feat: improve generatePath arg type

[tyankatsu0105]

What

This PR improves the params type of generatePath's argument.

type Star = "*"
type PathParam<
 Path extends string
> = Path extends `:${infer Param}/${infer Rest}`
   ? Param | PathParam<Rest>
   : Path extends `:${infer Param}`
     ? Param
     : Path extends `${any}/:${infer Param}`
         ? PathParam<`:${Param}`>
         : Path extends `${any}/${Star}`
           ? Star
           : Path extends Star
             ? Star 
             : never
export function generatePath<Path extends string>(path: Path, params: {
  [key in PathParam<Path>]: string
} = {} as any): string {
  return ""
}

generatePath("a", {}) // {}
//^?

generatePath(":a", {})// {"a": string;}
//^?

generatePath("/:a", {})// {"a": string;}
//^?

generatePath("/:a/b", {})// {"a": string;}
//^?

generatePath("/:a/:b", {})// {"a": string; "b": string;}
//^?

generatePath("/a/:b", {})// {"b": string;}
//^?

generatePath("/:a/b/:c", {})// {"a": string; "c": string;}
//^?

generatePath("*", {})// {"*": string;}
//^?

generatePath("/*", {})// {"*": string;}
//^?

generatePath("/a/*/b", {})// {}
//^?

generatePath("/a/b/*", {})// {"*": string;}
//^?

You can try on TS Playground

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[remix-cla-bot]

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[brophdawg11]

I'll preface this with the fact that I'm no TS expert :). But It feels like this is doing something very similar (if not the same thing) as ParamParseSegment/Params higher up in this file? Do you think there's any chance to leverage a shared type?

Also going to ping @pcattori on this one as our in-house TS guru

[pcattori]

To my eyes, this looks like a simpler and more complete version of ParamParseSegment (more complete, because it accounts for "*" params).

It also returns either a union of string or just never when parsing fails (instead of ParamParseSegment's type ParamParseFailed = { failed: true }) , so its suitable to use directly as a property key.

If we can migrate or rewrite the comments from ParamParseSegment to PathParams, I'd be in favor of replacing ParamParseSegment with this.

---

Also we'd need to refactor ParamParseKey to use PathParams:

export type ParamParseKey<Segment extends string> =
  [PathParams<Segment>] extends [never]
    ? string
    : PathParams<Segment>;

*corrected^

---

Action items:

• Move comments from ParamParseSegment to PathParams
• Remove ParamParseSegment

[pcattori]

Naming-wise, I think singular nouns work better for unions. So PathParam feels better to me. Like "a path param can be any of these". But not a strong opinion there.

[tyankatsu0105]

I think singular nouns work better for unions

I totally agree. To be honest, I don't have an opinion on the naming. So, this opinion looks good to me.

[tyankatsu0105]

@pcattori
I did all tasks.
Please review my feature.

[pcattori]

I think we want to swap the branches here:

export type ParamParseKey<Segment extends string> =
  [PathParam<Segment>] extends [never]
    ? string
    : PathParam<Segment>;

[pcattori]

@tyankatsu0105 I'm going to merge this as-is and continue the work in a separate PR so that we can get these improvements into our next prerelease. Thank you for your work!