GoScrobble/web/node_modules/resolve-url-loader/lib/engine/rework.js

102 lines
3.2 KiB
JavaScript

/*
* MIT License http://opensource.org/licenses/MIT
* Author: Ben Holloway @bholloway
*/
'use strict';
var path = require('path'),
convert = require('convert-source-map'),
rework = require('rework'),
visit = require('rework-visit');
var fileProtocol = require('../file-protocol');
/**
* Process the given CSS content into reworked CSS content.
*
* @param {string} sourceFile The absolute path of the file being processed
* @param {string} sourceContent CSS content without source-map
* @param {{outputSourceMap: boolean, transformDeclaration:function, absSourceMap:object,
* sourceMapConsumer:object}} params Named parameters
* @return {{content: string, map: object}} Reworked CSS and optional source-map
*/
function process(sourceFile, sourceContent, params) {
// embed source-map in css
// prepend file protocol to all sources to avoid problems with source map
var contentWithMap = sourceContent + (
params.absSourceMap ?
convert.fromObject(fileProtocol.prepend(params.absSourceMap)).toComment({multiline: true}) :
''
);
// need to prepend file protocol to source as well to avoid problems with source map
var reworked = rework(contentWithMap, {source: fileProtocol.prepend(sourceFile)})
.use(reworkPlugin)
.toString({
sourcemap : params.outputSourceMap,
sourcemapAsObject: params.outputSourceMap
});
// complete with source-map
if (params.outputSourceMap) {
return {
content: reworked.code,
map : fileProtocol.remove(reworked.map)
};
}
// complete without source-map
else {
return {
content: reworked,
map : null
};
}
/**
* Plugin for css rework that follows SASS transpilation.
*
* @param {object} stylesheet AST for the CSS output from SASS
*/
function reworkPlugin(stylesheet) {
// visit each node (selector) in the stylesheet recursively using the official utility method
// each node may have multiple declarations
visit(stylesheet, function visitor(declarations) {
if (declarations) {
declarations.forEach(eachDeclaration);
}
});
/**
* Process a declaration from the syntax tree.
* @param declaration
*/
function eachDeclaration(declaration) {
var isValid = declaration.value && (declaration.value.indexOf('url') >= 0);
if (isValid) {
// reverse the original source-map to find the original source file before transpilation
var startPosApparent = declaration.position.start,
startPosOriginal = params.sourceMapConsumer &&
params.sourceMapConsumer.originalPositionFor(startPosApparent);
// we require a valid directory for the specified file
var directory =
startPosOriginal &&
startPosOriginal.source &&
fileProtocol.remove(path.dirname(startPosOriginal.source));
if (directory) {
declaration.value = params.transformDeclaration(declaration.value, directory);
}
// source-map present but invalid entry
else if (params.sourceMapConsumer) {
throw new Error('source-map information is not available at url() declaration');
}
}
}
}
}
module.exports = process;