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added support def functions and lists, next up: desugaring

pull/21/head
Wesley Kerfoot 12 years ago
parent
46632aa579
commit
942b92caa4
4 changed files with 128 additions and 53 deletions
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  1. 149
      parse.js
  2. 17
      representation.js
  3. 14
      test.jl
  4. 1
      tokenize.js

149
parse.js
View File

@ -1,4 +1,4 @@
#! /usr/bin/nodejs
#! /usr/bin/node
var typ = require("./representation.js");
var tool = require("./tools.js");
@ -16,9 +16,7 @@ function snd(ts) {
//Checks if the next token is not followed by any of ``checks''
function notFollowedBy(tokens, checks) {
var nextT = fst(tokens)[0];
if (!snd(tokens))
console.log("Error: "+ fst(tokens)[0] +" must be followed by something");
else if (checks.some(function (x) {return x === nextT;}))
if (checks.some(function (x) {return x === nextT;}))
return false;
else
return true;
@ -69,7 +67,63 @@ function parseMany(exprType, valid, tokens) {
return results;
}
/* Tries to parse exprType separated by the token between
* e.g. <identifier>,<identifier>,...
*/
function parseBetween(exprType, between, tokens) {
var first = parse(tokens);
if (!exprType(first)) {
console.log("Error, unexpected token:"+fst(tokens)[0]);
return;
}
var items = [first];
var parsed;
if (tokens.length > 1 && fst(tokens)[0] === between) {
while (fst(tokens)[0] === between) {
tokens.pop();
parsed = parse(tokens);
items.push(parsed);
}
return items;
}
return items;
}
function parseList(tokens) {
var xs = parseBetween(function (x) { return true; }, "comma", tokens);
if (fst(tokens)[0] !== "right_square") {
console.log("Error, list must be terminated by ]");
return undefined;
}
tokens.pop();
return new typ.ListT(xs);
}
function parseDefFunction(tokens) {
var fname = parse(tokens);
if (!fname.exprType === "identifier") {
console.log("Error, expected an identifier in function definition");
return undefined;
}
var parameters = parseMany(validName, validFormPar, tokens);
if ((fst(tokens)[0]) !== "right_paren") {
console.log("Error, formal parameters must be followed by )");
return undefined;
}
tokens.pop();
var body = parse(tokens);
return new typ.DefFunc(fname, parameters, body);
}
function parseDef(tokens) {
if (fst(tokens)[0] === "left_paren") {
// It's a function definition
tokens.pop();
return parseDefFunction(tokens);
}
if (notFollowedBy(tokens, ["identifier"])) {
console.log("Error: def must be followed by identifier, not "+fst(tokens)[0]);
return undefined;
@ -132,47 +186,6 @@ var validArgument = tool.compose(tool.not, makeChecker(invalidArguments));
var validArgTypes = tool.compose(tool.not, makeChecker(["Definition"]));
var validOperator = makeChecker(["identifier"]);
function parse(tokens) {
if (fst(tokens))
var toktype = fst(tokens)[0];
else {
//console.log("Unexpected end of source")
process.exit(code=1);
}
var token = fst(tokens)[1];
tokens.pop();
if (toktype === "stringlit")
return new typ.StrT(token);
else if (toktype === "lambda")
return checkParse(parseLambda(tokens));
else if (toktype === "integer")
return new typ.IntT(token);
else if (toktype === "float")
return new typ.FloatT(token);
else if (toktype === "identifier")
return new typ.Name(token);
else if (toktype === "truelit" || toktype === "falselit")
return new typ.BoolT(token);
else if (toktype === "def")
return checkParse(parseDef(tokens));
else if (toktype === "ifexp")
return checkParse(parseIf(tokens));
else if (toktype === "left_paren") {
if (fst(tokens)[0] === "lambda") {
tokens.pop();
var parsed = checkParse(parseLambda(tokens));
tokens.pop();
return parsed;
}
else
return computeApp(tokens);
}
else {
console.log("Unexpected token: " + toktype);
process.exit(code=1);
}
}
function checkParse(p) {
if (p === undefined) {
console.log("Quitting, could not finish parsing!");
@ -252,6 +265,49 @@ function parseInfix(tokens, minPrec, lhs) {
return lhs;
}
function parse(tokens) {
if (fst(tokens))
var toktype = fst(tokens)[0];
else {
//console.log("Unexpected end of source")
process.exit(code=1);
}
var token = fst(tokens)[1];
tokens.pop();
if (toktype === "stringlit")
return new typ.StrT(token);
else if (toktype === "left_square")
return parseList(tokens);
else if (toktype === "lambda")
return checkParse(parseLambda(tokens));
else if (toktype === "integer")
return new typ.IntT(token);
else if (toktype === "float")
return new typ.FloatT(token);
else if (toktype === "identifier")
return new typ.Name(token);
else if (toktype === "truelit" || toktype === "falselit")
return new typ.BoolT(token);
else if (toktype === "def")
return checkParse(parseDef(tokens));
else if (toktype === "ifexp")
return checkParse(parseIf(tokens));
else if (toktype === "left_paren") {
if (fst(tokens)[0] === "lambda") {
tokens.pop();
var parsed = checkParse(parseLambda(tokens));
tokens.pop();
return parsed;
}
else
return computeApp(tokens);
}
else {
console.log("Unexpected token: " + toktype);
process.exit(code=1);
}
}
function pprintName(ident) {
return pprint(ident.val);
}
@ -310,9 +366,8 @@ function pprint(expr) {
var input = fs.readFileSync('/dev/stdin').toString();
var tokenized = tokenizer.tokenize(input).reverse().filter(function(x) { return x[0] !== "whitespace";});
//console.log(tokenized);
while (tokenized !== []) {
console.log(pprint(parse(tokenized)));
console.log(parse(tokenized));
if (!tokenized)
break;
}

17
representation.js
View File

@ -55,9 +55,8 @@ function BoolT(b) {
BoolT.prototype = Expression;
function ListT(x, xs) {
this.x = x;
this.rest = xs;
function ListT(xs) {
this.xs = xs;
this.val = xs;
this.exprType = "List";
return this;
@ -109,6 +108,15 @@ function Def(ident, exp) {
return this;
}
function DefFunc(ident, params, body) {
this.ident = ident;
this.val = this.ident;
this.params = params;
this.body = body;
this.exprType = "FunctionDefinition";
return this;
}
function If(condition, thenexp, elseexp) {
this.condition = condition;
this.thenexp = thenexp;
@ -163,4 +171,5 @@ module.exports =
OpT : OpT,
OPInfo : OPInfo,
makeApp : makeApp,
If : If}
If : If,
DefFunc : DefFunc}

14
test.jl
View File

@ -16,4 +16,16 @@ def fact
else
(n * (fact (n - 1))))
def main (print (fact 15))
def fib
(lambda n ->
if (n == 0)
then 0
else
if (n == 1)
then 1
else
(+
(fib (n - 1))
(fib (n - 2))))
def main (print (fib 15))

1
tokenize.js
View File

@ -273,5 +273,4 @@ module.exports = {tokenize : tokenize};
//var tokstream = fs.readFileSync("/dev/stdin").toString();
//console.log(isIdentifier(')'));
//console.log(tokenize(tokstream));
//tokenize(tokstream);

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