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87 lines
2.2 KiB
87 lines
2.2 KiB
#! /usr/bin/node
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var typ = require("./representation.js");
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var parse = require("./parse.js");
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var tokenizer = require("./tokenize.js");
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var pprint = require("./pprint.js");
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var env = require("./environments.js");
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var fs = require("fs");
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var istr = fs.readFileSync('/dev/stdin').toString();
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var ast = parse.parseFull(tokenizer.tokenize(istr));
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var testenv = env.makeEnv("toplevel",
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[
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["+", function(a) { return function(b) { return a + b; } }],
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["*", function(a) { return function(b) { return a * b; } }],
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["-", function(a) { return function(b) { return a - b; } }],
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["a", 2],
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["b", 3]]);
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console.log(JSON.stringify(evaluate(ast.ast[ast.ast.length-1], testenv)));
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function lookup(ident, env) {
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var func = evaluate(env.bindings[ident], env);
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return func;
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}
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function evaluateString(input) {
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var parsed = parse.parseFull(tokenizer.tokenize(input)).ast;
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var evaluated = evaluateAll(parsed, testenv);
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return evaluated;
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}
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function apply(func, p) {
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return func(evaluate(p));
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}
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function evaluateAll(ast, environment) {
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var l = ast.length;
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var evaled = [];
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for (var i = 0; i < l; i++) {
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// should look for closures?
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evaled.push(evaluate(ast[i], environment));
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}
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return evaled;
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}
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function evaluate(ast, environment) {
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if (ast.exprType == "Application") {
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var func = evaluate(ast.func, environment);
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return apply(
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func,
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evaluate(ast.p, environment));
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}
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else if (ast.exprType === "Unary") {
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/* Unary function application */
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var func = evaluate(ast.op, environment);
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return apply(
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func,
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evaluate(ast.val, environment));
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}
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else if (ast.exprType === "Name") {
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return lookup(ast.ident, environment);
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}
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else if (ast.exprType === "If") {
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if (evaluate(ast.condition, environment)) {
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return evaluate(ast.thenexp, environment);
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}
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else {
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return evaluate(ast.elseexp, environment);
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}
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}
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else if (ast.exprType === "Definition") {
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return; /* XXX */
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}
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else if (ast.exprType === "Integer") {
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return ast.val;
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}
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else {
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return ast;
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}
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}
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module.exports = {
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"evaluate" : evaluateString
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};
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