Expose FileCheck's AddFixedStringToRegEx as Regex::escape

Both FileCheck and clang's -verify need to escape strings for regexes,
so let's expose this as a utility in the Regex class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197096 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Regex.h

@@ -81,6 +81,9 @@ namespace llvm {
     /// expression that matches Str and only Str.
     static bool isLiteralERE(StringRef Str);
 
+    /// \brief Turn String into a regex by escaping its special characters.
+    static std::string escape(StringRef String);
+
   private:
     struct llvm_regex *preg;
     int error;

lib/Support/Regex.cpp

@@ -175,3 +175,32 @@ bool Regex::isLiteralERE(StringRef Str) {
   // regular expression specification.
   return Str.find_first_of("()^$|*+?.[]\\{}") == StringRef::npos;
 }
+
+std::string Regex::escape(StringRef String) {
+  std::string RegexStr;
+
+  for (unsigned i = 0, e = String.size(); i != e; ++i) {
+    switch (String[i]) {
+    // These are the special characters matched in "p_ere_exp".
+    case '(':
+    case ')':
+    case '^':
+    case '$':
+    case '|':
+    case '*':
+    case '+':
+    case '?':
+    case '.':
+    case '[':
+    case '\\':
+    case '{':
+      RegexStr += '\\';
+      // FALL THROUGH.
+    default:
+      RegexStr += String[i];
+      break;
+    }
+  }
+
+  return RegexStr;
+}

utils/FileCheck/FileCheck.cpp

@@ -136,7 +136,6 @@ public:
   Check::CheckType getCheckTy() const { return CheckTy; }
 
 private:
-  static void AddFixedStringToRegEx(StringRef FixedStr, std::string &TheStr);
   bool AddRegExToRegEx(StringRef RS, unsigned &CurParen, SourceMgr &SM);
   void AddBackrefToRegEx(unsigned BackrefNum);
 
@@ -314,40 +313,13 @@ bool Pattern::ParsePattern(StringRef PatternStr,
     // Find the end, which is the start of the next regex.
     size_t FixedMatchEnd = PatternStr.find("{{");
     FixedMatchEnd = std::min(FixedMatchEnd, PatternStr.find("[["));
-    AddFixedStringToRegEx(PatternStr.substr(0, FixedMatchEnd), RegExStr);
+    RegExStr += Regex::escape(PatternStr.substr(0, FixedMatchEnd));
     PatternStr = PatternStr.substr(FixedMatchEnd);
   }
 
   return false;
 }
 
-void Pattern::AddFixedStringToRegEx(StringRef FixedStr, std::string &TheStr) {
-  // Add the characters from FixedStr to the regex, escaping as needed.  This
-  // avoids "leaning toothpicks" in common patterns.
-  for (unsigned i = 0, e = FixedStr.size(); i != e; ++i) {
-    switch (FixedStr[i]) {
-    // These are the special characters matched in "p_ere_exp".
-    case '(':
-    case ')':
-    case '^':
-    case '$':
-    case '|':
-    case '*':
-    case '+':
-    case '?':
-    case '.':
-    case '[':
-    case '\\':
-    case '{':
-      TheStr += '\\';
-      // FALL THROUGH.
-    default:
-      TheStr += FixedStr[i];
-      break;
-    }
-  }
-}
-
 bool Pattern::AddRegExToRegEx(StringRef RS, unsigned &CurParen,
                               SourceMgr &SM) {
   Regex R(RS);
@@ -428,8 +400,8 @@ size_t Pattern::Match(StringRef Buffer, size_t &MatchLen,
         if (it == VariableTable.end())
           return StringRef::npos;
 
-        // Look up the value and escape it so that we can plop it into the regex.
+        // Look up the value and escape it so that we can put it into the regex.
-        AddFixedStringToRegEx(it->second, Value);
+        Value += Regex::escape(it->second);
       }
 
       // Plop it into the regex at the adjusted offset.