Include RE2 library

third_party/re2/util/strutil.cc

+// Copyright 1999-2005 The RE2 Authors.  All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "util/util.h"
+#include "re2/stringpiece.h"
+
+namespace re2 {
+
+// ----------------------------------------------------------------------
+// CEscapeString()
+//    Copies 'src' to 'dest', escaping dangerous characters using
+//    C-style escape sequences.  'src' and 'dest' should not overlap.
+//    Returns the number of bytes written to 'dest' (not including the \0)
+//    or -1 if there was insufficient space.
+// ----------------------------------------------------------------------
+int CEscapeString(const char* src, int src_len, char* dest,
+                  int dest_len) {
+  const char* src_end = src + src_len;
+  int used = 0;
+
+  for (; src < src_end; src++) {
+    if (dest_len - used < 2)   // Need space for two letter escape
+      return -1;
+
+    unsigned char c = *src;
+    switch (c) {
+      case '\n': dest[used++] = '\\'; dest[used++] = 'n';  break;
+      case '\r': dest[used++] = '\\'; dest[used++] = 'r';  break;
+      case '\t': dest[used++] = '\\'; dest[used++] = 't';  break;
+      case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break;
+      case '\'': dest[used++] = '\\'; dest[used++] = '\''; break;
+      case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break;
+      default:
+        // Note that if we emit \xNN and the src character after that is a hex
+        // digit then that digit must be escaped too to prevent it being
+        // interpreted as part of the character code by C.
+        if (c < ' ' || c > '~') {
+          if (dest_len - used < 4) // need space for 4 letter escape
+            return -1;
+          sprintf(dest + used, "\\%03o", c);
+          used += 4;
+        } else {
+          dest[used++] = c; break;
+        }
+    }
+  }
+
+  if (dest_len - used < 1)   // make sure that there is room for \0
+    return -1;
+
+  dest[used] = '\0';   // doesn't count towards return value though
+  return used;
+}
+
+
+// ----------------------------------------------------------------------
+// CEscape()
+//    Copies 'src' to result, escaping dangerous characters using
+//    C-style escape sequences.  'src' and 'dest' should not overlap. 
+// ----------------------------------------------------------------------
+string CEscape(const StringPiece& src) {
+  const int dest_length = src.size() * 4 + 1; // Maximum possible expansion
+  char* dest = new char[dest_length];
+  const int len = CEscapeString(src.data(), src.size(),
+                                dest, dest_length);
+  string s = string(dest, len);
+  delete[] dest;
+  return s;
+}
+
+string PrefixSuccessor(const StringPiece& prefix) {
+  // We can increment the last character in the string and be done
+  // unless that character is 255, in which case we have to erase the
+  // last character and increment the previous character, unless that
+  // is 255, etc. If the string is empty or consists entirely of
+  // 255's, we just return the empty string.
+  bool done = false;
+  string limit(prefix.data(), prefix.size());
+  int index = limit.length() - 1;
+  while (!done && index >= 0) {
+    if ((limit[index]&255) == 255) {
+      limit.erase(index);
+      index--;
+    } else {
+      limit[index]++;
+      done = true;
+    }
+  }
+  if (!done) {
+    return "";
+  } else {
+    return limit;
+  }
+}
+
+}  // namespace re2