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/*
Ousía
Copyright (C) 2014 Benjamin Paaßen, Andreas Stöckel
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file DynamicTokenizer.hpp
*
* Tokenizer that can be reconfigured at runtime used for parsing the plain
* text format.
*
* @author Andreas Stöckel (astoecke@techfak.uni-bielefeld.de)
*/
#ifndef _OUSIA_DYNAMIC_TOKENIZER_HPP_
#define _OUSIA_DYNAMIC_TOKENIZER_HPP_
#include <core/common/Location.hpp>
namespace ousia {
// Forward declarations
class CharReader;
class TokenDescriptor;
/**
* The DynamicToken structure describes a token discovered by the Tokenizer.
*/
struct DynamicToken {
/**
* Pointer pointing at the TokenDescriptor instance this token corresponds
* to. May be one of the special TokenDescriptors defined as static members
* of the DynamicTokenizer class.
*/
TokenDescriptor const *descriptor;
/**
* String that was matched.
*/
std::string str;
/**
* Location from which the string was extracted.
*/
SourceLocation location;
};
/**
* Enum specifying the whitespace handling of the DynamicTokenizer class when
* reading non-token text.
*/
enum class WhitespaceMode {
/**
* Preserves all whitespaces as they are found in the source file.
*/
PRESERVE,
/**
* Trims whitespace at the beginning and the end of the found text.
*/
TRIM,
/**
* Whitespaces are trimmed and collapsed, multiple whitespace characters
* are replaced by a single space character.
*/
COLLAPSE
};
/**
* The DynamicTokenizer is used to extract tokens and chunks of text from a
* CharReader. It allows to register and unregister tokens while parsing and
* to modify the handling of whitespace characters.
*/
class DynamicTokenizer {
private:
/**
* Reference at the char reader.
*/
CharReader &reader;
/**
* Flag defining whether whitespaces should be preserved or not.
*/
WhitespaceMode whitespaceMode;
/**
* Vector containing all registered token descriptors.
*/
std::vector<std::unique_ptr<TokenDescriptor>> descriptors;
public:
/**
* Constructor of the DynamicTokenizer class.
*
* @param reader is the CharReader that should be used for reading the
* tokens.
* @param preserveWhitespaces should be set to true if all whitespaces
* should be preserved (for preformated environments).
*/
DynamicTokenizer(CharReader &reader)
: reader(reader),
preserveWhitespaces(preserveWhitespaces),
location(reader.getSourceId()),
empty(true),
hasWhitespace(false)
{
}
/**
* Destructor of the DynamicTokenizer class.
*/
~DynamicTokenizer();
/**
* Registers the given string as a token. Returns a const pointer at a
* TokenDescriptor that will be used to reference the newly created token.
*
* @param token is the token string that should be registered.
* @return a pointer at a TokenDescriptor which is representative for the
* newly registered token. Returns nullptr if a token with this string
* was already registered.
*/
const TokenDescriptor* registerToken(const std::string &token);
/**
* Unregisters the token belonging to the given TokenDescriptor.
*
* @param descr is a TokenDescriptor that was previously returned by
* registerToken.
* @return true if the operation was successful, false otherwise (e.g.
* because the given TokenDescriptor was already unregistered).
*/
bool unregisterToken(const TokenDescriptor *descr);
/**
* Sets the whitespace mode.
*
* @param whitespaceMode defines how whitespace should be treated in text
* tokens.
*/
void setWhitespaceMode(WhitespaceMode mode);
/**
* Returns the current value of the whitespace mode.
*
* @return the whitespace mode.
*/
WhitespaceMode getWhitespaceMode();
/**
* Reads a new token from the CharReader and stores it in the given
* DynamicToken instance.
*
* @param token is a reference at the token instance into which the Token
* information should be written.
* @return true if a token could be read, false if the end of the stream
* has been reached.
*/
bool read(DynamicToken &token);
/**
* TokenDescriptor representing an empty token.
*/
static const *TokenDescriptor Empty;
/**
* TokenDescriptor representing generic text.
*/
static const *TokenDescriptor Text;
};
}
#endif /* _OUSIA_DYNAMIC_TOKENIZER_HPP_ */
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