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'use strict';
var esprima;
// Browserified version does not have esprima
//
// 1. For node.js just require module as deps
// 2. For browser try to require mudule via external AMD system.
// If not found - try to fallback to window.esprima. If not
// found too - then fail to parse.
//
try {
// workaround to exclude package from browserify list.
var _require = require;
esprima = _require('esprima');
} catch (_) {
/*global window */
if (typeof window !== 'undefined') esprima = window.esprima;
}
var Type = require('../../type');
function resolveJavascriptFunction(data) {
if (data === null) return false;
try {
var source = '(' + data + ')',
ast = esprima.parse(source, { range: true });
if (ast.type !== 'Program' ||
ast.body.length !== 1 ||
ast.body[0].type !== 'ExpressionStatement' ||
(ast.body[0].expression.type !== 'ArrowFunctionExpression' &&
ast.body[0].expression.type !== 'FunctionExpression')) {
return false;
}
return true;
} catch (err) {
return false;
}
}
function constructJavascriptFunction(data) {
/*jslint evil:true*/
var source = '(' + data + ')',
ast = esprima.parse(source, { range: true }),
params = [],
body;
if (ast.type !== 'Program' ||
ast.body.length !== 1 ||
ast.body[0].type !== 'ExpressionStatement' ||
(ast.body[0].expression.type !== 'ArrowFunctionExpression' &&
ast.body[0].expression.type !== 'FunctionExpression')) {
throw new Error('Failed to resolve function');
}
ast.body[0].expression.params.forEach(function (param) {
params.push(param.name);
});
body = ast.body[0].expression.body.range;
// Esprima's ranges include the first '{' and the last '}' characters on
// function expressions. So cut them out.
if (ast.body[0].expression.body.type === 'BlockStatement') {
/*eslint-disable no-new-func*/
return new Function(params, source.slice(body[0] + 1, body[1] - 1));
}
// ES6 arrow functions can omit the BlockStatement. In that case, just return
// the body.
/*eslint-disable no-new-func*/
return new Function(params, 'return ' + source.slice(body[0], body[1]));
}
function representJavascriptFunction(object /*, style*/) {
return object.toString();
}
function isFunction(object) {
return Object.prototype.toString.call(object) === '[object Function]';
}
module.exports = new Type('tag:yaml.org,2002:js/function', {
kind: 'scalar',
resolve: resolveJavascriptFunction,
construct: constructJavascriptFunction,
predicate: isFunction,
represent: representJavascriptFunction
});
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