@W-20806053 Implement Private Methods #5711
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,110 @@ | ||
| /* | ||
| * Copyright (c) 2025, salesforce.com, inc. | ||
| * All rights reserved. | ||
| * SPDX-License-Identifier: MIT | ||
| * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT | ||
| */ | ||
| import { DecoratorErrors } from '@lwc/errors'; | ||
| import { PRIVATE_METHOD_PREFIX, PRIVATE_METHOD_METADATA_KEY } from './constants'; | ||
| import { handleError } from './utils'; | ||
| import type { BabelAPI, LwcBabelPluginPass } from './types'; | ||
| import type { NodePath, Visitor } from '@babel/core'; | ||
| import type { types } from '@babel/core'; | ||
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| /** | ||
| * Transforms private method identifiers from #privateMethod to __lwc_component_class_internal_private_privateMethod | ||
| * This function returns a Program visitor that transforms private methods before other plugins process them | ||
| */ | ||
| export default function privateMethodTransform({ | ||
| types: t, | ||
| }: BabelAPI): Visitor<LwcBabelPluginPass> { | ||
| return { | ||
| Program: { | ||
| enter(path: NodePath<types.Program>, state: LwcBabelPluginPass) { | ||
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| const transformedNames = new Set<string>(); | ||
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| // Transform private methods BEFORE any other plugin processes them | ||
| path.traverse( | ||
| { | ||
| ClassPrivateMethod( | ||
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| methodPath: NodePath<types.ClassPrivateMethod>, | ||
| methodState: LwcBabelPluginPass | ||
| ) { | ||
| const key = methodPath.get('key'); | ||
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| // We only want kind: 'method'. | ||
| // Other options not included are 'get', 'set', and 'constructor'. | ||
| const methodKind = 'method'; | ||
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| if (key.isPrivateName() && methodPath.node.kind === methodKind) { | ||
| const node = methodPath.node; | ||
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| // Reject private methods with decorators (e.g. @api, @track, @wire) | ||
| if (node.decorators && node.decorators.length > 0) { | ||
| handleError( | ||
| methodPath, | ||
| { errorInfo: DecoratorErrors.DECORATOR_ON_PRIVATE_METHOD }, | ||
| methodState | ||
| ); | ||
| return; | ||
| } | ||
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| const privateName = key.node.id.name; | ||
| const transformedName = `${PRIVATE_METHOD_PREFIX}${privateName}`; | ||
| const keyReplacement = t.identifier(transformedName); | ||
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| // Create a new ClassMethod node to replace the ClassPrivateMethod | ||
| // https://babeljs.io/docs/babel-types#classmethod | ||
| const classMethod = t.classMethod( | ||
| methodKind, | ||
| keyReplacement, | ||
| node.params, | ||
| node.body, | ||
| node.computed, | ||
| node.static, | ||
| node.generator, | ||
| node.async | ||
| ) as types.ClassMethod; | ||
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| // Preserve TypeScript annotations and source location when present | ||
| if (node.returnType != null) { | ||
| classMethod.returnType = node.returnType; | ||
| } | ||
| if (node.typeParameters != null) { | ||
| classMethod.typeParameters = node.typeParameters; | ||
| } | ||
| if (node.loc != null) { | ||
| classMethod.loc = node.loc; | ||
| } | ||
| // Preserve TypeScript/ECMAScript modifier flags (excluded from t.classMethod() builder) | ||
| if (node.abstract != null) { | ||
| classMethod.abstract = node.abstract; | ||
| } | ||
| if (node.access != null) { | ||
| classMethod.access = node.access; | ||
| } | ||
| if (node.accessibility != null) { | ||
| classMethod.accessibility = node.accessibility; | ||
| } | ||
| if (node.optional != null) { | ||
| classMethod.optional = node.optional; | ||
| } | ||
| if (node.override != null) { | ||
| classMethod.override = node.override; | ||
| } | ||
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| // Replace the entire ClassPrivateMethod node with the new ClassMethod node | ||
| // (we can't just replace the key of type PrivateName with type Identifier) | ||
| methodPath.replaceWith(classMethod); | ||
| transformedNames.add(transformedName); | ||
| } | ||
| }, | ||
| }, | ||
| state | ||
| ); | ||
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| (state.file.metadata as any)[PRIVATE_METHOD_METADATA_KEY] = transformedNames; | ||
| }, | ||
| }, | ||
| }; | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| /* | ||
| * Copyright (c) 2025, salesforce.com, inc. | ||
| * All rights reserved. | ||
| * SPDX-License-Identifier: MIT | ||
| * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT | ||
| */ | ||
| import { DecoratorErrors } from '@lwc/errors'; | ||
| import { PRIVATE_METHOD_PREFIX, PRIVATE_METHOD_METADATA_KEY } from './constants'; | ||
| import type { BabelAPI, LwcBabelPluginPass } from './types'; | ||
| import type { types, NodePath, Visitor } from '@babel/core'; | ||
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| /** | ||
| * Reverses the private method transformation by converting methods with prefix {@link PRIVATE_METHOD_PREFIX} | ||
| * back to ClassPrivateMethod nodes. This runs after babelClassPropertiesPlugin to restore private methods. | ||
| * | ||
| * Round-trip parity: to match {@link ./private-method-transform.ts}, this transform must copy the same | ||
| * properties from ClassMethod onto ClassPrivateMethod when present: returnType, typeParameters, loc, | ||
| * abstract, access, accessibility, optional, override (plus async, generator, computed from the builder). | ||
| * | ||
| * @see {@link ./private-method-transform.ts} for original transformation | ||
| */ | ||
| export default function reversePrivateMethodTransform({ | ||
| types: t, | ||
| }: BabelAPI): Visitor<LwcBabelPluginPass> { | ||
| // Scoped to this plugin instance's closure. Safe as long as each Babel run creates a | ||
| // fresh plugin via LwcReversePrivateMethodTransform(); would accumulate across files if | ||
| // the same instance were ever reused. | ||
| const reverseTransformedNames = new Set<string>(); | ||
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| return { | ||
| ClassMethod(path: NodePath<types.ClassMethod>, state: LwcBabelPluginPass) { | ||
| const key = path.get('key'); | ||
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| // Check if the key is an identifier with our special prefix | ||
| // kind: 'method' | 'get' | 'set' - only 'method' is in scope. | ||
| if (key.isIdentifier() && path.node.kind === 'method') { | ||
| const methodName = key.node.name; | ||
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| // Check if this method has our special prefix | ||
| if (methodName.startsWith(PRIVATE_METHOD_PREFIX)) { | ||
| const forwardTransformedNames: Set<string> | undefined = ( | ||
| state.file.metadata as any | ||
| )[PRIVATE_METHOD_METADATA_KEY]; | ||
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| // If the method was not transformed by the forward pass, it is a | ||
| // user-defined method that collides with the reserved prefix. | ||
| // This will throw an error to tell the user to rename their function. | ||
| if (!forwardTransformedNames || !forwardTransformedNames.has(methodName)) { | ||
| const message = | ||
| DecoratorErrors.PRIVATE_METHOD_NAME_COLLISION.message.replace( | ||
| '{0}', | ||
| methodName | ||
| ); | ||
| throw path.buildCodeFrameError(message); | ||
| } | ||
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| // Extract the original private method name | ||
| const originalPrivateName = methodName.replace(PRIVATE_METHOD_PREFIX, ''); | ||
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| // Create a new ClassPrivateMethod node to replace the ClassMethod | ||
| const node = path.node; | ||
| const classPrivateMethod = t.classPrivateMethod( | ||
| 'method', | ||
| t.privateName(t.identifier(originalPrivateName)), // key | ||
| node.params, | ||
| node.body, | ||
| node.static | ||
| ); | ||
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| // Properties the t.classPrivateMethod() builder doesn't accept (same as forward transform) | ||
| classPrivateMethod.async = node.async; | ||
| classPrivateMethod.generator = node.generator; | ||
| classPrivateMethod.computed = node.computed; | ||
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| // Round-trip parity with private-method-transform: preserve TS annotations and modifier flags | ||
| if (node.returnType != null) classPrivateMethod.returnType = node.returnType; | ||
| if (node.typeParameters != null) | ||
| classPrivateMethod.typeParameters = node.typeParameters; | ||
| if (node.loc != null) classPrivateMethod.loc = node.loc; | ||
| if (node.abstract != null) classPrivateMethod.abstract = node.abstract; | ||
| if (node.access != null) classPrivateMethod.access = node.access; | ||
| if (node.accessibility != null) | ||
| classPrivateMethod.accessibility = node.accessibility; | ||
| if (node.optional != null) classPrivateMethod.optional = node.optional; | ||
| if (node.override != null) classPrivateMethod.override = node.override; | ||
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| // Replace the entire ClassMethod with the new ClassPrivateMethod | ||
| path.replaceWith(classPrivateMethod); | ||
| reverseTransformedNames.add(methodName); | ||
| } | ||
| } | ||
| }, | ||
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| // After all nodes have been visited, verify that every method the forward transform | ||
| // renamed was also restored by the reverse transform. A mismatch here means an | ||
| // intermediate plugin (e.g. @babel/plugin-transform-class-properties) removed or | ||
| // renamed a prefixed method, leaving a mangled name in the final output. | ||
| Program: { | ||
| exit(_path: NodePath<types.Program>, state: LwcBabelPluginPass) { | ||
| const forwardTransformedNames: Set<string> | undefined = ( | ||
| state.file.metadata as any | ||
| )[PRIVATE_METHOD_METADATA_KEY]; | ||
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| if (!forwardTransformedNames) { | ||
| return; | ||
| } | ||
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| // Identify methods that were forward-transformed but never reverse-transformed | ||
| const missingFromReverse: string[] = []; | ||
| for (const name of forwardTransformedNames) { | ||
| if (!reverseTransformedNames.has(name)) { | ||
| missingFromReverse.push(name); | ||
| } | ||
| } | ||
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| if (missingFromReverse.length > 0) { | ||
| throw new Error( | ||
| `Private method transform count mismatch: ` + | ||
| `forward transformed ${forwardTransformedNames.size} method(s), ` + | ||
| `but reverse transformed ${reverseTransformedNames.size}. ` + | ||
| `Missing reverse transforms for: ${missingFromReverse.join(', ')}` | ||
| ); | ||
| } | ||
| }, | ||
| }, | ||
| }; | ||
| } | ||
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