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Diffstat (limited to 'node_modules/terser/lib/compress/drop-side-effect-free.js')
| -rw-r--r-- | node_modules/terser/lib/compress/drop-side-effect-free.js | 375 |
1 files changed, 0 insertions, 375 deletions
diff --git a/node_modules/terser/lib/compress/drop-side-effect-free.js b/node_modules/terser/lib/compress/drop-side-effect-free.js deleted file mode 100644 index 8f31df7f..00000000 --- a/node_modules/terser/lib/compress/drop-side-effect-free.js +++ /dev/null @@ -1,375 +0,0 @@ -/*********************************************************************** - - A JavaScript tokenizer / parser / beautifier / compressor. - https://github.com/mishoo/UglifyJS2 - - -------------------------------- (C) --------------------------------- - - Author: Mihai Bazon - <mihai.bazon@gmail.com> - http://mihai.bazon.net/blog - - Distributed under the BSD license: - - Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com> - - Redistribution and use in source and binary forms, with or without - modification, are permitted provided that the following conditions - are met: - - * Redistributions of source code must retain the above - copyright notice, this list of conditions and the following - disclaimer. - - * Redistributions in binary form must reproduce the above - copyright notice, this list of conditions and the following - disclaimer in the documentation and/or other materials - provided with the distribution. - - THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY - EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR - PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE - LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, - OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, - PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR - PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR - TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF - THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - SUCH DAMAGE. - - ***********************************************************************/ - -import { - AST_Accessor, - AST_Array, - AST_Arrow, - AST_Assign, - AST_Binary, - AST_Call, - AST_Chain, - AST_Class, - AST_ClassStaticBlock, - AST_ClassProperty, - AST_ConciseMethod, - AST_Conditional, - AST_Constant, - AST_DefClass, - AST_Dot, - AST_Expansion, - AST_Function, - AST_Node, - AST_Number, - AST_Object, - AST_ObjectGetter, - AST_ObjectKeyVal, - AST_ObjectProperty, - AST_ObjectSetter, - AST_PropAccess, - AST_Scope, - AST_Sequence, - AST_SimpleStatement, - AST_Sub, - AST_SymbolRef, - AST_TemplateSegment, - AST_TemplateString, - AST_This, - AST_Unary, -} from "../ast.js"; -import { make_node, return_null, return_this } from "../utils/index.js"; -import { first_in_statement } from "../utils/first_in_statement.js"; - -import { pure_prop_access_globals } from "./native-objects.js"; -import { lazy_op, unary_side_effects, is_nullish_shortcircuited } from "./inference.js"; -import { WRITE_ONLY, set_flag, clear_flag } from "./compressor-flags.js"; -import { make_sequence, is_func_expr, is_iife_call } from "./common.js"; - -// AST_Node#drop_side_effect_free() gets called when we don't care about the value, -// only about side effects. We'll be defining this method for each node type in this module -// -// Examples: -// foo++ -> foo++ -// 1 + func() -> func() -// 10 -> (nothing) -// knownPureFunc(foo++) -> foo++ - -function def_drop_side_effect_free(node, func) { - node.DEFMETHOD("drop_side_effect_free", func); -} - -// Drop side-effect-free elements from an array of expressions. -// Returns an array of expressions with side-effects or null -// if all elements were dropped. Note: original array may be -// returned if nothing changed. -function trim(nodes, compressor, first_in_statement) { - var len = nodes.length; - if (!len) return null; - - var ret = [], changed = false; - for (var i = 0; i < len; i++) { - var node = nodes[i].drop_side_effect_free(compressor, first_in_statement); - changed |= node !== nodes[i]; - if (node) { - ret.push(node); - first_in_statement = false; - } - } - return changed ? ret.length ? ret : null : nodes; -} - -def_drop_side_effect_free(AST_Node, return_this); -def_drop_side_effect_free(AST_Constant, return_null); -def_drop_side_effect_free(AST_This, return_null); - -def_drop_side_effect_free(AST_Call, function (compressor, first_in_statement) { - if (is_nullish_shortcircuited(this, compressor)) { - return this.expression.drop_side_effect_free(compressor, first_in_statement); - } - - if (!this.is_callee_pure(compressor)) { - if (this.expression.is_call_pure(compressor)) { - var exprs = this.args.slice(); - exprs.unshift(this.expression.expression); - exprs = trim(exprs, compressor, first_in_statement); - return exprs && make_sequence(this, exprs); - } - if (is_func_expr(this.expression) - && (!this.expression.name || !this.expression.name.definition().references.length)) { - var node = this.clone(); - node.expression.process_expression(false, compressor); - return node; - } - return this; - } - - var args = trim(this.args, compressor, first_in_statement); - return args && make_sequence(this, args); -}); - -def_drop_side_effect_free(AST_Accessor, return_null); - -def_drop_side_effect_free(AST_Function, return_null); - -def_drop_side_effect_free(AST_Arrow, return_null); - -def_drop_side_effect_free(AST_Class, function (compressor) { - const with_effects = []; - const trimmed_extends = this.extends && this.extends.drop_side_effect_free(compressor); - if (trimmed_extends) - with_effects.push(trimmed_extends); - - for (const prop of this.properties) { - if (prop instanceof AST_ClassStaticBlock) { - if (prop.has_side_effects(compressor)) { - return this; // Be cautious about these - } - } else { - const trimmed_prop = prop.drop_side_effect_free(compressor); - if (trimmed_prop) { - if (trimmed_prop.contains_this()) return this; - - with_effects.push(trimmed_prop); - } - } - } - - if (!with_effects.length) - return null; - - const exprs = make_sequence(this, with_effects); - if (this instanceof AST_DefClass) { - // We want a statement - return make_node(AST_SimpleStatement, this, { body: exprs }); - } else { - return exprs; - } -}); - -def_drop_side_effect_free(AST_ClassProperty, function (compressor) { - const key = this.computed_key() && this.key.drop_side_effect_free(compressor); - - const value = this.static && this.value - && this.value.drop_side_effect_free(compressor); - - if (key && value) - return make_sequence(this, [key, value]); - return key || value || null; -}); - -def_drop_side_effect_free(AST_Binary, function (compressor, first_in_statement) { - var right = this.right.drop_side_effect_free(compressor); - if (!right) - return this.left.drop_side_effect_free(compressor, first_in_statement); - if (lazy_op.has(this.operator)) { - if (right === this.right) - return this; - var node = this.clone(); - node.right = right; - return node; - } else { - var left = this.left.drop_side_effect_free(compressor, first_in_statement); - if (!left) - return this.right.drop_side_effect_free(compressor, first_in_statement); - return make_sequence(this, [left, right]); - } -}); - -def_drop_side_effect_free(AST_Assign, function (compressor) { - if (this.logical) - return this; - - var left = this.left; - if (left.has_side_effects(compressor) - || compressor.has_directive("use strict") - && left instanceof AST_PropAccess - && left.expression.is_constant()) { - return this; - } - set_flag(this, WRITE_ONLY); - while (left instanceof AST_PropAccess) { - left = left.expression; - } - if (left.is_constant_expression(compressor.find_parent(AST_Scope))) { - return this.right.drop_side_effect_free(compressor); - } - return this; -}); - -def_drop_side_effect_free(AST_Conditional, function (compressor) { - var consequent = this.consequent.drop_side_effect_free(compressor); - var alternative = this.alternative.drop_side_effect_free(compressor); - if (consequent === this.consequent && alternative === this.alternative) - return this; - if (!consequent) - return alternative ? make_node(AST_Binary, this, { - operator: "||", - left: this.condition, - right: alternative - }) : this.condition.drop_side_effect_free(compressor); - if (!alternative) - return make_node(AST_Binary, this, { - operator: "&&", - left: this.condition, - right: consequent - }); - var node = this.clone(); - node.consequent = consequent; - node.alternative = alternative; - return node; -}); - -def_drop_side_effect_free(AST_Unary, function (compressor, first_in_statement) { - if (unary_side_effects.has(this.operator)) { - if (!this.expression.has_side_effects(compressor)) { - set_flag(this, WRITE_ONLY); - } else { - clear_flag(this, WRITE_ONLY); - } - return this; - } - if (this.operator == "typeof" && this.expression instanceof AST_SymbolRef) - return null; - var expression = this.expression.drop_side_effect_free(compressor, first_in_statement); - if (first_in_statement && expression && is_iife_call(expression)) { - if (expression === this.expression && this.operator == "!") - return this; - return expression.negate(compressor, first_in_statement); - } - return expression; -}); - -def_drop_side_effect_free(AST_SymbolRef, function (compressor) { - const safe_access = this.is_declared(compressor) - || pure_prop_access_globals.has(this.name); - return safe_access ? null : this; -}); - -def_drop_side_effect_free(AST_Object, function (compressor, first_in_statement) { - var values = trim(this.properties, compressor, first_in_statement); - return values && make_sequence(this, values); -}); - -def_drop_side_effect_free(AST_ObjectProperty, function (compressor, first_in_statement) { - const computed_key = this instanceof AST_ObjectKeyVal && this.key instanceof AST_Node; - const key = computed_key && this.key.drop_side_effect_free(compressor, first_in_statement); - const value = this.value && this.value.drop_side_effect_free(compressor, first_in_statement); - if (key && value) { - return make_sequence(this, [key, value]); - } - return key || value; -}); - -def_drop_side_effect_free(AST_ConciseMethod, function () { - return this.computed_key() ? this.key : null; -}); - -def_drop_side_effect_free(AST_ObjectGetter, function () { - return this.computed_key() ? this.key : null; -}); - -def_drop_side_effect_free(AST_ObjectSetter, function () { - return this.computed_key() ? this.key : null; -}); - -def_drop_side_effect_free(AST_Array, function (compressor, first_in_statement) { - var values = trim(this.elements, compressor, first_in_statement); - return values && make_sequence(this, values); -}); - -def_drop_side_effect_free(AST_Dot, function (compressor, first_in_statement) { - if (is_nullish_shortcircuited(this, compressor)) { - return this.expression.drop_side_effect_free(compressor, first_in_statement); - } - if (!this.optional && this.expression.may_throw_on_access(compressor)) { - return this; - } - - return this.expression.drop_side_effect_free(compressor, first_in_statement); -}); - -def_drop_side_effect_free(AST_Sub, function (compressor, first_in_statement) { - if (is_nullish_shortcircuited(this, compressor)) { - return this.expression.drop_side_effect_free(compressor, first_in_statement); - } - if (!this.optional && this.expression.may_throw_on_access(compressor)) { - return this; - } - - var property = this.property.drop_side_effect_free(compressor); - if (property && this.optional) return this; - - var expression = this.expression.drop_side_effect_free(compressor, first_in_statement); - - if (expression && property) return make_sequence(this, [expression, property]); - return expression || property; -}); - -def_drop_side_effect_free(AST_Chain, function (compressor, first_in_statement) { - return this.expression.drop_side_effect_free(compressor, first_in_statement); -}); - -def_drop_side_effect_free(AST_Sequence, function (compressor) { - var last = this.tail_node(); - var expr = last.drop_side_effect_free(compressor); - if (expr === last) - return this; - var expressions = this.expressions.slice(0, -1); - if (expr) - expressions.push(expr); - if (!expressions.length) { - return make_node(AST_Number, this, { value: 0 }); - } - return make_sequence(this, expressions); -}); - -def_drop_side_effect_free(AST_Expansion, function (compressor, first_in_statement) { - return this.expression.drop_side_effect_free(compressor, first_in_statement); -}); - -def_drop_side_effect_free(AST_TemplateSegment, return_null); - -def_drop_side_effect_free(AST_TemplateString, function (compressor) { - var values = trim(this.segments, compressor, first_in_statement); - return values && make_sequence(this, values); -}); |