diff options
| -rw-r--r-- | rust/spectrum.rs | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/rust/spectrum.rs b/rust/spectrum.rs index 8a82a33..317dce2 100644 --- a/rust/spectrum.rs +++ b/rust/spectrum.rs @@ -27,6 +27,7 @@ enum SchemeExpr<'a> { SchemeNum(f64), SchemeBuiltin(&'a str), SchemeSymbol(&'a str), + SchemeIdentifier(&'a str), SchemeStr(&'a str), SchemeProcedure( Vec<&'a str>, @@ -41,17 +42,21 @@ enum SchemeExpr<'a> { fn is_scheme_whitespace(c: char) -> bool{ " \r\n".find(c) != None } + fn is_scheme_sep(c: char) -> bool { "()".find(c) != None } -fn is_valid_symbol(s: &str) -> bool { +fn is_valid_identifier(s: &str) -> bool { // TODO: this could be an 'any' or 'filter' call? if s.len() == 0 { return false; } + if s.starts_with("-") || s.ends_with("-") { + return false; + } for c in s.chars() { - if !c.is_alphabetic() && c != '-' { + if !(c.is_alphabetic() || c == '-') { return false; } } @@ -63,6 +68,7 @@ fn scheme_tokenize<'a>(raw_str: &'a str) -> Result<Vec<&'a str>, &'static str> { let mut ret = Vec::<&str>::new(); let mut food: usize = 0; let mut quoted: bool = false; + let mut commented: bool = false; for (i, c) in raw_str.chars().enumerate() { if quoted { if c == '"' && raw_str.chars().collect::<Vec<char>>()[i-1] != '\\' { @@ -74,6 +80,14 @@ fn scheme_tokenize<'a>(raw_str: &'a str) -> Result<Vec<&'a str>, &'static str> { } else { food += 1; } + } else if commented { + food = 0; + if c == '\n' { + commented = false; + } + } else if c == ';' { + commented = true; + food = 0; } else if c == '"' { if food > 0 { return Err("unexpected quote char"); @@ -125,11 +139,16 @@ fn scheme_parse_token(token: &str) -> Result<SchemeExpr, &'static str> { return Ok(SchemeExpr::SchemeStr(token)); } - // If it's all alphas, must be a symbol - if is_valid_symbol(token) { + // Is it a symbol? + if token.starts_with("'") && is_valid_identifier(&token[1..]) { return Ok(SchemeExpr::SchemeSymbol(token)); } + // Else, we'll treat it as an identifier + if is_valid_identifier(token) { + return Ok(SchemeExpr::SchemeIdentifier(token)); + } + return Err("unparsable token"); } @@ -180,6 +199,7 @@ fn scheme_repr(ast: &SchemeExpr) -> Result<String, &'static str> { &SchemeExpr::SchemeBuiltin(b)=> Ok(b.to_string()), &SchemeExpr::SchemeStr(s)=> Ok(s.to_string()), &SchemeExpr::SchemeSymbol(s)=> Ok(s.to_string()), + &SchemeExpr::SchemeIdentifier(s)=> Ok("'".to_string() + s), &SchemeExpr::SchemeProcedure(ref binds, ref body, _) => { let mut ret = "(lambda (".to_string(); for bind in binds { @@ -253,7 +273,7 @@ fn lambda_action<'a>(list: &Vec<SchemeExpr<'a>>, ctx: HashMap<&'a str, SchemeExp }; for bind in bind_list { match bind { - &SchemeExpr::SchemeSymbol(name) => + &SchemeExpr::SchemeIdentifier(name) => binds.push(name), _ => return Err("lambda binds must all be non-builtin symbols") } @@ -399,12 +419,13 @@ fn scheme_meaning<'a>(ast: &SchemeExpr<'a>, ctx: HashMap<&'a str, SchemeExpr<'a> &SchemeExpr::SchemeFalse => Ok(ast.clone()), &SchemeExpr::SchemeNull => Ok(ast.clone()), &SchemeExpr::SchemeStr(_) => Ok(ast.clone()), + &SchemeExpr::SchemeSymbol(_) => Ok(ast.clone()), &SchemeExpr::SchemeNum(_) => Ok(ast.clone()), &SchemeExpr::SchemeBuiltin(_) => Ok(ast.clone()), &SchemeExpr::SchemeProcedure(_, _, _) => Ok(ast.clone()), &SchemeExpr::SchemeQuote(ref list) => Ok(SchemeExpr::SchemeList(list.clone())), - &SchemeExpr::SchemeSymbol(sym) => match ctx.get(sym) { + &SchemeExpr::SchemeIdentifier(sym) => match ctx.get(sym) { // the "lookup action" Some(val) => Ok(val.clone()), None => Err("symbol not defined"), |