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Destructuring nothing fix #453

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Merged
tomblind merged 4 commits into from
Feb 26, 2019
Merged

Destructuring nothing fix #453

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8d586e7
fixes for empty destructuring
tomblind Feb 25, 2019
ef5517f
cleanup
tomblind Feb 25, 2019
c535548
union destructuring test
tomblind Feb 25, 2019
8f38f89
removing duplicate test
tomblind Feb 25, 2019
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25 changes: 19 additions & 6 deletions src/LuaTransformer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1673,7 +1673,9 @@ export class LuaTransformer {
throw TSTLErrors.ForbiddenEllipsisDestruction(statement);
}

const vars = statement.name.elements.map(e => this.transformArrayBindingElement(e));
const vars = statement.name.elements.length > 0
? statement.name.elements.map(e => this.transformArrayBindingElement(e))
: tstl.createAnnonymousIdentifier(statement.name);

// Don't unpack TupleReturn decorated functions
if (statement.initializer) {
Expand Down Expand Up @@ -2448,10 +2450,14 @@ export class LuaTransformer {

if (ts.isArrayLiteralExpression(expression.left)) {
// Destructuring assignment
const left = expression.left.elements.map(e => this.transformExpression(e));
const left = expression.left.elements.length > 0
? expression.left.elements.map(e => this.transformExpression(e))
: [tstl.createAnnonymousIdentifier(expression.left)];
let right: tstl.Expression[];
if (ts.isArrayLiteralExpression(expression.right)) {
right = expression.right.elements.map(e => this.transformExpression(e));
right = expression.right.elements.length > 0
? expression.right.elements.map(e => this.transformExpression(e))
: [tstl.createNilLiteral()];
} else if (tsHelper.isTupleReturnCall(expression.right, this.checker)) {
right = [this.transformExpression(expression.right)];
} else {
Expand Down Expand Up @@ -2479,16 +2485,20 @@ export class LuaTransformer {
if (ts.isArrayLiteralExpression(expression.left)) {
// Destructuring assignment
// (function() local ${tmps} = ${right}; ${left} = ${tmps}; return {${tmps}} end)()
const left = expression.left.elements.map(e => this.transformExpression(e));
const left = expression.left.elements.length > 0
? expression.left.elements.map(e => this.transformExpression(e))
: [tstl.createAnnonymousIdentifier(expression.left)];
let right: tstl.Expression[];
if (ts.isArrayLiteralExpression(expression.right)) {
right = expression.right.elements.map(e => this.transformExpression(e));
right = expression.right.elements.length > 0
? expression.right.elements.map(e => this.transformExpression(e))
: [tstl.createNilLiteral()];
} else if (tsHelper.isTupleReturnCall(expression.right, this.checker)) {
right = [this.transformExpression(expression.right)];
} else {
right = [this.createUnpackCall(this.transformExpression(expression.right), expression.right)];
}
const tmps = expression.left.elements.map((_, i) => tstl.createIdentifier(`____TS_tmp${i}`));
const tmps = left.map((_, i) => tstl.createIdentifier(`____TS_tmp${i}`));
const statements: tstl.Statement[] = [
tstl.createVariableDeclarationStatement(tmps, right),
tstl.createAssignmentStatement(left as tstl.IdentifierOrTableIndexExpression[], tmps),
Expand Down Expand Up @@ -4130,6 +4140,9 @@ export class LuaTransformer {

const fromTypeNode = this.checker.typeToTypeNode(fromType);
const toTypeNode = this.checker.typeToTypeNode(toType);
if (!fromTypeNode || !toTypeNode) {
return;
}

if ((ts.isArrayTypeNode(toTypeNode) || ts.isTupleTypeNode(toTypeNode))
&& (ts.isArrayTypeNode(fromTypeNode) || ts.isTupleTypeNode(fromTypeNode))) {
Expand Down
23 changes: 23 additions & 0 deletions test/unit/assignmentDestructuring.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -37,4 +37,27 @@ export class AssignmentDestructuringTests {
// Assert
Expect(lua).toBe(`local a, b = unpack(myFunc());`);
}

@TestCase("function foo(): [] { return []; }; let [] = foo();")
@TestCase("let [] = ['a', 'b', 'c'];")
@TestCase("let [] = [];")
@TestCase("let [] = [] = [];")
@TestCase("function foo(): [] { return []; }; [] = foo();")
@TestCase("[] = ['a', 'b', 'c'];")
@TestCase("[] = [];")
@TestCase("[] = [] = [];")
@Test("Empty destructuring")
public emptyDestructuring(code: string): void {
Expect(() => util.transpileAndExecute(code)).not.toThrow();
}

@Test("Union destructuring")
public unionDestructuring(): void {
const code =
`function foo(): [string] | [] { return ["bar"]; }
let x: string;
[x] = foo();
return x;`;
Expect(util.transpileAndExecute(code)).toBe("bar");
}
}