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fixup: more tests, yield*, etc.
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@addaleax
addaleax committed Oct 5, 2023
1 parent 42aad30 commit 906d16f
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Showing 4 changed files with 162 additions and 25 deletions.
97 changes: 96 additions & 1 deletion packages/async-rewriter2/src/async-writer-babel.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,24 @@ describe('AsyncWriter', function () {
[Symbol.for('@@mongosh.uncatchable')]: true,
});
},
regularIterable: function* () {
yield* [1, 2, 3];
},
regularAsyncIterable: async function* () {
await Promise.resolve();
yield* [1, 2, 3];
},
implicitlyAsyncIterable: function () {
return Object.assign(
(async function* () {
await Promise.resolve();
yield* [1, 2, 3];
})(),
{
[Symbol.for('@@mongosh.syntheticAsyncIterable')]: true,
}
);
},
});
runTranspiledCode = (code: string, context?: any) => {
const transpiled = asyncWriter.process(code);
Expand Down Expand Up @@ -543,6 +561,44 @@ describe('AsyncWriter', function () {
expect(await ret).to.equal('bar');
});

context('for-of', function () {
it('can iterate over implicit iterables', async function () {
expect(
await runTranspiledCode(`(function() {
let sum = 0;
for (const value of implicitlyAsyncIterable())
sum += value;
return sum;
})()`)
).to.equal(6);
});

it('can iterate over implicit iterables in async functions', async function () {
expect(
await runTranspiledCode(`(async function() {
let sum = 0;
for (const value of implicitlyAsyncIterable())
sum += value;
return sum;
})()`)
).to.equal(6);
});

it('can implicitly yield* inside of async generator functions', async function () {
expect(
await runTranspiledCode(`(async function() {
const gen = (async function*() {
yield* implicitlyAsyncIterable();
})();
let sum = 0;
for await (const value of gen)
sum += value;
return sum;
})()`)
).to.equal(6);
});
});

context('invalid implicit awaits', function () {
beforeEach(function () {
runUntranspiledCode(asyncWriter.runtimeSupportCode());
Expand Down Expand Up @@ -594,6 +650,45 @@ describe('AsyncWriter', function () {
'[ASYNC-10012] Result of expression "compareFn(...args)" cannot be used in this context'
);
});

context('for-of', function () {
it('cannot implicitly yield* inside of generator functions', function () {
expect(() =>
runTranspiledCode(`(function() {
const gen = (function*() {
yield* implicitlyAsyncIterable();
})();
for (const value of gen) return value;
})()`)
).to.throw(
'[ASYNC-10013] Result of expression "implicitlyAsyncIterable()" cannot be iterated in this context'
);
});

it('cannot implicitly for-of inside of generator functions', function () {
expect(() =>
runTranspiledCode(`(function() {
const gen = (function*() {
for (const item of implicitlyAsyncIterable()) yield item;
})();
for (const value of gen) return value;
})()`)
).to.throw(
'[ASYNC-10013] Result of expression "implicitlyAsyncIterable()" cannot be iterated in this context'
);
});

it('cannot implicitly for-of await inside of class constructors', function () {
expect(
() =>
runTranspiledCode(`class A {
constructor() { for (this.foo of implicitlyAsyncIterable()) {} }
}; new A()`).value
).to.throw(
'[ASYNC-10013] Result of expression "implicitlyAsyncIterable()" cannot be iterated in this context'
);
});
});
});
});

Expand Down Expand Up @@ -1040,7 +1135,7 @@ describe('AsyncWriter', function () {
runTranspiledCode(
'globalThis.abcdefghijklmnopqrstuvwxyz = {}; abcdefghijklmnopqrstuvwxyz()'
)
).to.throw('abcdefghijklm ... uvwxyz is not a function');
).to.throw('abcdefghijklmn ... uvwxyz is not a function');
});
});

Expand Down
21 changes: 21 additions & 0 deletions packages/async-rewriter2/src/error-codes.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,27 @@ enum AsyncRewriterErrors {
* **Solution: Do not use calls directly in such functions. If necessary, place these calls in an inner 'async' function.**
*/
SyntheticPromiseInAlwaysSyncContext = 'ASYNC-10012',
/**
* Signals the iteration of a Mongosh API object in a place where it is not supported.
* This occurs inside of constructors and (non-async) generator functions.
*
* Examples causing error:
* ```javascript
* class SomeClass {
* constructor() {
* for (const item of db.coll.find()) { ... }
* }
* }
*
* function*() {
* for (const item of db.coll.find()) yield item;
* yield* db.coll.find();
* }
* ```
*
* **Solution: Do not use calls directly in such functions. If necessary, place these calls in an inner 'async' function.**
*/
SyntheticAsyncIterableInAlwaysSyncContext = 'ASYNC-10013',
}

export { AsyncRewriterErrors };
56 changes: 32 additions & 24 deletions packages/async-rewriter2/src/stages/transform-maybe-await.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -56,8 +56,9 @@ export default ({
// of helpers which are available inside the function.
const identifierGroupKey = '@@mongosh.identifierGroup';

const syntheticPromiseSymbolTemplate = babel.template.statement(`
const syntheticPromiseSymbolTemplate = babel.template.statements(`
const SP_IDENTIFIER = Symbol.for("@@mongosh.syntheticPromise");
const SAI_IDENTIFIER = Symbol.for("@@mongosh.syntheticAsyncIterable");
`);

const markSyntheticPromiseTemplate = babel.template.statement(`
Expand All @@ -75,19 +76,23 @@ export default ({
`);

const assertNotSyntheticPromiseTemplate = babel.template.statement(`
function ANSP_IDENTIFIER(p, s) {
function ANSP_IDENTIFIER(p, s, i = false) {
if (p && p[SP_IDENTIFIER]) {
throw new CUSTOM_ERROR_BUILDER(
'Result of expression "' + s + '" cannot be used in this context',
'SyntheticPromiseInAlwaysSyncContext');
}
if (i && p && p[SAI_IDENTIFIER]) {
throw new CUSTOM_ERROR_BUILDER(
'Result of expression "' + s + '" cannot be iterated in this context',
'SyntheticAsyncIterableInAlwaysSyncContext');
}
return p;
}
`);

const adaptAsyncIterableToSyncIterableTemplate = babel.template.statement(`
function AAITSI_IDENTIFIER(original) {
const SAI_IDENTIFIER = Symbol.for("@@mongosh.syntheticAsyncIterable");
if (!original || !original[SAI_IDENTIFIER]) {
return { iterable: original, isSyntheticAsyncIterable: false };
}
Expand Down Expand Up @@ -169,10 +174,6 @@ export default ({
}
);

const assertNotSyntheticExpressionTemplate = babel.template.expression(`
ANSP_IDENTIFIER(NODE, ORIGINAL_SOURCE)
`);

const rethrowTemplate = babel.template.statement(`
try {
ORIGINAL_CODE;
Expand Down Expand Up @@ -248,7 +249,7 @@ export default ({
node.start !== undefined
? file.code.slice(node.start ?? undefined, node.end ?? undefined)
: '<unknown>',
24
25
);

if (!wrap) return t.stringLiteral(prettyOriginalString);
Expand Down Expand Up @@ -349,11 +350,11 @@ export default ({
const commonHelpers = existingIdentifiers
? []
: [
Object.assign(
syntheticPromiseSymbolTemplate({
SP_IDENTIFIER: syntheticPromiseSymbol,
}),
{ [isGeneratedHelper]: true }
...syntheticPromiseSymbolTemplate({
SP_IDENTIFIER: syntheticPromiseSymbol,
SAI_IDENTIFIER: syntheticAsyncIterableSymbol,
}).map((helper) =>
Object.assign(helper, { [isGeneratedHelper]: true })
),
Object.assign(
expressionHolderVariableTemplate({
Expand Down Expand Up @@ -400,6 +401,7 @@ export default ({
assertNotSyntheticPromiseTemplate({
ANSP_IDENTIFIER: assertNotSyntheticPromise,
SP_IDENTIFIER: syntheticPromiseSymbol,
SAI_IDENTIFIER: syntheticAsyncIterableSymbol,
CUSTOM_ERROR_BUILDER:
(this as any).opts.customErrorBuilder ?? t.identifier('Error'),
}),
Expand Down Expand Up @@ -666,17 +668,23 @@ export default ({

if (!functionParent.node.async) {
// Transform expression `foo` into `assertNotSyntheticPromise(foo, 'foo')`.
const args = [
path.node,
getOriginalSourceString(this, path.node, {
wrap: false,
}),
];
if (
(path.parent.type === 'ForOfStatement' &&
path.node === path.parent.right) ||
(path.parent.type === 'YieldExpression' && path.parent.delegate)
) {
args.push(t.booleanLiteral(true));
}
path.replaceWith(
Object.assign(
assertNotSyntheticExpressionTemplate({
ORIGINAL_SOURCE: getOriginalSourceString(this, path.node, {
wrap: false,
}),
NODE: path.node,
ANSP_IDENTIFIER: assertNotSyntheticPromise,
}),
{ [isGeneratedHelper]: true }
)
Object.assign(t.callExpression(assertNotSyntheticPromise, args), {
[isGeneratedHelper]: true,
})
);
return;
}
Expand Down Expand Up @@ -732,7 +740,7 @@ export default ({
},
},
ForOfStatement(path) {
if (path.node.await) return;
if (path.node.await || !path.getFunctionParent()?.node.async) return;

if (
path.find(
Expand Down
13 changes: 13 additions & 0 deletions packages/e2e-tests/test/e2e.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -794,6 +794,19 @@ describe('e2e', function () {
const result = await shell.executeLine('out[1]');
expect(result).to.include('i: 1');
});

it('works with for-of iteration', async function () {
await shell.executeLine('out = [];');
const before =
await shell.executeLine(`for (const doc of db.coll.find()) {
print('enter for-of');
out.push(db.coll.findOne({_id:doc._id}));
print('leave for-of');
} print('after');`);
expect(before).to.match(/(enter for-of\r?\nleave for-of\r?\n){3}after/);
const result = await shell.executeLine('out[1]');
expect(result).to.include('i: 1');
});
});
});

Expand Down

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