[cindex.py] Add cache for CompletionChunk spellings

Most of the CompletionChunks represent braces, colons or other one
character spellings. There is no need to call libclang, to figure out
how to write a colon. Instead we use an internal cache to retrieve the
correct spelling. As function calls from python are very expensive and
this is a performance critical part of auto completion this patch makes
formatting of auto completion results a lot faster.

Formatting time changes from 0.57 to 0.45 seconds

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172901 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/bindings/python/clang/cindex.py b/bindings/python/clang/cindex.py
index 5e261f8657..446d80d176 100644
--- a/bindings/python/clang/cindex.py
+++ b/bindings/python/clang/cindex.py
@@ -1645,6 +1645,33 @@ class _CXUnsavedFile(Structure):
     """Helper for passing unsaved file arguments."""
     _fields_ = [("name", c_char_p), ("contents", c_char_p), ('length', c_ulong)]
 
+# Functions calls through the python interface are rather slow. Fortunately,
+# for most symboles, we do not need to perform a function call. Their spelling
+# never changes and is consequently provided by this spelling cache.
+SpellingCache = {
+            # 0: CompletionChunk.Kind("Optional"),
+            # 1: CompletionChunk.Kind("TypedText"),
+            # 2: CompletionChunk.Kind("Text"),
+            # 3: CompletionChunk.Kind("Placeholder"),
+            # 4: CompletionChunk.Kind("Informative"),
+            # 5 : CompletionChunk.Kind("CurrentParameter"),
+            6: '(',   # CompletionChunk.Kind("LeftParen"),
+            7: ')',   # CompletionChunk.Kind("RightParen"),
+            8: ']',   # CompletionChunk.Kind("LeftBracket"),
+            9: ']',   # CompletionChunk.Kind("RightBracket"),
+            10: '{',  # CompletionChunk.Kind("LeftBrace"),
+            11: '}',  # CompletionChunk.Kind("RightBrace"),
+            12: '<',  # CompletionChunk.Kind("LeftAngle"),
+            13: '>',  # CompletionChunk.Kind("RightAngle"),
+            14: ', ', # CompletionChunk.Kind("Comma"),
+            # 15: CompletionChunk.Kind("ResultType"),
+            16: ':',  # CompletionChunk.Kind("Colon"),
+            17: ';',  # CompletionChunk.Kind("SemiColon"),
+            18: '=',  # CompletionChunk.Kind("Equal"),
+            19: ' ',  # CompletionChunk.Kind("HorizontalSpace"),
+            # 20: CompletionChunk.Kind("VerticalSpace")
+}
+
 class CompletionChunk:
     class Kind:
         def __init__(self, name):
@@ -1666,6 +1693,8 @@ class CompletionChunk:
 
     @CachedProperty
     def spelling(self):
+	if self.__kindNumber in SpellingCache:
+		return SpellingCache[self.__kindNumber]
         return conf.lib.clang_getCompletionChunkText(self.cs, self.key).spelling
 
     # We do not use @CachedProperty here, as the manual implementation is