postcss.js
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/*
* MIT License http://opensource.org/licenses/MIT
* Author: Ben Holloway @bholloway
*/
'use strict';
var os = require('os'),
path = require('path'),
postcss = require('postcss');
var fileProtocol = require('../file-protocol');
var ORPHAN_CR_REGEX = /\r(?!\n)(.|\n)?/g;
/**
* 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, removeCR:boolean}} params Named parameters
* @return {{content: string, map: object}} Reworked CSS and optional source-map
*/
function process(sourceFile, sourceContent, params) {
// #107 libsass emits orphan CR not considered newline, postcss does consider newline (content vs source-map mismatch)
var correctedContent = params.removeCR && (os.EOL !== '\r') ?
sourceContent.replace(ORPHAN_CR_REGEX, ' $1') :
sourceContent;
// prepend file protocol to all sources to avoid problems with source map
return postcss([
postcss.plugin('postcss-resolve-url', postcssPlugin)
])
.process(correctedContent, {
from: fileProtocol.prepend(sourceFile),
map : params.outputSourceMap && {
prev : !!params.absSourceMap && fileProtocol.prepend(params.absSourceMap),
inline : false,
annotation : false,
sourcesContent: true // #98 sourcesContent missing from output map
}
})
.then(result => ({
content: result.css,
map : params.outputSourceMap ? fileProtocol.remove(result.map.toJSON()) : null
}));
/**
* Plugin for postcss that follows SASS transpilation.
*/
function postcssPlugin() {
return function(styles) {
styles.walkDecls(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.source.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 ' +
(ORPHAN_CR_REGEX.test(sourceContent) ? '(found orphan CR, try removeCR option)' : '(no orphan CR found)')
);
}
}
}
}
}
module.exports = process;