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Adds strict type definitions to sprintf #18

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1 change: 1 addition & 0 deletions packages/sprintf/.gitignore
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
!types/*
25 changes: 9 additions & 16 deletions packages/sprintf/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -53,26 +53,19 @@ var PATTERN =
* sprintf( 'Hello %s!', 'world' );
* // ⇒ 'Hello world!'
* ```
*
* @param {string} string printf format string
* @param {...string|string[]|Object<string,string>} [args] String arguments.
* @template {string} T
* @param {T} string - string printf format string
* @param {import('./types/index.d').SprintfArgs<T>|import('./types/index.d').SprintfArgs<T>[]} args String arguments.
*
* @return {string} Formatted string.
*/
export default function sprintf(string, args) {
var i;
export default function sprintf(string, ...args) {
var i = 0;

if (!Array.isArray(args)) {
// Construct a copy of arguments from index one, used for replace
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// function placeholder substitution.
args = new Array(arguments.length - 1);
for (i = 1; i < arguments.length; i++) {
args[i - 1] = arguments[i];
}
if (Array.isArray(args[0])) {
args = /** @type {import('./types/index.d').SprintfArgs<T>[]} */ args[0];
}

i = 1;

return string.replace(PATTERN, function () {
var index, name, precision, type, value;

Expand All @@ -89,14 +82,14 @@ export default function sprintf(string, args) {

// Asterisk precision determined by peeking / shifting next argument.
if (precision === '*') {
precision = args[i - 1];
precision = args[i];
i++;
}

if (name === undefined) {
// If not a positional argument, use counter value.
if (index === undefined) {
index = i;
index = i + 1;
}

i++;
Expand Down
1 change: 1 addition & 0 deletions packages/sprintf/package.json
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
"files": [
"index.js",
"index.d.ts",
"types/index.d.ts",
"build",
"dist"
],
Expand Down
25 changes: 25 additions & 0 deletions packages/sprintf/types/index.d.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
type Specifiers = {
's': string,
'd': number,
'f': number
};
type S = keyof Specifiers;

type ExtractNamedPlaceholders<T extends string> =
T extends `${any}%(${infer Key})${infer Spec}${infer Rest}`
? Spec extends S
? { [K in Key]: Specifiers[Spec]} & ExtractNamedPlaceholders<Rest>
: never
: {};

type ExtractUnnamedPlaceholders<T extends string> =
T extends `${any}%${infer Spec}${infer Rest}`
? Spec extends S
? [Specifiers[Spec], ...ExtractUnnamedPlaceholders<Rest>]
: never
: [];

export type SprintfArgs<T extends string> =
ExtractUnnamedPlaceholders<T> extends never
? [values: ExtractNamedPlaceholders<T>]
: ExtractUnnamedPlaceholders<T>;
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