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197 lines
5.1 KiB
197 lines
5.1 KiB
var List = require('css-tree').List;
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var clone = require('css-tree').clone;
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var usageUtils = require('./usage');
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var clean = require('./clean');
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var replace = require('./replace');
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var restructure = require('./restructure');
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var walk = require('css-tree').walk;
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function readChunk(children, specialComments) {
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var buffer = new List();
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var nonSpaceTokenInBuffer = false;
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var protectedComment;
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children.nextUntil(children.head, function(node, item, list) {
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if (node.type === 'Comment') {
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if (!specialComments || node.value.charAt(0) !== '!') {
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list.remove(item);
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return;
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}
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if (nonSpaceTokenInBuffer || protectedComment) {
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return true;
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}
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list.remove(item);
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protectedComment = node;
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return;
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}
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if (node.type !== 'WhiteSpace') {
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nonSpaceTokenInBuffer = true;
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}
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buffer.insert(list.remove(item));
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});
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return {
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comment: protectedComment,
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stylesheet: {
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type: 'StyleSheet',
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loc: null,
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children: buffer
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}
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};
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}
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function compressChunk(ast, firstAtrulesAllowed, num, options) {
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options.logger('Compress block #' + num, null, true);
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var seed = 1;
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if (ast.type === 'StyleSheet') {
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ast.firstAtrulesAllowed = firstAtrulesAllowed;
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ast.id = seed++;
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}
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walk(ast, {
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visit: 'Atrule',
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enter: function markScopes(node) {
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if (node.block !== null) {
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node.block.id = seed++;
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}
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}
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});
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options.logger('init', ast);
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// remove redundant
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clean(ast, options);
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options.logger('clean', ast);
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// replace nodes for shortened forms
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replace(ast, options);
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options.logger('replace', ast);
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// structure optimisations
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if (options.restructuring) {
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restructure(ast, options);
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}
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return ast;
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}
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function getCommentsOption(options) {
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var comments = 'comments' in options ? options.comments : 'exclamation';
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if (typeof comments === 'boolean') {
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comments = comments ? 'exclamation' : false;
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} else if (comments !== 'exclamation' && comments !== 'first-exclamation') {
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comments = false;
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}
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return comments;
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}
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function getRestructureOption(options) {
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if ('restructure' in options) {
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return options.restructure;
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}
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return 'restructuring' in options ? options.restructuring : true;
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}
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function wrapBlock(block) {
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return new List().appendData({
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type: 'Rule',
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loc: null,
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prelude: {
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type: 'SelectorList',
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loc: null,
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children: new List().appendData({
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type: 'Selector',
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loc: null,
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children: new List().appendData({
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type: 'TypeSelector',
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loc: null,
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name: 'x'
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})
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})
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},
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block: block
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});
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}
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module.exports = function compress(ast, options) {
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ast = ast || { type: 'StyleSheet', loc: null, children: new List() };
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options = options || {};
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var compressOptions = {
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logger: typeof options.logger === 'function' ? options.logger : function() {},
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restructuring: getRestructureOption(options),
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forceMediaMerge: Boolean(options.forceMediaMerge),
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usage: options.usage ? usageUtils.buildIndex(options.usage) : false
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};
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var specialComments = getCommentsOption(options);
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var firstAtrulesAllowed = true;
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var input;
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var output = new List();
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var chunk;
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var chunkNum = 1;
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var chunkChildren;
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if (options.clone) {
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ast = clone(ast);
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}
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if (ast.type === 'StyleSheet') {
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input = ast.children;
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ast.children = output;
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} else {
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input = wrapBlock(ast);
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}
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do {
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chunk = readChunk(input, Boolean(specialComments));
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compressChunk(chunk.stylesheet, firstAtrulesAllowed, chunkNum++, compressOptions);
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chunkChildren = chunk.stylesheet.children;
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if (chunk.comment) {
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// add \n before comment if there is another content in output
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if (!output.isEmpty()) {
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output.insert(List.createItem({
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type: 'Raw',
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value: '\n'
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}));
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}
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output.insert(List.createItem(chunk.comment));
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// add \n after comment if chunk is not empty
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if (!chunkChildren.isEmpty()) {
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output.insert(List.createItem({
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type: 'Raw',
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value: '\n'
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}));
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}
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}
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if (firstAtrulesAllowed && !chunkChildren.isEmpty()) {
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var lastRule = chunkChildren.last();
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if (lastRule.type !== 'Atrule' ||
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(lastRule.name !== 'import' && lastRule.name !== 'charset')) {
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firstAtrulesAllowed = false;
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}
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}
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if (specialComments !== 'exclamation') {
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specialComments = false;
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}
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output.appendList(chunkChildren);
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} while (!input.isEmpty());
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return {
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ast: ast
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};
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};
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