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Merged
Perryvw merged 4 commits into from
Mar 30, 2023
Merged

Don't output parameter initializer statement if default value is nil #1424

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9bb4c40
Don't output initializer if default value is nil
GlassBricks Mar 27, 2023
c530dde
Handle preceding statements in default parameter value
GlassBricks Mar 27, 2023
8033502
Update test snapshots
GlassBricks Mar 27, 2023
25a0e67
Changes for PR
GlassBricks Mar 28, 2023
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36 changes: 22 additions & 14 deletions src/transformation/visitors/function.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,19 +24,25 @@ import { transformBindingPattern } from "./variable-declaration";
function transformParameterDefaultValueDeclaration(
context: TransformationContext,
parameterName: lua.Identifier,
value?: ts.Expression,
value: ts.Expression,
tsOriginal?: ts.Node
): lua.Statement {
const parameterValue = value ? context.transformExpression(value) : undefined;
const assignment = lua.createAssignmentStatement(parameterName, parameterValue);
): lua.Statement | undefined {
const { precedingStatements: statements, result: parameterValue } = transformInPrecedingStatementScope(
context,
() => context.transformExpression(value)
);
if (!lua.isNilLiteral(parameterValue)) {
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@Perryvw Perryvw Mar 28, 2023

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Couldn't we do that at the top of the function? Check ts.isUndefinedLiteral || ts.isNullLiteral? That way we can avoid a whole bunch of transformations.

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@GlassBricks GlassBricks Mar 28, 2023 •
edited
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Doing this makes this the most general; it applies to anything that results in a nil literal (casts/parenthesis/etc, language extensions, plugins) and shouldn't have any performance impact.

statements.push(lua.createAssignmentStatement(parameterName, parameterValue));
}
if (statements.length === 0) return undefined;

const nilCondition = lua.createBinaryExpression(
parameterName,
lua.createNilLiteral(),
lua.SyntaxKind.EqualityOperator
);

const ifBlock = lua.createBlock([assignment]);
const ifBlock = lua.createBlock(statements, tsOriginal);

return lua.createIfStatement(nilCondition, ifBlock, undefined, tsOriginal);
}
Expand Down Expand Up @@ -106,7 +112,7 @@ export function transformFunctionBodyHeader(
parameters: ts.NodeArray<ts.ParameterDeclaration>,
spreadIdentifier?: lua.Identifier
): lua.Statement[] {
const headerStatements = [];
const headerStatements: lua.Statement[] = [];

// Add default parameters and object binding patterns
const bindingPatternDeclarations: lua.Statement[] = [];
Expand All @@ -116,9 +122,12 @@ export function transformFunctionBodyHeader(
const identifier = lua.createIdentifier(`____bindingPattern${bindPatternIndex++}`);
if (declaration.initializer !== undefined) {
// Default binding parameter
headerStatements.push(
transformParameterDefaultValueDeclaration(context, identifier, declaration.initializer)
const initializer = transformParameterDefaultValueDeclaration(
context,
identifier,
declaration.initializer
);
if (initializer) headerStatements.push(initializer);
}

// Binding pattern
Expand All @@ -129,13 +138,12 @@ export function transformFunctionBodyHeader(
bindingPatternDeclarations.push(...precedingStatements, ...bindings);
} else if (declaration.initializer !== undefined) {
// Default parameter
headerStatements.push(
transformParameterDefaultValueDeclaration(
context,
transformIdentifier(context, declaration.name),
declaration.initializer
)
const initializer = transformParameterDefaultValueDeclaration(
context,
transformIdentifier(context, declaration.name),
declaration.initializer
);
if (initializer) headerStatements.push(initializer);
}
}

Expand Down
22 changes: 22 additions & 0 deletions test/unit/functions/__snapshots__/functions.spec.ts.snap
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@@ -1,5 +1,27 @@
// Jest Snapshot v1, https://goo.gl/fbAQLP

exports[`Function default parameter with value "null" 1`] = `
"local ____exports = {}
function ____exports.__main(self)
local function foo(self, x)
return x
end
return foo(nil)
end
return ____exports"
`;

exports[`Function default parameter with value "undefined" 1`] = `
"local ____exports = {}
function ____exports.__main(self)
local function foo(self, x)
return x
end
return foo(nil)
end
return ____exports"
`;

exports[`function.length unsupported ("5.0"): code 1`] = `
"local ____exports = {}
function ____exports.__main(self)
Expand Down
42 changes: 42 additions & 0 deletions test/unit/functions/functions.spec.ts
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Expand Up @@ -107,6 +107,48 @@ test("Function default binding parameter maintains order", () => {
`.expectToMatchJsResult();
});

test.each(["undefined", "null"])("Function default parameter with value %p", defaultValue => {
util.testFunction`
function foo(x = ${defaultValue}) {
return x;
}
return foo();
`
.expectToMatchJsResult()
.tap(builder => {
const lua = builder.getMainLuaCodeChunk();
expect(lua).not.toMatch("if x == nil then");
})
.expectLuaToMatchSnapshot();
});

test("Function default parameter with preceding statements", () => {
util.testFunction`
let i = 1
function foo(x = i++) {
return x;
}
return [i, foo(), i];
`.expectToMatchJsResult();
});

test("Function default parameter with nil value and preceding statements", () => {
util.testFunction`
const a = new LuaTable()
a.set("foo", "bar")
function foo(x: any = a.set("foo", "baz")) {
return x ?? "nil";
}
return [a.get("foo"), foo(), a.get("foo")];
`
.withLanguageExtensions()
.tap(builder => {
const lua = builder.getMainLuaCodeChunk();
expect(lua).not.toMatch(" x = nil");
})
.expectToEqual(["bar", "nil", "baz"]);
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@Perryvw Perryvw Mar 28, 2023

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Would prefer if you could just use expectToMatchJsResult here, using default TS (no language extensions) with an object and helper function for example.

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@GlassBricks GlassBricks Mar 28, 2023 •
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Could you give a more detailed example what that could look like?
Besides using language extensions, I can't think of a good method that transpiles to nil (not just returns undefined) that works both in JS and lua.

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@Perryvw Perryvw Mar 30, 2023

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Oh I see what you are testing now, that seems maybe a bit too specific but okay

});

test("Class method call", () => {
util.testFunction`
class TestClass {
Expand Down