Files F95388224

compress.js
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Created: Sun, Dec 15, 07:11

compress.js
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	var List = require('css-tree').List;
	var clone = require('css-tree').clone;
	var usageUtils = require('./usage');
	var clean = require('./clean');
	var replace = require('./replace');
	var restructure = require('./restructure');
	var walk = require('css-tree').walk;

	function readChunk(children, specialComments) {
	var buffer = new List();
	var nonSpaceTokenInBuffer = false;
	var protectedComment;

	children.nextUntil(children.head, function(node, item, list) {
	if (node.type === 'Comment') {
	if (!specialComments \|\| node.value.charAt(0) !== '!') {
	list.remove(item);
	return;
	}

	if (nonSpaceTokenInBuffer \|\| protectedComment) {
	return true;
	}

	list.remove(item);
	protectedComment = node;
	return;
	}

	if (node.type !== 'WhiteSpace') {
	nonSpaceTokenInBuffer = true;
	}

	buffer.insert(list.remove(item));
	});

	return {
	comment: protectedComment,
	stylesheet: {
	type: 'StyleSheet',
	loc: null,
	children: buffer
	}
	};
	}

	function compressChunk(ast, firstAtrulesAllowed, num, options) {
	options.logger('Compress block #' + num, null, true);

	var seed = 1;

	if (ast.type === 'StyleSheet') {
	ast.firstAtrulesAllowed = firstAtrulesAllowed;
	ast.id = seed++;
	}

	walk(ast, {
	visit: 'Atrule',
	enter: function markScopes(node) {
	if (node.block !== null) {
	node.block.id = seed++;
	}
	}
	});
	options.logger('init', ast);

	// remove redundant
	clean(ast, options);
	options.logger('clean', ast);

	// replace nodes for shortened forms
	replace(ast, options);
	options.logger('replace', ast);

	// structure optimisations
	if (options.restructuring) {
	restructure(ast, options);
	}

	return ast;
	}

	function getCommentsOption(options) {
	var comments = 'comments' in options ? options.comments : 'exclamation';

	if (typeof comments === 'boolean') {
	comments = comments ? 'exclamation' : false;
	} else if (comments !== 'exclamation' && comments !== 'first-exclamation') {
	comments = false;
	}

	return comments;
	}

	function getRestructureOption(options) {
	if ('restructure' in options) {
	return options.restructure;
	}

	return 'restructuring' in options ? options.restructuring : true;
	}

	function wrapBlock(block) {
	return new List().appendData({
	type: 'Rule',
	loc: null,
	prelude: {
	type: 'SelectorList',
	loc: null,
	children: new List().appendData({
	type: 'Selector',
	loc: null,
	children: new List().appendData({
	type: 'TypeSelector',
	loc: null,
	name: 'x'
	})
	})
	},
	block: block
	});
	}

	module.exports = function compress(ast, options) {
	ast = ast \|\| { type: 'StyleSheet', loc: null, children: new List() };
	options = options \|\| {};

	var compressOptions = {
	logger: typeof options.logger === 'function' ? options.logger : function() {},
	restructuring: getRestructureOption(options),
	forceMediaMerge: Boolean(options.forceMediaMerge),
	usage: options.usage ? usageUtils.buildIndex(options.usage) : false
	};
	var specialComments = getCommentsOption(options);
	var firstAtrulesAllowed = true;
	var input;
	var output = new List();
	var chunk;
	var chunkNum = 1;
	var chunkChildren;

	if (options.clone) {
	ast = clone(ast);
	}

	if (ast.type === 'StyleSheet') {
	input = ast.children;
	ast.children = output;
	} else {
	input = wrapBlock(ast);
	}

	do {
	chunk = readChunk(input, Boolean(specialComments));
	compressChunk(chunk.stylesheet, firstAtrulesAllowed, chunkNum++, compressOptions);
	chunkChildren = chunk.stylesheet.children;

	if (chunk.comment) {
	// add \n before comment if there is another content in output
	if (!output.isEmpty()) {
	output.insert(List.createItem({
	type: 'Raw',
	value: '\n'
	}));
	}

	output.insert(List.createItem(chunk.comment));

	// add \n after comment if chunk is not empty
	if (!chunkChildren.isEmpty()) {
	output.insert(List.createItem({
	type: 'Raw',
	value: '\n'
	}));
	}
	}

	if (firstAtrulesAllowed && !chunkChildren.isEmpty()) {
	var lastRule = chunkChildren.last();

	if (lastRule.type !== 'Atrule' \|\|
	(lastRule.name !== 'import' && lastRule.name !== 'charset')) {
	firstAtrulesAllowed = false;
	}
	}

	if (specialComments !== 'exclamation') {
	specialComments = false;
	}

	output.appendList(chunkChildren);
	} while (!input.isEmpty());

	return {
	ast: ast
	};
	};

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