tests.js

var FILE = require("file");

require.paths.unshift(FILE.join(FILE.dirname(module.path),
                                "jsmacros/vendor/jison/lib"));
var Parser = require("jison").Parser;
require.paths.shift();

var grammar = {
    lex: {
        rules: [
            ["\\s+", "/* skip whitespace */"],
            ["\\d+", "return 'NUMBER'"],
            ["\\+", "return '+'"],
            ["$", "return 'EOF'"]
        ]
    },
    operators: [
        ["left", "+"]
    ],
    bnf: {
        expressions: [
            ["e EOF",   "return $1"]
        ],
        e: [
            ["e + e", "$$ = '' + $1 + $2 + $3"],
            ["NUMBER", "$$ = new Number($1)"]
        ]
    }
};

exports.generateParser = function () {
    return new Parser(grammar);
};

exports.parse = function (code) {
    return exports.generateParser().parse(code);
};

exports.addExpression = function (pattern, rule, pos) {
    pos = pos || grammar.bnf.e.length;
    grammar.bnf.e.splice.apply(grammar.bnf.e, [pos, 0, [pattern, rule]]);
};

exports.addLex = function (pattern, rule) {
    grammar.lex.rules.push([pattern, rule]);
};

exports.addOp = function (direction, op, pos) {
    pos = pos || grammar.operators.length;
    var opRule;
    if ( (opRule = grammar.operators[pos]) && opRule[0] === direction ) {
        opRule.push(op);
    } else {
        grammar.operators.splice.apply(grammar.operators, [pos, 0, [direction, op]]);
    }
};

print(exports.parse("9 + 3"));

exports.addOp("left", "-", 0);
exports.addLex("\\-", "return '-'");
exports.addExpression("e - e", "$$ = '' + $1 + $2 + $3", 1);

print(exports.parse("9 - 3"));