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Fix async try #1278

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Merged
Perryvw merged 5 commits into from
May 29, 2022
Merged

Fix async try #1278

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930f161
Initial prototype
Perryvw May 23, 2022
a38dc32
this works
Perryvw May 28, 2022
fb626b1
Kinda works but not really
Perryvw May 28, 2022
91a5eed
Actually it does work but test was wrong
Perryvw May 29, 2022
ea1ec0d
finalize solution
Perryvw May 29, 2022
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48 changes: 15 additions & 33 deletions src/lualib/Await.ts
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Expand Up @@ -16,62 +16,44 @@

import { __TS__Promise } from "./Promise";

type ErrorHandler = (this: void, error: unknown) => unknown;

// eslint-disable-next-line @typescript-eslint/promise-function-async
export function __TS__AsyncAwaiter(this: void, generator: (this: void) => void) {
return new Promise((resolve, reject) => {
let resolved = false;
const asyncCoroutine = coroutine.create(generator);

// eslint-disable-next-line @typescript-eslint/promise-function-async
function adopt(value: unknown) {
return value instanceof __TS__Promise ? value : Promise.resolve(value);
}
function fulfilled(value: unknown) {
const [success, errorOrErrorHandler, resultOrError] = coroutine.resume(asyncCoroutine, value);
const [success, resultOrError] = coroutine.resume(asyncCoroutine, value);
if (success) {
step(resultOrError, errorOrErrorHandler);
} else {
reject(errorOrErrorHandler);
}
}
function rejected(handler: ErrorHandler | undefined) {
if (handler) {
return (value: unknown) => {
const [success, hasReturnedOrError, returnedValue] = pcall(handler, value);
if (success) {
if (hasReturnedOrError) {
resolve(returnedValue);
} else {
step(hasReturnedOrError, handler);
}
} else {
reject(hasReturnedOrError);
}
};
step(resultOrError);
} else {
// If no catch clause, just reject
return value => {
reject(value);
};
reject(resultOrError);
}
}
function step(result: unknown, errorHandler: ErrorHandler | undefined) {
function step(result: unknown) {
if (resolved) return;
if (coroutine.status(asyncCoroutine) === "dead") {
resolve(result);
} else {
adopt(result).then(fulfilled, rejected(errorHandler));
adopt(result).then(fulfilled, reject);
}
}
const [success, errorOrErrorHandler, resultOrError] = coroutine.resume(asyncCoroutine);
const [success, resultOrError] = coroutine.resume(asyncCoroutine, (v: unknown) => {
resolved = true;
adopt(v).then(resolve, reject);
});
if (success) {
step(resultOrError, errorOrErrorHandler);
step(resultOrError);
} else {
reject(errorOrErrorHandler);
reject(resultOrError);
}
});
}

export function __TS__Await(this: void, errorHandler: ErrorHandler, thing: unknown) {
return coroutine.yield(errorHandler, thing);
export function __TS__Await(this: void, thing: unknown) {
return coroutine.yield(thing);
}
29 changes: 13 additions & 16 deletions src/transformation/visitors/async-await.ts
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Expand Up @@ -3,35 +3,32 @@ import * as lua from "../../LuaAST";
import { FunctionVisitor, TransformationContext } from "../context";
import { awaitMustBeInAsyncFunction } from "../utils/diagnostics";
import { importLuaLibFeature, LuaLibFeature, transformLuaLibFunction } from "../utils/lualib";
import { findFirstNodeAbove } from "../utils/typescript";
import { isInAsyncFunction } from "../utils/typescript";

export const transformAwaitExpression: FunctionVisitor<ts.AwaitExpression> = (node, context) => {
// Check if await is inside an async function, it is not allowed at top level or in non-async functions
const containingFunction = findFirstNodeAbove(node, ts.isFunctionLike);
if (
containingFunction === undefined ||
!containingFunction.modifiers?.some(m => m.kind === ts.SyntaxKind.AsyncKeyword)
) {
if (!isInAsyncFunction(node)) {
context.diagnostics.push(awaitMustBeInAsyncFunction(node));
}

const expression = context.transformExpression(node.expression);
const catchIdentifier = lua.createIdentifier("____catch");
return transformLuaLibFunction(context, LuaLibFeature.Await, node, catchIdentifier, expression);
return transformLuaLibFunction(context, LuaLibFeature.Await, node, expression);
};

export function isAsyncFunction(declaration: ts.FunctionLikeDeclaration): boolean {
return declaration.modifiers?.some(m => m.kind === ts.SyntaxKind.AsyncKeyword) ?? false;
}

export function wrapInAsyncAwaiter(context: TransformationContext, statements: lua.Statement[]): lua.Statement[] {
export function wrapInAsyncAwaiter(
context: TransformationContext,
statements: lua.Statement[],
includeResolveParameter = true
): lua.CallExpression {
importLuaLibFeature(context, LuaLibFeature.Await);

return [
lua.createReturnStatement([
lua.createCallExpression(lua.createIdentifier("__TS__AsyncAwaiter"), [
lua.createFunctionExpression(lua.createBlock(statements)),
]),
]),
];
const parameters = includeResolveParameter ? [lua.createIdentifier("____awaiter_resolve")] : [];

return lua.createCallExpression(lua.createIdentifier("__TS__AsyncAwaiter"), [
lua.createFunctionExpression(lua.createBlock(statements), parameters),
]);
}
96 changes: 77 additions & 19 deletions src/transformation/visitors/errors.ts
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@@ -1,24 +1,22 @@
import * as ts from "typescript";
import { LuaTarget } from "../..";
import { LuaLibFeature, LuaTarget } from "../..";
import * as lua from "../../LuaAST";
import { FunctionVisitor } from "../context";
import { FunctionVisitor, TransformationContext } from "../context";
import { unsupportedForTarget, unsupportedForTargetButOverrideAvailable } from "../utils/diagnostics";
import { createUnpackCall } from "../utils/lua-ast";
import { ScopeType } from "../utils/scope";
import { transformLuaLibFunction } from "../utils/lualib";
import { Scope, ScopeType } from "../utils/scope";
import { isInAsyncFunction, isInGeneratorFunction } from "../utils/typescript";
import { wrapInAsyncAwaiter } from "./async-await";
import { transformScopeBlock } from "./block";
import { transformIdentifier } from "./identifier";
import { isInMultiReturnFunction } from "./language-extensions/multi";
import { createReturnStatement } from "./return";

export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statement, context) => {
const [tryBlock, tryScope] = transformScopeBlock(context, statement.tryBlock, ScopeType.Try);
const transformAsyncTry: FunctionVisitor<ts.TryStatement> = (statement, context) => {
const [tryBlock] = transformScopeBlock(context, statement.tryBlock, ScopeType.Try);

if (
context.options.luaTarget === LuaTarget.Lua51 &&
isInAsyncFunction(statement) &&
!context.options.lua51AllowTryCatchInAsyncAwait
) {
if (context.options.luaTarget === LuaTarget.Lua51 && !context.options.lua51AllowTryCatchInAsyncAwait) {
context.diagnostics.push(
unsupportedForTargetButOverrideAvailable(
statement,
Expand All @@ -30,6 +28,57 @@ export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statemen
return tryBlock.statements;
}

// __TS__AsyncAwaiter(<catch block>)
const awaiter = wrapInAsyncAwaiter(context, tryBlock.statements, false);
const awaiterIdentifier = lua.createIdentifier("____try");
const awaiterDefinition = lua.createVariableDeclarationStatement(awaiterIdentifier, awaiter);

// local ____try = __TS__AsyncAwaiter(<catch block>)
const result: lua.Statement[] = [awaiterDefinition];

if (statement.finallyBlock) {
const awaiterFinally = lua.createTableIndexExpression(awaiterIdentifier, lua.createStringLiteral("finally"));
const finallyFunction = lua.createFunctionExpression(
lua.createBlock(context.transformStatements(statement.finallyBlock.statements))
);
const finallyCall = lua.createCallExpression(
awaiterFinally,
[awaiterIdentifier, finallyFunction],
statement.finallyBlock
);
// ____try.finally(<finally function>)
result.push(lua.createExpressionStatement(finallyCall));
}

if (statement.catchClause) {
// ____try.catch(<catch function>)
const [catchFunction] = transformCatchClause(context, statement.catchClause);
if (catchFunction.params) {
catchFunction.params.unshift(lua.createAnonymousIdentifier());
}

const awaiterCatch = lua.createTableIndexExpression(awaiterIdentifier, lua.createStringLiteral("catch"));
const catchCall = lua.createCallExpression(awaiterCatch, [awaiterIdentifier, catchFunction]);

// await ____try.catch(<catch function>)
const promiseAwait = transformLuaLibFunction(context, LuaLibFeature.Await, statement, catchCall);
result.push(lua.createExpressionStatement(promiseAwait, statement));
} else {
// await ____try
const promiseAwait = transformLuaLibFunction(context, LuaLibFeature.Await, statement, awaiterIdentifier);
result.push(lua.createExpressionStatement(promiseAwait, statement));
}

return result;
};

export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statement, context) => {
if (isInAsyncFunction(statement)) {
return transformAsyncTry(statement, context);
}

const [tryBlock, tryScope] = transformScopeBlock(context, statement.tryBlock, ScopeType.Try);

if (context.options.luaTarget === LuaTarget.Lua51 && isInGeneratorFunction(statement)) {
context.diagnostics.push(
unsupportedForTarget(statement, "try/catch inside generator functions", LuaTarget.Lua51)
Expand All @@ -50,15 +99,7 @@ export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statemen

if (statement.catchClause && statement.catchClause.block.statements.length > 0) {
// try with catch
const [catchBlock, catchScope] = transformScopeBlock(context, statement.catchClause.block, ScopeType.Catch);

const catchParameter = statement.catchClause.variableDeclaration
? transformIdentifier(context, statement.catchClause.variableDeclaration.name as ts.Identifier)
: undefined;
const catchFunction = lua.createFunctionExpression(
catchBlock,
catchParameter ? [lua.cloneIdentifier(catchParameter)] : []
);
const [catchFunction, catchScope] = transformCatchClause(context, statement.catchClause);
const catchIdentifier = lua.createIdentifier("____catch");
result.push(lua.createVariableDeclarationStatement(catchIdentifier, catchFunction));

Expand Down Expand Up @@ -138,3 +179,20 @@ export const transformThrowStatement: FunctionVisitor<ts.ThrowStatement> = (stat
statement
);
};

function transformCatchClause(
context: TransformationContext,
catchClause: ts.CatchClause
): [lua.FunctionExpression, Scope] {
const [catchBlock, catchScope] = transformScopeBlock(context, catchClause.block, ScopeType.Catch);

const catchParameter = catchClause.variableDeclaration
? transformIdentifier(context, catchClause.variableDeclaration.name as ts.Identifier)
: undefined;
const catchFunction = lua.createFunctionExpression(
catchBlock,
catchParameter ? [lua.cloneIdentifier(catchParameter)] : []
);

return [catchFunction, catchScope];
}
2 changes: 1 addition & 1 deletion src/transformation/visitors/function.ts
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Expand Up @@ -163,7 +163,7 @@ export function transformFunctionBody(
scope.node = node;
let bodyStatements = transformFunctionBodyContent(context, body);
if (node && isAsyncFunction(node)) {
bodyStatements = wrapInAsyncAwaiter(context, bodyStatements);
bodyStatements = [lua.createReturnStatement([wrapInAsyncAwaiter(context, bodyStatements)])];
}
const headerStatements = transformFunctionBodyHeader(context, scope, parameters, spreadIdentifier);
popScope(context);
Expand Down
9 changes: 6 additions & 3 deletions src/transformation/visitors/return.ts
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Expand Up @@ -85,12 +85,15 @@ export function createReturnStatement(
): lua.ReturnStatement {
const results = [...values];

if (isInAsyncFunction(node)) {
return lua.createReturnStatement([
lua.createCallExpression(lua.createIdentifier("____awaiter_resolve"), [lua.createNilLiteral(), ...values]),
]);
}

if (isInTryCatch(context)) {
// Bubble up explicit return flag and check if we're inside a try/catch block
results.unshift(lua.createBooleanLiteral(true));
} else if (isInAsyncFunction(node)) {
// Add nil error handler in async function and not in try
results.unshift(lua.createNilLiteral());
}

return lua.createReturnStatement(results, node);
Expand Down
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