dlib C++ Library - tokenizer_kernel_abstract.h

// Copyright (C) 2005 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#undef DLIB_TOKENIZER_KERNEl_ABSTRACT_
#ifdef DLIB_TOKENIZER_KERNEl_ABSTRACT_
#include <string>
#include <ioswfd>
namespace dlib
{
 class tokenizer 
 {
 /*!
 INITIAL VALUE
 stream_is_set() == false
 get_identifier_head() == "_" + lowercase_letters() + uppercase_letters()
 get_identifier_body() == "_" + lowercase_letters() + uppercase_letters() + 
 numbers()
 WHAT THIS OBJECT REPRESENTS
 This object represents a simple tokenizer for textual data.
 BUFFERING
 This object is allowed to buffer data from the input stream.
 Thus if you clear it or switch streams (via calling set_stream())
 any buffered data will be lost.
 TOKENS
 When picking out tokens the tokenizer will always extract the 
 longest token it can. For example, if faced with the string 
 "555" it will consider the three 5s to be a single NUMBER 
 token not three smaller NUMBER tokens.
 Also note that no characters in the input stream are discarded.
 They will all be returned in the text of some token. 
 Additionally, each character will never be returned more than once. 
 This means that if you concatenated all returned tokens it would exactly
 reproduce the contents of the input stream.
 The tokens are defined as follows:
 END_OF_LINE
 This is a single character token and is always the '\n' 
 character.
 END_OF_FILE
 This token represents the end of file. It doesn't have any
 actual characters associated with it. 
 IDENTIFIER
 This is a multi-character token. It is defined as a string that
 begins with a character from get_identifier_head() and is 
 followed by any number of characters from get_identifier_body().
 
 NUMBER
 This is a multi-character token. It is defined as a sequence of
 numbers. 
 WHITE_SPACE
 This is a multi character token. It is defined as a sequence of
 one or more spaces, carrage returns, and tabs. I.e. It is
 composed of characters from the following string " \r\t".
 CHAR
 This is a single character token. It matches anything that isn't
 part of one of the above tokens. 
 !*/
 public:
 enum 
 {
 END_OF_LINE,
 END_OF_FILE,
 IDENTIFIER,
 CHAR,
 NUMBER,
 WHITE_SPACE
 };
 tokenizer ( 
 );
 /*!
 ensures 
 - #*this is properly initialized
 throws
 - std::bad_alloc
 !*/
 virtual ~tokenizer (
 );
 /*!
 ensures
 - any resources associated with *this have been released
 !*/
 void clear(
 );
 /*!
 ensures
 - #*this has its initial value
 throws
 - std::bad_alloc
 If this exception is thrown then #*this is unusable 
 until clear() is called and succeeds.
 !*/
 void set_stream (
 std::istream& in
 );
 /*!
 ensures
 - #*this will read data from in and tokenize it
 - #stream_is_set() == true
 - #get_stream() == in
 !*/
 bool stream_is_set (
 ) const;
 /*!
 ensures
 - returns true if a stream has been associated with *this by calling
 set_stream()
 !*/
 std::istream& get_stream (
 ) const;
 /*!
 requires
 - stream_is_set() == true
 ensures
 - returns a reference to the istream object that *this is reading 
 from.
 !*/
 void get_token (
 int& type,
 std::string& token
 );
 /*!
 requires
 - stream_is_set() == true
 ensures
 - #token == the next token from the input stream get_stream()
 - #type == the type of the token in #token
 throws
 - bad_alloc
 If this exception is thrown then the call to this function will 
 have no effect on *this but the values of #type and #token will be 
 undefined. Additionally, some characters may have been read
 from the stream get_stream() and lost.
 !*/
 int peek_type (
 ) const;
 /*!
 requires
 - stream_is_set() == true
 ensures
 - returns the type of the token that will be returned from
 the next call to get_token()
 throws
 - bad_alloc
 If this exception is thrown then the call to this function will 
 have no effect on *this. However, some characters may have been 
 read from the stream get_stream() and lost.
 !*/
 const std::string& peek_token (
 ) const;
 /*!
 requires
 - stream_is_set() == true
 ensures
 - returns the text of the token that will be returned from
 the next call to get_token()
 throws
 - bad_alloc
 If this exception is thrown then the call to this function will 
 have no effect on *this. However, some characters may have been 
 read from the stream get_stream() and lost.
 !*/
 void set_identifier_token (
 const std::string& head,
 const std::string& body
 );
 /*!
 requires
 - head.find_first_of(" \r\t\n0123456789") == std::string::npos
 (i.e. head doesn't contain any characters from the string
 " \r\t\n0123456789").
 - body.find_frst_of(" \r\t\n") == std::string::npos
 (i.e. body doesn't contain any characters from the string " \r\t\n").
 ensures
 - #get_identifier_head() == head
 - #get_identifier_body() == body
 throws
 - std::bad_alloc
 If this exception is thrown then #*this is unusable 
 until clear() is called and succeeds.
 !*/
 const std::string get_identifier_head (
 ) const;
 /*!
 ensures
 - returns a string containing the characters that can be the start
 of an IDENTIFIER token.
 throws
 - std::bad_alloc
 If this exception is thrown then the call to this function
 has no effect.
 !*/
 const std::string get_identifier_body (
 ) const;
 /*!
 ensures
 - returns a string containing the characters that can appear in the
 body of an IDENTIFIER token.
 throws
 - std::bad_alloc
 If this exception is thrown then the call to this function
 has no effect.
 !*/
 const std::string lowercase_letters (
 ) const;
 /*!
 ensures
 - returns "abcdefghijklmnopqrstuvwxyz"
 throws
 - std::bad_alloc
 If this exception is thrown then the call to this function
 has no effect.
 !*/
 const std::string uppercase_letters (
 ) const;
 /*!
 ensures
 - returns "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 throws
 - std::bad_alloc
 If this exception is thrown then the call to this function
 has no effect.
 !*/
 const std::string numbers (
 ) const;
 /*!
 ensures
 - returns "0123456789"
 throws
 - std::bad_alloc
 If this exception is thrown then the call to this function
 has no effect.
 !*/
 void swap (
 tokenizer& item
 );
 /*!
 ensures
 - swaps *this and item
 !*/ 
 private:
 // restricted functions
 tokenizer(const tokenizer&); // copy constructor
 tokenizer& operator=(const tokenizer&); // assignment operator
 }; 
 inline void swap (
 tokenizer& a, 
 tokenizer& b 
 ) { a.swap(b); } 
 /*!
 provides a global swap function
 !*/
}
#endif // DLIB_TOKENIZER_KERNEl_ABSTRACT_