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Extract unshadow logic to utils file
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89 changes: 89 additions & 0 deletions
89
packages/babel-plugin-transform-parameters/src/shadow-utils.ts
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,89 @@ | ||
| import { types as t } from "@babel/core"; | ||
| import type { NodePath, Scope, Visitor } from "@babel/traverse"; | ||
|
|
||
| type State = { | ||
| needsOuterBinding: boolean; | ||
| scope: Scope; | ||
| }; | ||
|
|
||
| export const iifeVisitor: Visitor<State> = { | ||
| "ReferencedIdentifier|BindingIdentifier"( | ||
| path: NodePath<t.Identifier>, | ||
| state, | ||
| ) { | ||
| const { scope, node } = path; | ||
| const { name } = node; | ||
|
|
||
| if ( | ||
| name === "eval" || | ||
| (scope.getBinding(name) === state.scope.parent.getBinding(name) && | ||
| state.scope.hasOwnBinding(name)) | ||
| ) { | ||
| state.needsOuterBinding = true; | ||
| path.stop(); | ||
| } | ||
| }, | ||
| // type annotations don't use or introduce "real" bindings | ||
| "TypeAnnotation|TSTypeAnnotation|TypeParameterDeclaration|TSTypeParameterDeclaration": | ||
| (path: NodePath) => path.skip(), | ||
| }; | ||
|
|
||
| export function collectShadowedParamsNames( | ||
| param: NodePath<t.Function["params"][number]>, | ||
| functionScope: Scope, | ||
| shadowedParams: Set<string>, | ||
| ) { | ||
| for (const name of Object.keys(param.getBindingIdentifiers())) { | ||
| const constantViolations = functionScope.bindings[name]?.constantViolations; | ||
| if (constantViolations) { | ||
| for (const redeclarator of constantViolations) { | ||
| const node = redeclarator.node; | ||
| // If a constant violation is a var or a function declaration, | ||
| // we first check to see if it's a var without an init. | ||
| // If so, we remove that declarator. | ||
| // Otherwise, we have to wrap it in an IIFE. | ||
| switch (node.type) { | ||
| case "VariableDeclarator": { | ||
| if (node.init === null) { | ||
| const declaration = redeclarator.parentPath; | ||
| // The following uninitialized var declarators should not be removed | ||
| // for (var x in {}) | ||
| // for (var x;;) | ||
| if ( | ||
| !declaration.parentPath.isFor() || | ||
| declaration.parentPath.get("body") === declaration | ||
| ) { | ||
| redeclarator.remove(); | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| shadowedParams.add(name); | ||
| break; | ||
| } | ||
| case "FunctionDeclaration": | ||
| shadowedParams.add(name); | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| export function buildScopeIIFE( | ||
| shadowedParams: Set<string>, | ||
| body: t.BlockStatement, | ||
| ) { | ||
| const args = []; | ||
| const params = []; | ||
|
|
||
| for (const name of shadowedParams) { | ||
| // We create them twice; the other option is to use t.cloneNode | ||
| args.push(t.identifier(name)); | ||
| params.push(t.identifier(name)); | ||
| } | ||
|
|
||
| return t.returnStatement( | ||
| t.callExpression(t.arrowFunctionExpression(params, body), args), | ||
| ); | ||
| } |