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feat: transform tslib __rest helper using goog.reflect.objectProperty
Typescript when target is less than ES2018 emits `__rest` helper for object spread syntax, which references properties' name via string literal hence breaks Closure Compilation. We transforms such names to appropriate `goog.reflect.objectProperty` calls to make it compatible with Closure Compiler, as described in angular/tsickle#1047.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,93 @@ | ||
| import * as ts from 'typescript'; | ||
| import {TsickleHost} from 'tsickle'; | ||
| import {createGoogCall, findImportedVariable, findGoogRequiredVariable, identifierIsEmitHelper} from './transformer_utils' | ||
|
|
||
| export default abstract class TsHelperTransformer { | ||
| constructor( | ||
| private tsickleHost: TsickleHost, | ||
| private context: ts.TransformationContext, | ||
| private sf: ts.SourceFile | ||
| ) {} | ||
|
|
||
| protected abstract readonly HELPER_NAME: string; | ||
|
|
||
| /** | ||
| * Determines whether the given node is a tslib helper call. Such a call expression looks similar | ||
| * to usual `__decorate(...)` function calls, except that the identifier node __decorate has | ||
| * a hidden emitNode property. This is encoded in `identifierIsEmitHelper` call and this method | ||
| * uses it. | ||
| */ | ||
| protected isTsGeneratedHelperCall(node: ts.Node): node is ts.CallExpression { | ||
| if (!ts.isCallExpression(node)) return false; | ||
| const caller = node.expression; | ||
| if (!ts.isIdentifier(caller)) return false; | ||
| if (caller.escapedText !== ts.escapeLeadingUnderscores(this.HELPER_NAME)) return false; | ||
| if (!identifierIsEmitHelper(caller)) return false; | ||
| return true; | ||
| } | ||
|
|
||
| /** | ||
| * Queries whether a visiting node is a call to tslib helper functions, such as | ||
| * `tslib_1.__decorate(...)` that is generated by the TS compiler, and if so, returns a new node. | ||
| * Otherwise, return undefined. | ||
| */ | ||
| protected abstract onHelperCall(node: ts.CallExpression, googReflectImport: ts.Identifier): ts.CallExpression | ||
|
|
||
| private maybeTsGeneratedHelperCall(node: ts.Node, googReflectImport: ts.Identifier): ts.Node { | ||
| if (!this.isTsGeneratedHelperCall(node)) return; | ||
| return this.onHelperCall(node, googReflectImport); | ||
| } | ||
|
|
||
| transformSourceFile(): ts.SourceFile { | ||
| const sf = this.sf; | ||
| // There's nothing to do when tslib was not imported to the module. | ||
| if (!findImportedVariable(sf, 'tslib')) return sf; | ||
| const existingGoogReflectImport = | ||
| findImportedVariable(sf, 'goog:goog.reflect') || | ||
| findGoogRequiredVariable(sf, 'goog.reflect'); | ||
| const googReflectImport = | ||
| existingGoogReflectImport || | ||
| ts.createIdentifier(`tscc_goog_reflect_injected`); | ||
|
|
||
| let foundTransformedDecorateCall = false; | ||
| const visitor = (node: ts.Node): ts.Node => { | ||
| let transformed = this.maybeTsGeneratedHelperCall(node, googReflectImport); | ||
| if (transformed) { | ||
| foundTransformedDecorateCall = true; | ||
| return transformed; | ||
| } | ||
| return ts.visitEachChild(node, visitor, this.context); | ||
| }; | ||
|
|
||
| const newSf = visitor(sf) as ts.SourceFile; | ||
| if (!foundTransformedDecorateCall) return newSf; | ||
| const stmts = this.combineStatements( | ||
| newSf.statements.slice(), | ||
| existingGoogReflectImport ? undefined : googReflectImport | ||
| ); | ||
|
|
||
| return ts.updateSourceFileNode(newSf, ts.setTextRange(ts.createNodeArray(stmts), newSf.statements)); | ||
| } | ||
|
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||
| protected combineStatements(stmts: ts.Statement[], googReflectImport?: ts.Identifier) { | ||
| if (!googReflectImport) return stmts; | ||
| const requireReflect = this.createGoogReflectRequire(googReflectImport); | ||
| stmts.unshift(requireReflect); | ||
| return stmts; | ||
| } | ||
|
|
||
| private createGoogReflectRequire(ident: ts.Identifier) { | ||
| return ts.createVariableStatement( | ||
| undefined, | ||
| ts.createVariableDeclarationList( | ||
| [ | ||
| ts.createVariableDeclaration( | ||
| ident, | ||
| undefined, | ||
| createGoogCall("require", ts.createStringLiteral('goog.reflect')) | ||
| ) | ||
| ], | ||
| this.tsickleHost.es5Mode ? undefined : ts.NodeFlags.Const) | ||
| ); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| import * as ts from 'typescript'; | ||
| import {TsickleHost} from 'tsickle'; | ||
| import TsHelperTransformer from './TsHelperTransformer'; | ||
|
|
||
| export default function decoratorPropertyTransformer(tsickleHost: TsickleHost): | ||
| (context: ts.TransformationContext) => ts.Transformer<ts.SourceFile> { | ||
| return (context: ts.TransformationContext) => { | ||
| return (sf: ts.SourceFile) => { | ||
| return new RestHelperTransformer(tsickleHost, context, sf).transformSourceFile(); | ||
| }; | ||
| }; | ||
| } | ||
|
|
||
| class RestHelperTransformer extends TsHelperTransformer { | ||
| protected HELPER_NAME = "__rest"; | ||
| /** | ||
| * Rest helper call signature: | ||
| * __rest(<target>, [propertiesArray]) | ||
| */ | ||
| protected onHelperCall(node: ts.CallExpression, googReflectImport: ts.Identifier) { | ||
| let caller = node.expression; | ||
| let target = node.arguments[0]; | ||
| let propertiesArray = <ts.ArrayLiteralExpression>node.arguments[1]; | ||
|
|
||
| // Create new array with goog.reflect.objectProperty | ||
| // Note that for computed properties, Typescript creates a temp variable | ||
| // that stores the computed value (_p), and put | ||
| // ``` | ||
| // typeof _p === 'symbol' ? _c : _c + "" | ||
| // ``` | ||
| const convertedArray = ts.setTextRange( | ||
| ts.createArrayLiteral( | ||
| propertiesArray.elements.map((propNameLiteral: ts.Expression) => { | ||
| if (!ts.isStringLiteral(propNameLiteral)) return propNameLiteral; | ||
| const googReflectObjectProperty = ts.setTextRange( | ||
| ts.createCall( | ||
| ts.createPropertyAccess( | ||
| googReflectImport, | ||
| ts.createIdentifier('objectProperty') | ||
| ), | ||
| undefined, | ||
| [ | ||
| ts.createStringLiteral(propNameLiteral.text), | ||
| ts.getMutableClone(target) | ||
| ] | ||
| ), | ||
| propNameLiteral | ||
| ); | ||
| return googReflectObjectProperty; | ||
| }) | ||
| ), | ||
| propertiesArray | ||
| ); | ||
| const restArgs = node.arguments.slice(); | ||
| restArgs.splice(1, 1, convertedArray); | ||
| const newCallExpression = ts.createCall(caller, undefined, restArgs); | ||
| return newCallExpression; | ||
| } | ||
| } |
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