NCBI C++ Toolkit Cross Reference

   // Copyright (c) 2005, Google Inc.
   // All rights reserved.
   //
   // Redistribution and use in source and binary forms, with or without
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   // met:
   //
   //     * Redistributions of source code must retain the above copyright
   // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // Author: Sanjay Ghemawat
  //
  // Regular-expression based scanner for parsing an input stream.
  //
  // Example 1: parse a sequence of "var = number" entries from input:
  //
  //      Scanner scanner(input);
  //      string var;
  //      int number;
  //      scanner.SetSkipExpression("\\s+"); // Skip any white space we encounter
  //      while (scanner.Consume("(\\w+) = (\\d+)", &var, &number)) {
  //        ...;
  //      }
  
  #ifndef _PCRE_SCANNER_H
  #define _PCRE_SCANNER_H
  
  #include <assert.h>
  #include <string>
  #include <vector>
  
  #include <pcrecpp.h>
  #include <pcre_stringpiece.h>
  
  namespace pcrecpp {
  
  class PCRECPP_EXP_DEFN Scanner {
   public:
    Scanner();
    explicit Scanner(const std::string& input);
    ~Scanner();
  
    // Return current line number.  The returned line-number is
    // one-based.  I.e. it returns 1 + the number of consumed newlines.
    //
    // Note: this method may be slow.  It may take time proportional to
    // the size of the input.
    int LineNumber() const;
  
    // Return the byte-offset that the scanner is looking in the
    // input data;
    int Offset() const;
  
    // Return true iff the start of the remaining input matches "re"
    bool LookingAt(const RE& re) const;
  
    // Return true iff all of the following are true
    //    a. the start of the remaining input matches "re",
    //    b. if any arguments are supplied, matched sub-patterns can be
    //       parsed and stored into the arguments.
    // If it returns true, it skips over the matched input and any
    // following input that matches the "skip" regular expression.
    bool Consume(const RE& re,
                 const Arg& arg0 = RE::no_arg,
                 const Arg& arg1 = RE::no_arg,
                 const Arg& arg2 = RE::no_arg
                 // TODO: Allow more arguments?
                 );
  
    // Set the "skip" regular expression.  If after consuming some data,
    // a prefix of the input matches this RE, it is automatically
    // skipped.  For example, a programming language scanner would use
    // a skip RE that matches white space and comments.
    //
    //    scanner.SetSkipExpression("\\s+|//.*|/[*](.|\n)*?[*]/");
    //
    // Skipping repeats as long as it succeeds.  We used to let people do
    // this by writing "(...)*" in the regular expression, but that added
    // up to lots of recursive calls within the pcre library, so now we
    // control repetition explicitly via the function call API.
   //
   // You can pass NULL for "re" if you do not want any data to be skipped.
   void Skip(const char* re);   // DEPRECATED; does *not* repeat
   void SetSkipExpression(const char* re);
 
   // Temporarily pause "skip"ing. This
   //   Skip("Foo"); code ; DisableSkip(); code; EnableSkip()
   // is similar to
   //   Skip("Foo"); code ; Skip(NULL); code ; Skip("Foo");
   // but avoids creating/deleting new RE objects.
   void DisableSkip();
 
   // Reenable previously paused skipping.  Any prefix of the input
   // that matches the skip pattern is immediately dropped.
   void EnableSkip();
 
   /***** Special wrappers around SetSkip() for some common idioms *****/
 
   // Arranges to skip whitespace, C comments, C++ comments.
   // The overall RE is a disjunction of the following REs:
   //    \\s                     whitespace
   //    //.*\n                  C++ comment
   //    /[*](.|\n)*?[*]/        C comment (x*? means minimal repetitions of x)
   // We get repetition via the semantics of SetSkipExpression, not by using *
   void SkipCXXComments() {
     SetSkipExpression("\\s|//.*\n|/[*](?:\n|.)*?[*]/");
   }
 
   void set_save_comments(bool comments) {
     save_comments_ = comments;
   }
 
   bool save_comments() {
     return save_comments_;
   }
 
   // Append to vector ranges the comments found in the
   // byte range [start,end] (inclusive) of the input data.
   // Only comments that were extracted entirely within that
   // range are returned: no range splitting of atomically-extracted
   // comments is performed.
   void GetComments(int start, int end, std::vector<StringPiece> *ranges);
 
   // Append to vector ranges the comments added
   // since the last time this was called. This
   // functionality is provided for efficiency when
   // interleaving scanning with parsing.
   void GetNextComments(std::vector<StringPiece> *ranges);
 
  private:
   std::string   data_;          // All the input data
   StringPiece   input_;         // Unprocessed input
   RE*           skip_;          // If non-NULL, RE for skipping input
   bool          should_skip_;   // If true, use skip_
   bool          skip_repeat_;   // If true, repeat skip_ as long as it works
   bool          save_comments_; // If true, aggregate the skip expression
 
   // the skipped comments
   // TODO: later consider requiring that the StringPieces be added
   // in order by their start position
   std::vector<StringPiece> *comments_;
 
   // the offset into comments_ that has been returned by GetNextComments
   int           comments_offset_;
 
   // helper function to consume *skip_ and honour
   // save_comments_
   void ConsumeSkip();
 };
 
 }   // namespace pcrecpp
 
 #endif /* _PCRE_SCANNER_H */