From 6792127600c9e0a25585c10a3a71abb4803ceb99 Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Tue, 7 Oct 2014 22:47:47 +0200
Subject: [PATCH] Reworked CSS parser rules.

This includes better rules for parsing separate path members, pseudo class
arguments and some changes to remove all remaining parsing conflicts.
---
 lib/oga/css/parser.y                       | 57 +++++++++++++---------
 spec/oga/css/parser/axes_spec.rb           | 45 +++++++++++++++++
 spec/oga/css/parser/pseudo_classes_spec.rb |  8 +++
 3 files changed, 86 insertions(+), 24 deletions(-)

diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index 71c4507..c612752 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -3,30 +3,44 @@
 #
 class Oga::CSS::Parser
 
+token T_IDENT T_PIPE T_LBRACK T_RBRACK T_COLON T_SPACE T_LPAREN T_RPAREN T_MINUS
+token T_EQ T_SPACE_IN T_STARTS_WITH T_ENDS_WITH T_IN T_HYPHEN_IN
+token T_CHILD T_FOLLOWING T_FOLLOWING_DIRECT
+token T_NTH T_INT T_STRING T_ODD T_EVEN
+
 options no_result_var
 
+prechigh
+  left T_COLON
+  left T_CHILD T_FOLLOWING T_FOLLOWING_DIRECT
+preclow
+
 rule
   css
-    : path       { val[0] }
+    : expression { val[0] }
     | /* none */ { nil }
     ;
 
+  expression
+    : path
+    | path_member
+    ;
+
+  path
+    : path_members { s(:path, *val[0]) }
+    ;
+
+  path_members
+    : path_member T_SPACE path_member  { [val[0], val[2]] }
+    | path_member T_SPACE path_members { [val[0], *val[2]] }
+    ;
+
   path_member
     : node_test
     | axis
     | pseudo_class
     ;
 
-  path_members
-    : path_member path_member  { [val[0], val[1]] }
-    | path_member path_members { [val[0], *val[1]] }
-    ;
-
-  path
-    : path_members { s(:path, *val[0]) }
-    | path_member
-    ;
-
   node_test
     : node_name           { s(:test, *val[0]) }
     | node_name predicate { s(:test, *val[0], val[1]) }
@@ -68,19 +82,19 @@ rule
 
   axis
     # x > y
-    : node_test T_CHILD node_test
+    : path_member T_CHILD path_member
       {
         s(:axis, 'child', val[0], val[2])
       }
 
     # x + y
-    | node_test T_FOLLOWING node_test
+    | path_member T_FOLLOWING path_member
       {
         s(:axis, 'following', val[0], val[2])
       }
 
     # x ~ y
-    | node_test T_FOLLOWING_DIRECT node_test
+    | path_member T_FOLLOWING_DIRECT path_member
       {
         s(:axis, 'following-direct', val[0], val[2])
       }
@@ -88,20 +102,15 @@ rule
 
   pseudo_class
     # x:root
-    : node_test T_COLON T_IDENT { s(:pseudo, val[2], val[0]) }
+    : path_member T_COLON T_IDENT { s(:pseudo, val[2], val[0]) }
 
     # x:nth-child(2)
-    | node_test T_COLON T_IDENT T_LPAREN pseudo_args T_RPAREN
+    | path_member T_COLON T_IDENT T_LPAREN pseudo_arg T_RPAREN
       {
-        s(:pseudo, val[2], val[0], *val[4])
+        s(:pseudo, val[2], val[0], val[4])
       }
     ;
 
-  pseudo_args
-    : pseudo_args pseudo_arg { val[0] << val[1] }
-    | pseudo_arg             { val }
-    ;
-
   pseudo_arg
     : integer
     | odd
@@ -129,8 +138,8 @@ rule
     ;
 
   integer
-    : T_INT { s(:int, val[0].to_i) }
-    ;
+   : T_INT { s(:int, val[0].to_i) }
+   ;
 end
 
 ---- inner
diff --git a/spec/oga/css/parser/axes_spec.rb b/spec/oga/css/parser/axes_spec.rb
index c13ef71..22022a8 100644
--- a/spec/oga/css/parser/axes_spec.rb
+++ b/spec/oga/css/parser/axes_spec.rb
@@ -11,6 +11,15 @@ describe Oga::CSS::Parser do
       )
     end
 
+    example 'parse the > axis called on another > axis' do
+      parse_css('a > b > c').should == s(
+        :axis,
+        'child',
+        s(:axis, 'child', s(:test, nil, 'a'), s(:test, nil, 'b')),
+        s(:test, nil, 'c')
+      )
+    end
+
     example 'parse the + axis' do
       parse_css('x + y').should == s(
         :axis,
@@ -20,6 +29,15 @@ describe Oga::CSS::Parser do
       )
     end
 
+    example 'parse the + axis called on another + axis' do
+      parse_css('a + b + c').should == s(
+        :axis,
+        'following-direct',
+        s(:axis, 'following-direct', s(:test, nil, 'a'), s(:test, nil, 'b')),
+        s(:test, nil, 'c')
+      )
+    end
+
     example 'parse the ~ axis' do
       parse_css('x ~ y').should == s(
         :axis,
@@ -36,5 +54,32 @@ describe Oga::CSS::Parser do
         s(:test, nil, 'z')
       )
     end
+
+    example 'parse the ~ axis called on another ~ axis' do
+      parse_css('a ~ b ~ c').should == s(
+        :axis,
+        'following',
+        s(:axis, 'following', s(:test, nil, 'a'), s(:test, nil, 'b')),
+        s(:test, nil, 'c')
+      )
+    end
+
+    example 'parse a pseudo class followed by the ~ axis' do
+      parse_css('x:root ~ a').should == s(
+        :axis,
+        'following',
+        s(:pseudo, 'root', s(:test, nil, 'x')),
+        s(:test, nil, 'a')
+      )
+    end
+
+    example 'parse the ~ axis followed by a pseudo class' do
+      parse_css('a ~ x:root').should == s(
+        :axis,
+        'following',
+        s(:test, nil, 'a'),
+        s(:pseudo, 'root', s(:test, nil, 'x'))
+      )
+    end
   end
 end
diff --git a/spec/oga/css/parser/pseudo_classes_spec.rb b/spec/oga/css/parser/pseudo_classes_spec.rb
index 702f332..de90e4c 100644
--- a/spec/oga/css/parser/pseudo_classes_spec.rb
+++ b/spec/oga/css/parser/pseudo_classes_spec.rb
@@ -86,5 +86,13 @@ describe Oga::CSS::Parser do
         s(:nth, s(:int, -2), s(:int, -1))
       )
     end
+
+    example 'parse two pseudo selectors' do
+      parse_css('x:focus:hover').should == s(
+        :pseudo,
+        'hover',
+        s(:pseudo, 'focus', s(:test, nil, 'x'))
+      )
+    end
   end
 end