"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.getLoopBodyBindings = getLoopBodyBindings;
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exports.getUsageInBody = getUsageInBody;
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exports.isVarInLoopHead = isVarInLoopHead;
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exports.wrapLoopBody = wrapLoopBody;
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var _core = require("@babel/core");
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const collectLoopBodyBindingsVisitor = {
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"Expression|Declaration|Loop"(path) {
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path.skip();
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},
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Scope(path, state) {
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if (path.isFunctionParent()) path.skip();
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const {
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bindings
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} = path.scope;
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for (const name of Object.keys(bindings)) {
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const binding = bindings[name];
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if (binding.kind === "let" || binding.kind === "const" || binding.kind === "hoisted") {
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state.blockScoped.push(binding);
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}
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}
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}
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};
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function getLoopBodyBindings(loopPath) {
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const state = {
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blockScoped: []
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};
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loopPath.traverse(collectLoopBodyBindingsVisitor, state);
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return state.blockScoped;
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}
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function getUsageInBody(binding, loopPath) {
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const seen = new WeakSet();
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let capturedInClosure = false;
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const constantViolations = filterMap(binding.constantViolations, path => {
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const {
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inBody,
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inClosure
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} = relativeLoopLocation(path, loopPath);
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if (!inBody) return null;
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capturedInClosure || (capturedInClosure = inClosure);
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const id = path.isUpdateExpression() ? path.get("argument") : path.isAssignmentExpression() ? path.get("left") : null;
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if (id) seen.add(id.node);
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return id;
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});
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const references = filterMap(binding.referencePaths, path => {
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if (seen.has(path.node)) return null;
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const {
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inBody,
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inClosure
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} = relativeLoopLocation(path, loopPath);
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if (!inBody) return null;
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capturedInClosure || (capturedInClosure = inClosure);
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return path;
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});
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return {
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capturedInClosure,
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hasConstantViolations: constantViolations.length > 0,
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usages: references.concat(constantViolations)
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};
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}
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function relativeLoopLocation(path, loopPath) {
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const bodyPath = loopPath.get("body");
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let inClosure = false;
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for (let currPath = path; currPath; currPath = currPath.parentPath) {
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if (currPath.isFunction() || currPath.isClass()) inClosure = true;
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if (currPath === bodyPath) {
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return {
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inBody: true,
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inClosure
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};
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} else if (currPath === loopPath) {
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return {
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inBody: false,
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inClosure
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};
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}
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}
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throw new Error("Internal Babel error: path is not in loop. Please report this as a bug.");
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}
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const collectCompletionsAndVarsVisitor = {
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Function(path) {
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path.skip();
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},
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LabeledStatement: {
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enter({
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node
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}, state) {
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state.labelsStack.push(node.label.name);
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},
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exit({
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node
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}, state) {
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const popped = state.labelsStack.pop();
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if (popped !== node.label.name) {
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throw new Error("Assertion failure. Please report this bug to Babel.");
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}
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}
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},
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Loop: {
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enter(_, state) {
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state.labellessContinueTargets++;
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state.labellessBreakTargets++;
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},
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exit(_, state) {
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state.labellessContinueTargets--;
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state.labellessBreakTargets--;
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}
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},
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SwitchStatement: {
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enter(_, state) {
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state.labellessBreakTargets++;
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},
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exit(_, state) {
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state.labellessBreakTargets--;
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}
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},
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"BreakStatement|ContinueStatement"(path, state) {
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const {
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label
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} = path.node;
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if (label) {
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if (state.labelsStack.includes(label.name)) return;
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} else if (path.isBreakStatement() ? state.labellessBreakTargets > 0 : state.labellessContinueTargets > 0) {
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return;
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}
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state.breaksContinues.push(path);
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},
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ReturnStatement(path, state) {
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state.returns.push(path);
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},
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VariableDeclaration(path, state) {
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if (path.parent === state.loopNode && isVarInLoopHead(path)) return;
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if (path.node.kind === "var") state.vars.push(path);
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}
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};
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function wrapLoopBody(loopPath, captured, updatedBindingsUsages) {
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const loopNode = loopPath.node;
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const state = {
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breaksContinues: [],
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returns: [],
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labelsStack: [],
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labellessBreakTargets: 0,
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labellessContinueTargets: 0,
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vars: [],
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loopNode
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};
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loopPath.traverse(collectCompletionsAndVarsVisitor, state);
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const callArgs = [];
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const closureParams = [];
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const updater = [];
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for (const [name, updatedUsage] of updatedBindingsUsages) {
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callArgs.push(_core.types.identifier(name));
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const innerName = loopPath.scope.generateUid(name);
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closureParams.push(_core.types.identifier(innerName));
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updater.push(_core.types.assignmentExpression("=", _core.types.identifier(name), _core.types.identifier(innerName)));
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for (const path of updatedUsage) path.replaceWith(_core.types.identifier(innerName));
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}
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for (const name of captured) {
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if (updatedBindingsUsages.has(name)) continue;
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callArgs.push(_core.types.identifier(name));
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closureParams.push(_core.types.identifier(name));
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}
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const id = loopPath.scope.generateUid("loop");
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const fn = _core.types.functionExpression(null, closureParams, _core.types.toBlock(loopNode.body));
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let call = _core.types.callExpression(_core.types.identifier(id), callArgs);
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const fnParent = loopPath.findParent(p => p.isFunction());
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if (fnParent) {
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const {
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async,
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generator
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} = fnParent.node;
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fn.async = async;
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fn.generator = generator;
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if (generator) call = _core.types.yieldExpression(call, true);else if (async) call = _core.types.awaitExpression(call);
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}
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const updaterNode = updater.length > 0 ? _core.types.expressionStatement(_core.types.sequenceExpression(updater)) : null;
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if (updaterNode) fn.body.body.push(updaterNode);
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const [varPath] = loopPath.insertBefore(_core.types.variableDeclaration("var", [_core.types.variableDeclarator(_core.types.identifier(id), fn)]));
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const bodyStmts = [];
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const varNames = [];
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for (const varPath of state.vars) {
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const assign = [];
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for (const decl of varPath.node.declarations) {
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varNames.push(...Object.keys(_core.types.getBindingIdentifiers(decl.id)));
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if (decl.init) {
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assign.push(_core.types.assignmentExpression("=", decl.id, decl.init));
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}
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}
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if (assign.length > 0) {
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let replacement = assign.length === 1 ? assign[0] : _core.types.sequenceExpression(assign);
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if (!_core.types.isForStatement(varPath.parent, {
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init: varPath.node
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}) && !_core.types.isForXStatement(varPath.parent, {
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left: varPath.node
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})) {
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replacement = _core.types.expressionStatement(replacement);
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}
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varPath.replaceWith(replacement);
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} else {
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varPath.remove();
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}
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}
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if (varNames.length) {
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bodyStmts.push(_core.types.variableDeclaration("var", varNames.map(name => _core.types.variableDeclarator(_core.types.identifier(name)))));
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}
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if (state.breaksContinues.length === 0 && state.returns.length === 0) {
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bodyStmts.push(_core.types.expressionStatement(call));
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} else {
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const completionId = loopPath.scope.generateUid("ret");
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bodyStmts.push(_core.types.variableDeclaration("var", [_core.types.variableDeclarator(_core.types.identifier(completionId), call)]));
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const injected = new Set();
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for (const path of state.breaksContinues) {
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const {
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node
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} = path;
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const {
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type,
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label
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} = node;
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let name = type === "BreakStatement" ? "break" : "continue";
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if (label) name += "|" + label.name;
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path.replaceWith(_core.types.returnStatement(_core.types.stringLiteral(name)));
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if (updaterNode) path.insertBefore(_core.types.cloneNode(updaterNode));
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if (injected.has(name)) continue;
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injected.add(name);
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bodyStmts.push(_core.template.statement.ast`
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if (
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${_core.types.identifier(completionId)} === ${_core.types.stringLiteral(name)}
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) ${node}
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`);
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}
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if (state.returns.length) {
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for (const path of state.returns) {
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const arg = path.node.argument || path.scope.buildUndefinedNode();
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path.replaceWith(_core.template.statement.ast`
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return { v: ${arg} };
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`);
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}
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bodyStmts.push(_core.template.statement.ast`
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if (typeof ${_core.types.identifier(completionId)} === "object")
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return ${_core.types.identifier(completionId)}.v;
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`);
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}
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}
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loopNode.body = _core.types.blockStatement(bodyStmts);
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return varPath;
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}
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function isVarInLoopHead(path) {
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if (_core.types.isForStatement(path.parent)) return path.key === "init";
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if (_core.types.isForXStatement(path.parent)) return path.key === "left";
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return false;
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}
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function filterMap(list, fn) {
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const result = [];
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for (const item of list) {
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const mapped = fn(item);
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if (mapped) result.push(mapped);
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}
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return result;
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}
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//# sourceMappingURL=loop.js.map
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