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/*
* MIT License http://opensource.org/licenses/MIT
* Author: Ben Holloway @bholloway
*/
'use strict';
var path = require('path'),
loaderUtils = require('loader-utils');
/**
* Create a value processing function for a given file path.
*
* @param {function(Object):string} join The inner join function
* @param {string} root The loader options.root value where given
* @param {string} directory The directory of the file webpack is currently processing
* @return {function} value processing function
*/
function valueProcessor({ join, root, directory }) {
var URL_STATEMENT_REGEX = /(url\s*\(\s*)(?:(['"])((?:(?!\2).)*)(\2)|([^'"](?:(?!\)).)*[^'"]))(\s*\))/g,
QUERY_REGEX = /([?#])/g;
/**
* Process the given CSS declaration value.
*
* @param {string} value A declaration value that may or may not contain a url() statement
* @param {function(number):Object} getPathsAtChar Given an offset in the declaration value get a
* list of possible absolute path strings
*/
return function transformValue(value, getPathsAtChar) {
// allow multiple url() values in the declaration
// split by url statements and process the content
// additional capture groups are needed to match quotations correctly
// escaped quotations are not considered
return value
.split(URL_STATEMENT_REGEX)
.map(initialise)
.map(eachSplitOrGroup)
.join('');
/**
* Ensure all capture group tokens are a valid string.
*
* @param {string|void} token A capture group or uncaptured token
* @returns {string}
*/
function initialise(token) {
return typeof token === 'string' ? token : '';
}
/**
* An Array reduce function that accumulates string length.
*/
function accumulateLength(accumulator, element) {
return accumulator + element.length;
}
/**
* Encode the content portion of <code>url()</code> statements.
* There are 6 capture groups in the split making every 7th unmatched.
*
* @param {string} element A single split item
* @param {number} i The index of the item in the split
* @param {Array} arr The array of split values
* @returns {string} Every 3 or 5 items is an encoded url everything else is as is
*/
function eachSplitOrGroup(element, i, arr) {
// the content of the url() statement is either in group 3 or group 5
var mod = i % 7;
// only one of the capture groups 3 or 5 will match the other will be falsey
if (element && ((mod === 3) || (mod === 5))) {
// calculate the offset of the match from the front of the string
var position = arr.slice(0, i - mod + 1).reduce(accumulateLength, 0);
// detect quoted url and unescape backslashes
var before = arr[i - 1],
after = arr[i + 1],
isQuoted = (before === after) && ((before === '\'') || (before === '"')),
unescaped = isQuoted ? element.replace(/\\{2}/g, '\\') : element;
// split into uri and query/hash and then determine if the uri is some type of file
var split = unescaped.split(QUERY_REGEX),
uri = split[0],
query = split.slice(1).join(''),
isRelative = testIsRelative(uri),
isAbsolute = testIsAbsolute(uri);
// file like URIs are processed but not all URIs are files
if (isRelative || isAbsolute) {
var bases = getPathsAtChar(position), // construct iterator as late as possible in case sourcemap invalid
absolute = join({ uri, query, isAbsolute, bases });
if (typeof absolute === 'string') {
var relative = path.relative(directory, absolute)
.replace(/\\/g, '/'); // #6 - backslashes are not legal in URI
return loaderUtils.urlToRequest(relative + query);
}
}
}
// everything else, including parentheses and quotation (where present) and media statements
return element;
}
};
/**
* The loaderUtils.isUrlRequest() doesn't support windows absolute paths on principle. We do not subscribe to that
* dogma so we add path.isAbsolute() check to allow them.
*
* We also eliminate module relative (~) paths.
*
* @param {string|undefined} uri A uri string possibly empty or undefined
* @return {boolean} True for relative uri
*/
function testIsRelative(uri) {
return !!uri && loaderUtils.isUrlRequest(uri, false) && !path.isAbsolute(uri) && (uri.indexOf('~') !== 0);
}
/**
* The loaderUtils.isUrlRequest() doesn't support windows absolute paths on principle. We do not subscribe to that
* dogma so we add path.isAbsolute() check to allow them.
*
* @param {string|undefined} uri A uri string possibly empty or undefined
* @return {boolean} True for absolute uri
*/
function testIsAbsolute(uri) {
return !!uri && (typeof root === 'string') && loaderUtils.isUrlRequest(uri, root) &&
(/^\//.test(uri) || path.isAbsolute(uri));
}
}
module.exports = valueProcessor;