Create StringOrdinal to allow placement of strings in sorted lists

chrome/common/string_index.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_COMMON_STRING_INDEX_H_
+#define CHROME_COMMON_STRING_INDEX_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+
+class StringIndex {
+ public:
+  StringIndex();
+  ~StringIndex() {}
+
+  // Create a string that is lexigraphically greater than start and
+  // lexigraphically less than end, ideally the string will be a
+  // middle value between the two strings.
+  // Use an empty string to signify no ending or starting limit.
+  // The range of values returns from here are (A..K*).
+  std::string CreateStringBetween(const std::string& start,

[akalin, 2011/10/11 19:34:39]

since kmaxDigitvalue and kMidDigitValue are constants, then this can be static,
too.  Since this is static, then there's no need for the class at all, at least
how this CL stands.

[csharp1, 2011/10/12 15:31:12]

Ok, I've changed it to just be a namespace.

On 2011/10/11 19:34:39, akalin wrote:

+                                  const std::string& end);
+ private:
+  // Used to add kMidDigitValue to the value at position index because
+  // the previous index values had an odd difference, so their correct
+  // middle value is x and a half, so we are inserting the half here.
+  void AddHalf(int position, std::string& value);
+
+  // Remove all trailing zeros from a value as they provide no value.
+  std::string RemoveTrailingZeros(const std::string& value);
+
+  // Get the value of the string index, padding with 0s if the
+  // string isn't long enough.
+  int GetPositionValue(const std::string& value, size_t index);
+
+  static const char kZeroDigit = 'A';
+  static const char kMinDigit = 'B';
+  static const char kMidDigit = 'M';
+  static const char kMaxDigit = 'Z';
+
+  const int kMaxDigitValue;
+  const int kMidDigitValue;
+
+
+  DISALLOW_COPY_AND_ASSIGN(StringIndex);
+};
+#endif  // CHROME_COMMON_STRING_INDEX_H_