54 lines
1.7 KiB
TypeScript
54 lines
1.7 KiB
TypeScript
// @declaration: true
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type PrimitiveName = 'string' | 'number' | 'boolean';
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function getFalsyPrimitive(x: "string"): string;
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function getFalsyPrimitive(x: "number"): number;
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function getFalsyPrimitive(x: "boolean"): boolean;
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function getFalsyPrimitive(x: "boolean" | "string"): boolean | string;
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function getFalsyPrimitive(x: "boolean" | "number"): boolean | number;
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function getFalsyPrimitive(x: "number" | "string"): number | string;
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function getFalsyPrimitive(x: "number" | "string" | "boolean"): number | string | boolean;
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function getFalsyPrimitive(x: PrimitiveName): number | string | boolean {
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if (x === "string") {
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return "";
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}
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if (x === "number") {
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return 0;
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}
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if (x === "boolean") {
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return false;
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}
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// Should be unreachable.
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throw "Invalid value";
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}
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namespace Consts1 {
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const EMPTY_STRING = getFalsyPrimitive("string");
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const ZERO = getFalsyPrimitive('number');
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const FALSE = getFalsyPrimitive("boolean");
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}
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const string: "string" = "string"
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const number: "number" = "number"
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const boolean: "boolean" = "boolean"
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const stringOrNumber = string || number;
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const stringOrBoolean = string || boolean;
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const booleanOrNumber = number || boolean;
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const stringOrBooleanOrNumber = stringOrBoolean || number;
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namespace Consts2 {
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const EMPTY_STRING = getFalsyPrimitive(string);
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const ZERO = getFalsyPrimitive(number);
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const FALSE = getFalsyPrimitive(boolean);
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const a = getFalsyPrimitive(stringOrNumber);
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const b = getFalsyPrimitive(stringOrBoolean);
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const c = getFalsyPrimitive(booleanOrNumber);
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const d = getFalsyPrimitive(stringOrBooleanOrNumber);
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}
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