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Much of the AST visitor code was ported from Chrome DevTools code written by Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>. PR-URL: nodejs#15566 Fixes: nodejs#13209 Refs: https://chromium.googlesource.com/chromium/src/+/e8111c396fef38da6654093433b4be93bed01dce Reviewed-By: Stephen Belanger <admin@stephenbelanger.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| 'use strict'; | ||
|
|
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| const acorn = require('internal/deps/acorn/dist/acorn'); | ||
| const walk = require('internal/deps/acorn/dist/walk'); | ||
|
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| const noop = () => {}; | ||
| const visitorsWithoutAncestors = { | ||
| ClassDeclaration(node, state, c) { | ||
| if (state.ancestors[state.ancestors.length - 2] === state.body) { | ||
| state.prepend(node, `${node.id.name}=`); | ||
| } | ||
| walk.base.ClassDeclaration(node, state, c); | ||
| }, | ||
| FunctionDeclaration(node, state, c) { | ||
| state.prepend(node, `${node.id.name}=`); | ||
| }, | ||
| FunctionExpression: noop, | ||
| ArrowFunctionExpression: noop, | ||
| MethodDefinition: noop, | ||
| AwaitExpression(node, state, c) { | ||
| state.containsAwait = true; | ||
| walk.base.AwaitExpression(node, state, c); | ||
| }, | ||
| ReturnStatement(node, state, c) { | ||
| state.containsReturn = true; | ||
| walk.base.ReturnStatement(node, state, c); | ||
| }, | ||
| VariableDeclaration(node, state, c) { | ||
| if (node.kind === 'var' || | ||
| state.ancestors[state.ancestors.length - 2] === state.body) { | ||
| if (node.declarations.length === 1) { | ||
| state.replace(node.start, node.start + node.kind.length, 'void'); | ||
| } else { | ||
| state.replace(node.start, node.start + node.kind.length, 'void ('); | ||
| } | ||
|
|
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| for (const decl of node.declarations) { | ||
| state.prepend(decl, '('); | ||
| state.append(decl, decl.init ? ')' : '=undefined)'); | ||
| } | ||
|
|
||
| if (node.declarations.length !== 1) { | ||
| state.append(node.declarations[node.declarations.length - 1], ')'); | ||
| } | ||
| } | ||
|
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| walk.base.VariableDeclaration(node, state, c); | ||
| } | ||
| }; | ||
|
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| const visitors = {}; | ||
| for (const nodeType of Object.keys(walk.base)) { | ||
| const callback = visitorsWithoutAncestors[nodeType] || walk.base[nodeType]; | ||
| visitors[nodeType] = (node, state, c) => { | ||
| const isNew = node !== state.ancestors[state.ancestors.length - 1]; | ||
| if (isNew) { | ||
| state.ancestors.push(node); | ||
| } | ||
| callback(node, state, c); | ||
| if (isNew) { | ||
| state.ancestors.pop(); | ||
| } | ||
| }; | ||
| } | ||
|
|
||
| function processTopLevelAwait(src) { | ||
| const wrapped = `(async () => { ${src} })()`; | ||
| const wrappedArray = wrapped.split(''); | ||
| let root; | ||
| try { | ||
| root = acorn.parse(wrapped, { ecmaVersion: 8 }); | ||
| } catch (err) { | ||
| return null; | ||
| } | ||
| const body = root.body[0].expression.callee.body; | ||
| const state = { | ||
| body, | ||
| ancestors: [], | ||
| replace(from, to, str) { | ||
| for (var i = from; i < to; i++) { | ||
| wrappedArray[i] = ''; | ||
| } | ||
| if (from === to) str += wrappedArray[from]; | ||
| wrappedArray[from] = str; | ||
| }, | ||
| prepend(node, str) { | ||
| wrappedArray[node.start] = str + wrappedArray[node.start]; | ||
| }, | ||
| append(node, str) { | ||
| wrappedArray[node.end - 1] += str; | ||
| }, | ||
| containsAwait: false, | ||
| containsReturn: false | ||
| }; | ||
|
|
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| walk.recursive(body, state, visitors); | ||
|
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| // Do not transform if | ||
| // 1. False alarm: there isn't actually an await expression. | ||
| // 2. There is a top-level return, which is not allowed. | ||
| if (!state.containsAwait || state.containsReturn) { | ||
| return null; | ||
| } | ||
|
|
||
| const last = body.body[body.body.length - 1]; | ||
| if (last.type === 'ExpressionStatement') { | ||
| // For an expression statement of the form | ||
| // ( expr ) ; | ||
| // ^^^^^^^^^^ // last | ||
| // ^^^^ // last.expression | ||
| // | ||
| // We do not want the left parenthesis before the `return` keyword; | ||
| // therefore we prepend the `return (` to `last`. | ||
| // | ||
| // On the other hand, we do not want the right parenthesis after the | ||
| // semicolon. Since there can only be more right parentheses between | ||
| // last.expression.end and the semicolon, appending one more to | ||
| // last.expression should be fine. | ||
| state.prepend(last, 'return ('); | ||
| state.append(last.expression, ')'); | ||
| } | ||
|
|
||
| return wrappedArray.join(''); | ||
| } | ||
|
|
||
| module.exports = { | ||
| processTopLevelAwait | ||
| }; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,68 @@ | ||
| 'use strict'; | ||
|
|
||
| require('../common'); | ||
| const assert = require('assert'); | ||
| const { processTopLevelAwait } = require('internal/repl/await'); | ||
|
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| // Flags: --expose-internals | ||
|
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| // This test was created based on | ||
| // https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/http/tests/inspector-unit/preprocess-top-level-awaits.js?rcl=358caaba5e763e71c4abb9ada2d9cd8b1188cac9 | ||
|
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| const testCases = [ | ||
| [ '0', | ||
| null ], | ||
| [ 'await 0', | ||
| '(async () => { return (await 0) })()' ], | ||
| [ 'await 0;', | ||
| '(async () => { return (await 0); })()' ], | ||
| [ '(await 0)', | ||
| '(async () => { return ((await 0)) })()' ], | ||
| [ '(await 0);', | ||
| '(async () => { return ((await 0)); })()' ], | ||
| [ 'async function foo() { await 0; }', | ||
| null ], | ||
| [ 'async () => await 0', | ||
| null ], | ||
| [ 'class A { async method() { await 0 } }', | ||
| null ], | ||
| [ 'await 0; return 0;', | ||
| null ], | ||
| [ 'var a = await 1', | ||
| '(async () => { void (a = await 1) })()' ], | ||
| [ 'let a = await 1', | ||
| '(async () => { void (a = await 1) })()' ], | ||
| [ 'const a = await 1', | ||
| '(async () => { void (a = await 1) })()' ], | ||
| [ 'for (var i = 0; i < 1; ++i) { await i }', | ||
| '(async () => { for (void (i = 0); i < 1; ++i) { await i } })()' ], | ||
| [ 'for (let i = 0; i < 1; ++i) { await i }', | ||
| '(async () => { for (let i = 0; i < 1; ++i) { await i } })()' ], | ||
| [ 'var {a} = {a:1}, [b] = [1], {c:{d}} = {c:{d: await 1}}', | ||
| '(async () => { void ( ({a} = {a:1}), ([b] = [1]), ' + | ||
| '({c:{d}} = {c:{d: await 1}})) })()' ], | ||
| /* eslint-disable no-template-curly-in-string */ | ||
| [ 'console.log(`${(await { a: 1 }).a}`)', | ||
| '(async () => { return (console.log(`${(await { a: 1 }).a}`)) })()' ], | ||
| /* eslint-enable no-template-curly-in-string */ | ||
| [ 'await 0; function foo() {}', | ||
| '(async () => { await 0; foo=function foo() {} })()' ], | ||
| [ 'await 0; class Foo {}', | ||
| '(async () => { await 0; Foo=class Foo {} })()' ], | ||
| [ 'if (await true) { function foo() {} }', | ||
| '(async () => { if (await true) { foo=function foo() {} } })()' ], | ||
| [ 'if (await true) { class Foo{} }', | ||
| '(async () => { if (await true) { class Foo{} } })()' ], | ||
| [ 'if (await true) { var a = 1; }', | ||
| '(async () => { if (await true) { void (a = 1); } })()' ], | ||
| [ 'if (await true) { let a = 1; }', | ||
| '(async () => { if (await true) { let a = 1; } })()' ], | ||
| [ 'var a = await 1; let b = 2; const c = 3;', | ||
| '(async () => { void (a = await 1); void (b = 2); void (c = 3); })()' ], | ||
| [ 'let o = await 1, p', | ||
| '(async () => { void ( (o = await 1), (p=undefined)) })()' ] | ||
| ]; | ||
|
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| for (const [input, expected] of testCases) { | ||
| assert.strictEqual(processTopLevelAwait(input), expected); | ||
| } |
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