fbce4f6c98
* Introduce Uppercase<T> and Lowercase<T> intrinsic types * Accept new API baselines * Add Uppercase/Lowercase/Capitalize/Uncapitalize to lib.d.ts * Update fourslash * Add an 'intrinsic' keyword * Update template literal type tests * Accept new API baselines * Minor fixes * Switch Capitalize<T> and Uncapitalize<T> to intrinsic types * Add tests * Accept new baselines * Accept new baselines * Remove template literal type casing modifiers * Update tests * Accept new baselines * Add more tests * Normalize nested template literal types * Add normalization tests * Accept new baselines * Update tests
57 lines
1.8 KiB
TypeScript
57 lines
1.8 KiB
TypeScript
// @strict: true
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// @declaration: true
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type TU1 = Uppercase<'hello'>; // "HELLO"
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type TU2 = Uppercase<'foo' | 'bar'>; // "FOO" | "BAR"
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type TU3 = Uppercase<string>; // string
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type TU4 = Uppercase<any>; // any
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type TU5 = Uppercase<never>; // never
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type TU6 = Uppercase<42>; // Error
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type TL1 = Lowercase<'HELLO'>; // "hello"
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type TL2 = Lowercase<'FOO' | 'BAR'>; // "foo" | "bar"
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type TL3 = Lowercase<string>; // string
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type TL4 = Lowercase<any>; // any
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type TL5 = Lowercase<never>; // never
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type TL6 = Lowercase<42>; // Error
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type TC1 = Capitalize<'hello'>; // "Hello"
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type TC2 = Capitalize<'foo' | 'bar'>; // "Foo" | "Bar"
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type TC3 = Capitalize<string>; // string
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type TC4 = Capitalize<any>; // any
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type TC5 = Capitalize<never>; // never
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type TC6 = Capitalize<42>; // Error
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type TN1 = Uncapitalize<'Hello'>; // "hello"
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type TN2 = Uncapitalize<'Foo' | 'Bar'>; // "foo" | "bar"
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type TN3 = Uncapitalize<string>; // string
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type TN4 = Uncapitalize<any>; // any
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type TN5 = Uncapitalize<never>; // never
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type TN6 = Uncapitalize<42>; // Error
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type TX1<S extends string> = Uppercase<`aB${S}`>;
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type TX2 = TX1<'xYz'>; // "ABXYZ"
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type TX3<S extends string> = Lowercase<`aB${S}`>;
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type TX4 = TX3<'xYz'>; // "abxyz"
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type TX5 = `${Uppercase<'abc'>}${Lowercase<'XYZ'>}`; // "ABCxyz"
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type MyUppercase<S extends string> = intrinsic; // Error
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function foo1<T extends string, U extends T>(s: string, x: Uppercase<T>, y: Uppercase<U>) {
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s = x;
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s = y;
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x = s; // Error
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x = y;
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y = s; // Error
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y = x; // Error
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}
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function foo2<T extends 'foo' | 'bar'>(x: Uppercase<T>) {
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let s: 'FOO' | 'BAR' = x;
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}
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declare function foo3<T extends string>(x: Uppercase<T>): T;
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function foo4<U extends string>(x: Uppercase<U>) {
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return foo3(x);
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}
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