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/**
* @license Apache-2.0
*
* Copyright (c) 2019 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MAIN //
var walk = require( 'acorn-walk' ).ancestor;
var resolveLocalScopes = require( './resolve_local_scopes.js' );
var contains = require( './contains.js' );
var appendUnique = require( './append_unique.js' );
// FUNCTIONS //
/**
* Tests whether an AST node declares an `arguments` variable.
*
* @private
* @param {Node} node - AST node
* @returns {boolean} boolean indicating whether an AST node declares an `arguments` variable
*/
function declaresArguments( node ) {
return (
node.type === 'FunctionExpression' ||
node.type === 'FunctionDeclaration'
);
}
/**
* Tests whether an AST node declares a `this` variable.
*
* @private
* @param {Node} node - AST node
* @returns {boolean} boolean indicating whether an AST node declares a `this` variable
*/
function declaresThis( node ) {
return (
node.type === 'FunctionExpression' ||
node.type === 'FunctionDeclaration'
);
}
// MAIN //
/**
* Resolves global variables within an abstract syntax tree (AST).
*
* @private
* @param {AST} ast - abstract syntax tree (AST)
* @throws {TypeError} must provide a program AST node
* @returns {Array} list of global variables
*/
function resolveGlobals( ast ) {
var visitors;
var globals;
if ( ast.type !== 'Program' ) {
throw new TypeError( 'invalid argument. Must provide a program AST node.' );
}
globals = [];
// Resolve local scopes:
ast = resolveLocalScopes( ast );
// Define callbacks for relevant AST nodes:
visitors = {
'VariablePattern': Identifier,
'Identifier': Identifier,
'ThisExpression': ThisExpression
};
// Walk the AST to resolve globals:
walk( ast, visitors );
return globals;
/**
* Callback invoked upon encountering an identifier AST node.
*
* @private
* @param {Node} node - AST node
* @param {Array} parents - array of parent AST nodes
*/
function Identifier( node, parents ) {
var locals;
var name;
var i;
name = node.name;
if ( name === 'undefined' ) {
return;
}
for ( i = 0; i < parents.length; i++ ) {
if ( name === 'arguments' && declaresArguments( parents[ i ] ) ) {
return;
}
locals = parents[ i ].locals;
if ( locals && contains( locals.length, locals, 1, 0, name ) ) {
return;
}
}
appendUnique( globals, name );
}
/**
* Callback invoked upon encountering a `ThisExpression` AST node.
*
* @private
* @param {Node} node - AST node
* @param {Array} parents - array of parent AST nodes
*/
function ThisExpression( node, parents ) {
var i;
for ( i = 0; i < parents.length; i++ ) {
if ( declaresThis( parents[ i ] ) ) {
return;
}
}
appendUnique( globals, 'this' );
}
}
// EXPORTS //
module.exports = resolveGlobals;
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