Introduce an NthIndexCache type and pipe it from ThreadLocalStyleContext to MatchingContext.

Some future refactoring here to pass fewer things as parameters would be nice.

1 files changed, 12 insertions, 1 deletions

diff --git a/components/selectors/context.rs b/components/selectors/context.rs
index 31ce04b37a1..46991d349ce 100644
--- a/components/selectors/context.rs
+++ b/components/selectors/context.rs
@@ -69,15 +69,22 @@ impl QuirksMode {
     }
 }
 
+/// A cache to speed up matching of nth-index-like selectors.
+///
+/// NB: This is just a dummy type right now, it will be fleshed out in later patches.
+#[derive(Default)]
+pub struct NthIndexCache(usize);
+
 /// Data associated with the matching process for a element.  This context is
 /// used across many selectors for an element, so it's not appropriate for
 /// transient data that applies to only a single selector.
-#[derive(Clone)]
 pub struct MatchingContext<'a> {
     /// Input with the matching mode we should use when matching selectors.
     pub matching_mode: MatchingMode,
     /// Input with the bloom filter used to fast-reject selectors.
     pub bloom_filter: Option<&'a BloomFilter>,
+    /// An optional cache to speed up nth-index-like selectors.
+    nth_index_cache: Option<&'a mut NthIndexCache>,
     /// Input that controls how matching for links is handled.
     pub visited_handling: VisitedHandlingMode,
     /// Output that records whether we encountered a "relevant link" while
@@ -94,12 +101,14 @@ impl<'a> MatchingContext<'a> {
     /// Constructs a new `MatchingContext`.
     pub fn new(matching_mode: MatchingMode,
                bloom_filter: Option<&'a BloomFilter>,
+               nth_index_cache: Option<&'a mut NthIndexCache>,
                quirks_mode: QuirksMode)
                -> Self
     {
         Self {
             matching_mode: matching_mode,
             bloom_filter: bloom_filter,
+            nth_index_cache: nth_index_cache,
             visited_handling: VisitedHandlingMode::AllLinksUnvisited,
             relevant_link_found: false,
             quirks_mode: quirks_mode,
@@ -110,6 +119,7 @@ impl<'a> MatchingContext<'a> {
     /// Constructs a new `MatchingContext` for use in visited matching.
     pub fn new_for_visited(matching_mode: MatchingMode,
                            bloom_filter: Option<&'a BloomFilter>,
+                           nth_index_cache: Option<&'a mut NthIndexCache>,
                            visited_handling: VisitedHandlingMode,
                            quirks_mode: QuirksMode)
                            -> Self
@@ -119,6 +129,7 @@ impl<'a> MatchingContext<'a> {
             bloom_filter: bloom_filter,
             visited_handling: visited_handling,
             relevant_link_found: false,
+            nth_index_cache: nth_index_cache,
             quirks_mode: quirks_mode,
             classes_and_ids_case_sensitivity: quirks_mode.classes_and_ids_case_sensitivity(),
         }