Move clang's ParseHelper into Support (clang part)

[olista01]

Summary

This moves clang's ParseHelper class (currently used to parse comments for the -verify option) into the Support library so that it can be used elsewhere in LLVM.

[hans]

I've commented on the llvm side. Adding cfe-commits as well since it affects clang.

[EricWF]

Resigning as a reviewer since I don't feel comfortable reviewing generic LLVM patches.

lib/Frontend/VerifyDiagnosticConsumer.cpp

 #include "clang/Frontend/VerifyDiagnosticConsumer.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/TextDiagnosticBuffer.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/Support/ParseHelper.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace clang;
 typedef VerifyDiagnosticConsumer::Directive Directive;
 typedef VerifyDiagnosticConsumer::DirectiveList DirectiveList;
 typedef VerifyDiagnosticConsumer::ExpectedData ExpectedData;
 
public:
   bool match(StringRef S) override {
     return Regex.match(S);
   }
 
 private:
   llvm::Regex Regex;
 };
 
-class ParseHelper
-{
-public:
-  ParseHelper(StringRef S)
-    : Begin(S.begin()), End(S.end()), C(Begin), P(Begin), PEnd(nullptr) {}
-
-  // Return true if string literal is next.
-  bool Next(StringRef S) {
-    P = C;
-    PEnd = C + S.size();
-    if (PEnd > End)
-      return false;
-    return !memcmp(P, S.data(), S.size());
-  }
-
-  // Return true if number is next.
-  // Output N only if number is next.
-  bool Next(unsigned &N) {
-    unsigned TMP = 0;
-    P = C;
-    for (; P < End && P[0] >= '0' && P[0] <= '9'; ++P) {
-      TMP *= 10;
-      TMP += P[0] - '0';
-    }
-    if (P == C)
-      return false;
-    PEnd = P;
-    N = TMP;
-    return true;
-  }
-
-  // Return true if string literal is found.
-  // When true, P marks begin-position of S in content.
-  bool Search(StringRef S, bool EnsureStartOfWord = false) {
-    do {
-      P = std::search(C, End, S.begin(), S.end());
-      PEnd = P + S.size();
-      if (P == End)
-        break;
-      if (!EnsureStartOfWord
-            // Check if string literal starts a new word.
-            || P == Begin || isWhitespace(P[-1])
-            // Or it could be preceded by the start of a comment.
-            || (P > (Begin + 1) && (P[-1] == '/' || P[-1] == '*')
-                                &&  P[-2] == '/'))
-        return true;
-      // Otherwise, skip and search again.
-    } while (Advance());
-    return false;
-  }
-
-  // Return true if a CloseBrace that closes the OpenBrace at the current nest
-  // level is found. When true, P marks begin-position of CloseBrace.
-  bool SearchClosingBrace(StringRef OpenBrace, StringRef CloseBrace) {
-    unsigned Depth = 1;
-    P = C;
-    while (P < End) {
-      StringRef S(P, End - P);
-      if (S.startswith(OpenBrace)) {
-        ++Depth;
-        P += OpenBrace.size();
-      } else if (S.startswith(CloseBrace)) {
-        --Depth;
-        if (Depth == 0) {
-          PEnd = P + CloseBrace.size();
-          return true;
-        }
-        P += CloseBrace.size();
-      } else {
-        ++P;
-      }
-    }
-    return false;
-  }
-
-  // Advance 1-past previous next/search.
-  // Behavior is undefined if previous next/search failed.
-  bool Advance() {
-    C = PEnd;
-    return C < End;
-  }
-
-  // Skip zero or more whitespace.
-  void SkipWhitespace() {
-    for (; C < End && isWhitespace(*C); ++C)
-      ;
-  }
-
-  // Return true if EOF reached.
-  bool Done() {
-    return !(C < End);
-  }
-
-  const char * const Begin; // beginning of expected content
-  const char * const End;   // end of expected content (1-past)
-  const char *C;            // position of next char in content
-  const char *P;
-
-private:
-  const char *PEnd; // previous next/search subject end (1-past)
-};
-
 } // namespace anonymous
 
 /// ParseDirective - Go through the comment and see if it indicates expected
 /// diagnostics. If so, then put them in the appropriate directive list.
 ///
 /// Returns true if any valid directives were found.
 static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
                            Preprocessor *PP, SourceLocation Pos,
                            VerifyDiagnosticConsumer::DirectiveStatus &Status) {
   DiagnosticsEngine &Diags = PP ? PP->getDiagnostics() : SM.getDiagnostics();
 
   // A single comment may contain multiple directives.
   bool FoundDirective = false;
-  for (ParseHelper PH(S); !PH.Done();) {
+  for (llvm::ParseHelper PH(S); !PH.Done();) {
     // Search for token: expected
     if (!PH.Search("expected", true))
       break;
     PH.Advance();
 
     // Next token: -
     if (!PH.Next("-"))
       continue;