Initial lib

css-explain.js

@@ -0,0 +1,148 @@
+(function() {
+  "use strict";
+
+  // From Sizzle
+  //   https://github.com/jquery/sizzle/blob/master/sizzle.js
+  var chunker = /((?:\((?:\([^()]+\)|[^()]+)+\)|\[(?:\[[^\[\]]*\]|['"][^'"]*['"]|[^\[\]'"]+)+\]|\\.|[^ >+~,(\[\\]+)+|[>+~])(\s*,\s*)?((?:.|\r|\n)*)/g;
+  var match = {
+    ID: /#((?:[\w\u00c0-\uFFFF\-]|\\.)+)/g,
+    CLASS: /\.((?:[\w\u00c0-\uFFFF\-]|\\.)+)/g,
+    TAG: /^((?:[\w\u00c0-\uFFFF\-]|\\.)+)/g,
+    ATTR: /\[\s*((?:[\w\u00c0-\uFFFF\-]|\\.)+)\s*(?:(\S?=)\s*(?:(['"])(.*?)\3|(#?(?:[\w\u00c0-\uFFFF\-]|\\.)*)|)|)\s*\]/g,
+    PSEUDO: /:((?:[\w\u00c0-\uFFFF\-]|\\.)+)(?:\((['"]?)((?:\([^\)]+\)|[^\(\)]*)+)\2\))?/g
+  };
+
+  function parse(selector) {
+    var m, rest = selector, parts = [];
+
+    do {
+      chunker.exec("");
+      m = chunker.exec(rest);
+      if (m) {
+        rest = m[3];
+        parts.push(m[1]);
+        if (m[2]) {
+          break;
+        }
+      }
+    } while (m);
+
+    return parts;
+  }
+
+
+  function computeSpecificity(parts) {
+    var a = 0, b = 0, c = 0;
+
+    var part, m, i, len;
+    for (i = 0, len = parts.length; i < len; i++) {
+      part = parts[i];
+
+      m = part.match(match.ID);
+      if (m) a += m.length;
+
+      m = part.match(match.ATTR);
+      if (m) b += m.length;
+
+      m = part.match(match.CLASS);
+      if (m) b += m.length;
+
+      m = part.match(match.TAG);
+      if (m) c += m.length;
+
+      m = part.match(match.PSEUDO);
+      if (m) c += m.length;
+    }
+
+    return [a, b, c];
+  }
+
+  function detectCategory(parts) {
+    var last = parts[parts.length-1];
+    if (last.match(match.ID)) {
+      return 'id';
+    } else if (last.match(match.CLASS)) {
+      return 'class';
+    } else if (last.match(match.TAG)) {
+      return 'tag';
+    } else {
+      return 'universal';
+    }
+  }
+
+  function computeScore(parts) {
+    var last = parts[parts.length-1];
+
+    // Descendant selectors
+    if (parts.length > 1) {
+      // Child selectors
+      if (parts[parts.length-2] === '>') {
+        if (last.match(match.ID)) {
+          return 3;
+        } else if (last.match(match.CLASS)) {
+          return 5;
+        } else if (last.match(match.TAG)) {
+          return 7;
+        } else {
+          return 9;
+        }
+
+      // Descendant selectors
+      } else {
+        if (last.match(match.ID)) {
+          return 4;
+        } else if (last.match(match.CLASS)) {
+          return 6;
+        } else if (last.match(match.TAG)) {
+          return 8;
+        } else {
+          return 10;
+        }
+      }
+
+    // Simple selectors
+    } else {
+      if (last.match(match.ID)) {
+        // Over qualified ID
+        if (last.match(match.CLASS) || last.match(match.TAG)) {
+          return 2;
+
+        // Basic ID
+        } else {
+          return 0;
+        }
+
+      // Simple tag
+      } else if (last.match(match.TAG)) {
+        return 2;
+
+      // Simple class
+      } else if (last.match(match.CLASS)) {
+        return 1;
+
+      } else {
+        return 0;
+      }
+    }
+  }
+
+  function cssExplain(selector) {
+    var parts       = parse(selector);
+    var specificity = computeSpecificity(parts);
+    var category    = detectCategory(parts);
+    var score       = computeScore(parts);
+
+    return {
+      parts: parts,
+      category: category,
+      specificity: specificity,
+      score: score
+    };
+  }
+
+  if (typeof exports !== 'undefined') {
+    exports.cssExplain = cssExplain;
+  } else {
+    window.cssExplain = cssExplain;
+  }
+})();