From 8466d8cfa486fb30d1755c4261b781135083787b Mon Sep 17 00:00:00 2001
From: Bryan Newbold <bnewbold@robocracy.org>
Date: Mon, 20 Feb 2017 00:05:29 -0800
Subject: Import Upstream version 3a1

---
 priorque.scm | 73 ++++++++++++++++++++++++++++--------------------------------
 1 file changed, 34 insertions(+), 39 deletions(-)

(limited to 'priorque.scm')

diff --git a/priorque.scm b/priorque.scm
index 0ad3007..9f1591f 100644
--- a/priorque.scm
+++ b/priorque.scm
@@ -8,7 +8,7 @@
 ;1.  Any copy made of this software must include this copyright notice
 ;in full.
 ;
-;2.  I have made no warrantee or representation that the operation of
+;2.  I have made no warranty or representation that the operation of
 ;this software will be error-free, and I am under no obligation to
 ;provide any services, by way of maintenance, update, or otherwise.
 ;
@@ -17,21 +17,20 @@
 ;promotional, or sales literature without prior written consent in
 ;each case.
 
-;;; Algorithm from:
-;;; Introduction to Algorithms by T. Cormen, C. Leiserson, R. Rivest.
-;;; 1989 MIT Press.
+;;@code{(require 'priority-queue)}
+;;@ftindex priority-queue
+;;
+;;@noindent
+;;This algorithm for priority queues is due to
+;;@cite{Introduction to Algorithms}
+;;by T. Cormen, C. Leiserson, R. Rivest.
+;;1989 MIT Press.
 
 (require 'record)
 
 ;; Record type.
 (define heap:rtd (make-record-type "heap" '(array size heap<?)))
 
-;; Constructor.
-(define heap:make-heap
-  (let ((cstr (record-constructor heap:rtd)))
-    (lambda (pred<?)
-      (cstr (make-vector 4) 0 pred<?))))
-
 ;; Reference an element.
 (define heap:ref
   (let ((ra (record-accessor heap:rtd 'array)))
@@ -55,10 +54,6 @@
 	(vector-set! ra i (vector-ref ra j))
 	(vector-set! ra j tmp)))))
 
-
-;; Get length.
-(define heap:length (record-accessor heap:rtd 'size))
-
 (define heap:heap<? (record-accessor heap:rtd 'heap<?))
 
 (define heap:set-size!
@@ -92,7 +87,24 @@
 	   (heap:exchange a i largest)
 	   (heap:heapify a largest)))))
 
-(define (heap:insert! a key)
+;;;; Externals
+
+;;@body
+;;Returns a binary heap suitable which can be used for priority queue
+;;operations.
+(define make-heap
+  (let ((cstr (record-constructor heap:rtd)))
+    (lambda (pred<?)
+      (cstr (make-vector 4) 0 pred<?))))
+
+;;@args heap
+;;Returns the number of elements in @1.
+(define heap-length (record-accessor heap:rtd 'size))
+
+;;@args heap item
+;;Inserts @2 into @1.  @2 can be inserted multiple
+;;times.  The value returned is unspecified.
+(define (heap-insert! a key)
   (define i (+ 1 (heap:length a)))
   (heap:set-size! a i)
   (do ()
@@ -102,7 +114,11 @@
     (set! i (heap:parent i)))
   (heap:set! a i key))
 
-(define (heap:extract-max! a)
+;;@args heap
+;;Returns the item which is larger than all others according to the
+;;@var{pred<?} argument to @code{make-heap}.  If there are no items in
+;;@1, an error is signaled.
+(define (heap-extract-max! a)
   (if (< (heap:length a) 1)
       (slib:error "heap underflow" a))
   (let ((max (heap:ref a 1)))
@@ -111,26 +127,5 @@
     (heap:heapify a 1)
     max))
 
-;;
-;; Externals.
-;;
-(define make-heap heap:make-heap)
-(define heap-insert! heap:insert!)
-(define heap-extract-max! heap:extract-max!)
-(define heap-length heap:length)
-
-(define (heap:test)
-  (require 'debug)
-  (let ((heap #f))
-    (set! heap (make-heap char>?))
-    (heap-insert! heap #\A)
-    (heap-insert! heap #\Z)
-    (heap-insert! heap #\G)
-    (heap-insert! heap #\B)
-    (heap-insert! heap #\G)
-    (heap-insert! heap #\Q)
-    (heap-insert! heap #\S)
-    (heap-insert! heap #\R)
-    (do ((i 7 (+ -1 i)))
-	((negative? i))
-      (write (heap-extract-max! heap)) (newline))))
+;; Internal protect.
+(define heap:length heap-length)
-- 
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