From ab9f0760a07eeaab510686d58123088fe737dfd7 Mon Sep 17 00:00:00 2001
From: Vincent Wochnik <v.wochnik@gmail.com>
Date: Mon, 20 Feb 2017 10:20:02 +0100
Subject: [PATCH] fix: Limits the number of class-combinations to avoid freeze
 (#23)

* Limits the number of class-combinations to avoid freeze

* add test

* add jsdoc
---
 src/getCombinations.js  | 44 +++++++++++++++++++++++++++++++++++++++++
 src/index.js            | 28 ++------------------------
 test/unique-selector.js |  9 +++++++++
 3 files changed, 55 insertions(+), 26 deletions(-)
 create mode 100644 src/getCombinations.js

diff --git a/src/getCombinations.js b/src/getCombinations.js
new file mode 100644
index 0000000..abfdba6
--- /dev/null
+++ b/src/getCombinations.js
@@ -0,0 +1,44 @@
+/**
+ * Recursively combinate items.
+ * @param  { Array } result
+ * @param  { Array } items
+ * @param  { Array } data
+ * @param  { Number } start
+ * @param  { Number } end
+ * @param  { Number } index
+ * @param  { Number } k
+ */
+function kCombinations( result, items, data, start, end, index, k )
+{
+    if( index === k )
+    {
+        result.push( data.slice( 0, index ).join( '' ) );
+        return;
+    }
+
+    for( let i = start; i <= end && end - i + 1 >= k - index; ++i )
+    {
+        data[index] = items[i];
+        kCombinations( result, items, data, i + 1, end, index + 1, k );
+    }
+}
+
+/**
+ * Returns all the possible selector combinations
+ * @param  { Array } items
+ * @param  { Number } k
+ * @return { Array }
+ */
+export function getCombinations( items, k )
+{
+    const result = [],
+          n = items.length,
+          data = [];
+
+    for( var l = 1; l <= k; ++l )
+    {
+        kCombinations( result, items, data, 0, n - 1, 0, l );
+    }
+
+    return result;
+}
diff --git a/src/index.js b/src/index.js
index 9b5d7b0..7a899a6 100644
--- a/src/index.js
+++ b/src/index.js
@@ -4,6 +4,7 @@
 
 import { getID } from './getID';
 import { getClassSelectors } from './getClasses';
+import { getCombinations } from './getCombinations';
 import { getAttributes } from './getAttributes';
 import { getNthChild } from './getNthChild';
 import { getTag } from './getTag';
@@ -56,7 +57,7 @@ function testUniqueness( element, selector )
  */
 function getUniqueCombination( element, items, tag )
 {
-  const combinations = getCombinations( items );
+  const combinations = getCombinations( items, 3 );
   const uniqCombinations = combinations.filter( testUniqueness.bind( this, element ) );
   if( uniqCombinations.length ) return uniqCombinations[ 0 ];
 
@@ -132,31 +133,6 @@ function getUniqueSelector( element, selectorTypes, attributesToIgnore )
   return '*';
 }
 
-/**
- * Returns all the possible selector combinations
- */
-function getCombinations( items )
-{
-  items = items ? items : [];
-  let result = [[]];
-  let i, j, k, l, ref, ref1;
-
-  for ( i = k = 0, ref = items.length - 1; 0 <= ref ? k <= ref : k >= ref; i = 0 <= ref ? ++k : --k )
-  {
-    for ( j = l = 0, ref1 = result.length - 1; 0 <= ref1 ? l <= ref1 : l >= ref1; j = 0 <= ref1 ? ++l : --l )
-    {
-      result.push( result[ j ].concat( items[ i ] ) );
-    }
-  }
-
-  result.shift();
-  result = result.sort( ( a, b ) => a.length - b.length );
-  result = result.map( item => item.join( '' ) );
-
-  return result;
-}
-
-
 /**
  * Generate unique CSS selector for given DOM element
  *
diff --git a/test/unique-selector.js b/test/unique-selector.js
index 285685c..b461c02 100644
--- a/test/unique-selector.js
+++ b/test/unique-selector.js
@@ -35,6 +35,15 @@ describe( 'Unique Selector Tests', () =>
     expect( uniqueSelector ).to.equal( 'body > :nth-child(1)' );
   } );
 
+  it( 'Classes', () =>
+  {
+    $( 'body' ).get( 0 ).innerHTML = ''; //Clear previous appends
+    $( 'body' ).append( '<div class="test2 ca cb cc cd cx"></div><div class="test2 ca cb cc cd ce"></div><div class="test2 ca cb cc cd ce"></div><div class="test2 ca cb cd ce cf cx"></div>' );
+    const findNode = $( 'body' ).find( '.test2' ).get( 0 );
+    const uniqueSelector = unique( findNode );
+    expect( uniqueSelector ).to.equal( '.cc.cx' );
+  } );
+
 
   it( 'Tag', () =>
   {