new loplugin: singlevalfields

look for fields that only have a single constant value assigned to them

Change-Id: Iafcd37fdb8a8119bbc00f92981a1a01badf9c5a2

1 files changed, 69 insertions, 0 deletions

diff --git a/compilerplugins/clang/singlevalfields.py b/compilerplugins/clang/singlevalfields.py
new file mode 100755
index 000000000000..523ffa5520f2
--- /dev/null
+++ b/compilerplugins/clang/singlevalfields.py
@@ -0,0 +1,69 @@
+#!/usr/bin/python
+
+import sys
+import re
+import io
+
+definitionToSourceLocationMap = dict() # dict of tuple(parentClass, fieldName) to sourceLocation
+fieldAssignDict = dict() # dict of tuple(parentClass, fieldName) to (set of values)
+
+# clang does not always use exactly the same numbers in the type-parameter vars it generates
+# so I need to substitute them to ensure we can match correctly.
+normalizeTypeParamsRegex = re.compile(r"type-parameter-\d+-\d+")
+def normalizeTypeParams( line ):
+    return normalizeTypeParamsRegex.sub("type-parameter-?-?", line)
+
+# reading as binary (since we known it is pure ascii) is much faster than reading as unicode
+with io.open("singlevalfields.log", "rb", buffering=1024*1024) as txt:
+    for line in txt:
+        if line.startswith("defn:\t"):
+            idx1 = line.find("\t")
+            idx2 = line.find("\t",idx1+1)
+            idx3 = line.find("\t",idx2+1)
+            parentClass = normalizeTypeParams(line[idx1+1:idx2])
+            fieldName = normalizeTypeParams(line[idx2+1:idx3])
+            sourceLocation = line[idx3+1:].strip()
+            fieldInfo = (parentClass, fieldName)
+            definitionToSourceLocationMap[fieldInfo] = sourceLocation
+        elif line.startswith("asgn:\t"):
+            idx1 = line.find("\t")
+            idx2 = line.find("\t",idx1+1)
+            idx3 = line.find("\t",idx2+1)
+            parentClass = normalizeTypeParams(line[idx1+1:idx2])
+            fieldName = normalizeTypeParams(line[idx2+1:idx3])
+            assignValue = line[idx3+1:].strip()
+            fieldInfo = (parentClass, fieldName)
+            if not fieldInfo in fieldAssignDict:
+                fieldAssignDict[fieldInfo] = set()
+            fieldAssignDict[fieldInfo].add(assignValue)
+
+tmp1list = list()
+for fieldInfo, assignValues in fieldAssignDict.iteritems():
+    if len(assignValues) != 1:
+        continue
+    if "?" in assignValues:
+        continue
+    # if it contains anything other than this set, ignore it
+    if len(assignValues - set(["0", "1", "-1", "nullptr"])) > 0:
+        continue
+    v0 = fieldInfo[0] + " " + fieldInfo[1]
+    v1 = (",".join(assignValues))
+    v2 = ""
+    if fieldInfo in definitionToSourceLocationMap:
+        v2 = definitionToSourceLocationMap[fieldInfo]
+    tmp1list.append((v0,v1,v2))
+
+# sort results by filename:lineno
+def natural_sort_key(s, _nsre=re.compile('([0-9]+)')):
+    return [int(text) if text.isdigit() else text.lower()
+            for text in re.split(_nsre, s)]
+tmp1list.sort(key=lambda v: natural_sort_key(v[2]))
+
+# print out the results
+with open("loplugin.singlevalfields", "wt") as f:
+    for v in tmp1list:
+        f.write(v[2] + "\n")
+        f.write("    " + v[0] + "\n")
+        f.write("    " + v[1] + "\n")
+
+