676 lines
19 KiB
JavaScript
676 lines
19 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_Accessor,
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AST_Array,
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AST_Assign,
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AST_Await,
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AST_Binary,
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AST_Block,
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AST_Call,
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AST_Case,
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AST_Chain,
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AST_Class,
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AST_ClassExpression,
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AST_Conditional,
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AST_Default,
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AST_Defun,
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AST_Destructuring,
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AST_Do,
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AST_Exit,
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AST_Expansion,
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AST_For,
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AST_ForIn,
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AST_If,
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AST_LabeledStatement,
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AST_Lambda,
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AST_New,
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AST_Node,
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AST_Number,
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AST_ObjectKeyVal,
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AST_PropAccess,
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AST_Sequence,
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AST_SimpleStatement,
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AST_Symbol,
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AST_SymbolCatch,
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AST_SymbolConst,
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AST_SymbolDefun,
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AST_SymbolFunarg,
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AST_SymbolLambda,
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AST_SymbolRef,
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AST_This,
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AST_Toplevel,
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AST_Try,
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AST_Unary,
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AST_UnaryPrefix,
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AST_Undefined,
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AST_VarDef,
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AST_While,
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AST_Yield,
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walk,
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walk_body,
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_INLINE,
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_NOINLINE,
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_PURE
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} from "../ast.js";
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import { HOP, make_node, noop } from "../utils/index.js";
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import { lazy_op, is_modified } from "./inference.js";
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import { INLINED, clear_flag } from "./compressor-flags.js";
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import { read_property, has_break_or_continue, is_recursive_ref } from "./common.js";
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// Define the method AST_Node#reduce_vars, which goes through the AST in
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// execution order to perform basic flow analysis
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function def_reduce_vars(node, func) {
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node.DEFMETHOD("reduce_vars", func);
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}
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def_reduce_vars(AST_Node, noop);
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function reset_def(compressor, def) {
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def.assignments = 0;
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def.chained = false;
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def.direct_access = false;
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def.escaped = 0;
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def.recursive_refs = 0;
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def.references = [];
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def.single_use = undefined;
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if (def.scope.pinned()) {
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def.fixed = false;
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} else if (def.orig[0] instanceof AST_SymbolConst || !compressor.exposed(def)) {
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def.fixed = def.init;
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} else {
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def.fixed = false;
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}
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}
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function reset_variables(tw, compressor, node) {
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node.variables.forEach(function(def) {
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reset_def(compressor, def);
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if (def.fixed === null) {
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tw.defs_to_safe_ids.set(def.id, tw.safe_ids);
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mark(tw, def, true);
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} else if (def.fixed) {
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tw.loop_ids.set(def.id, tw.in_loop);
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mark(tw, def, true);
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}
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});
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}
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function reset_block_variables(compressor, node) {
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if (node.block_scope) node.block_scope.variables.forEach((def) => {
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reset_def(compressor, def);
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});
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}
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function push(tw) {
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tw.safe_ids = Object.create(tw.safe_ids);
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}
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function pop(tw) {
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tw.safe_ids = Object.getPrototypeOf(tw.safe_ids);
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}
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function mark(tw, def, safe) {
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tw.safe_ids[def.id] = safe;
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}
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function safe_to_read(tw, def) {
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if (def.single_use == "m") return false;
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if (tw.safe_ids[def.id]) {
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if (def.fixed == null) {
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var orig = def.orig[0];
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if (orig instanceof AST_SymbolFunarg || orig.name == "arguments") return false;
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def.fixed = make_node(AST_Undefined, orig);
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}
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return true;
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}
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return def.fixed instanceof AST_Defun;
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}
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function safe_to_assign(tw, def, scope, value) {
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if (def.fixed === undefined) return true;
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let def_safe_ids;
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if (def.fixed === null
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&& (def_safe_ids = tw.defs_to_safe_ids.get(def.id))
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) {
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def_safe_ids[def.id] = false;
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tw.defs_to_safe_ids.delete(def.id);
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return true;
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}
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if (!HOP(tw.safe_ids, def.id)) return false;
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if (!safe_to_read(tw, def)) return false;
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if (def.fixed === false) return false;
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if (def.fixed != null && (!value || def.references.length > def.assignments)) return false;
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if (def.fixed instanceof AST_Defun) {
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return value instanceof AST_Node && def.fixed.parent_scope === scope;
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}
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return def.orig.every((sym) => {
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return !(sym instanceof AST_SymbolConst
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|| sym instanceof AST_SymbolDefun
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|| sym instanceof AST_SymbolLambda);
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});
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}
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function ref_once(tw, compressor, def) {
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return compressor.option("unused")
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&& !def.scope.pinned()
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&& def.references.length - def.recursive_refs == 1
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&& tw.loop_ids.get(def.id) === tw.in_loop;
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}
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function is_immutable(value) {
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if (!value) return false;
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return value.is_constant()
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|| value instanceof AST_Lambda
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|| value instanceof AST_This;
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}
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// A definition "escapes" when its value can leave the point of use.
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// Example: `a = b || c`
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// In this example, "b" and "c" are escaping, because they're going into "a"
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//
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// def.escaped is != 0 when it escapes.
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//
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// When greater than 1, it means that N chained properties will be read off
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// of that def before an escape occurs. This is useful for evaluating
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// property accesses, where you need to know when to stop.
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function mark_escaped(tw, d, scope, node, value, level = 0, depth = 1) {
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var parent = tw.parent(level);
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if (value) {
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if (value.is_constant()) return;
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if (value instanceof AST_ClassExpression) return;
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}
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if (
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parent instanceof AST_Assign && (parent.operator === "=" || parent.logical) && node === parent.right
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|| parent instanceof AST_Call && (node !== parent.expression || parent instanceof AST_New)
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|| parent instanceof AST_Exit && node === parent.value && node.scope !== d.scope
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|| parent instanceof AST_VarDef && node === parent.value
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|| parent instanceof AST_Yield && node === parent.value && node.scope !== d.scope
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) {
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if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1;
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if (!d.escaped || d.escaped > depth) d.escaped = depth;
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return;
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} else if (
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parent instanceof AST_Array
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|| parent instanceof AST_Await
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|| parent instanceof AST_Binary && lazy_op.has(parent.operator)
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|| parent instanceof AST_Conditional && node !== parent.condition
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|| parent instanceof AST_Expansion
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|| parent instanceof AST_Sequence && node === parent.tail_node()
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) {
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mark_escaped(tw, d, scope, parent, parent, level + 1, depth);
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} else if (parent instanceof AST_ObjectKeyVal && node === parent.value) {
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var obj = tw.parent(level + 1);
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mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
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} else if (parent instanceof AST_PropAccess && node === parent.expression) {
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value = read_property(value, parent.property);
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mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
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if (value) return;
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}
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if (level > 0) return;
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if (parent instanceof AST_Sequence && node !== parent.tail_node()) return;
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if (parent instanceof AST_SimpleStatement) return;
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d.direct_access = true;
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}
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const suppress = node => walk(node, node => {
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if (!(node instanceof AST_Symbol)) return;
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var d = node.definition();
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if (!d) return;
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if (node instanceof AST_SymbolRef) d.references.push(node);
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d.fixed = false;
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});
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def_reduce_vars(AST_Accessor, function(tw, descend, compressor) {
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push(tw);
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reset_variables(tw, compressor, this);
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descend();
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pop(tw);
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return true;
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});
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def_reduce_vars(AST_Assign, function(tw, descend, compressor) {
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var node = this;
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if (node.left instanceof AST_Destructuring) {
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suppress(node.left);
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return;
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}
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const finish_walk = () => {
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if (node.logical) {
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node.left.walk(tw);
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push(tw);
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node.right.walk(tw);
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pop(tw);
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return true;
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}
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};
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var sym = node.left;
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if (!(sym instanceof AST_SymbolRef)) return finish_walk();
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var def = sym.definition();
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var safe = safe_to_assign(tw, def, sym.scope, node.right);
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def.assignments++;
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if (!safe) return finish_walk();
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var fixed = def.fixed;
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if (!fixed && node.operator != "=" && !node.logical) return finish_walk();
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var eq = node.operator == "=";
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var value = eq ? node.right : node;
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if (is_modified(compressor, tw, node, value, 0)) return finish_walk();
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def.references.push(sym);
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if (!node.logical) {
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if (!eq) def.chained = true;
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def.fixed = eq ? function() {
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return node.right;
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} : function() {
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return make_node(AST_Binary, node, {
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operator: node.operator.slice(0, -1),
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left: fixed instanceof AST_Node ? fixed : fixed(),
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right: node.right
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});
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};
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}
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if (node.logical) {
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mark(tw, def, false);
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push(tw);
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node.right.walk(tw);
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pop(tw);
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return true;
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}
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mark(tw, def, false);
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node.right.walk(tw);
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mark(tw, def, true);
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mark_escaped(tw, def, sym.scope, node, value, 0, 1);
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return true;
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});
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def_reduce_vars(AST_Binary, function(tw) {
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if (!lazy_op.has(this.operator)) return;
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this.left.walk(tw);
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push(tw);
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this.right.walk(tw);
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pop(tw);
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return true;
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});
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def_reduce_vars(AST_Block, function(tw, descend, compressor) {
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reset_block_variables(compressor, this);
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});
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def_reduce_vars(AST_Case, function(tw) {
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push(tw);
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this.expression.walk(tw);
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pop(tw);
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push(tw);
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walk_body(this, tw);
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pop(tw);
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return true;
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});
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def_reduce_vars(AST_Class, function(tw, descend) {
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clear_flag(this, INLINED);
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push(tw);
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descend();
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pop(tw);
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return true;
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});
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def_reduce_vars(AST_Conditional, function(tw) {
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this.condition.walk(tw);
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push(tw);
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this.consequent.walk(tw);
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pop(tw);
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push(tw);
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this.alternative.walk(tw);
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pop(tw);
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|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Chain, function(tw, descend) {
|
||
|
|
// Chains' conditions apply left-to-right, cumulatively.
|
||
|
|
// If we walk normally we don't go in that order because we would pop before pushing again
|
||
|
|
// Solution: AST_PropAccess and AST_Call push when they are optional, and never pop.
|
||
|
|
// Then we pop everything when they are done being walked.
|
||
|
|
const safe_ids = tw.safe_ids;
|
||
|
|
|
||
|
|
descend();
|
||
|
|
|
||
|
|
// Unroll back to start
|
||
|
|
tw.safe_ids = safe_ids;
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Call, function (tw) {
|
||
|
|
this.expression.walk(tw);
|
||
|
|
|
||
|
|
if (this.optional) {
|
||
|
|
// Never pop -- it's popped at AST_Chain above
|
||
|
|
push(tw);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (const arg of this.args) arg.walk(tw);
|
||
|
|
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_PropAccess, function (tw) {
|
||
|
|
if (!this.optional) return;
|
||
|
|
|
||
|
|
this.expression.walk(tw);
|
||
|
|
|
||
|
|
// Never pop -- it's popped at AST_Chain above
|
||
|
|
push(tw);
|
||
|
|
|
||
|
|
if (this.property instanceof AST_Node) this.property.walk(tw);
|
||
|
|
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Default, function(tw, descend) {
|
||
|
|
push(tw);
|
||
|
|
descend();
|
||
|
|
pop(tw);
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
function mark_lambda(tw, descend, compressor) {
|
||
|
|
clear_flag(this, INLINED);
|
||
|
|
push(tw);
|
||
|
|
reset_variables(tw, compressor, this);
|
||
|
|
if (this.uses_arguments) {
|
||
|
|
descend();
|
||
|
|
pop(tw);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
var iife;
|
||
|
|
if (!this.name
|
||
|
|
&& (iife = tw.parent()) instanceof AST_Call
|
||
|
|
&& iife.expression === this
|
||
|
|
&& !iife.args.some(arg => arg instanceof AST_Expansion)
|
||
|
|
&& this.argnames.every(arg_name => arg_name instanceof AST_Symbol)
|
||
|
|
) {
|
||
|
|
// Virtually turn IIFE parameters into variable definitions:
|
||
|
|
// (function(a,b) {...})(c,d) => (function() {var a=c,b=d; ...})()
|
||
|
|
// So existing transformation rules can work on them.
|
||
|
|
this.argnames.forEach((arg, i) => {
|
||
|
|
if (!arg.definition) return;
|
||
|
|
var d = arg.definition();
|
||
|
|
// Avoid setting fixed when there's more than one origin for a variable value
|
||
|
|
if (d.orig.length > 1) return;
|
||
|
|
if (d.fixed === undefined && (!this.uses_arguments || tw.has_directive("use strict"))) {
|
||
|
|
d.fixed = function() {
|
||
|
|
return iife.args[i] || make_node(AST_Undefined, iife);
|
||
|
|
};
|
||
|
|
tw.loop_ids.set(d.id, tw.in_loop);
|
||
|
|
mark(tw, d, true);
|
||
|
|
} else {
|
||
|
|
d.fixed = false;
|
||
|
|
}
|
||
|
|
});
|
||
|
|
}
|
||
|
|
descend();
|
||
|
|
pop(tw);
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Lambda, mark_lambda);
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Do, function(tw, descend, compressor) {
|
||
|
|
reset_block_variables(compressor, this);
|
||
|
|
const saved_loop = tw.in_loop;
|
||
|
|
tw.in_loop = this;
|
||
|
|
push(tw);
|
||
|
|
this.body.walk(tw);
|
||
|
|
if (has_break_or_continue(this)) {
|
||
|
|
pop(tw);
|
||
|
|
push(tw);
|
||
|
|
}
|
||
|
|
this.condition.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
tw.in_loop = saved_loop;
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_For, function(tw, descend, compressor) {
|
||
|
|
reset_block_variables(compressor, this);
|
||
|
|
if (this.init) this.init.walk(tw);
|
||
|
|
const saved_loop = tw.in_loop;
|
||
|
|
tw.in_loop = this;
|
||
|
|
push(tw);
|
||
|
|
if (this.condition) this.condition.walk(tw);
|
||
|
|
this.body.walk(tw);
|
||
|
|
if (this.step) {
|
||
|
|
if (has_break_or_continue(this)) {
|
||
|
|
pop(tw);
|
||
|
|
push(tw);
|
||
|
|
}
|
||
|
|
this.step.walk(tw);
|
||
|
|
}
|
||
|
|
pop(tw);
|
||
|
|
tw.in_loop = saved_loop;
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_ForIn, function(tw, descend, compressor) {
|
||
|
|
reset_block_variables(compressor, this);
|
||
|
|
suppress(this.init);
|
||
|
|
this.object.walk(tw);
|
||
|
|
const saved_loop = tw.in_loop;
|
||
|
|
tw.in_loop = this;
|
||
|
|
push(tw);
|
||
|
|
this.body.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
tw.in_loop = saved_loop;
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_If, function(tw) {
|
||
|
|
this.condition.walk(tw);
|
||
|
|
push(tw);
|
||
|
|
this.body.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
if (this.alternative) {
|
||
|
|
push(tw);
|
||
|
|
this.alternative.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
}
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_LabeledStatement, function(tw) {
|
||
|
|
push(tw);
|
||
|
|
this.body.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_SymbolCatch, function() {
|
||
|
|
this.definition().fixed = false;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_SymbolRef, function(tw, descend, compressor) {
|
||
|
|
var d = this.definition();
|
||
|
|
d.references.push(this);
|
||
|
|
if (d.references.length == 1
|
||
|
|
&& !d.fixed
|
||
|
|
&& d.orig[0] instanceof AST_SymbolDefun) {
|
||
|
|
tw.loop_ids.set(d.id, tw.in_loop);
|
||
|
|
}
|
||
|
|
var fixed_value;
|
||
|
|
if (d.fixed === undefined || !safe_to_read(tw, d)) {
|
||
|
|
d.fixed = false;
|
||
|
|
} else if (d.fixed) {
|
||
|
|
fixed_value = this.fixed_value();
|
||
|
|
if (
|
||
|
|
fixed_value instanceof AST_Lambda
|
||
|
|
&& is_recursive_ref(tw, d)
|
||
|
|
) {
|
||
|
|
d.recursive_refs++;
|
||
|
|
} else if (fixed_value
|
||
|
|
&& !compressor.exposed(d)
|
||
|
|
&& ref_once(tw, compressor, d)
|
||
|
|
) {
|
||
|
|
d.single_use =
|
||
|
|
fixed_value instanceof AST_Lambda && !fixed_value.pinned()
|
||
|
|
|| fixed_value instanceof AST_Class
|
||
|
|
|| d.scope === this.scope && fixed_value.is_constant_expression();
|
||
|
|
} else {
|
||
|
|
d.single_use = false;
|
||
|
|
}
|
||
|
|
if (is_modified(compressor, tw, this, fixed_value, 0, is_immutable(fixed_value))) {
|
||
|
|
if (d.single_use) {
|
||
|
|
d.single_use = "m";
|
||
|
|
} else {
|
||
|
|
d.fixed = false;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
mark_escaped(tw, d, this.scope, this, fixed_value, 0, 1);
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Toplevel, function(tw, descend, compressor) {
|
||
|
|
this.globals.forEach(function(def) {
|
||
|
|
reset_def(compressor, def);
|
||
|
|
});
|
||
|
|
reset_variables(tw, compressor, this);
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Try, function(tw, descend, compressor) {
|
||
|
|
reset_block_variables(compressor, this);
|
||
|
|
push(tw);
|
||
|
|
walk_body(this, tw);
|
||
|
|
pop(tw);
|
||
|
|
if (this.bcatch) {
|
||
|
|
push(tw);
|
||
|
|
this.bcatch.walk(tw);
|
||
|
|
pop(tw);
|
||
|
|
}
|
||
|
|
if (this.bfinally) this.bfinally.walk(tw);
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_Unary, function(tw) {
|
||
|
|
var node = this;
|
||
|
|
if (node.operator !== "++" && node.operator !== "--") return;
|
||
|
|
var exp = node.expression;
|
||
|
|
if (!(exp instanceof AST_SymbolRef)) return;
|
||
|
|
var def = exp.definition();
|
||
|
|
var safe = safe_to_assign(tw, def, exp.scope, true);
|
||
|
|
def.assignments++;
|
||
|
|
if (!safe) return;
|
||
|
|
var fixed = def.fixed;
|
||
|
|
if (!fixed) return;
|
||
|
|
def.references.push(exp);
|
||
|
|
def.chained = true;
|
||
|
|
def.fixed = function() {
|
||
|
|
return make_node(AST_Binary, node, {
|
||
|
|
operator: node.operator.slice(0, -1),
|
||
|
|
left: make_node(AST_UnaryPrefix, node, {
|
||
|
|
operator: "+",
|
||
|
|
expression: fixed instanceof AST_Node ? fixed : fixed()
|
||
|
|
}),
|
||
|
|
right: make_node(AST_Number, node, {
|
||
|
|
value: 1
|
||
|
|
})
|
||
|
|
});
|
||
|
|
};
|
||
|
|
mark(tw, def, true);
|
||
|
|
return true;
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_VarDef, function(tw, descend) {
|
||
|
|
var node = this;
|
||
|
|
if (node.name instanceof AST_Destructuring) {
|
||
|
|
suppress(node.name);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
var d = node.name.definition();
|
||
|
|
if (node.value) {
|
||
|
|
if (safe_to_assign(tw, d, node.name.scope, node.value)) {
|
||
|
|
d.fixed = function() {
|
||
|
|
return node.value;
|
||
|
|
};
|
||
|
|
tw.loop_ids.set(d.id, tw.in_loop);
|
||
|
|
mark(tw, d, false);
|
||
|
|
descend();
|
||
|
|
mark(tw, d, true);
|
||
|
|
return true;
|
||
|
|
} else {
|
||
|
|
d.fixed = false;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
});
|
||
|
|
|
||
|
|
def_reduce_vars(AST_While, function(tw, descend, compressor) {
|
||
|
|
reset_block_variables(compressor, this);
|
||
|
|
const saved_loop = tw.in_loop;
|
||
|
|
tw.in_loop = this;
|
||
|
|
push(tw);
|
||
|
|
descend();
|
||
|
|
pop(tw);
|
||
|
|
tw.in_loop = saved_loop;
|
||
|
|
return true;
|
||
|
|
});
|