aaac7fed
 liuqimichale
add
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'use strict';
/**
* Cache results of the first function call to ensure only calling once.
*
* ```js
* var utils = require('lazy-cache')(require);
* // cache the call to `require('ansi-yellow')`
* utils('ansi-yellow', 'yellow');
* // use `ansi-yellow`
* console.log(utils.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);
// check both boolean and string in case `process.env` cases to string
if (process.env.UNLAZY === 'true' || process.env.UNLAZY === true || process.env.TRAVIS) {
cache[name] = fn(mod);
}
Object.defineProperty(proxy, name, {
enumerable: true,
configurable: true,
get: getter
});
function getter() {
if (cache.hasOwnProperty(name)) {
return cache[name];
}
return (cache[name] = fn(mod));
}
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;
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