8-restructRuleset.js
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var List = require('../../utils/list.js');
var utils = require('./utils.js');
var walkRulesRight = require('../../utils/walk.js').rulesRight;
function calcSelectorLength(list) {
var length = 0;
list.each(function(data) {
length += data.id.length + 1;
});
return length - 1;
}
function calcDeclarationsLength(tokens) {
var length = 0;
for (var i = 0; i < tokens.length; i++) {
length += tokens[i].length;
}
return (
length + // declarations
tokens.length - 1 // delimeters
);
}
function processRuleset(node, item, list) {
var avoidRulesMerge = this.stylesheet.avoidRulesMerge;
var selectors = node.selector.selectors;
var block = node.block;
var disallowDownMarkers = Object.create(null);
var allowMergeUp = true;
var allowMergeDown = true;
list.prevUntil(item.prev, function(prev, prevItem) {
// skip non-ruleset node if safe
if (prev.type !== 'Ruleset') {
return utils.unsafeToSkipNode.call(selectors, prev);
}
var prevSelectors = prev.selector.selectors;
var prevBlock = prev.block;
if (node.pseudoSignature !== prev.pseudoSignature) {
return true;
}
allowMergeDown = !prevSelectors.some(function(selector) {
return selector.compareMarker in disallowDownMarkers;
});
// try prev ruleset if simpleselectors has no equal specifity and element selector
if (!allowMergeDown && !allowMergeUp) {
return true;
}
// try to join by selectors
if (allowMergeUp && utils.isEqualLists(prevSelectors, selectors)) {
prevBlock.declarations.appendList(block.declarations);
list.remove(item);
return true;
}
// try to join by properties
var diff = utils.compareDeclarations(block.declarations, prevBlock.declarations);
// console.log(diff.eq, diff.ne1, diff.ne2);
if (diff.eq.length) {
if (!diff.ne1.length && !diff.ne2.length) {
// equal blocks
if (allowMergeDown) {
utils.addSelectors(selectors, prevSelectors);
list.remove(prevItem);
}
return true;
} else if (!avoidRulesMerge) { /* probably we don't need to prevent those merges for @keyframes
TODO: need to be checked */
if (diff.ne1.length && !diff.ne2.length) {
// prevBlock is subset block
var selectorLength = calcSelectorLength(selectors);
var blockLength = calcDeclarationsLength(diff.eq); // declarations length
if (allowMergeUp && selectorLength < blockLength) {
utils.addSelectors(prevSelectors, selectors);
block.declarations = new List(diff.ne1);
}
} else if (!diff.ne1.length && diff.ne2.length) {
// node is subset of prevBlock
var selectorLength = calcSelectorLength(prevSelectors);
var blockLength = calcDeclarationsLength(diff.eq); // declarations length
if (allowMergeDown && selectorLength < blockLength) {
utils.addSelectors(selectors, prevSelectors);
prevBlock.declarations = new List(diff.ne2);
}
} else {
// diff.ne1.length && diff.ne2.length
// extract equal block
var newSelector = {
type: 'Selector',
info: {},
selectors: utils.addSelectors(prevSelectors.copy(), selectors)
};
var newBlockLength = calcSelectorLength(newSelector.selectors) + 2; // selectors length + curly braces length
var blockLength = calcDeclarationsLength(diff.eq); // declarations length
// create new ruleset if declarations length greater than
// ruleset description overhead
if (allowMergeDown && blockLength >= newBlockLength) {
var newRuleset = {
type: 'Ruleset',
info: {},
pseudoSignature: node.pseudoSignature,
selector: newSelector,
block: {
type: 'Block',
info: {},
declarations: new List(diff.eq)
}
};
block.declarations = new List(diff.ne1);
prevBlock.declarations = new List(diff.ne2.concat(diff.ne2overrided));
list.insert(list.createItem(newRuleset), prevItem);
return true;
}
}
}
}
if (allowMergeUp) {
// TODO: disallow up merge only if any property interception only (i.e. diff.ne2overrided.length > 0);
// await property families to find property interception correctly
allowMergeUp = !prevSelectors.some(function(prevSelector) {
return selectors.some(function(selector) {
return selector.compareMarker === prevSelector.compareMarker;
});
});
}
prevSelectors.each(function(data) {
disallowDownMarkers[data.compareMarker] = true;
});
});
};
module.exports = function restructRuleset(ast) {
walkRulesRight(ast, function(node, item, list) {
if (node.type === 'Ruleset') {
processRuleset.call(this, node, item, list);
}
});
};