From 8d8d74ec413a1223d835c182c0acae0851dbc672 Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Sun, 2 Nov 2014 19:19:05 +0100
Subject: [PATCH] Drop nth-child support of all negative sequences

This removes parsing support for selectors such as :nth-child(-n-6). According
to the CSS spec this isn't valid anyway (confirmed by testing it in Chromium).
As a result there's no point in supporting it in any way.
---
 lib/oga/css/parser.y                                |  6 +-----
 .../oga/css/parser/pseudo_classes/nth_child_spec.rb | 13 -------------
 .../parser/pseudo_classes/nth_last_child_spec.rb    |  6 ------
 3 files changed, 1 insertion(+), 24 deletions(-)

diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index 738787e..7b03892 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -413,12 +413,8 @@ end
         compare = :lte
       end
 
-      # -n-6, -n-4, etc
-      if !step and non_positive_number?(offset)
-        node = s(:eq, count_call, s(:int, -1))
-
       # 2n+2, 2n-4, etc
-      elsif offset
+      if offset
         # -2n
         if step and non_positive_number?(step)
           mod_val = s(:int, -step.children[0])
diff --git a/spec/oga/css/parser/pseudo_classes/nth_child_spec.rb b/spec/oga/css/parser/pseudo_classes/nth_child_spec.rb
index e13ce3c..c62345b 100644
--- a/spec/oga/css/parser/pseudo_classes/nth_child_spec.rb
+++ b/spec/oga/css/parser/pseudo_classes/nth_child_spec.rb
@@ -52,12 +52,6 @@ describe Oga::CSS::Parser do
       )
     end
 
-    example 'parse the x:nth-child(-n-6) pseudo class' do
-      parse_css('x:nth-child(-n-6)').should == parse_xpath(
-        'descendant-or-self::x[count(preceding-sibling::*) = -1]'
-      )
-    end
-
     example 'parse the x:nth-child(2n) pseudo class' do
       parse_css('x:nth-child(2n)').should == parse_css('x:nth-child(even)')
     end
@@ -83,13 +77,6 @@ describe Oga::CSS::Parser do
       )
     end
 
-    example 'parse the x:nth-child(-2n-6) pseudo class' do
-      parse_css('x:nth-child(-2n-6)').should == parse_xpath(
-        'descendant-or-self::x[((count(preceding-sibling::*) + 1) <= -2) ' \
-          'and (((count(preceding-sibling::*) + 1) - -2) mod 2) = 0]'
-      )
-    end
-
     example 'parse the x:nth-child(-2n+6) pseudo class' do
       parse_css('x:nth-child(-2n+6)').should == parse_xpath(
         'descendant-or-self::x[((count(preceding-sibling::*) + 1) <= 6) ' \
diff --git a/spec/oga/css/parser/pseudo_classes/nth_last_child_spec.rb b/spec/oga/css/parser/pseudo_classes/nth_last_child_spec.rb
index 359807c..8212191 100644
--- a/spec/oga/css/parser/pseudo_classes/nth_last_child_spec.rb
+++ b/spec/oga/css/parser/pseudo_classes/nth_last_child_spec.rb
@@ -52,12 +52,6 @@ describe Oga::CSS::Parser do
       )
     end
 
-    example 'parse the x:nth-last-child(-n-6) pseudo class' do
-      parse_css('x:nth-last-child(-n-6)').should == parse_xpath(
-        'descendant-or-self::x[count(following-sibling::*) = -1]'
-      )
-    end
-
     example 'parse the x:nth-last-child(2n) pseudo class' do
       parse_css('x:nth-last-child(2n)').should == parse_css(
         'x:nth-last-child(even)'