327 lines
9.5 KiB
C++
327 lines
9.5 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2006 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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#ifndef MAPNIK_ENUMERATION_INCLUDED
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#define MAPNIK_ENUMERATION_INCLUDED
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#include <mapnik/config.hpp>
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#include <vector>
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#include <bitset>
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#include <iostream>
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#include <cstdlib>
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namespace mapnik {
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class illegal_enum_value : public std::exception
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{
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public:
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illegal_enum_value() {}
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illegal_enum_value( const std::string & what ) :
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what_( what )
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{
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}
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virtual ~illegal_enum_value() throw() {};
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virtual const char * what() const throw()
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{
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return what_.c_str();
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}
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protected:
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std::string what_;
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};
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/** Slim wrapper for enumerations. It creates a new type from a native enum and
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* a char pointer array. It almost exactly behaves like a native enumeration
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* type. It supports string conversion through stream operators. This is usefull
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* for debugging, serialization/deserialization and also helps with implementing
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* language bindings. The two convinient macros DEFINE_ENUM() and IMPLEMENT_ENUM()
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* are provided to help with instanciation.
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*
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* @par Limitations:
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* - The enum must start at zero.
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* - The enum must be consecutive.
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* - The enum must be terminated with a special token consisting of the enum's
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* name plus "_MAX".
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* - The corresponding char pointer array must be terminated with an empty string.
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* - The names must only consist of characters and digits (<i>a-z, A-Z, 0-9</i>),
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* underscores (<i>_</i>) and dashes (<i>-</i>).
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*
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*
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* @warning At the moment the verify() method is called during static initialization.
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* It quits the application with exit code 1 if any error is detected. The other solution
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* i thought of is to do the checks at compile time (using boost::mpl).
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*
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* @par Example:
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* The following code goes into the header file:
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* @code
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* enum fruit_enum {
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* APPLE,
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* CHERRY,
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* BANANA,
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* PASSION_FRUIT,
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* fruit_enum_MAX
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* };
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*
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* static const char * fruit_strings[] = {
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* "apple",
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* "cherry",
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* "banana",
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* "passion_fruit",
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* ""
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* };
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*
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* DEFINE_ENUM( fruit, fruit_enum);
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* @endcode
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* In the corresponding cpp file do:
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* @code
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* IMPLEMENT_ENUM( fruit, fruit_strings );
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* @endcode
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* And here is how to use the resulting type Fruit
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* @code
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*
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* int
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* main(int argc, char * argv[]) {
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* fruit f(APPLE);
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* switch ( f ) {
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* case BANANA:
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* case APPLE:
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* cerr << "No thanks. I hate " << f << "s" << endl;
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* break;
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* default:
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* cerr << "Hmmm ... yummy " << f << endl;
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* break;
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* }
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*
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* f = CHERRY;
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*
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* fruit_enum native_enum = f;
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*
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* f.from_string("passion_fruit");
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*
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* for (unsigned i = 0; i < fruit::MAX; ++i) {
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* cerr << i << " = " << fruit::get_string(i) << endl;
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* }
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*
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* f.from_string("elephant"); // throws illegal_enum_value
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*
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* return 0;
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* }
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* @endcode
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*/
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template <class ENUM, int THE_MAX>
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class MAPNIK_DECL enumeration {
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public:
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typedef ENUM native_type;
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enumeration() {};
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enumeration( ENUM v ) : value_(v) {}
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enumeration( const enumeration & other ) : value_(other.value_) {}
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/** Assignment operator for native enum values. */
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void operator=(ENUM v)
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{
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value_ = v;
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}
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/** Assignment operator. */
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void operator=(const enumeration & other)
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{
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value_ = other.value_;
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}
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/** Conversion operator for native enum values. */
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operator ENUM() const
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{
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return value_;
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}
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enum Max
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{
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MAX = THE_MAX
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};
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ENUM max() const
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{
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return THE_MAX;
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}
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/** Converts @p str to an enum.
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* @throw illegal_enum_value @p str is not a legal identifier.
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* */
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void from_string(const std::string & str)
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{
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for (unsigned i = 0; i < THE_MAX; ++i)
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{
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if (str == our_strings_[i])
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{
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value_ = static_cast<ENUM>(i);
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return;
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}
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}
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throw illegal_enum_value(std::string("Illegal enumeration value '") +
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str + "' for enum " + our_name_);
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}
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/** Parses the input stream @p is for a word consisting of characters and
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* digits (<i>a-z, A-Z, 0-9</i>) and underscores (<i>_</i>).
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* The failbit of the stream is set if the word is not a valid identifier.
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*/
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std::istream & parse(std::istream & is)
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{
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std::string word;
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char c;
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while ( is.peek() != std::char_traits< char >::eof())
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{
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is >> c;
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if ( isspace(c) && word.empty() )
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{
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continue;
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}
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if ( isalnum(c) || (c == '_') || c == '-' )
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{
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word += c;
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}
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else
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{
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is.unget();
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break;
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}
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}
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try
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{
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from_string( word );
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}
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catch (const illegal_enum_value &)
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{
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is.setstate(std::ios::failbit);
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}
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return is;
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}
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/** Returns the current value as a string identifier. */
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std::string as_string() const
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{
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return our_strings_[value_];
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}
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/** Prints the string identifier to the output stream @p os. */
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std::ostream & print(std::ostream & os = std::cerr) const
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{
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return os << our_strings_[value_];
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}
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/** Static helper function to iterate over valid identifiers. */
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static const char * get_string(unsigned i)
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{
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return our_strings_[i];
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}
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/** Performs some simple checks and quits the application if
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* any error is detected. Tries to print helpful error messages.
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*/
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static bool verify(const char * filename, unsigned line_no)
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{
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for (unsigned i = 0; i < THE_MAX; ++i)
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{
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if (our_strings_[i] == 0 )
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{
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std::cerr << "### FATAL: Not enough strings for enum "
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<< our_name_ << " defined in file '" << filename
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<< "' at line " << line_no << std::endl;
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std::exit(1);
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}
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}
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if ( std::string("") != our_strings_[THE_MAX])
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{
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std::cerr << "### FATAL: The string array for enum " << our_name_
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<< " defined in file '" << filename << "' at line " << line_no
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<< " has too many items or is not terminated with an "
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<< "empty string." << std::endl;
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std::exit(1);
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}
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return true;
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}
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static const std::string & get_full_qualified_name()
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{
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return our_name_;
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}
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static std::string get_name()
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{
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std::string::size_type idx = our_name_.find_last_of(":");
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if ( idx == std::string::npos )
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{
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return our_name_;
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} else {
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return our_name_.substr( idx + 1 );
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}
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}
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private:
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ENUM value_;
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static const char ** our_strings_ ;
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static std::string our_name_ ;
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static bool our_verified_flag_;
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};
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/** ostream operator for enumeration
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* @relates mapnik::enumeration
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*/
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template <class ENUM, int THE_MAX>
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std::ostream &
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operator<<(std::ostream & os, const mapnik::enumeration<ENUM, THE_MAX> & e)
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{
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e.print( os );
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return os;
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}
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/** istream operator for enumeration
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* @relates mapnik::enumeration
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*/
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template <class ENUM, int THE_MAX>
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std::istream &
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operator>>(std::istream & is, mapnik::enumeration<ENUM, THE_MAX> & e)
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{
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e.parse( is );
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return is;
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}
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} // end of namespace
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/** Helper macro. Creates a typedef.
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* @relates mapnik::enumeration
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*/
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#define DEFINE_ENUM( name, e) \
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typedef mapnik::enumeration<e, e ## _MAX> name;
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/** Helper macro. Runs the verify() method during static initialization.
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* @relates mapnik::enumeration
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*/
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#define IMPLEMENT_ENUM( name, strings ) \
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template <> const char ** name ::our_strings_ = strings; \
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template <> std::string name ::our_name_ = #name; \
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template <> bool name ::our_verified_flag_( name ::verify(__FILE__, __LINE__));
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#endif // MAPNIK_ENUMERATION_INCLUDED
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