add support to convert lambda to function and vice-versa #28250
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lambda to fn
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| function getFunctionInfo(file: SourceFile, startPosition: number): FunctionInfo | undefined { | ||
| const token = getTokenAtPosition(file, startPosition); | ||
| let maybeFunc; |
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This could just be two different variables, one for each time it's assigned to.
| let maybeFunc; | ||
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| maybeFunc = getArrowFunctionFromVariableDeclaration(token.parent); | ||
| if (!!maybeFunc) return { selectedVariableDeclaration: true, func: maybeFunc }; |
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No need to have !! for the condition of an if, it automatically booleanifies everything.
| return getEditInfoForConvertToArrowFunction(context, func); | ||
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| default: | ||
| Debug.fail("invalid action"); |
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You can just return Debug.fail("Invalid action"); since it returns never.
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| function getEditInfoForConvertToArrowFunction(context: RefactorContext, func: FunctionExpression | ArrowFunction): RefactorEditInfo | undefined { | ||
| const { file } = context; | ||
| if (!isFunctionExpression(func)) return undefined; |
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The parameter type should just be FunctionExpression then?
| } | ||
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| function canBeConvertedToExpression(body: Block, head: Statement): head is ReturnStatement | ExpressionStatement { | ||
| return body.statements.length === 1 && ((isReturnStatement(head) && !!head.expression) || isExpressionStatement(head)); |
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Not sure about the last condition there. () => foo() has a different type from () => { foo(); }.
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you're right.
to clarify
let epsilon = () => "epsilon";
let foo = () => epsilon() // foo: () => string
let bar = () => { epsilon() } // bar: () => void
| body = func.body; | ||
| } | ||
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| const newNode = createArrowFunction(func.modifiers, func.typeParameters, func.parameters, func.type, /* equalsGreaterThanToken */ undefined, body); |
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Suprised this works without the token -- seems like it would be better to createToken(SyntaxKind.EqualsGreaterThanToken) even if the emitter doesn't currently require it.
| const body = convertToBlock(func.body); | ||
| const newNode = createFunctionExpression(func.modifiers, func.asteriskToken, /* name */ undefined, func.typeParameters, func.parameters, func.type, body); | ||
| const edits = textChanges.ChangeTracker.with(context, t => t.replaceNode(file, func, newNode)); | ||
| return { renameFilename: undefined, renameLocation: undefined, edits }; |
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It may be better for these functions to just return the edits, and some outer function to wrap them in RefactorEditInfo.
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You can't change the following function expression into an arrow function: [1,2,3].map(function isEven(n): boolean {
return n === 0 ? true : n === 1 ? false : isEven(n - 2);
});But you should be able to change the following: [1,2,3].map(function isEven(n) {
return n % 2 === 0;
});[1,2,3].map(function(n) {
return n % 2 === 0;
}); |
| @@ -0,0 +1,13 @@ | |||
| /// <reference path='fourslash.ts' /> | |||
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| //// let foo = /*x*/(/*y*/) => 1 + 1; | |||
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There should be tests where the function expression isn't preceded by a variable declaration.
ghost
mentioned this pull request
because this behaves differently in arrow than in function
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Hi @Andy-MS I've solved that using forEachChild to detect whether a body contains a Are the any auxiliary function which can provide a better way to solve this? |
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@bigaru Make sure you're not testing any nested functions or classes, which would come with their own meaning of |
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@D0nGiovanni if you are still interested in this PR I would like to get it in once the merge conflicts are resolved. Thanks! |
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@jessetrinity Alright! I should have it done by the end of the weekend. |
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When @D0nGiovanni told me, I was so excited that I resolved the conflicts. Thanks @jessetrinity for your effort! |
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@D0nGiovanni @bigaru thank you for the contribution to TypeScript! |
Fixes #23299