301 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			301 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
var resolveProperty = require('css-tree').property;
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var resolveKeyword = require('css-tree').keyword;
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var walk = require('css-tree').walk;
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var generate = require('css-tree').generate;
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var fingerprintId = 1;
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var dontRestructure = {
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    'src': 1 // https://github.com/afelix/csso/issues/50
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};
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var DONT_MIX_VALUE = {
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    // https://developer.mozilla.org/en-US/docs/Web/CSS/display#Browser_compatibility
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    'display': /table|ruby|flex|-(flex)?box$|grid|contents|run-in/i,
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    // https://developer.mozilla.org/en/docs/Web/CSS/text-align
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    'text-align': /^(start|end|match-parent|justify-all)$/i
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};
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var SAFE_VALUES = {
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    cursor: [
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        'auto', 'crosshair', 'default', 'move', 'text', 'wait', 'help',
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        'n-resize', 'e-resize', 's-resize', 'w-resize',
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        'ne-resize', 'nw-resize', 'se-resize', 'sw-resize',
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        'pointer', 'progress', 'not-allowed', 'no-drop', 'vertical-text', 'all-scroll',
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        'col-resize', 'row-resize'
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    ],
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    overflow: [
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        'hidden', 'visible', 'scroll', 'auto'
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    ],
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    position: [
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        'static', 'relative', 'absolute', 'fixed'
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    ]
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};
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var NEEDLESS_TABLE = {
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    'border-width': ['border'],
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    'border-style': ['border'],
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    'border-color': ['border'],
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    'border-top': ['border'],
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    'border-right': ['border'],
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    'border-bottom': ['border'],
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    'border-left': ['border'],
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    'border-top-width': ['border-top', 'border-width', 'border'],
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    'border-right-width': ['border-right', 'border-width', 'border'],
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    'border-bottom-width': ['border-bottom', 'border-width', 'border'],
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    'border-left-width': ['border-left', 'border-width', 'border'],
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    'border-top-style': ['border-top', 'border-style', 'border'],
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    'border-right-style': ['border-right', 'border-style', 'border'],
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    'border-bottom-style': ['border-bottom', 'border-style', 'border'],
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    'border-left-style': ['border-left', 'border-style', 'border'],
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    'border-top-color': ['border-top', 'border-color', 'border'],
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    'border-right-color': ['border-right', 'border-color', 'border'],
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    'border-bottom-color': ['border-bottom', 'border-color', 'border'],
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    'border-left-color': ['border-left', 'border-color', 'border'],
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    'margin-top': ['margin'],
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    'margin-right': ['margin'],
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    'margin-bottom': ['margin'],
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    'margin-left': ['margin'],
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    'padding-top': ['padding'],
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    'padding-right': ['padding'],
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    'padding-bottom': ['padding'],
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    'padding-left': ['padding'],
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    'font-style': ['font'],
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    'font-variant': ['font'],
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    'font-weight': ['font'],
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    'font-size': ['font'],
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    'font-family': ['font'],
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    'list-style-type': ['list-style'],
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    'list-style-position': ['list-style'],
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    'list-style-image': ['list-style']
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};
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function getPropertyFingerprint(propertyName, declaration, fingerprints) {
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    var realName = resolveProperty(propertyName).basename;
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    if (realName === 'background') {
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        return propertyName + ':' + generate(declaration.value);
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    }
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    var declarationId = declaration.id;
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    var fingerprint = fingerprints[declarationId];
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    if (!fingerprint) {
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        switch (declaration.value.type) {
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            case 'Value':
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                var vendorId = '';
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                var iehack = '';
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                var special = {};
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                var raw = false;
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                declaration.value.children.each(function walk(node) {
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                    switch (node.type) {
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                        case 'Value':
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                        case 'Brackets':
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                        case 'Parentheses':
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                            node.children.each(walk);
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                            break;
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                        case 'Raw':
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                            raw = true;
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                            break;
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                        case 'Identifier':
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                            var name = node.name;
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                            if (!vendorId) {
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                                vendorId = resolveKeyword(name).vendor;
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                            }
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                            if (/\\[09]/.test(name)) {
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                                iehack = RegExp.lastMatch;
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                            }
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                            if (SAFE_VALUES.hasOwnProperty(realName)) {
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                                if (SAFE_VALUES[realName].indexOf(name) === -1) {
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                                    special[name] = true;
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                                }
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                            } else if (DONT_MIX_VALUE.hasOwnProperty(realName)) {
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                                if (DONT_MIX_VALUE[realName].test(name)) {
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                                    special[name] = true;
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                                }
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                            }
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                            break;
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                        case 'Function':
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                            var name = node.name;
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                            if (!vendorId) {
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                                vendorId = resolveKeyword(name).vendor;
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                            }
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                            if (name === 'rect') {
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                                // there are 2 forms of rect:
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                                //   rect(<top>, <right>, <bottom>, <left>) - standart
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                                //   rect(<top> <right> <bottom> <left>) – backwards compatible syntax
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                                // only the same form values can be merged
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                                var hasComma = node.children.some(function(node) {
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                                    return node.type === 'Operator' && node.value === ',';
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                                });
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                                if (!hasComma) {
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                                    name = 'rect-backward';
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                                }
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                            }
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                            special[name + '()'] = true;
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                            // check nested tokens too
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                            node.children.each(walk);
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                            break;
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                        case 'Dimension':
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                            var unit = node.unit;
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                            if (/\\[09]/.test(unit)) {
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                                iehack = RegExp.lastMatch;
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                            }
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                            switch (unit) {
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                                // is not supported until IE11
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                                case 'rem':
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                                // v* units is too buggy across browsers and better
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                                // don't merge values with those units
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                                case 'vw':
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                                case 'vh':
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                                case 'vmin':
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                                case 'vmax':
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                                case 'vm': // IE9 supporting "vm" instead of "vmin".
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                                    special[unit] = true;
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                                    break;
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                            }
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                            break;
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                    }
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                });
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                fingerprint = raw
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                    ? '!' + fingerprintId++
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                    : '!' + Object.keys(special).sort() + '|' + iehack + vendorId;
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                break;
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            case 'Raw':
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                fingerprint = '!' + declaration.value.value;
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                break;
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            default:
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                fingerprint = generate(declaration.value);
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        }
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        fingerprints[declarationId] = fingerprint;
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    }
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    return propertyName + fingerprint;
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}
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function needless(props, declaration, fingerprints) {
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    var property = resolveProperty(declaration.property);
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    if (NEEDLESS_TABLE.hasOwnProperty(property.basename)) {
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        var table = NEEDLESS_TABLE[property.basename];
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        for (var i = 0; i < table.length; i++) {
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            var ppre = getPropertyFingerprint(property.prefix + table[i], declaration, fingerprints);
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            var prev = props.hasOwnProperty(ppre) ? props[ppre] : null;
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            if (prev && (!declaration.important || prev.item.data.important)) {
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                return prev;
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            }
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        }
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    }
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}
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function processRule(rule, item, list, props, fingerprints) {
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    var declarations = rule.block.children;
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    declarations.eachRight(function(declaration, declarationItem) {
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        var property = declaration.property;
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        var fingerprint = getPropertyFingerprint(property, declaration, fingerprints);
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        var prev = props[fingerprint];
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        if (prev && !dontRestructure.hasOwnProperty(property)) {
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            if (declaration.important && !prev.item.data.important) {
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                props[fingerprint] = {
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                    block: declarations,
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                    item: declarationItem
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                };
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                prev.block.remove(prev.item);
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                // TODO: use it when we can refer to several points in source
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                // declaration.loc = {
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                //     primary: declaration.loc,
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                //     merged: prev.item.data.loc
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                // };
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            } else {
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                declarations.remove(declarationItem);
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                // TODO: use it when we can refer to several points in source
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                // prev.item.data.loc = {
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                //     primary: prev.item.data.loc,
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                //     merged: declaration.loc
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                // };
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            }
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        } else {
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            var prev = needless(props, declaration, fingerprints);
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            if (prev) {
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                declarations.remove(declarationItem);
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                // TODO: use it when we can refer to several points in source
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                // prev.item.data.loc = {
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                //     primary: prev.item.data.loc,
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                //     merged: declaration.loc
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                // };
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            } else {
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                declaration.fingerprint = fingerprint;
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                props[fingerprint] = {
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                    block: declarations,
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                    item: declarationItem
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                };
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            }
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        }
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    });
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    if (declarations.isEmpty()) {
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        list.remove(item);
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    }
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}
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module.exports = function restructBlock(ast) {
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    var stylesheetMap = {};
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    var fingerprints = Object.create(null);
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    walk(ast, {
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        visit: 'Rule',
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        reverse: true,
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        enter: function(node, item, list) {
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            var stylesheet = this.block || this.stylesheet;
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            var ruleId = (node.pseudoSignature || '') + '|' + node.prelude.children.first().id;
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            var ruleMap;
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            var props;
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            if (!stylesheetMap.hasOwnProperty(stylesheet.id)) {
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                ruleMap = {};
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                stylesheetMap[stylesheet.id] = ruleMap;
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            } else {
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                ruleMap = stylesheetMap[stylesheet.id];
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            }
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            if (ruleMap.hasOwnProperty(ruleId)) {
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                props = ruleMap[ruleId];
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            } else {
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                props = {};
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                ruleMap[ruleId] = props;
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            }
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            processRule.call(this, node, item, list, props, fingerprints);
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        }
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    });
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};
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