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TMessagesProj/jni/voip/webrtc/base/strings/string_tokenizer.h

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+// 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 BASE_STRINGS_STRING_TOKENIZER_H_
+#define BASE_STRINGS_STRING_TOKENIZER_H_
+
+#include <algorithm>
+#include <string>
+
+#include "base/strings/string_piece.h"
+
+namespace base {
+
+// StringTokenizerT is a simple string tokenizer class.  It works like an
+// iterator that with each step (see the Advance method) updates members that
+// refer to the next token in the input string.  The user may optionally
+// configure the tokenizer to return delimiters.
+//
+// EXAMPLE 1:
+//
+//   char input[] = "this is a test";
+//   CStringTokenizer t(input, input + strlen(input), " ");
+//   while (t.GetNext()) {
+//     printf("%s\n", t.token().c_str());
+//   }
+//
+// Output:
+//
+//   this
+//   is
+//   a
+//   test
+//
+//
+// EXAMPLE 2:
+//
+//   std::string input = "no-cache=\"foo, bar\", private";
+//   StringTokenizer t(input, ", ");
+//   t.set_quote_chars("\"");
+//   while (t.GetNext()) {
+//     printf("%s\n", t.token().c_str());
+//   }
+//
+// Output:
+//
+//   no-cache="foo, bar"
+//   private
+//
+//
+// EXAMPLE 3:
+//
+//   bool next_is_option = false, next_is_value = false;
+//   std::string input = "text/html; charset=UTF-8; foo=bar";
+//   StringTokenizer t(input, "; =");
+//   t.set_options(StringTokenizer::RETURN_DELIMS);
+//   while (t.GetNext()) {
+//     if (t.token_is_delim()) {
+//       switch (*t.token_begin()) {
+//         case ';':
+//           next_is_option = true;
+//           break;
+//         case '=':
+//           next_is_value = true;
+//           break;
+//       }
+//     } else {
+//       const char* label;
+//       if (next_is_option) {
+//         label = "option-name";
+//         next_is_option = false;
+//       } else if (next_is_value) {
+//         label = "option-value";
+//         next_is_value = false;
+//       } else {
+//         label = "mime-type";
+//       }
+//       printf("%s: %s\n", label, t.token().c_str());
+//     }
+//   }
+//
+//
+template <class str, class const_iterator>
+class StringTokenizerT {
+ public:
+  typedef typename str::value_type char_type;
+
+  // Options that may be pass to set_options()
+  enum {
+    // Specifies the delimiters should be returned as tokens
+    RETURN_DELIMS = 1 << 0,
+
+    // Specifies that empty tokens should be returned. Treats the beginning and
+    // ending of the string as implicit delimiters, though doesn't return them
+    // as tokens if RETURN_DELIMS is also used.
+    RETURN_EMPTY_TOKENS = 1 << 1,
+  };
+
+  // The string object must live longer than the tokenizer. In particular, this
+  // should not be constructed with a temporary. The deleted rvalue constructor
+  // blocks the most obvious instances of this (e.g. passing a string literal to
+  // the constructor), but caution must still be exercised.
+  StringTokenizerT(const str& string,
+                   const str& delims) {
+    Init(string.begin(), string.end(), delims);
+  }
+
+  // Don't allow temporary strings to be used with string tokenizer, since
+  // Init() would otherwise save iterators to a temporary string.
+  StringTokenizerT(str&&, const str& delims) = delete;
+
+  StringTokenizerT(const_iterator string_begin,
+                   const_iterator string_end,
+                   const str& delims) {
+    Init(string_begin, string_end, delims);
+  }
+
+  // Set the options for this tokenizer.  By default, this is 0.
+  void set_options(int options) { options_ = options; }
+
+  // Set the characters to regard as quotes.  By default, this is empty.  When
+  // a quote char is encountered, the tokenizer will switch into a mode where
+  // it ignores delimiters that it finds.  It switches out of this mode once it
+  // finds another instance of the quote char.  If a backslash is encountered
+  // within a quoted string, then the next character is skipped.
+  void set_quote_chars(const str& quotes) { quotes_ = quotes; }
+
+  // Call this method to advance the tokenizer to the next delimiter.  This
+  // returns false if the tokenizer is complete.  This method must be called
+  // before calling any of the token* methods.
+  bool GetNext() {
+    if (quotes_.empty() && options_ == 0)
+      return QuickGetNext();
+    else
+      return FullGetNext();
+  }
+
+  // Start iterating through tokens from the beginning of the string.
+  void Reset() {
+    token_end_ = start_pos_;
+  }
+
+  // Returns true if token is a delimiter.  When the tokenizer is constructed
+  // with the RETURN_DELIMS option, this method can be used to check if the
+  // returned token is actually a delimiter. Returns true before the first
+  // time GetNext() has been called, and after GetNext() returns false.
+  bool token_is_delim() const { return token_is_delim_; }
+
+  // If GetNext() returned true, then these methods may be used to read the
+  // value of the token.
+  const_iterator token_begin() const { return token_begin_; }
+  const_iterator token_end() const { return token_end_; }
+  str token() const { return str(token_begin_, token_end_); }
+  BasicStringPiece<str> token_piece() const {
+    return BasicStringPiece<str>(&*token_begin_,
+                                 std::distance(token_begin_, token_end_));
+  }
+
+ private:
+  void Init(const_iterator string_begin,
+            const_iterator string_end,
+            const str& delims) {
+    start_pos_ = string_begin;
+    token_begin_ = string_begin;
+    token_end_ = string_begin;
+    end_ = string_end;
+    delims_ = delims;
+    options_ = 0;
+    token_is_delim_ = true;
+  }
+
+  // Implementation of GetNext() for when we have no quote characters. We have
+  // two separate implementations because AdvanceOne() is a hot spot in large
+  // text files with large tokens.
+  bool QuickGetNext() {
+    token_is_delim_ = false;
+    for (;;) {
+      token_begin_ = token_end_;
+      if (token_end_ == end_) {
+        token_is_delim_ = true;
+        return false;
+      }
+      ++token_end_;
+      if (delims_.find(*token_begin_) == str::npos)
+        break;
+      // else skip over delimiter.
+    }
+    while (token_end_ != end_ && delims_.find(*token_end_) == str::npos)
+      ++token_end_;
+    return true;
+  }
+
+  // Implementation of GetNext() for when we have to take quotes into account.
+  bool FullGetNext() {
+    AdvanceState state;
+
+    for (;;) {
+      if (token_is_delim_) {
+        // Last token was a delimiter. Note: This is also the case at the start.
+        //
+        //    ... D T T T T D ...
+        //        ^ ^
+        //        | |
+        //        | |token_end_| : The next character to look at or |end_|.
+        //        |
+        //        |token_begin_| : Points to delimiter or |token_end_|.
+        //
+        // The next token is always a non-delimiting token. It could be empty,
+        // however.
+        token_is_delim_ = false;
+        token_begin_ = token_end_;
+
+        // Slurp all non-delimiter characters into the token.
+        while (token_end_ != end_ && AdvanceOne(&state, *token_end_)) {
+          ++token_end_;
+        }
+
+        // If it's non-empty, or empty tokens were requested, return the token.
+        if (token_begin_ != token_end_ || (options_ & RETURN_EMPTY_TOKENS))
+          return true;
+      }
+
+      DCHECK(!token_is_delim_);
+      // Last token was a regular token.
+      //
+      //    ... T T T D T T ...
+      //        ^     ^
+      //        |     |
+      //        |     token_end_ : The next character to look at. Always one
+      //        |                  char beyond the token boundary.
+      //        |
+      //        token_begin_ : Points to beginning of token. Note: token could
+      //                       be empty, in which case
+      //                       token_begin_ == token_end_.
+      //
+      // The next token is always a delimiter. It could be |end_| however, but
+      // |end_| is also an implicit delimiter.
+      token_is_delim_ = true;
+      token_begin_ = token_end_;
+
+      if (token_end_ == end_)
+        return false;
+
+      // Look at the delimiter.
+      ++token_end_;
+      if (options_ & RETURN_DELIMS)
+        return true;
+    }
+
+    return false;
+  }
+
+  bool IsDelim(char_type c) const {
+    return delims_.find(c) != str::npos;
+  }
+
+  bool IsQuote(char_type c) const {
+    return quotes_.find(c) != str::npos;
+  }
+
+  struct AdvanceState {
+    bool in_quote;
+    bool in_escape;
+    char_type quote_char;
+    AdvanceState() : in_quote(false), in_escape(false), quote_char('\0') {}
+  };
+
+  // Returns true if a delimiter was not hit.
+  bool AdvanceOne(AdvanceState* state, char_type c) {
+    if (state->in_quote) {
+      if (state->in_escape) {
+        state->in_escape = false;
+      } else if (c == '\\') {
+        state->in_escape = true;
+      } else if (c == state->quote_char) {
+        state->in_quote = false;
+      }
+    } else {
+      if (IsDelim(c))
+        return false;
+      state->in_quote = IsQuote(state->quote_char = c);
+    }
+    return true;
+  }
+
+  const_iterator start_pos_;
+  const_iterator token_begin_;
+  const_iterator token_end_;
+  const_iterator end_;
+  str delims_;
+  str quotes_;
+  int options_;
+  bool token_is_delim_;
+};
+
+typedef StringTokenizerT<std::string, std::string::const_iterator>
+    StringTokenizer;
+typedef StringTokenizerT<string16, string16::const_iterator> String16Tokenizer;
+typedef StringTokenizerT<std::string, const char*> CStringTokenizer;
+
+}  // namespace base
+
+#endif  // BASE_STRINGS_STRING_TOKENIZER_H_