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evaluate.js
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evaluate.js
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var Frame = function() {
var env = {};
this.set = function(name, value) {
env[name] = value;
}
this.get = function(name) {
return env[name];
}
}
var Evaluator = function () {
global = new Frame();
this.eval = function(stmts, env){
if (!env) {
env = global;
}
var stmt = stmts.shift();
stack = [];
expr = [];
while (stmt) {
// if (KEYWORDS[token]) {
// return (new (Expression[token])(tokens));
// } else {
// if (tokens[0] == "=") {
// tokens.shift();
// temp = this.eval(tokens);
// env.set(token,temp);
// return None;
// } else {
// eval = evalToken(token);
val = eval[0];
type = eval[1];
if (type == "int" || type == "float") {
expr.push(eval);
}
if (type == "operator") {
while (stack.length != 0 && stack[stack.length-1][1]=="operator" && !priority(val, stack[stack.length-1][1])) {
expr.push(stack.pop());
}
stack.push(eval);
} else if (token == "(") {
stack.push(eval);
} else if (token == ")") {
temp = stack.pop();
while (temp[0] != "(") {
expr.push(temp);
temp = stack.pop();
}
}
token = tokens.shift();
}
while (stack.length != 0) {
expr.push(stack.pop());
}
return postfixEval(expr);
}
var priority = function(op1, op2) {
if (op1 == "**"){
return true;
}
if (op1 == "+" || op1 == "-") {
if (op2 == "*" || op2 == "/") {
return false;
}
}
return true;
}
var postfixEval = function(expr) {
tokens = expr;
stack = [];
for (t in tokens) {
var token = tokens[t];
var func;
if (token[1] == "operator") {
if (token[0] == "+") {
func = function(x,y){return x+y};
}
if (token[0] == "*") {
func = function(x,y){return x*y};
}
if (token[0] == "/") {
func = function(x,y){return x/y};
}
if (token[0] == "-") {
func = function(x,y){return x-y};
}
if (token[0] == "**") {
func = function(x,y){return pow(x,y)};
}
var first = stack.pop()[0];
var second = stack.pop()[0];
stack.push([func(second, first),'float'])
}
if (token[1] == "int" || token[1] == "float"){
stack.push(token);
}
}
return stack.pop()[0];
}
var isAtom = function() {
}
var evalToken = function(token) {
if (!isNaN(parseFloat(token)) || token.match(/-+]?[0-9]*\.?[0-9]/g)) {
return [parseFloat(token), "float"];
} else if (!isNaN(parseInt(token)) || token.match(/[0-9]+/g)) {
return [parseInt(token), "int"];
} else if (token.match(/[0-9]+[.][0-9]+/g)) {
return [parseFloat(token), "float"];
} else if (token.match(/[+*-/]/g) || token == "**") {
return [token, "operator"];
} else if (token == "(" || token == ")"){
return [token, "parentheses"];
} else {
var get = global.get(token);
if (get !== undefined) {
return evalToken(get);
}
throw(token+" not found!");
}
}
var isValid = function(tokens) {
var token = tokens.shift();
while (token) {
if (KEYWORDS[token]) {
var expr = new (KEYWORDS[token])(tokens);
} else {
}
token = tokens.shift();
}
return true;
}
}
var Expression = {
"def" : function(tokens) {
//I CLAIM THIS AS MY OWN
//--Stephen
this.name = tokens.shift()
this.formals = [];
tokens.shift()
formal = tokens.shift()
while (formal != ")") {
if (formal != ",") {
this.formals.push(formal);
}
formal = tokens.shift();
}
}
}
var KEYWORDS = {
"def" : true
}
var None = undefined;
module.exports = Evaluator;