545 lines
15 KiB
JavaScript
545 lines
15 KiB
JavaScript
import evaluate from '@/astride/evaluate.js';
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import Scope from '@/astride/scope.js';
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import traverse from '@/astride/traverse.js';
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const YIELD_NONE = 0;
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const YIELD_PROMISE = 1;
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const YIELD_LOOP_UPDATE = 2;
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const YIELD_RETURN = 3;
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export default class Sandbox {
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ast;
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$$execution;
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scopes;
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constructor(ast, context = {}) {
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this.ast = ast;
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this.$$context = context;
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this.compile();
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}
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compile() {
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let scope = new Scope();
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scope.context = this.$$context;
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this.scopes = new Map([[this.ast, scope]]);
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traverse(
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this.ast,
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(node, verb) => {
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if (
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'BlockStatement' === node.type
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|| 'ForStatement' === node.type
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) {
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switch (verb) {
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case 'enter': {
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scope = new Scope(scope);
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break;
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}
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case 'exit': {
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scope = scope.parent;
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break;
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}
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}
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}
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if ('enter' === verb) {
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this.scopes.set(node, scope);
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}
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},
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);
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}
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get context() {
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return this.$$context;
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}
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destructureArray(id, init) {
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const scope = this.scopes.get(id);
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const {elements} = id;
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for (let i = 0; i < elements.length; ++i) {
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const element = elements[i];
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if (null === element) {
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continue;
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}
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if ('Identifier' === element.type) {
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scope.allocate(element.name, init[i]);
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}
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/* v8 ignore next 3 */
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else {
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throw new Error(`destructureArray(): Can't array destructure type ${element.type}`);
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}
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}
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return init;
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}
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destructureObject(id, init) {
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const scope = this.scopes.get(id);
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const {properties} = id;
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for (let i = 0; i < properties.length; ++i) {
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const property = properties[i];
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if ('ObjectPattern' === property.value.type) {
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this.destructureObject(property.value, init[property.key.name]);
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}
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else {
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scope.allocate(
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property.value.name,
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init[property.key.name],
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);
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}
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}
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return init;
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}
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evaluate(node) {
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return evaluate(
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node,
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{scope: this.scopes.get(node)},
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);
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}
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evaluateToResult(node) {
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const {async, value} = this.evaluate(node);
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return {
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value,
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yield: async ? YIELD_PROMISE : YIELD_NONE,
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};
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}
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executeSync(node, depth) {
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let result;
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const isReplaying = depth < this.$$execution.stack.length;
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const isReplayingThisLevel = depth === this.$$execution.stack.length - 1;
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if (!isReplaying) {
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this.$$execution.stack.push(node);
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}
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// Substitute executing the node for its deferred result.
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else if (isReplayingThisLevel) {
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if (this.$$execution.stack[depth] === node) {
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result = this.$$execution.deferred.get(node);
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this.$$execution.deferred.delete(node);
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this.$$execution.stack.pop();
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return result;
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}
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}
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switch (node.type) {
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case 'ArrayExpression':
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case 'AssignmentExpression':
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case 'BinaryExpression':
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case 'CallExpression':
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case 'ChainExpression':
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case 'ObjectExpression':
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case 'Identifier':
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case 'LogicalExpression':
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case 'MemberExpression':
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case 'UnaryExpression':
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case 'UpdateExpression': {
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result = this.evaluateToResult(node);
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if (result.yield) {
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return result;
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}
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break;
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}
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case 'AwaitExpression': {
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const coerce = !this.$$execution.deferred.has(node.argument);
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result = this.executeSync(node.argument, depth + 1);
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if (coerce) {
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result = {
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value: result.value,
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yield: YIELD_PROMISE,
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};
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}
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if (result.yield) {
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return result;
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}
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/* v8 ignore next 2 */
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break;
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}
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case 'BlockStatement': {
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result = {
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value: undefined,
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yield: YIELD_NONE,
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};
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let skipping = isReplaying;
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for (const child of node.body) {
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if (skipping && child === this.$$execution.stack[depth + 1]) {
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skipping = false;
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}
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/* v8 ignore next 3 */
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if (skipping) {
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continue;
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}
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result = this.executeSync(child, depth + 1);
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if (result.yield) {
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return result;
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}
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}
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break;
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}
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case 'ConditionalExpression': {
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const shouldVisitChild = (child) => (
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isReplaying
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? (!this.$$execution.stack[depth + 1] || this.$$execution.stack[depth + 1] === child)
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: true
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);
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if (shouldVisitChild(node.test)) {
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const test = this.executeSync(node.test, depth + 1);
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if (test.yield) {
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return test;
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}
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this.$$execution.deferred.set(node.test, test);
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}
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const test = this.$$execution.deferred.get(node.test);
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if (test.value) {
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result = this.executeSync(node.consequent, depth + 1);
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}
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else {
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result = this.executeSync(node.alternate, depth + 1);
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}
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if (result.yield) {
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return result;
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}
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break;
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}
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case 'DoWhileStatement': {
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const shouldVisitChild = (child) => (
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isReplaying
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? (!this.$$execution.stack[depth + 1] || this.$$execution.stack[depth + 1] === child)
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: true
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);
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if (this.$$execution.stack[depth + 1] === node) {
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this.$$execution.stack.pop();
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}
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result = this.$$execution.deferred.get(node.body);
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if (shouldVisitChild(node.body)) {
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const body = this.executeSync(node.body, depth + 1);
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if (body.yield) {
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return body;
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}
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this.$$execution.deferred.set(node.body, body);
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}
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if (shouldVisitChild(node.test)) {
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const test = this.executeSync(node.test, depth + 1);
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if (test.yield) {
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return test;
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}
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if (!test.value) {
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this.$$execution.deferred.delete(node.body);
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break;
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}
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}
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// Yield
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this.$$execution.stack.push(node);
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return {
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value: undefined,
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yield: YIELD_LOOP_UPDATE,
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};
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}
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case 'ExpressionStatement': {
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result = this.executeSync(node.expression, depth + 1);
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if (result.yield) {
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return result;
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}
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break;
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}
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case 'ForStatement': {
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const shouldVisitChild = (child) => (
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isReplaying
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? (!this.$$execution.stack[depth + 1] || this.$$execution.stack[depth + 1] === child)
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: true
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);
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if (shouldVisitChild(node.init)) {
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const init = this.executeSync(node.init, depth + 1);
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if (init.yield) {
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return init;
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}
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}
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if (this.$$execution.stack[depth + 1] === node) {
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this.$$execution.stack.pop();
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}
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result = this.$$execution.deferred.get(node.body) || {
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value: undefined,
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yield: YIELD_NONE,
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};
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if (shouldVisitChild(node.test)) {
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const test = this.executeSync(node.test, depth + 1);
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if (test.yield) {
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return test;
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}
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if (!test.value) {
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this.$$execution.deferred.delete(node.body);
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break;
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}
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}
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if (shouldVisitChild(node.body)) {
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const body = this.executeSync(node.body, depth + 1);
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if (body.yield) {
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return body;
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}
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this.$$execution.deferred.set(node.body, body);
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}
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if (shouldVisitChild(node.update)) {
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const update = this.executeSync(node.update, depth + 1);
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if (update.yield) {
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return update;
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}
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this.$$execution.deferred.set(node.update, update);
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}
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// Yield
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this.$$execution.stack.push(node);
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const update = this.$$execution.deferred.get(node.update);
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this.$$execution.deferred.delete(node.update);
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return {
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value: update.value,
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yield: YIELD_LOOP_UPDATE,
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};
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}
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case 'IfStatement': {
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const shouldVisitChild = (child) => (
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isReplaying
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? (!this.$$execution.stack[depth + 1] || this.$$execution.stack[depth + 1] === child)
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: true
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);
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result = {
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value: undefined,
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yield: YIELD_NONE,
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};
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if (shouldVisitChild(node.test)) {
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const test = this.executeSync(node.test, depth + 1);
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if (test.yield) {
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return test;
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}
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this.$$execution.deferred.set(node.test, test);
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}
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const test = this.$$execution.deferred.get(node.test);
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if (test.value) {
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result = this.executeSync(node.consequent, depth + 1);
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}
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else if (node.alternate) {
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result = this.executeSync(node.alternate, depth + 1);
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}
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if (result.yield) {
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return result;
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}
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this.$$execution.deferred.delete(node.test);
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break;
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}
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case 'Literal': {
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result = {value: node.value, yield: YIELD_NONE};
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break;
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}
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case 'Program': {
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let skipping = isReplaying;
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for (const child of node.body) {
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if (skipping && child === this.$$execution.stack[depth + 1]) {
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skipping = false;
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}
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if (skipping) {
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continue;
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}
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result = this.executeSync(child, depth + 1);
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if (result.yield) {
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return result;
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}
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}
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result = {value: result.value, yield: YIELD_RETURN};
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break;
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}
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case 'ReturnStatement': {
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if (!node.argument) {
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return {
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value: undefined,
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yield: YIELD_RETURN,
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};
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}
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const argument = this.executeSync(node.argument, depth + 1);
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if (argument.yield) {
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return argument;
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}
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result = {
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value: argument.value,
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yield: YIELD_RETURN,
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};
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break;
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}
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case 'VariableDeclaration': {
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let skipping = isReplaying;
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for (const child of node.declarations) {
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if (skipping && child === this.$$execution.stack[depth + 1]) {
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skipping = false;
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}
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/* v8 ignore next 3 */
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if (skipping) {
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continue;
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}
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const result = this.executeSync(child, depth + 1);
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if (result.yield) {
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return result;
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}
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}
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result = {value: undefined, yield: YIELD_NONE};
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break;
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}
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case 'VariableDeclarator': {
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const {id} = node;
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const scope = this.scopes.get(node);
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if (null === node.init) {
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scope.allocate(id.name, undefined);
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result = {value: undefined, yield: YIELD_NONE};
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}
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else {
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const init = this.executeSync(node.init, depth + 1);
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if ('Identifier' === id.type) {
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if (init.yield) {
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return {
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value: Promise.resolve(init.value)
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.then((value) => scope.allocate(id.name, value)),
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yield: init.yield,
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};
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}
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else {
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result = {
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value: scope.allocate(id.name, init.value),
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yield: YIELD_NONE,
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};
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}
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}
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else if ('ArrayPattern' === id.type) {
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if (init.yield) {
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return {
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value: Promise.resolve(init.value)
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.then((value) => this.destructureArray(id, value)),
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yield: init.yield,
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};
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}
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else {
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result = {
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value: this.destructureArray(id, init.value),
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yield: YIELD_NONE,
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};
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}
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}
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else if ('ObjectPattern' === id.type) {
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if (init.yield) {
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return {
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value: Promise.resolve(init.value)
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.then((value) => this.destructureObject(id, value)),
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yield: init.yield,
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};
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}
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else {
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result = {
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value: this.destructureObject(id, init.value),
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yield: YIELD_NONE,
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};
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}
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}
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}
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break;
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}
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case 'WhileStatement': {
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const shouldVisitChild = (child) => (
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isReplaying
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? (!this.$$execution.stack[depth + 1] || this.$$execution.stack[depth + 1] === child)
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: true
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);
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if (this.$$execution.stack[depth + 1] === node) {
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this.$$execution.stack.pop();
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}
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result = this.$$execution.deferred.get(node.body) || {
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value: undefined,
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yield: YIELD_NONE,
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};
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if (shouldVisitChild(node.test)) {
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const test = this.executeSync(node.test, depth + 1);
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if (test.yield) {
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return test;
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}
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if (!test.value) {
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this.$$execution.deferred.delete(node.body);
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break;
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}
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}
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if (shouldVisitChild(node.body)) {
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const body = this.executeSync(node.body, depth + 1);
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if (body.yield) {
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return body;
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}
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this.$$execution.deferred.set(node.body, body);
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}
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// Yield
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this.$$execution.stack.push(node);
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return {
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value: undefined,
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yield: YIELD_LOOP_UPDATE,
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};
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}
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/* v8 ignore next 7 */
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default:
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console.log(
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node.type,
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Object.keys(node)
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.filter((key) => !['start', 'end'].includes(key)),
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);
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throw new Error('not implemented');
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}
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this.$$execution.stack.pop();
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return result;
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}
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reset() {
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this.$$execution = undefined;
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for (const scope of this.scopes.values()) {
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scope.context = {};
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}
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this.scopes.get(this.ast).context = this.$$context;
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}
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run(ops = 1000) {
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let result;
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for (let i = 0; i < ops; ++i) {
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result = this.step();
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if (result.done || result.async) {
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break;
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}
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}
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return result;
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}
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step() {
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if (!this.$$execution) {
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this.$$execution = {
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deferred: new Map(),
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stack: [],
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};
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}
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let result = this.executeSync(this.ast, 0);
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const stepResult = {async: false, done: false, value: undefined};
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switch (result.yield) {
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case YIELD_PROMISE: {
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stepResult.async = true;
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stepResult.value = Promise.resolve(result.value)
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.then((value) => {
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const top = this.$$execution.stack[this.$$execution.stack.length - 1];
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this.$$execution.deferred.set(top, {
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value,
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yield: YIELD_NONE,
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});
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});
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break;
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}
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case YIELD_LOOP_UPDATE: {
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stepResult.value = result.value;
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break;
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}
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case YIELD_RETURN: {
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stepResult.done = true;
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stepResult.value = result.value;
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}
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}
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if (stepResult.done) {
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this.reset();
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}
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return stepResult;
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}
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}
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