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TheLartianstomblind
TheLartians
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tomblind
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simplify ternary transpilation (#310)
* simplify ternary transpilation * remove ternary from lualib * remove reference to ternary * replace boxing with IIFE * use boxing ternary in luajit transpiler * add transpilation tests for ternary * transpile unprotected ternary for non falsible whenTrue type * resolve merge conflict * add test for undefined whenTrue * add test for literal and non-literal values * add support for strictNullChecks * handle union types * add tests for strictNullChecks * remove FocusTest * added literal ternary test * remove PossiblyFalsy flag check as it is not applicable to lua * correctly handle null * add Void and Never to falsible falgs * refactor isNonFalsible() -> isFalisble() * check for strict mode
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6 files changed

+78
-15
lines changed

6 files changed

+78
-15
lines changed

‎src/LuaLib.ts‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -26,7 +26,6 @@ export enum LuaLibFeature {
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StringReplace = "StringReplace",
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StringSplit = "StringSplit",
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Symbol = "Symbol",
29-
Ternary = "Ternary",
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}
3130

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const luaLibDependencies: { [lib in LuaLibFeature]?: LuaLibFeature[] } = {

‎src/TSHelper.ts‎

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@@ -453,4 +453,28 @@ export class TSHelper {
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public static isDefaultArrayPropertyName(methodName: string): boolean {
454454
return defaultArrayPropertyNames.has(methodName);
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}
456+
457+
public static isFalsible(type: ts.Type, strictNullChecks: boolean): boolean {
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const falsibleFlags = ts.TypeFlags.Boolean
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| ts.TypeFlags.BooleanLiteral
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| ts.TypeFlags.Undefined
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| ts.TypeFlags.Null
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| ts.TypeFlags.Never
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| ts.TypeFlags.Void
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| ts.TypeFlags.Any;
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if (type.flags & falsibleFlags) {
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return true;
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} else if (!strictNullChecks && !type.isLiteral()) {
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return true;
470+
} else if (type.isUnion()) {
471+
for (const subType of type.types) {
472+
if (this.isFalsible(subType, strictNullChecks)) {
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return true;
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}
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}
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}
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return false;
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}
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}

‎src/Transpiler.ts‎

Lines changed: 13 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -780,7 +780,7 @@ export abstract class LuaTranspiler {
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return this.transpileBinaryExpression(node as ts.BinaryExpression, brackets);
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case ts.SyntaxKind.ConditionalExpression:
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// Add brackets to preserve ordering
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return this.transpileConditionalExpression(node as ts.ConditionalExpression, brackets);
783+
return this.transpileConditionalExpression(node as ts.ConditionalExpression);
784784
case ts.SyntaxKind.CallExpression:
785785
return this.transpileCallExpression(node as ts.CallExpression);
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case ts.SyntaxKind.PropertyAccessExpression:
@@ -1030,13 +1030,22 @@ export abstract class LuaTranspiler {
10301030
return parts.join("..");
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}
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1033-
public transpileConditionalExpression(node: ts.ConditionalExpression, brackets?: boolean): string {
1033+
public transpileProtectedConditionalExpression(node: ts.ConditionalExpression): string {
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const condition = this.transpileExpression(node.condition);
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const val1 = this.transpileExpression(node.whenTrue);
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const val2 = this.transpileExpression(node.whenFalse);
1037+
return `((${condition}) and function() return ${val1}; end or function() return ${val2}; end)()`;
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}
10371039

1038-
return this.transpileLuaLibFunction(LuaLibFeature.Ternary, condition,
1039-
`function() return ${val1} end`, `function() return ${val2} end`);
1040+
public transpileConditionalExpression(node: ts.ConditionalExpression): string {
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const isStrict = this.options.strict || this.options.strictNullChecks;
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if (tsHelper.isFalsible(this.checker.getTypeAtLocation(node.whenTrue), isStrict)) {
1043+
return this.transpileProtectedConditionalExpression(node);
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}
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const condition = this.transpileExpression(node.condition);
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const val1 = this.transpileExpression(node.whenTrue);
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const val2 = this.transpileExpression(node.whenFalse);
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return `((${condition}) and (${val1}) or (${val2}))`;
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}
10411050

10421051
public transpileBinaryAssignmentExpression(

‎src/lualib/Ternary.ts‎

Lines changed: 0 additions & 7 deletions
This file was deleted.

‎src/targets/Transpiler.JIT.ts‎

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Original file line numberDiff line numberDiff line change
@@ -44,4 +44,12 @@ export class LuaTranspilerJIT extends LuaTranspiler52 {
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public transpileSpreadElement(node: ts.SpreadElement): string {
4545
return "unpack(" + this.transpileExpression(node.expression) + ")";
4646
}
47+
48+
/** @override */
49+
public transpileProtectedConditionalExpression(node: ts.ConditionalExpression): string {
50+
const condition = this.transpileExpression(node.condition);
51+
const val1 = this.transpileExpression(node.whenTrue);
52+
const val2 = this.transpileExpression(node.whenFalse);
53+
return `((${condition}) and {${val1}} or {${val2}})[1]`;
54+
}
4755
}

‎test/unit/expressions.spec.ts‎

Lines changed: 33 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -192,6 +192,36 @@ export class ExpressionTests {
192192
Expect(util.transpileString("undefined")).toBe("nil;");
193193
}
194194

195+
@TestCase("true ? 'a' : 'b'", "a")
196+
@TestCase("false ? 'a' : 'b'", "b")
197+
@TestCase("true ? false : true", false)
198+
@TestCase("false ? false : true", true)
199+
@TestCase("true ? literalValue : true", "literal")
200+
@TestCase("true ? variableValue : true", undefined)
201+
@TestCase("true ? maybeUndefinedValue : true", undefined)
202+
@TestCase("true ? maybeBooleanValue : true", false)
203+
@TestCase("true ? maybeUndefinedValue : true", undefined, { strictNullChecks: true })
204+
@TestCase("true ? maybeBooleanValue : true", false, { strictNullChecks: true })
205+
@TestCase("true ? undefined : true", undefined, { strictNullChecks: true })
206+
@TestCase("true ? null : true", undefined, { strictNullChecks: true })
207+
@TestCase("true ? false : true", false, { luaTarget: LuaTarget.Lua51 })
208+
@TestCase("false ? false : true", true, { luaTarget: LuaTarget.Lua51 })
209+
@TestCase("true ? undefined : true", undefined, { luaTarget: LuaTarget.Lua51 })
210+
@TestCase("true ? false : true", false, { luaTarget: LuaTarget.LuaJIT })
211+
@TestCase("false ? false : true", true, { luaTarget: LuaTarget.LuaJIT })
212+
@TestCase("true ? undefined : true", undefined, { luaTarget: LuaTarget.LuaJIT })
213+
@Test("Ternary operator")
214+
public ternaryOperator(input: string, expected: any, options?: ts.CompilerOptions): void {
215+
const source = `const literalValue = 'literal';`
216+
+ `let variableValue:string;`
217+
+ `let maybeBooleanValue:string|boolean = false;`
218+
+ `let maybeUndefinedValue:string|undefined;`
219+
+ `return ${input};`;
220+
const lua = util.transpileString(source, options);
221+
const result = util.executeLua(lua);
222+
Expect(result).toBe(expected);
223+
}
224+
195225
@TestCase("inst.field", 8)
196226
@TestCase("inst.field + 3", 8 + 3)
197227
@TestCase("inst.field * 3", 8 * 3)
@@ -260,7 +290,7 @@ export class ExpressionTests {
260290
@TestCase("inst.superBaseField", 4)
261291
@Test("Inherited accessors")
262292
public inheritedAccessors(expression: string, expected: any): void {
263-
const source = `class MyBaseClass {`
293+
const source = `class MyBaseClass {`
264294
+ ` public _baseField: number;`
265295
+ ` public get baseField(): number { return this._baseField + 6; }`
266296
+ ` public set baseField(v: number) { this._baseField = v; }`
@@ -269,13 +299,13 @@ export class ExpressionTests {
269299
+ ` public _field: number;`
270300
+ ` public get field(): number { return this._field + 4; }`
271301
+ ` public set field(v: number) { this._field = v; }`
272-
+ `}`
302+
+ `}`
273303
+ `class MySuperClass extends MyClass {`
274304
+ ` public _superField: number;`
275305
+ ` public get superField(): number { return this._superField + 2; }`
276306
+ ` public set superField(v: number) { this._superField = v; }`
277307
+ ` public get superBaseField() { return this.baseField - 3; }`
278-
+ `}`
308+
+ `}`
279309
+ `var inst = new MySuperClass();`
280310
+ `inst.baseField = 1;`
281311
+ `inst.field = 2;`

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