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more/gen/identifier.h

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00001 //  Copyright (C) 2001--2002  Petter Urkedal
00002 //
00003 //  This file is free software; you can redistribute it and/or modify
00004 //  it under the terms of the GNU General Public License as published by
00005 //  the Free Software Foundation; either version 2 of the License, or
00006 //  (at your option) any later version.
00007 //
00008 //  This file is distributed in the hope that it will be useful,
00009 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
00010 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00011 //  GNU General Public License for more details.
00012 //
00013 //  You should have received a copy of the GNU General Public License
00014 //  along with this program; if not, write to the Free Software
00015 //  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00016 //
00017 //  As a special exception, you may use this file as part of a free
00018 //  software library without restriction.  Specifically, if other files
00019 //  instantiate templates or use macros or inline functions from this
00020 //  file, or you compile this file and link it with other files to
00021 //  produce an executable, this file does not by itself cause the
00022 //  resulting executable to be covered by the GNU General Public
00023 //  License.  This exception does not however invalidate any other
00024 //  reasons why the executable file might be covered by the GNU General
00025 //  Public License.
00026 //
00027 //  $Id: identifier.h,v 1.2 2002/08/24 13:58:10 petter_urkedal Exp $
00028 
00029 
00030 #ifndef MORE_GEN_IDENTIFIER_H
00031 #define MORE_GEN_IDENTIFIER_H
00032 
00033 #include <iosfwd>
00034 #include <more/io/fwd.h>
00035 #include <cstring>
00036 
00037 namespace more {
00038 namespace gen {
00039 
00040   /** \class identifier identifier.h more/gen/identifier.h
00041    **
00042    ** An identifier.  This is just a simple string-like class with
00043    ** constant-time comparison.  String manipulation is not provided
00044    ** by intention, as that would lead to generation of redundant
00045    ** unique string pointers.  Use \c std::string or \c gc_string to
00046    ** create the string first, if needed. */
00047   struct identifier
00048   {
00049       typedef std::size_t size_type;
00050 
00051       /** Construct an invalid identifier.  Ideally this ctor would
00052           create an anonymous unique identifier, but that may have
00053           lead to many redundant allocations declared and defined
00054           separately. */
00055       identifier()
00056           : m_str(0) {}
00057 
00058       /// Construct an object identified by "str".
00059       identifier(char const* str);
00060 
00061       /** Return a C string which is lexically equal to the string
00062           this object was constructed from. */
00063       char const* c_str() const { return m_str; }
00064 
00065       size_type length() const { return m_str? std::strlen(m_str) : 0; }
00066 
00067       /// True iff the identifier is valid.
00068       bool is_defined() const { return m_str; }
00069 
00070       /// Equivalent to "strcmp(c_str(), rhs.c_str()) == 0", but faster.
00071       bool operator==(identifier const& rhs) const
00072       {
00073           return m_str == rhs.m_str;
00074       }
00075 
00076       /// True if the identifiers are different.
00077       bool operator!=(identifier const& rhs) const
00078       {
00079           return m_str != rhs.m_str;
00080       }
00081 
00082       /// Provides an arbitrary ordering if identifiers.
00083       bool operator<(identifier const& rhs) const
00084       {
00085           return m_str < rhs.m_str;
00086       }
00087 
00088       void sync(io::syncstream&);
00089 
00090       friend std::ostream& operator<<(std::ostream&, identifier const&);
00091 
00092     private:
00093       char const* m_str;
00094   };
00095 
00096 }}
00097 
00098 #endif

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