[Modules] Use global index to improve typo correction performance

Typo correction for an unqualified name needs to walk through all of the identifier tables of all modules.
When we have a global index, just walk its identifier table only.

rdar://13425732

llvm-svn: 179730

1 files changed, 31 insertions, 0 deletions

diff --git a/clang/lib/Serialization/GlobalModuleIndex.cpp b/clang/lib/Serialization/GlobalModuleIndex.cpp
index f9acb84..b6693e4 100644
--- a/clang/lib/Serialization/GlobalModuleIndex.cpp
+++ b/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -818,3 +818,34 @@ GlobalModuleIndex::writeIndex(FileManager &FileMgr, StringRef Path) {
   // We're done.
   return EC_None;
 }
+
+namespace {
+  class GlobalIndexIdentifierIterator : public IdentifierIterator {
+    /// \brief The current position within the identifier lookup table.
+    IdentifierIndexTable::key_iterator Current;
+
+    /// \brief The end position within the identifier lookup table.
+    IdentifierIndexTable::key_iterator End;
+
+  public:
+    explicit GlobalIndexIdentifierIterator(IdentifierIndexTable &Idx) {
+      Current = Idx.key_begin();
+      End = Idx.key_end();
+    }
+
+    virtual StringRef Next() {
+      if (Current == End)
+        return StringRef();
+
+      StringRef Result = *Current;
+      ++Current;
+      return Result;
+    }
+  };
+}
+
+IdentifierIterator *GlobalModuleIndex::createIdentifierIterator() const {
+  IdentifierIndexTable &Table =
+    *static_cast<IdentifierIndexTable *>(IdentifierIndex);
+  return new GlobalIndexIdentifierIterator(Table);
+}