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16 KiB
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{"version":3,"names":["declare","api","opts","assertVersion","throwIfClosureRequired","tdz","tdzEnabled","Error","name","visitor","traverse","visitors","merge","annexB33FunctionsVisitor","Loop","path","state","isForStatement","headPath","get","isForXStatement","needsBodyWrap","markNeedsBodyWrap","buildCodeFrameError","body","bodyScope","isBlockStatement","scope","bindings","getLoopBodyBindings","binding","capturedInClosure","getUsageInBody","captured","updatedBindingsUsages","Map","isBlockScoped","node","names","Object","keys","getBindingIdentifiers","headScope","hasOwnBinding","getOwnBinding","crawl","usages","hasConstantViolations","parent","hasBinding","hasGlobal","newName","generateUid","rename","push","set","varPath","wrapLoopBody","isVariableDeclaration","transformBlockScopedVariable","unwrapFunctionEnvironment","VariableDeclaration","ClassDeclaration","id","parentPath","isVarScope","noUids","conflictingFunctionsVisitor","Scope","kind","skip","dynamicTDZNames","validateUsage","bindingNames","isInLoop","isVarInLoopHead","length","decl","declarations","init","buildUndefinedNode","blockScope","varScope","getFunctionParent","getProgramParent","moveBindingTo","t","identifier","addHelper","isLetOrConst","isLoop","isFunctionParent","BLOCK_SCOPED_SYMBOL"],"sources":["../src/index.ts"],"sourcesContent":["import { declare } from \"@babel/helper-plugin-utils\";\nimport type { NodePath, Scope, Visitor } from \"@babel/traverse\";\nimport { type PluginPass, types as t, traverse } from \"@babel/core\";\n\nimport {\n getLoopBodyBindings,\n getUsageInBody,\n isVarInLoopHead,\n wrapLoopBody,\n} from \"./loop\";\nimport { validateUsage } from \"./validation\";\nimport { annexB33FunctionsVisitor, isVarScope } from \"./annex-B_3_3\";\n\nexport interface Options {\n tdz?: boolean;\n throwIfClosureRequired?: boolean;\n}\n\nexport default declare((api, opts: Options) => {\n api.assertVersion(7);\n\n const { throwIfClosureRequired = false, tdz: tdzEnabled = false } = opts;\n if (typeof throwIfClosureRequired !== \"boolean\") {\n throw new Error(`.throwIfClosureRequired must be a boolean, or undefined`);\n }\n if (typeof tdzEnabled !== \"boolean\") {\n throw new Error(`.tdz must be a boolean, or undefined`);\n }\n\n return {\n name: \"transform-block-scoping\",\n\n visitor: traverse.visitors.merge<PluginPass>([\n // TODO: Consider adding an option to control Annex B behavior.\n annexB33FunctionsVisitor,\n {\n Loop(path: NodePath<t.Loop>, state) {\n const isForStatement = path.isForStatement();\n const headPath = isForStatement\n ? path.get(\"init\")\n : path.isForXStatement()\n ? path.get(\"left\")\n : null;\n\n let needsBodyWrap = false;\n const markNeedsBodyWrap = () => {\n if (throwIfClosureRequired) {\n throw path.buildCodeFrameError(\n \"Compiling let/const in this block would add a closure \" +\n \"(throwIfClosureRequired).\",\n );\n }\n needsBodyWrap = true;\n };\n\n const body = path.get(\"body\");\n let bodyScope: Scope | null;\n if (body.isBlockStatement()) {\n bodyScope = body.scope;\n\n const bindings = getLoopBodyBindings(path);\n for (const binding of bindings) {\n const { capturedInClosure } = getUsageInBody(binding, path);\n if (capturedInClosure) markNeedsBodyWrap();\n }\n }\n\n const captured: string[] = [];\n const updatedBindingsUsages: Map<string, NodePath<t.Identifier>[]> =\n new Map();\n\n if (headPath && isBlockScoped(headPath.node)) {\n const names = Object.keys(headPath.getBindingIdentifiers());\n const headScope = headPath.scope;\n\n for (let name of names) {\n if (bodyScope?.hasOwnBinding(name)) continue; // shadowed\n\n let binding = headScope.getOwnBinding(name);\n if (!binding) {\n headScope.crawl();\n binding = headScope.getOwnBinding(name);\n }\n const { usages, capturedInClosure, hasConstantViolations } =\n getUsageInBody(binding, path);\n\n if (\n headScope.parent.hasBinding(name) ||\n headScope.parent.hasGlobal(name)\n ) {\n // If the binding is not captured, there is no need\n // of adding it to the closure param. However, rename\n // it if it shadows an outer binding, because the\n // closure will be moved to an outer level.\n const newName = headScope.generateUid(name);\n headScope.rename(name, newName);\n name = newName;\n }\n\n if (capturedInClosure) {\n markNeedsBodyWrap();\n captured.push(name);\n }\n\n if (isForStatement && hasConstantViolations) {\n updatedBindingsUsages.set(name, usages);\n }\n }\n }\n\n if (needsBodyWrap) {\n const varPath = wrapLoopBody(path, captured, updatedBindingsUsages);\n\n if (headPath?.isVariableDeclaration<t.Node>()) {\n // If we wrap the loop body, we transform the var\n // declaration in the loop head now, to avoid\n // invalid references that break other plugins:\n //\n // for (let head of x) {\n // let i = head;\n // setTimeout(() => i);\n // }\n //\n // would become\n //\n // function _loop() {\n // let i = head;\n // setTimeout(() => i);\n // }\n // for (let head of x) _loop();\n //\n // which references `head` in a scope where it's not visible.\n transformBlockScopedVariable(headPath, state, tdzEnabled);\n }\n\n varPath.get(\"declarations.0.init\").unwrapFunctionEnvironment();\n }\n },\n\n VariableDeclaration(path, state) {\n transformBlockScopedVariable(path, state, tdzEnabled);\n },\n\n // Class declarations are block-scoped: if there is\n // a class declaration in a nested block that conflicts\n // with an outer block-scoped binding, rename it.\n // TODO: Should this be moved to the classes plugin?\n ClassDeclaration(path) {\n const { id } = path.node;\n if (!id) return;\n\n const { scope } = path.parentPath;\n if (\n !isVarScope(scope) &&\n scope.parent.hasBinding(id.name, { noUids: true })\n ) {\n path.scope.rename(id.name);\n }\n },\n },\n ]),\n };\n});\n\nconst conflictingFunctionsVisitor: Visitor<{ names: string[] }> = {\n Scope(path, { names }) {\n for (const name of names) {\n const binding = path.scope.getOwnBinding(name);\n if (binding && binding.kind === \"hoisted\") {\n path.scope.rename(name);\n }\n }\n },\n \"Expression|Declaration\"(path) {\n path.skip();\n },\n};\n\nfunction transformBlockScopedVariable(\n path: NodePath<t.VariableDeclaration>,\n state: PluginPass,\n tdzEnabled: boolean,\n) {\n if (!isBlockScoped(path.node)) return;\n\n const dynamicTDZNames = validateUsage(path, state, tdzEnabled);\n\n path.node.kind = \"var\";\n\n const bindingNames = Object.keys(path.getBindingIdentifiers());\n for (const name of bindingNames) {\n const binding = path.scope.getOwnBinding(name);\n if (!binding) continue;\n binding.kind = \"var\";\n }\n\n if (\n (isInLoop(path) && !isVarInLoopHead(path)) ||\n dynamicTDZNames.length > 0\n ) {\n for (const decl of path.node.declarations) {\n // We explicitly add `void 0` to cases like\n // for (;;) { let a; }\n // to make sure that `a` doesn't keep the value from\n // the previous iteration.\n decl.init ??= path.scope.buildUndefinedNode();\n }\n }\n\n const blockScope = path.scope;\n const varScope =\n blockScope.getFunctionParent() || blockScope.getProgramParent();\n\n if (varScope !== blockScope) {\n for (const name of bindingNames) {\n let newName = name;\n if (\n // We pass `noUids` true because, if `name` was a generated\n // UID, it has been used to declare the current variable in\n // a nested scope and thus we don't need to assume that it\n // may be declared (but not registered yet) in an upper one.\n blockScope.parent.hasBinding(name, { noUids: true }) ||\n blockScope.parent.hasGlobal(name)\n ) {\n newName = blockScope.generateUid(name);\n blockScope.rename(name, newName);\n }\n\n blockScope.moveBindingTo(newName, varScope);\n }\n }\n\n blockScope.path.traverse(conflictingFunctionsVisitor, {\n names: bindingNames,\n });\n\n for (const name of dynamicTDZNames) {\n path.scope.push({\n id: t.identifier(name),\n init: state.addHelper(\"temporalUndefined\"),\n });\n }\n}\n\nfunction isLetOrConst(kind: string): kind is \"let\" | \"const\" {\n return kind === \"let\" || kind === \"const\";\n}\n\nfunction 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