forked from rollup/rollup
/
ArrowFunctionExpression.ts
155 lines (141 loc) · 4.58 KB
/
ArrowFunctionExpression.ts
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import type { NormalizedTreeshakingOptions } from '../../rollup/types';
import { type CallOptions, NO_ARGS } from '../CallOptions';
import {
BROKEN_FLOW_NONE,
type HasEffectsContext,
type InclusionContext
} from '../ExecutionContext';
import ReturnValueScope from '../scopes/ReturnValueScope';
import type Scope from '../scopes/Scope';
import { type ObjectPath, UNKNOWN_PATH, UnknownKey } from '../utils/PathTracker';
import BlockStatement from './BlockStatement';
import Identifier from './Identifier';
import * as NodeType from './NodeType';
import RestElement from './RestElement';
import type SpreadElement from './SpreadElement';
import { type ExpressionEntity, UNKNOWN_EXPRESSION } from './shared/Expression';
import {
type ExpressionNode,
type GenericEsTreeNode,
type IncludeChildren,
NodeBase
} from './shared/Node';
import type { PatternNode } from './shared/Pattern';
export default class ArrowFunctionExpression extends NodeBase {
declare async: boolean;
declare body: BlockStatement | ExpressionNode;
declare params: readonly PatternNode[];
declare preventChildBlockScope: true;
declare scope: ReturnValueScope;
declare type: NodeType.tArrowFunctionExpression;
private deoptimizedReturn = false;
createScope(parentScope: Scope): void {
this.scope = new ReturnValueScope(parentScope, this.context);
}
deoptimizePath(path: ObjectPath): void {
// A reassignment of UNKNOWN_PATH is considered equivalent to having lost track
// which means the return expression needs to be reassigned
if (path.length === 1 && path[0] === UnknownKey) {
this.scope.getReturnExpression().deoptimizePath(UNKNOWN_PATH);
}
}
// Arrow functions do not mutate their context
deoptimizeThisOnEventAtPath(): void {}
getReturnExpressionWhenCalledAtPath(path: ObjectPath): ExpressionEntity {
if (path.length !== 0) {
return UNKNOWN_EXPRESSION;
}
if (this.async) {
if (!this.deoptimizedReturn) {
this.deoptimizedReturn = true;
this.scope.getReturnExpression().deoptimizePath(UNKNOWN_PATH);
this.context.requestTreeshakingPass();
}
return UNKNOWN_EXPRESSION;
}
return this.scope.getReturnExpression();
}
hasEffects(): boolean {
return false;
}
hasEffectsWhenAccessedAtPath(path: ObjectPath): boolean {
return path.length > 1;
}
hasEffectsWhenAssignedAtPath(path: ObjectPath): boolean {
return path.length > 1;
}
hasEffectsWhenCalledAtPath(
path: ObjectPath,
_callOptions: CallOptions,
context: HasEffectsContext
): boolean {
if (path.length > 0) return true;
if (this.async) {
const { propertyReadSideEffects } = this.context.options
.treeshake as NormalizedTreeshakingOptions;
const returnExpression = this.scope.getReturnExpression();
if (
returnExpression.hasEffectsWhenCalledAtPath(
['then'],
{ args: NO_ARGS, thisParam: null, withNew: false },
context
) ||
(propertyReadSideEffects &&
(propertyReadSideEffects === 'always' ||
returnExpression.hasEffectsWhenAccessedAtPath(['then'], context)))
) {
return true;
}
}
for (const param of this.params) {
if (param.hasEffects(context)) return true;
}
const { ignore, brokenFlow } = context;
context.ignore = {
breaks: false,
continues: false,
labels: new Set(),
returnYield: true
};
if (this.body.hasEffects(context)) return true;
context.ignore = ignore;
context.brokenFlow = brokenFlow;
return false;
}
include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
this.included = true;
for (const param of this.params) {
if (!(param instanceof Identifier)) {
param.include(context, includeChildrenRecursively);
}
}
const { brokenFlow } = context;
context.brokenFlow = BROKEN_FLOW_NONE;
this.body.include(context, includeChildrenRecursively);
context.brokenFlow = brokenFlow;
}
includeCallArguments(
context: InclusionContext,
args: readonly (ExpressionNode | SpreadElement)[]
): void {
this.scope.includeCallArguments(context, args);
}
initialise(): void {
this.scope.addParameterVariables(
this.params.map(param => param.declare('parameter', UNKNOWN_EXPRESSION)),
this.params[this.params.length - 1] instanceof RestElement
);
if (this.body instanceof BlockStatement) {
this.body.addImplicitReturnExpressionToScope();
} else {
this.scope.addReturnExpression(this.body);
}
}
parseNode(esTreeNode: GenericEsTreeNode): void {
if (esTreeNode.body.type === NodeType.BlockStatement) {
this.body = new BlockStatement(esTreeNode.body, this, this.scope.hoistedBodyVarScope);
}
super.parseNode(esTreeNode);
}
}
ArrowFunctionExpression.prototype.preventChildBlockScope = true;