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// 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_
|
