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Merged
Perryvw merged 3 commits into from
Jan 19, 2019
+64 −6
Merged

Switch transformer #347

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5be3206
Switch transformer
Perryvw Jan 19, 2019
2d45b7f
Changed incorrect version comparison to equality
Perryvw Jan 19, 2019
d2410ad
Added missing =
Perryvw Jan 19, 2019
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61 changes: 58 additions & 3 deletions src/LuaTransformer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1351,12 +1351,67 @@ export class LuaTransformer {
);
}

public transformSwitchStatement(arg0: ts.SwitchStatement): StatementVisitResult {
throw new Error("Method not implemented.");
public transformSwitchStatement(statement: ts.SwitchStatement): StatementVisitResult {
if (this.options.luaTarget === LuaTarget.Lua51) {
throw TSTLErrors.UnsupportedForTarget("Switch statements", this.options.luaTarget, statement);
}

this.pushScope(ScopeType.Switch);

// Give the switch a unique name to prevent nested switches from acting up.
const switchName = `____TS_switch${this.scopeStack.length}`;

const expression = this.transformExpression(statement.expression);
const switchVariable = tstl.createIdentifier(switchName);
const switchVariableDeclaration = tstl.createVariableDeclarationStatement(switchVariable, expression);

const statements: tstl.Statement[] = [switchVariableDeclaration];

const caseClauses = statement.caseBlock.clauses.filter(c => ts.isCaseClause(c)) as ts.CaseClause[];

for (let i = 0; i < caseClauses.length; i++) {
const clause = caseClauses[i];
// If the clause condition holds, go to the correct label
const condition = tstl.createBinaryExpression(
switchVariable,
this.transformExpression(clause.expression),
tstl.SyntaxKind.EqualityOperator
);
const goto = tstl.createGotoStatement(`${switchName}_case_${i}`);
const conditionalGoto = tstl.createIfStatement(condition, tstl.createBlock([goto]));
statements.push(conditionalGoto);
}

const hasDefaultCase = statement.caseBlock.clauses.some(c => ts.isDefaultClause(c));
if (hasDefaultCase) {
statements.push(tstl.createGotoStatement(`${switchName}_case_default`));
} else {
statements.push(tstl.createGotoStatement(`${switchName}_end`));
}

for (let i = 0; i < statement.caseBlock.clauses.length; i++) {
const clause = statement.caseBlock.clauses[i];
const label = ts.isCaseClause(clause)
? tstl.createLabelStatement(`${switchName}_case_${i}`)
: tstl.createLabelStatement(`${switchName}_case_default`);

const body = tstl.createDoStatement(this.transformStatements(clause.statements));
statements.push(label, body);
}

statements.push(tstl.createLabelStatement(`${switchName}_end`));

this.popScope();

return statements;
}

public transformBreakStatement(breakStatement: ts.BreakStatement): StatementVisitResult {
return tstl.createBreakStatement(undefined, breakStatement);
if (this.peekScope().type === ScopeType.Switch) {
return tstl.createGotoStatement(`____TS_switch${this.scopeStack.length}_end`);
} else {
return tstl.createBreakStatement(undefined, breakStatement);
}
}

public transformTryStatement(statement: ts.TryStatement): StatementVisitResult {
Expand Down
9 changes: 6 additions & 3 deletions test/unit/conditionals.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -222,10 +222,10 @@ export class LuaConditionalsTests {
Expect(result).toBe(expected);
}

@Test("switchLocalScope")
@TestCase(0, 0)
@TestCase(1, 2)
@TestCase(2, 2)
@Test("switchLocalScope")
public switchLocalScope(inp: number, expected: number): void {
const result = util.transpileAndExecute(
`let result: number = -1;
Expand Down Expand Up @@ -253,13 +253,16 @@ export class LuaConditionalsTests {
Expect(result).toBe(expected);
}

@Test("switchReturn")
@TestCase(0, 0)
@TestCase(1, 1)
@TestCase(2, 2)
@TestCase(3, -1)
@Test("switchReturn")
public switchReturn(inp: number, expected: number): void {
const result = util.transpileAndExecute(
`switch (<number>${inp}) {
`const result: number = -1;

switch (<number>${inp}) {
case 0:
return 0;
break;
Expand Down