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Simplify chaining of transforms (#22994)

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This commit is contained in:
Andy Hanson 2019-04-25 10:38:20 -07:00 committed by Ryan Cavanaugh
parent bc46c770bf
commit e007ccf97b
2 changed files with 7 additions and 34 deletions
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33
src/compiler/core.ts
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@ -1639,39 +1639,6 @@ namespace ts {
};
}
/**
* High-order function, creates a function that executes a function composition.
* For example, `chain(a, b)` is the equivalent of `x => ((a', b') => y => b'(a'(y)))(a(x), b(x))`
*
* @param args The functions to chain.
*/
export function chain<T, U>(...args: ((t: T) => (u: U) => U)[]): (t: T) => (u: U) => U;
export function chain<T, U>(a: (t: T) => (u: U) => U, b: (t: T) => (u: U) => U, c: (t: T) => (u: U) => U, d: (t: T) => (u: U) => U, e: (t: T) => (u: U) => U): (t: T) => (u: U) => U {
if (e) {
const args: ((t: T) => (u: U) => U)[] = [];
for (let i = 0; i < arguments.length; i++) {
args[i] = arguments[i];
}
return t => compose(...map(args, f => f(t)));
}
else if (d) {
return t => compose(a(t), b(t), c(t), d(t));
}
else if (c) {
return t => compose(a(t), b(t), c(t));
}
else if (b) {
return t => compose(a(t), b(t));
}
else if (a) {
return t => compose(a(t));
}
else {
return _ => u => u;
}
}
/**
* High-order function, composes functions. Note that functions are composed inside-out;
* for example, `compose(a, b)` is the equivalent of `x => b(a(x))`.

8
src/compiler/transformer.ts
View File

@ -151,7 +151,13 @@ namespace ts {
performance.mark("beforeTransform");
// Chain together and initialize each transformer.
const transformation = chain(...transformers)(context);
const transformersWithContext = transformers.map(t => t(context));
const transformation = (node: T): T => {
for (const transform of transformersWithContext) {
node = transform(node);
}
return node;
};
// prevent modification of transformation hooks.
state = TransformationState.Initialized;