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118 lines
4.2 KiB
JavaScript
118 lines
4.2 KiB
JavaScript
var unparse = require('escodegen').generate;
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module.exports = function (ast, vars) {
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if (!vars) vars = {};
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var FAIL = {};
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var result = (function walk (node) {
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if (node.type === 'Literal') {
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return node.value;
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}
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else if (node.type === 'UnaryExpression'){
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var val = walk(node.argument)
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if (node.operator === '+') return +val
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if (node.operator === '-') return -val
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if (node.operator === '~') return ~val
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if (node.operator === '!') return !val
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return FAIL
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}
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else if (node.type === 'ArrayExpression') {
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var xs = [];
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for (var i = 0, l = node.elements.length; i < l; i++) {
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var x = walk(node.elements[i]);
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if (x === FAIL) return FAIL;
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xs.push(x);
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}
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return xs;
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}
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else if (node.type === 'ObjectExpression') {
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var obj = {};
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for (var i = 0; i < node.properties.length; i++) {
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var prop = node.properties[i];
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var value = prop.value === null
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? prop.value
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: walk(prop.value)
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;
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if (value === FAIL) return FAIL;
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obj[prop.key.value || prop.key.name] = value;
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}
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return obj;
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}
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else if (node.type === 'BinaryExpression' ||
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node.type === 'LogicalExpression') {
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var l = walk(node.left);
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if (l === FAIL) return FAIL;
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var r = walk(node.right);
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if (r === FAIL) return FAIL;
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var op = node.operator;
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if (op === '==') return l == r;
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if (op === '===') return l === r;
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if (op === '!=') return l != r;
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if (op === '!==') return l !== r;
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if (op === '+') return l + r;
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if (op === '-') return l - r;
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if (op === '*') return l * r;
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if (op === '/') return l / r;
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if (op === '%') return l % r;
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if (op === '<') return l < r;
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if (op === '<=') return l <= r;
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if (op === '>') return l > r;
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if (op === '>=') return l >= r;
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if (op === '|') return l | r;
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if (op === '&') return l & r;
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if (op === '^') return l ^ r;
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if (op === '&&') return l && r;
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if (op === '||') return l || r;
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return FAIL;
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}
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else if (node.type === 'Identifier') {
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if ({}.hasOwnProperty.call(vars, node.name)) {
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return vars[node.name];
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}
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else return FAIL;
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}
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else if (node.type === 'CallExpression') {
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var callee = walk(node.callee);
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if (callee === FAIL) return FAIL;
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var ctx = node.callee.object ? walk(node.callee.object) : FAIL;
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if (ctx === FAIL) ctx = null;
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var args = [];
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for (var i = 0, l = node.arguments.length; i < l; i++) {
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var x = walk(node.arguments[i]);
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if (x === FAIL) return FAIL;
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args.push(x);
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}
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return callee.apply(ctx, args);
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}
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else if (node.type === 'MemberExpression') {
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var obj = walk(node.object);
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if (obj === FAIL) return FAIL;
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if (node.property.type === 'Identifier') {
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return obj[node.property.name];
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}
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var prop = walk(node.property);
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if (prop === FAIL) return FAIL;
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return obj[prop];
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}
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else if (node.type === 'ConditionalExpression') {
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var val = walk(node.test)
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if (val === FAIL) return FAIL;
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return val ? walk(node.consequent) : walk(node.alternate)
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}
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else if (node.type === 'FunctionExpression') {
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var keys = Object.keys(vars);
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var vals = keys.map(function(key) {
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return vars[key];
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});
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return Function(keys.join(', '), 'return ' + unparse(node)).apply(null, vals);
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}
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else return FAIL;
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})(ast);
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return result === FAIL ? undefined : result;
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};
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