karmen/node_modules/csso/lib/compressor/restructure/6-restructBlock.js

var resolveProperty = require('../../utils/names.js').property;
var resolveKeyword = require('../../utils/names.js').keyword;
var walkRulesRight = require('../../utils/walk.js').rulesRight;
var translate = require('../../utils/translate.js');
var dontRestructure = {
    'src': 1 // https://github.com/afelix/csso/issues/50
};

var DONT_MIX_VALUE = {
    // https://developer.mozilla.org/en-US/docs/Web/CSS/display#Browser_compatibility
    'display': /table|ruby|flex|-(flex)?box$|grid|contents|run-in/i,
    // https://developer.mozilla.org/en/docs/Web/CSS/text-align
    'text-align': /^(start|end|match-parent|justify-all)$/i
};

var CURSOR_SAFE_VALUE = [
    'auto', 'crosshair', 'default', 'move', 'text', 'wait', 'help',
    'n-resize', 'e-resize', 's-resize', 'w-resize',
    'ne-resize', 'nw-resize', 'se-resize', 'sw-resize',
    'pointer', 'progress', 'not-allowed', 'no-drop', 'vertical-text', 'all-scroll',
    'col-resize', 'row-resize'
];

var NEEDLESS_TABLE = {
    'border-width': ['border'],
    'border-style': ['border'],
    'border-color': ['border'],
    'border-top': ['border'],
    'border-right': ['border'],
    'border-bottom': ['border'],
    'border-left': ['border'],
    'border-top-width': ['border-top', 'border-width', 'border'],
    'border-right-width': ['border-right', 'border-width', 'border'],
    'border-bottom-width': ['border-bottom', 'border-width', 'border'],
    'border-left-width': ['border-left', 'border-width', 'border'],
    'border-top-style': ['border-top', 'border-style', 'border'],
    'border-right-style': ['border-right', 'border-style', 'border'],
    'border-bottom-style': ['border-bottom', 'border-style', 'border'],
    'border-left-style': ['border-left', 'border-style', 'border'],
    'border-top-color': ['border-top', 'border-color', 'border'],
    'border-right-color': ['border-right', 'border-color', 'border'],
    'border-bottom-color': ['border-bottom', 'border-color', 'border'],
    'border-left-color': ['border-left', 'border-color', 'border'],
    'margin-top': ['margin'],
    'margin-right': ['margin'],
    'margin-bottom': ['margin'],
    'margin-left': ['margin'],
    'padding-top': ['padding'],
    'padding-right': ['padding'],
    'padding-bottom': ['padding'],
    'padding-left': ['padding'],
    'font-style': ['font'],
    'font-variant': ['font'],
    'font-weight': ['font'],
    'font-size': ['font'],
    'font-family': ['font'],
    'list-style-type': ['list-style'],
    'list-style-position': ['list-style'],
    'list-style-image': ['list-style']
};

function getPropertyFingerprint(propertyName, declaration, fingerprints) {
    var realName = resolveProperty(propertyName).name;

    if (realName === 'background' ||
       (realName === 'filter' && declaration.value.sequence.first().type === 'Progid')) {
        return propertyName + ':' + translate(declaration.value);
    }

    var declarationId = declaration.id;
    var fingerprint = fingerprints[declarationId];

    if (!fingerprint) {
        var vendorId = '';
        var iehack = '';
        var special = {};

        declaration.value.sequence.each(function walk(node) {
            switch (node.type) {
                case 'Argument':
                case 'Value':
                case 'Braces':
                    node.sequence.each(walk);
                    break;

                case 'Identifier':
                    var name = node.name;

                    if (!vendorId) {
                        vendorId = resolveKeyword(name).vendor;
                    }

                    if (/\\[09]/.test(name)) {
                        iehack = RegExp.lastMatch;
                    }

                    if (realName === 'cursor') {
                        if (CURSOR_SAFE_VALUE.indexOf(name) === -1) {
                            special[name] = true;
                        }
                    } else if (DONT_MIX_VALUE.hasOwnProperty(realName)) {
                        if (DONT_MIX_VALUE[realName].test(name)) {
                            special[name] = true;
                        }
                    }

                    break;

                case 'Function':
                    var name = node.name;

                    if (!vendorId) {
                        vendorId = resolveKeyword(name).vendor;
                    }

                    if (name === 'rect') {
                        // there are 2 forms of rect:
                        //   rect(<top>, <right>, <bottom>, <left>) - standart
                        //   rect(<top> <right> <bottom> <left>) – backwards compatible syntax
                        // only the same form values can be merged
                        if (node.arguments.size < 4) {
                            name = 'rect-backward';
                        }
                    }

                    special[name + '()'] = true;

                    // check nested tokens too
                    node.arguments.each(walk);

                    break;

                case 'Dimension':
                    var unit = node.unit;

                    switch (unit) {
                        // is not supported until IE11
                        case 'rem':

                        // v* units is too buggy across browsers and better
                        // don't merge values with those units
                        case 'vw':
                        case 'vh':
                        case 'vmin':
                        case 'vmax':
                        case 'vm': // IE9 supporting "vm" instead of "vmin".
                            special[unit] = true;
                            break;
                    }
                    break;
            }
        });

        fingerprint = '|' + Object.keys(special).sort() + '|' + iehack + vendorId;

        fingerprints[declarationId] = fingerprint;
    }

    return propertyName + fingerprint;
}

function needless(props, declaration, fingerprints) {
    var property = resolveProperty(declaration.property.name);

    if (NEEDLESS_TABLE.hasOwnProperty(property.name)) {
        var table = NEEDLESS_TABLE[property.name];

        for (var i = 0; i < table.length; i++) {
            var ppre = getPropertyFingerprint(property.prefix + table[i], declaration, fingerprints);
            var prev = props[ppre];

            if (prev && (!declaration.value.important || prev.item.data.value.important)) {
                return prev;
            }
        }
    }
}

function processRuleset(ruleset, item, list, props, fingerprints) {
    var declarations = ruleset.block.declarations;

    declarations.eachRight(function(declaration, declarationItem) {
        var property = declaration.property.name;
        var fingerprint = getPropertyFingerprint(property, declaration, fingerprints);
        var prev = props[fingerprint];

        if (prev && !dontRestructure.hasOwnProperty(property)) {
            if (declaration.value.important && !prev.item.data.value.important) {
                props[fingerprint] = {
                    block: declarations,
                    item: declarationItem
                };

                prev.block.remove(prev.item);
                declaration.info = {
                    primary: declaration.info,
                    merged: prev.item.data.info
                };
            } else {
                declarations.remove(declarationItem);
                prev.item.data.info = {
                    primary: prev.item.data.info,
                    merged: declaration.info
                };
            }
        } else {
            var prev = needless(props, declaration, fingerprints);

            if (prev) {
                declarations.remove(declarationItem);
                prev.item.data.info = {
                    primary: prev.item.data.info,
                    merged: declaration.info
                };
            } else {
                declaration.fingerprint = fingerprint;

                props[fingerprint] = {
                    block: declarations,
                    item: declarationItem
                };
            }
        }
    });

    if (declarations.isEmpty()) {
        list.remove(item);
    }
};

module.exports = function restructBlock(ast) {
    var stylesheetMap = {};
    var fingerprints = Object.create(null);

    walkRulesRight(ast, function(node, item, list) {
        if (node.type !== 'Ruleset') {
            return;
        }

        var stylesheet = this.stylesheet;
        var rulesetId = (node.pseudoSignature || '') + '|' + node.selector.selectors.first().id;
        var rulesetMap;
        var props;

        if (!stylesheetMap.hasOwnProperty(stylesheet.id)) {
            rulesetMap = {};
            stylesheetMap[stylesheet.id] = rulesetMap;
        } else {
            rulesetMap = stylesheetMap[stylesheet.id];
        }

        if (rulesetMap.hasOwnProperty(rulesetId)) {
            props = rulesetMap[rulesetId];
        } else {
            props = {};
            rulesetMap[rulesetId] = props;
        }

        processRuleset.call(this, node, item, list, props, fingerprints);
    });
};