Add initial implementation of a TableGen backend for converting Clang-warnings
tablegen files to the original .def preprocessor include files. This is my first
TableGen backend; I don't claim that it is awesome.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66971 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/ClangDiagnosticsEmitter.cpp b/utils/TableGen/ClangDiagnosticsEmitter.cpp
new file mode 100644
index 0000000..fa139e7
--- /dev/null
+++ b/utils/TableGen/ClangDiagnosticsEmitter.cpp
@@ -0,0 +1,84 @@
+//=- ClangDiagnosticsEmitter.cpp - Generate Clang diagnostics tables -*- C++ -*-
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// These tablegen backends emit Clang diagnostics tables.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangDiagnosticsEmitter.h"
+#include "Record.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/ADT/VectorExtras.h"
+
+using namespace llvm;
+typedef std::vector<Record*> RecordVector;
+typedef std::vector<Record*> SuperClassVector;
+typedef std::vector<RecordVal> RecordValVector;
+
+static const RecordVal* findRecordVal(const RecordValVector& Vals,
+                                      const std::string &key) {
+  for (RecordValVector::const_iterator I=Vals.begin(), E=Vals.end(); I!=E; ++I)
+    if ((*I).getName() == key)
+      return &*I;
+  
+  return 0;
+}
+
+static const Record* getDiagKind(const Record* DiagClass, const Record &R) {  
+  const SuperClassVector &SC = R.getSuperClasses();
+  for (SuperClassVector::const_iterator I=SC.begin(), E=SC.end(); I!=E; ++I)
+    if ((*I)->isSubClassOf(DiagClass))
+      return *I;
+  
+  return 0;
+}
+
+static void EmitEscaped(std::ostream& OS, const std::string &s) {
+  for (std::string::const_iterator I=s.begin(), E=s.end(); I!=E; ++I)
+    switch (*I) {
+      default: OS << *I; break;
+      case '\"': OS << "\\" << *I; break;
+      case '\\': OS << "\\\\"; break;
+    }
+}
+
+static void ProcessDiag(std::ostream& OS, const Record* DiagClass,
+                        const Record& R) {
+
+  const Record* DiagKind = getDiagKind(DiagClass, R);
+  if (!DiagKind)
+    return;
+
+  OS << "DIAG(" << R.getName() << ", ";
+  
+  const std::string &s = DiagKind->getName();
+  for (std::string::const_iterator I=s.begin(), E=s.end(); I!=E; ++I)
+    OS << char(toupper(*I));
+  
+  const RecordVal* Text = findRecordVal(R.getValues(), "Text");
+  assert(Text && "No 'Text' entry in Diagnostic.");
+  const StringInit* TextVal = dynamic_cast<const StringInit*>(Text->getValue());
+  assert(TextVal && "Value 'Text' must be a string.");
+  OS << ", \"";
+  EmitEscaped(OS, TextVal->getValue());
+  OS << "\")\n";
+}
+
+void ClangDiagsDefsEmitter::run(std::ostream &OS) {
+  const RecordVector &Diags = Records.getAllDerivedDefinitions("Diagnostic");
+  
+  const Record* DiagClass = Records.getClass("Diagnostic");
+  assert(DiagClass && "No Diagnostic class defined.");  
+  
+  for (RecordVector::const_iterator I=Diags.begin(), E=Diags.end(); I!=E; ++I) {
+    // FIXME: Compare the component.
+    ProcessDiag(OS, DiagClass, **I);
+  }
+}
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