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Merged
merged 1 commit into from
May 24, 2025
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Convert unary + or - expressions to numbers #1635

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35 changes: 25 additions & 10 deletions src/transformation/visitors/unary-expression.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@ import {
transformCompoundAssignmentExpression,
transformCompoundAssignmentStatement,
} from "./binary-expression/compound";
import { isNumberType } from "../utils/typescript";
import { LuaLibFeature, transformLuaLibFunction } from "../utils/lualib";

export function transformUnaryExpressionStatement(
context: TransformationContext,
Expand Down Expand Up @@ -92,16 +94,29 @@ export const transformPrefixUnaryExpression: FunctionVisitor<ts.PrefixUnaryExpre
false
);

case ts.SyntaxKind.PlusToken:
// TODO: Wrap with `Number`
return context.transformExpression(expression.operand);

case ts.SyntaxKind.MinusToken:
return lua.createUnaryExpression(
context.transformExpression(expression.operand),
lua.SyntaxKind.NegationOperator
);

case ts.SyntaxKind.PlusToken: {
const operand = context.transformExpression(expression.operand);
const type = context.checker.getTypeAtLocation(expression.operand);
if (isNumberType(context, type)) {
return operand;
} else {
return transformLuaLibFunction(context, LuaLibFeature.Number, expression, operand);
}
}
case ts.SyntaxKind.MinusToken: {
const operand = context.transformExpression(expression.operand);
const type = context.checker.getTypeAtLocation(expression.operand);
if (isNumberType(context, type)) {
return lua.createUnaryExpression(operand, lua.SyntaxKind.NegationOperator);
} else {
return transformLuaLibFunction(
context,
LuaLibFeature.Number,
expression,
lua.createUnaryExpression(operand, lua.SyntaxKind.NegationOperator)
);
}
}
case ts.SyntaxKind.ExclamationToken:
return lua.createUnaryExpression(
context.transformExpression(expression.operand),
Expand Down
12 changes: 8 additions & 4 deletions test/unit/__snapshots__/expressions.spec.ts.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -589,9 +589,11 @@ return ____exports"
`;

exports[`Unary expressions basic ("+a") 1`] = `
"local ____exports = {}
"local ____lualib = require("lualib_bundle")
local __TS__Number = ____lualib.__TS__Number
local ____exports = {}
function ____exports.__main(self)
local ____ = a
__TS__Number(a)
end
return ____exports"
`;
Expand All @@ -605,9 +607,11 @@ return ____exports"
`;

exports[`Unary expressions basic ("-a") 1`] = `
"local ____exports = {}
"local ____lualib = require("lualib_bundle")
local __TS__Number = ____lualib.__TS__Number
local ____exports = {}
function ____exports.__main(self)
local ____ = -a
__TS__Number(-a)
end
return ____exports"
`;
Expand Down
15 changes: 15 additions & 0 deletions test/unit/builtins/numbers.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -224,3 +224,18 @@ test.each([
])("Numer constants have correct relative sizes (%p)", comparison => {
util.testExpression(comparison).expectToEqual(true);
});

// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1629
test("unary + casting to number (#1629)", () => {
util.testFunction`
let abc = "123";
return [+abc, +"456"];
`.expectToEqual([123, 456]);
});

test("unary - casting to number", () => {
util.testFunction`
let abc = "123";
return [-abc, -"456"];
`.expectToEqual([-123, -456]);
});
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