63 lines
1.5 KiB
JavaScript
63 lines
1.5 KiB
JavaScript
'use strict';
|
|
|
|
/**
|
|
* Cache results of the first function call to ensure only calling once.
|
|
*
|
|
* ```js
|
|
* var lazy = require('lazy-cache')(require);
|
|
* // cache the call to `require('ansi-yellow')`
|
|
* lazy('ansi-yellow', 'yellow');
|
|
* // use `ansi-yellow`
|
|
* console.log(lazy.yellow('this is yellow'));
|
|
* ```
|
|
*
|
|
* @param {Function} `fn` Function that will be called only once.
|
|
* @return {Function} Function that can be called to get the cached function
|
|
* @api public
|
|
*/
|
|
|
|
function lazyCache(fn) {
|
|
var cache = {};
|
|
var proxy = function (mod, name) {
|
|
name = name || camelcase(mod);
|
|
Object.defineProperty(proxy, name, {
|
|
get: getter
|
|
});
|
|
|
|
function getter () {
|
|
if (cache.hasOwnProperty(name)) {
|
|
return cache[name];
|
|
}
|
|
try {
|
|
return (cache[name] = fn(mod));
|
|
} catch (err) {
|
|
err.message = 'lazy-cache ' + err.message + ' ' + __filename;
|
|
throw err;
|
|
}
|
|
}
|
|
return getter;
|
|
};
|
|
return proxy;
|
|
}
|
|
|
|
/**
|
|
* Used to camelcase the name to be stored on the `lazy` object.
|
|
*
|
|
* @param {String} `str` String containing `_`, `.`, `-` or whitespace that will be camelcased.
|
|
* @return {String} camelcased string.
|
|
*/
|
|
|
|
function camelcase(str) {
|
|
if (str.length === 1) { return str.toLowerCase(); }
|
|
str = str.replace(/^[\W_]+|[\W_]+$/g, '').toLowerCase();
|
|
return str.replace(/[\W_]+(\w|$)/g, function (_, ch) {
|
|
return ch.toUpperCase();
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Expose `lazyCache`
|
|
*/
|
|
|
|
module.exports = lazyCache;
|