345 lines
11 KiB
JavaScript
345 lines
11 KiB
JavaScript
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/***********************************************************************
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A JavaScript tokenizer / parser / beautifier / compressor.
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https://github.com/mishoo/UglifyJS2
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-------------------------------- (C) ---------------------------------
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Author: Mihai Bazon
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<mihai.bazon@gmail.com>
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http://mihai.bazon.net/blog
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Distributed under the BSD license:
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Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com>
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above
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copyright notice, this list of conditions and the following
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disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials
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provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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SUCH DAMAGE.
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***********************************************************************/
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import {
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AST_Array,
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AST_Arrow,
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AST_BlockStatement,
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AST_Call,
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AST_Class,
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AST_Const,
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AST_Constant,
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AST_DefClass,
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AST_Defun,
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AST_EmptyStatement,
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AST_Export,
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AST_False,
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AST_Function,
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AST_Import,
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AST_Infinity,
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AST_LabeledStatement,
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AST_Lambda,
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AST_Let,
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AST_LoopControl,
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AST_NaN,
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AST_Node,
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AST_Null,
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AST_Number,
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AST_Object,
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AST_ObjectKeyVal,
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AST_PropAccess,
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AST_RegExp,
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AST_Scope,
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AST_Sequence,
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AST_SimpleStatement,
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AST_Statement,
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AST_String,
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AST_SymbolRef,
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AST_True,
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AST_UnaryPrefix,
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AST_Undefined,
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TreeWalker,
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walk,
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walk_abort,
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walk_parent,
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} from "../ast.js";
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import { make_node, regexp_source_fix, string_template, makePredicate } from "../utils/index.js";
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import { first_in_statement } from "../utils/first_in_statement.js";
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import { has_flag, TOP } from "./compressor-flags.js";
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export function merge_sequence(array, node) {
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if (node instanceof AST_Sequence) {
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array.push(...node.expressions);
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} else {
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array.push(node);
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}
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return array;
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}
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export function make_sequence(orig, expressions) {
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if (expressions.length == 1) return expressions[0];
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if (expressions.length == 0) throw new Error("trying to create a sequence with length zero!");
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return make_node(AST_Sequence, orig, {
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expressions: expressions.reduce(merge_sequence, [])
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});
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}
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export function make_node_from_constant(val, orig) {
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switch (typeof val) {
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case "string":
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return make_node(AST_String, orig, {
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value: val
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});
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case "number":
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if (isNaN(val)) return make_node(AST_NaN, orig);
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if (isFinite(val)) {
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return 1 / val < 0 ? make_node(AST_UnaryPrefix, orig, {
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operator: "-",
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expression: make_node(AST_Number, orig, { value: -val })
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}) : make_node(AST_Number, orig, { value: val });
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}
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return val < 0 ? make_node(AST_UnaryPrefix, orig, {
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operator: "-",
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expression: make_node(AST_Infinity, orig)
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}) : make_node(AST_Infinity, orig);
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case "boolean":
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return make_node(val ? AST_True : AST_False, orig);
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case "undefined":
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return make_node(AST_Undefined, orig);
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default:
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if (val === null) {
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return make_node(AST_Null, orig, { value: null });
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}
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if (val instanceof RegExp) {
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return make_node(AST_RegExp, orig, {
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value: {
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source: regexp_source_fix(val.source),
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flags: val.flags
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}
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});
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}
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throw new Error(string_template("Can't handle constant of type: {type}", {
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type: typeof val
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}));
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}
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}
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export function best_of_expression(ast1, ast2) {
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return ast1.size() > ast2.size() ? ast2 : ast1;
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}
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export function best_of_statement(ast1, ast2) {
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return best_of_expression(
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make_node(AST_SimpleStatement, ast1, {
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body: ast1
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}),
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make_node(AST_SimpleStatement, ast2, {
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body: ast2
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})
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).body;
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}
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/** Find which node is smaller, and return that */
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export function best_of(compressor, ast1, ast2) {
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if (first_in_statement(compressor)) {
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return best_of_statement(ast1, ast2);
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} else {
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return best_of_expression(ast1, ast2);
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}
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}
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/** Simplify an object property's key, if possible */
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export function get_simple_key(key) {
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if (key instanceof AST_Constant) {
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return key.getValue();
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}
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if (key instanceof AST_UnaryPrefix
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&& key.operator == "void"
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&& key.expression instanceof AST_Constant) {
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return;
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}
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return key;
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}
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export function read_property(obj, key) {
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key = get_simple_key(key);
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if (key instanceof AST_Node) return;
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var value;
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if (obj instanceof AST_Array) {
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var elements = obj.elements;
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if (key == "length") return make_node_from_constant(elements.length, obj);
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if (typeof key == "number" && key in elements) value = elements[key];
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} else if (obj instanceof AST_Object) {
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key = "" + key;
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var props = obj.properties;
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for (var i = props.length; --i >= 0;) {
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var prop = props[i];
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if (!(prop instanceof AST_ObjectKeyVal)) return;
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if (!value && props[i].key === key) value = props[i].value;
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}
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}
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return value instanceof AST_SymbolRef && value.fixed_value() || value;
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}
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export function has_break_or_continue(loop, parent) {
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var found = false;
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var tw = new TreeWalker(function(node) {
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if (found || node instanceof AST_Scope) return true;
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if (node instanceof AST_LoopControl && tw.loopcontrol_target(node) === loop) {
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return found = true;
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}
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});
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if (parent instanceof AST_LabeledStatement) tw.push(parent);
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tw.push(loop);
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loop.body.walk(tw);
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return found;
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}
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// we shouldn't compress (1,func)(something) to
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// func(something) because that changes the meaning of
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// the func (becomes lexical instead of global).
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export function maintain_this_binding(parent, orig, val) {
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if (
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parent instanceof AST_UnaryPrefix && parent.operator == "delete"
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|| parent instanceof AST_Call && parent.expression === orig
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&& (
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val instanceof AST_PropAccess
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|| val instanceof AST_SymbolRef && val.name == "eval"
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)
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) {
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const zero = make_node(AST_Number, orig, { value: 0 });
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return make_sequence(orig, [ zero, val ]);
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} else {
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return val;
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}
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}
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export function is_func_expr(node) {
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return node instanceof AST_Arrow || node instanceof AST_Function;
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}
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export function is_iife_call(node) {
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// Used to determine whether the node can benefit from negation.
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// Not the case with arrow functions (you need an extra set of parens).
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if (node.TYPE != "Call") return false;
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return node.expression instanceof AST_Function || is_iife_call(node.expression);
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}
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export function is_empty(thing) {
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if (thing === null) return true;
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if (thing instanceof AST_EmptyStatement) return true;
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if (thing instanceof AST_BlockStatement) return thing.body.length == 0;
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return false;
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}
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export const identifier_atom = makePredicate("Infinity NaN undefined");
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export function is_identifier_atom(node) {
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return node instanceof AST_Infinity
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|| node instanceof AST_NaN
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|| node instanceof AST_Undefined;
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}
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/** Check if this is a SymbolRef node which has one def of a certain AST type */
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export function is_ref_of(ref, type) {
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if (!(ref instanceof AST_SymbolRef)) return false;
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var orig = ref.definition().orig;
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for (var i = orig.length; --i >= 0;) {
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if (orig[i] instanceof type) return true;
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}
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}
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// Can we turn { block contents... } into just the block contents ?
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// Not if one of these is inside.
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export function can_be_evicted_from_block(node) {
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return !(
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node instanceof AST_DefClass ||
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node instanceof AST_Defun ||
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node instanceof AST_Let ||
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node instanceof AST_Const ||
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node instanceof AST_Export ||
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node instanceof AST_Import
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);
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}
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export function as_statement_array(thing) {
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if (thing === null) return [];
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if (thing instanceof AST_BlockStatement) return thing.body;
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if (thing instanceof AST_EmptyStatement) return [];
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if (thing instanceof AST_Statement) return [ thing ];
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throw new Error("Can't convert thing to statement array");
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}
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export function is_reachable(scope_node, defs) {
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const find_ref = node => {
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if (node instanceof AST_SymbolRef && defs.includes(node.definition())) {
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return walk_abort;
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}
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};
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return walk_parent(scope_node, (node, info) => {
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if (node instanceof AST_Scope && node !== scope_node) {
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var parent = info.parent();
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if (
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parent instanceof AST_Call
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&& parent.expression === node
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// Async/Generators aren't guaranteed to sync evaluate all of
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// their body steps, so it's possible they close over the variable.
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&& !(node.async || node.is_generator)
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) {
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return;
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}
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if (walk(node, find_ref)) return walk_abort;
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return true;
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}
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});
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}
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/** Check if a ref refers to the name of a function/class it's defined within */
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export function is_recursive_ref(compressor, def) {
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var node;
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for (var i = 0; node = compressor.parent(i); i++) {
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if (node instanceof AST_Lambda || node instanceof AST_Class) {
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var name = node.name;
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if (name && name.definition() === def) {
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return true;
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}
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}
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}
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return false;
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}
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// TODO this only works with AST_Defun, shouldn't it work for other ways of defining functions?
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export function retain_top_func(fn, compressor) {
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return compressor.top_retain
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&& fn instanceof AST_Defun
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&& has_flag(fn, TOP)
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&& fn.name
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&& compressor.top_retain(fn.name);
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}
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