autocomplete: Add AutocompleteMatch::MergeClassifications()

chrome/browser/autocomplete/autocomplete_match.cc

Index: chrome/browser/autocomplete/autocomplete_match.cc
diff --git a/chrome/browser/autocomplete/autocomplete_match.cc b/chrome/browser/autocomplete/autocomplete_match.cc
index d00ac976fcfb01120c87c6f359721bc80a857831..c13139f4000ef28bca769c4e812c54e1e6e99a8c 100644
--- a/chrome/browser/autocomplete/autocomplete_match.cc
+++ b/chrome/browser/autocomplete/autocomplete_match.cc
@@ -233,6 +233,29 @@ void AutocompleteMatch::ClassifyLocationInString(
 }
 
 // static
+AutocompleteMatch::ACMatchClassifications
+AutocompleteMatch::MergeClassifications(

[Peter Kasting, 2012/09/10 18:56:11]

Nit: Style guide is vague here; I usually suggest this line be indented 4

[Daniel Erat, 2012/09/10 19:36:17]

Done.

+    const ACMatchClassifications& classifications1,
+    const ACMatchClassifications& classifications2) {
+  ACMatchClassifications output;
+  for (ACMatchClassifications::const_iterator i = classifications1.begin(),

[Peter Kasting, 2012/09/10 18:56:11]

This is not quite safe.  If someone passes in an empty vector for
|classifications2| we'll deref garbage.

This function should get a guard like:

namespace {
bool IsTrivialClassification(const ACMatchClassifications& classifications) {
  return classifications.empty() ||
      ((classifications.size() == 1) &&
       (classifications.back().style == ACMatchClassification::NONE));
}
}

...

  if IsTrivialClassification(classifications1)
    return classifications2;
  if IsTrivialClassification(classifications2)
    return classifications1;
  ... (rest of function) ...

Then there should probably be some unittest cases for this.

[Daniel Erat, 2012/09/10 19:36:17]

Done.

+       j = classifications2.begin(); i != classifications1.end();) {
+    AutocompleteMatch::AddLastClassificationIfNecessary(&output,
+        std::max(i->offset, j->offset), i->style | j->style);
+    const size_t next_i_offset = (i + 1) == classifications1.end() ?
+        static_cast<size_t>(-1) : (i + 1)->offset;
+    const size_t next_j_offset = (j + 1) == classifications2.end() ?
+        static_cast<size_t>(-1) : (j + 1)->offset;
+    if (next_i_offset >= next_j_offset)
+      ++j;
+    if (next_j_offset >= next_i_offset)
+      ++i;
+  }
+
+  return output;
+}
+
+// static
 std::string AutocompleteMatch::ClassificationsToString(
     const ACMatchClassifications& classifications) {
   std::string serialized_classifications;