overrides the old.
The average and worst-case times required by this operation are
proportional to the logarithm of the number of associations in
<VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1071"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/add!</B> <I>wt-tree key datum</I>
<DD>Associates <VAR>datum</VAR> with <VAR>key</VAR> in <VAR>wt-tree</VAR> and returns an
unspecified value. If <VAR>wt-tree</VAR> already has an association for
<VAR>key</VAR>, that association is replaced. The average and worst-case
times required by this operation are proportional to the logarithm of
the number of associations in <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1072"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/member?</B> <I>key wt-tree</I>
<DD>Returns <CODE>#t</CODE> if <VAR>wt-tree</VAR> contains an association for
<VAR>key</VAR>, otherwise returns <CODE>#f</CODE>. The average and worst-case
times required by this operation are proportional to the logarithm of
the number of associations in <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1073"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/lookup</B> <I>wt-tree key default</I>
<DD>Returns the datum associated with <VAR>key</VAR> in <VAR>wt-tree</VAR>. If
<VAR>wt-tree</VAR> doesn't contain an association for <VAR>key</VAR>,
<VAR>default</VAR> is returned. The average and worst-case times required by
this operation are proportional to the logarithm of the number of
associations in <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1074"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/delete</B> <I>wt-tree key</I>
<DD>Returns a new tree containing all the associations in <VAR>wt-tree</VAR>,
except that if <VAR>wt-tree</VAR> contains an association for <VAR>key</VAR>, it
is removed from the result. The average and worst-case times required
by this operation are proportional to the logarithm of the number of
associations in <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1075"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/delete!</B> <I>wt-tree key</I>
<DD>If <VAR>wt-tree</VAR> contains an association for <VAR>key</VAR> the association
is removed. Returns an unspecified value. The average and worst-case
times required by this operation are proportional to the logarithm of
the number of associations in <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="Advanced Operations on Weight-Balanced Trees"></A>
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<H3> 6.3.3 Advanced Operations on Weight-Balanced Trees </H3>
<!--docid::SEC181::-->
<P>
In the following the <EM>size</EM> of a tree is the number of associations
that the tree contains, and a <EM>smaller</EM> tree contains fewer
associations.
</P>
<P>
<A NAME="IDX1076"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/split<</B> <I>wt-tree bound</I>
<DD>Returns a new tree containing all and only the associations in
<VAR>wt-tree</VAR> which have a key that is less than <VAR>bound</VAR> in the
ordering relation of the tree type of <VAR>wt-tree</VAR>. The average and
worst-case times required by this operation are proportional to the
logarithm of the size of <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1077"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/split></B> <I>wt-tree bound</I>
<DD>Returns a new tree containing all and only the associations in
<VAR>wt-tree</VAR> which have a key that is greater than <VAR>bound</VAR> in the
ordering relation of the tree type of <VAR>wt-tree</VAR>. The average and
worst-case times required by this operation are proportional to the
logarithm of size of <VAR>wt-tree</VAR>.
</DL>
<P>
<A NAME="IDX1078"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/union</B> <I>wt-tree-1 wt-tree-2</I>
<DD>Returns a new tree containing all the associations from both trees.
This operation is asymmetric: when both trees have an association for
the same key, the returned tree associates the datum from <VAR>wt-tree-2</VAR>
with the key. Thus if the trees are viewed as discrete maps then
<CODE>wt-tree/union</CODE> computes the map override of <VAR>wt-tree-1</VAR> by
<VAR>wt-tree-2</VAR>. If the trees are viewed as sets the result is the set
union of the arguments.
The worst-case time required by this operation
is proportional to the sum of the sizes of both trees.
If the minimum key of one tree is greater than the maximum key of
the other tree then the time required is at worst proportional to
the logarithm of the size of the larger tree.
</DL>
<P>
<A NAME="IDX1079"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/intersection</B> <I>wt-tree-1 wt-tree-2</I>
<DD>Returns a new tree containing all and only those associations from
<VAR>wt-tree-1</VAR> which have keys appearing as the key of an association
in <VAR>wt-tree-2</VAR>. Thus the associated data in the result are those
from <VAR>wt-tree-1</VAR>. If the trees are being used as sets the result is
the set intersection of the arguments. As a discrete map operation,
<CODE>wt-tree/intersection</CODE> computes the domain restriction of
<VAR>wt-tree-1</VAR> to (the domain of) <VAR>wt-tree-2</VAR>.
The time required by this operation is never worse that proportional to
the sum of the sizes of the trees.
</DL>
<P>
<A NAME="IDX1080"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/difference</B> <I>wt-tree-1 wt-tree-2</I>
<DD>Returns a new tree containing all and only those associations from
<VAR>wt-tree-1</VAR> which have keys that <EM>do not</EM> appear as the key of
an association in <VAR>wt-tree-2</VAR>. If the trees are viewed as sets the
result is the asymmetric set difference of the arguments. As a discrete
map operation, it computes the domain restriction of <VAR>wt-tree-1</VAR> to
the complement of (the domain of) <VAR>wt-tree-2</VAR>.
The time required by this operation is never worse that proportional to
the sum of the sizes of the trees.
</DL>
<P>
<A NAME="IDX1081"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/subset?</B> <I>wt-tree-1 wt-tree-2</I>
<DD>Returns <CODE>#t</CODE> iff the key of each association in <VAR>wt-tree-1</VAR> is
the key of some association in <VAR>wt-tree-2</VAR>, otherwise returns <CODE>#f</CODE>.
Viewed as a set operation, <CODE>wt-tree/subset?</CODE> is the improper subset
predicate.
A proper subset predicate can be constructed:
<P>
<TABLE><tr><td> </td><td class=example><pre>(define (proper-subset? s1 s2)
(and (wt-tree/subset? s1 s2)
(< (wt-tree/size s1) (wt-tree/size s2))))
</pre></td></tr></table><P>
As a discrete map operation, <CODE>wt-tree/subset?</CODE> is the subset
test on the domain(s) of the map(s). In the worst-case the time
required by this operation is proportional to the size of
<VAR>wt-tree-1</VAR>.
</P>
</DL>
<P>
<A NAME="IDX1082"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/set-equal?</B> <I>wt-tree-1 wt-tree-2</I>
<DD>Returns <CODE>#t</CODE> iff for every association in <VAR>wt-tree-1</VAR> there is
an association in <VAR>wt-tree-2</VAR> that has the same key, and <EM>vice
versa</EM>.
<P>
Viewing the arguments as sets <CODE>wt-tree/set-equal?</CODE> is the set
equality predicate. As a map operation it determines if two maps are
defined on the same domain.
</P>
<P>
This procedure is equivalent to
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(lambda (wt-tree-1 wt-tree-2)
(and (wt-tree/subset? wt-tree-1 wt-tree-2
(wt-tree/subset? wt-tree-2 wt-tree-1)))
</pre></td></tr></table><P>
In the worst-case the time required by this operation is proportional to
the size of the smaller tree.
</P>
</DL>
<P>
<A NAME="IDX1083"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/fold</B> <I>combiner initial wt-tree</I>
<DD>This procedure reduces <VAR>wt-tree</VAR> by combining all the associations,
using an reverse in-order traversal, so the associations are visited in
reverse order. <VAR>Combiner</VAR> is a procedure of three arguments: a key,
a datum and the accumulated result so far. Provided <VAR>combiner</VAR>
takes time bounded by a constant, <CODE>wt-tree/fold</CODE> takes time
proportional to the size of <VAR>wt-tree</VAR>.
<P>
A sorted association list can be derived simply:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(wt-tree/fold (lambda (key datum list)
(cons (cons key datum) list))
'()
<VAR>wt-tree</VAR>))
</pre></td></tr></table><P>
The data in the associations can be summed like this:
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>(wt-tree/fold (lambda (key datum sum) (+ sum datum))
0
<VAR>wt-tree</VAR>)
</pre></td></tr></table></DL>
<P>
<A NAME="IDX1084"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/for-each</B> <I>action wt-tree</I>
<DD>This procedure traverses the tree in-order, applying <VAR>action</VAR> to
each association.
The associations are processed in increasing order of their keys.
<VAR>Action</VAR> is a procedure of two arguments which take the key and
datum respectively of the association.
Provided <VAR>action</VAR> takes time bounded by a constant,
<CODE>wt-tree/for-each</CODE> takes time proportional to in the size of
<VAR>wt-tree</VAR>.
The example prints the tree:
<P>
<TABLE><tr><td> </td><td class=example><pre>(wt-tree/for-each (lambda (key value)
(display (list key value)))
<VAR>wt-tree</VAR>))
</pre></td></tr></table></DL>
<P>
<A NAME="Indexing Operations on Weight-Balanced Trees"></A>
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<H3> 6.3.4 Indexing Operations on Weight-Balanced Trees </H3>
<!--docid::SEC182::-->
<P>
Weight balanced trees support operations that view the tree as sorted
sequence of associations. Elements of the sequence can be accessed by
position, and the position of an element in the sequence can be
determined, both in logarthmic time.
</P>
<P>
<A NAME="IDX1085"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/index</B> <I>wt-tree index</I>
<DD><A NAME="IDX1086"></A>
<DT><U>procedure+:</U> <B>wt-tree/index-datum</B> <I>wt-tree index</I>
<DD><A NAME="IDX1087"></A>
<DT><U>procedure+:</U> <B>wt-tree/index-pair</B> <I>wt-tree index</I>
<DD>Returns the 0-based <VAR>index</VAR>th association of <VAR>wt-tree</VAR> in the
sorted sequence under the tree's ordering relation on the keys.
<CODE>wt-tree/index</CODE> returns the <VAR>index</VAR>th key,
<CODE>wt-tree/index-datum</CODE> returns the datum associated with the
<VAR>index</VAR>th key and <CODE>wt-tree/index-pair</CODE> returns a new pair
<CODE>(<VAR>key</VAR> . <VAR>datum</VAR>)</CODE> which is the <CODE>cons</CODE> of the
<VAR>index</VAR>th key and its datum. The average and worst-case times
required by this operation are proportional to the logarithm of the
number of associations in the tree.
<P>
These operations signal an error if the tree is empty, if
<VAR>index</VAR><CODE><0</CODE>, or if <VAR>index</VAR> is greater than or equal to the
number of associations in the tree.
</P>
<P>
Indexing can be used to find the median and maximum keys in the tree as
follows:
</P>
</DL>
<P>
<TABLE><tr><td> </td><td class=example><pre>median: (wt-tree/index <VAR>wt-tree</VAR> (quotient (wt-tree/size <VAR>wt-tree</VAR>) 2))
maximum: (wt-tree/index <VAR>wt-tree</VAR> (-1+ (wt-tree/size <VAR>wt-tree</VAR>)))
</pre></td></tr></table><P>
<A NAME="IDX1088"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/rank</B> <I>wt-tree key</I>
<DD>Determines the 0-based position of <VAR>key</VAR> in the sorted sequence of
the keys under the tree's ordering relation, or <CODE>#f</CODE> if the tree
has no association with for <VAR>key</VAR>. This procedure returns either an
exact non-negative integer or <CODE>#f</CODE>. The average and worst-case
times required by this operation are proportional to the logarithm of
the number of associations in the tree.
</DL>
<P>
<A NAME="IDX1089"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/min</B> <I>wt-tree</I>
<DD><A NAME="IDX1090"></A>
<DT><U>procedure+:</U> <B>wt-tree/min-datum</B> <I>wt-tree</I>
<DD><A NAME="IDX1091"></A>
<DT><U>procedure+:</U> <B>wt-tree/min-pair</B> <I>wt-tree</I>
<DD>Returns the association of <VAR>wt-tree</VAR> that has the least key under
the tree's ordering relation. <CODE>wt-tree/min</CODE> returns the least key,
<CODE>wt-tree/min-datum</CODE> returns the datum associated with the least key
and <CODE>wt-tree/min-pair</CODE> returns a new pair <CODE>(key . datum)</CODE>
which is the <CODE>cons</CODE> of the minimum key and its datum. The average
and worst-case times required by this operation are proportional to the
logarithm of the number of associations in the tree.
<P>
These operations signal an error if the tree is empty.
They could be written
<TABLE><tr><td> </td><td class=example><pre>(define (wt-tree/min tree) (wt-tree/index tree 0))
(define (wt-tree/min-datum tree) (wt-tree/index-datum tree 0))
(define (wt-tree/min-pair tree) (wt-tree/index-pair tree 0))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX1092"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/delete-min</B> <I>wt-tree</I>
<DD>Returns a new tree containing all of the associations in <VAR>wt-tree</VAR>
except the association with the least key under the <VAR>wt-tree</VAR>'s
ordering relation. An error is signalled if the tree is empty. The
average and worst-case times required by this operation are proportional
to the logarithm of the number of associations in the tree. This
operation is equivalent to
<P>
<TABLE><tr><td> </td><td class=example><pre>(wt-tree/delete <VAR>wt-tree</VAR> (wt-tree/min <VAR>wt-tree</VAR>))
</pre></td></tr></table></DL>
<P>
<A NAME="IDX1093"></A>
</P>
<DL>
<DT><U>procedure+:</U> <B>wt-tree/delete-min!</B> <I>wt-tree</I>
<DD>Removes the association with the least key under the <VAR>wt-tree</VAR>'s
ordering relation. An error is signalled if the tree is empty. The
average and worst-case times required by this operation are proportional
to the logarithm of the number of associations in the tree. This
operation is equivalent to
<P>
<TABLE><tr><td> </td><td class=example><pre>(wt-tree/delete! <VAR>wt-tree</VAR> (wt-tree/min <VAR>wt-tree</VAR>))
</pre></td></tr></table></DL>
<P>
<A NAME="Other Packages"></A>
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