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Diffstat (limited to 'src/core/utils/CharReader.hpp')
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diff --git a/src/core/utils/CharReader.hpp b/src/core/utils/CharReader.hpp deleted file mode 100644 index 1306026..0000000 --- a/src/core/utils/CharReader.hpp +++ /dev/null @@ -1,672 +0,0 @@ -/* - 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 CharReader.hpp - * - * Used within all parsers to read single characters from an underlying stream. - * - * @author Andreas Stöckel (astoecke@techfak.uni-bielefeld.de) - */ - -#ifndef _OUSIA_CHAR_READER_HPP_ -#define _OUSIA_CHAR_READER_HPP_ - -#include <istream> -#include <list> -#include <memory> -#include <vector> - -namespace ousia { -namespace utils { - -/** - * A chunked ring buffer used in CharReader to provide access to an input stream - * with multiple read cursors. The Buffer automatically expands to the - * size of the spanned by the read cursors while reusing already allocated - * memory. - */ -class Buffer { -public: - /** - * Callback function which is called whenever new data is requested from the - * input stream. - * - * @param buf is points a the target memory region. - * @param size is the requested number of bytes. - * @param userData is a pointer at some user defined data given in the - * constructor. - * @return the actual number of bytes read. If the result is smaller than - * the requested size, this tells the Buffer that the end of the input - * stream is reached. - */ - using ReadCallback = size_t (*)(char *buf, size_t size, void *userData); - - /** - * Handle used to identify a cursor. - */ - using CursorId = size_t; - -private: - /** - * Number of bytes to request from the input stream. Set to 64 KiB because - * this seems to be a nice value for I/O operations according to multiple - * sources. - */ - static constexpr size_t REQUEST_SIZE = 64 * 1024; - - /** - * Number of bytes the buffer guarantees to be capable of looking back - * for extracting the current context. - */ - static constexpr size_t LOOKBACK_SIZE = 128; - - /** - * Type used internally to represent one chunk of memory. - */ - using Bucket = std::vector<char>; - - /** - * Type used internally to represent a bucket container. - */ - using BucketList = std::list<Bucket>; - - /** - * Type used internally for representing iterators in the bucket list. - */ - using BucketIterator = BucketList::iterator; - - /** - * Type used internally to represent a read cursor. - */ - struct Cursor { - /** - * Iterator pointing at the current bucket. - */ - BucketIterator bucket; - - /** - * Index of the bucket relative to the start bucket. - */ - size_t bucketIdx; - - /** - * Current offset within that bucket. - */ - size_t bucketOffs; - }; - - /** - * List of buckets containing the buffered memory. - */ - BucketList buckets; - - /** - * List of cursors used to access the memory. Note that cursors can be - * marked as inactive and reused lateron (to avoid having to resize the - * vector). - */ - std::vector<Cursor> cursors; - - /** - * Bitfield specifying which of the cursors is actually valid. - */ - std::vector<bool> alive; - - /** - * Function to be called whenever new data is needed. Set to nullptr if the - * Buffer is not backed by an input stream. - */ - const ReadCallback callback; - - /** - * User data given in the constructor. - */ - void *userData; - - /** - * Set to true if the input stream is at its end. - */ - bool reachedEnd; - - /** - * Iterator pointing at the current start bucket. - */ - BucketIterator startBucket; - - /** - * Iterator pointing at the last bucket. - */ - BucketIterator endBucket; - - /** - * Byte offset of the start bucket relative to the beginning of the stream. - */ - size_t startOffset; - - /** - * Points at the smallest possible available cursor index, yet does not - * guarantee that this cursor index actuall is free. - */ - CursorId firstDead; - - /** - * Advances the bucket iterator, cares about wrapping around in the ring. - */ - void advance(BucketIterator &it); - - /** - * Advances the bucket iterator, cares about wrapping around in the ring. - */ - void advance(BucketList::const_iterator &it) const; - - /** - * Internally used to find the next free cursor in the cursors vector. The - * cursor is marked as active. - * - * @return the next free cursor index. - */ - CursorId nextCursor(); - - /** - * Returns a reference at the next bucket into which data should be - * inserted. - * - * @return a bucket into which the data can be inserted. - */ - Bucket &nextBucket(); - - /** - * Reads data from the input stream and places it in the next free buffer. - */ - void stream(); - - /** - * Moves the given cursor forward. - */ - size_t moveForward(CursorId cursor, size_t relativeOffs); - - /** - * Moves the given cursor backward. - */ - size_t moveBackward(CursorId cursor, size_t relativeOffs); - - /** - * Reads a character from the current cursor position and optionally - * advances. - */ - bool fetchCharacter(CursorId cursor, char &c, bool incr); - -public: - /** - * Intializes the Buffer with a reference to a ReadCallback that is used - * to fetch data from an underlying input stream. - * - * @param callback is the function that will be called whenever data is read - * from the ring buffer and the buffer does not hold enough data to fulfill - * this read request. - * @param userData is a pointer to user defined data which will be passed to - * the callback function. - */ - Buffer(ReadCallback callback, void *userData); - - /** - * Initializes the Buffer with a reference to an std::istream from which - * data will be read. - * - * @param istream is the input stream from which the data should be read. - */ - Buffer(std::istream &istream); - - /** - * Initializes the Buffer with the contents of the given string, after - * this operation the Buffer has a fixed size. - * - * @param str is the string containing the data that should be copied into - * the ring buffer. - */ - Buffer(const std::string &str); - -#ifndef NDEBUG - /** - * Destructor of the Buffer class. Makes sure that all cursors have been - * freed. - */ - ~Buffer(); -#endif - - // No copy - Buffer(const Buffer &) = delete; - - // No assign - Buffer &operator=(const Buffer &) = delete; - - /** - * Creates a new read cursor positioned at the smallest possible position - * in the ring buffer. - */ - CursorId createCursor(); - - /** - * Creates a new read cursor positioned at the same position as the given - * read cursor. - * - * @param ref is the read cursor that should be used as reference for the - * new read cursor. - */ - CursorId createCursor(CursorId ref); - - /** - * Copies the position of one cursor to another cursor. - * - * @param from is the cursor id of which the position should be copied. - * @param to is the cursor id to which the position should be copied. - */ - void copyCursor(CursorId from, CursorId to); - - /** - * Deletes the cursor with the given id. The cursor may no longer be used - * after this function has been called. - * - * @param cursor is the id of the cursor that should be freed. - */ - void deleteCursor(CursorId cursor); - - /** - * Moves a cursor by offs bytes. Note that moving backwards is theoretically - * limited by the LOOKBACK_SIZE of the Buffer, practically it will most - * likely be limited by the REQUEST_SIZE, so you can got at most 64 KiB - * backwards. - * - * @param cursor is the cursor that should be moved. - * @param relativeOffs is a positive or negative integer number specifying - * the number of bytes the cursor should be moved forward (positive numbers) - * or backwards (negative numbers). - * @return the actual number of bytes the cursor was moved. This number is - * smaller than the relativeOffs given in the constructor if the - */ - ssize_t moveCursor(CursorId cursor, ssize_t relativeOffs); - - /** - * Returns the current byte offset of the given cursor relative to the - * beginning of the stream. - * - * @param cursor is the cursor for which the byte offset relative to the - * beginning of the stream should be returned. - * @return the number of bytes since the beginning of the stream for the - * given cursor. - */ - size_t offset(CursorId cursor) const; - - /** - * Returns true if the given cursor currently is at the end of the stream. - * - * @param cursor is the cursor for which the atEnd flag should be returned. - * @return true if the there are no more bytes for this cursor. If false - * is returned, this means that there may be more bytes in the stream, - * nevertheless the end of the stream may be hit once the next read function - * is called. - */ - bool atEnd(CursorId cursor) const; - - /** - * Reads a single character from the ring buffer from the given cursor and - * moves to the next character. - * - * @param cursor specifies the cursor from which the data should be read. - * The cursor will be advanced by one byte. - * @param c is the character into which the data needs to be read. - * @return true if a character was read, false if the end of the stream has - * been reached. - */ - bool read(CursorId cursor, char &c); - - /** - * Returns a single character from the ring buffer from the current cursor - * position and stays at that position. - * - * @param cursor specifies the cursor from which the data should be read. - * The cursor will be advanced by one byte. - * @param c is the character into which the data needs to be read. - * @return true if a character could be fetched, false if the end of the - * stream has been reached. - */ - bool fetch(CursorId cursor, char &c); -}; - -// Forward declaration -class CharReaderFork; - -/** - * Used within parsers for convenient access to single characters in an input - * stream or buffer. It allows reading and peeking single characters from a - * buffer. Additionally it counts the current column/row (with correct handling - * for UTF-8) and contains an internal state machine that handles the detection - * of linebreaks and converts these to a single '\n'. - */ -class CharReader { -public: - /** - * The context struct is used to represent the current context the char - * reader is in. This context can for example be used when building error - * messages. - */ - struct Context { - /** - * Set to the content of the current line. - */ - std::string line; - - /** - * Relative position (in characters) within that line. - */ - size_t relPos; - - /** - * Set to true if the beginning of the line has been truncated (because - * the reader position is too far away from the actual position of the - * line). - */ - bool truncatedStart; - - /** - * Set to true if the end of the line has been truncated (because the - * reader position is too far away from the actual end position of the - * line. - */ - bool truncatedEnd; - - Context() - : line(), relPos(0), truncatedStart(false), truncatedEnd(false) - { - } - - Context(std::string line, size_t relPos, bool truncatedStart, - bool truncatedEnd) - : line(std::move(line)), - relPos(relPos), - truncatedStart(truncatedStart), - truncatedEnd(truncatedEnd) - { - } - }; - -protected: - /** - * Internally used cursor structure for managing the read and the peek - * cursor. - */ - struct Cursor { - /** - * Corresponding cursor in the underlying buffer instance. - */ - const Buffer::CursorId cursor; - - /** - * Current line the cursor is in. - */ - uint32_t line; - - /** - * Current column the cursor is in. - */ - uint32_t column; - - /** - * Constructor of the Cursor class. - * - * @param cursor is the underlying cursor in the Buffer instance. - */ - Cursor(Buffer::CursorId cursor, size_t line, size_t column) - : cursor(cursor), line(line), column(column) - { - } - - /** - * Assigns one cursor to another. - * - * @param buffer is the underlying buffer instance the internal cursor - * belongs to. - * @param cursor is the cursor from which the state should be copied. - */ - void assign(std::shared_ptr<Buffer> buffer, Cursor &cursor); - }; - -private: - /** - * Substitutes "\r", "\n\r", "\r\n" with a single "\n". - * - * @param cursor is the cursor from which the character should be read. - * @param c a reference to the character that should be written. - * @return true if another character needs to be read. - */ - bool substituteLinebreaks(Cursor &cursor, char &c); - - /** - * Reads a single character from the given cursor. - * - * @param cursor is the cursor from which the character should be read. - * @param c a reference to the character that should be written. - * @return true if a character was read, false if the end of the stream has - * been reached. - */ - bool readAtCursor(Cursor &cursor, char &c); - -protected: - /** - * Reference pointing at the underlying buffer. - */ - std::shared_ptr<Buffer> buffer; - - /** - * Cursor used for reading. - */ - Cursor readCursor; - - /** - * Cursor used for peeking. - */ - Cursor peekCursor; - - /** - * Set to true as long the underlying Buffer cursor is at the same position - * for the read and the peek cursor. This is only used for optimization - * purposes and makes consecutive reads a bit faster. - */ - bool coherent; - - /** - * Protected constructor of the CharReader base class. Creates new read - * and peek cursors for the given buffer. - * - * @param buffer is a reference to the underlying Buffer class responsible - * for allowing to read from a single input stream from multiple locations. - */ - CharReader(std::shared_ptr<Buffer> buffer, size_t line, size_t column); - -public: - /** - * Creates a new CharReader instance from a string. - * - * @param str is a string containing the input data. - * @param line is the start line. - * @param column is the start column. - */ - CharReader(const std::string &str, size_t line = 1, size_t column = 1); - - /** - * Creates a new CharReader instance for an input stream. - * - * @param istream is the input stream from which incomming data should be - * read. - * @param line is the start line. - * @param column is the start column. - */ - CharReader(std::istream &istream, size_t line = 1, size_t column = 1); - - /** - * Deletes the used cursors from the underlying buffer instance. - */ - ~CharReader(); - - // No copy - CharReader(const Buffer &) = delete; - - // No assign - CharReader &operator=(const Buffer &) = delete; - - /** - * Peeks a single character. If called multiple times, returns the - * character after the previously peeked character. - * - * @param c is a reference to the character to which the result should be - * written. - * @return true if the character was successfully read, false if there are - * no more characters to be read in the buffer. - */ - bool peek(char &c); - - /** - * Reads a character from the input data. If "peek" was called - * beforehand resets the peek pointer. - * - * @param c is a reference to the character to which the result should be - * written. - * @return true if the character was successfully read, false if there are - * no more characters to be read in the buffer. - */ - bool read(char &c); - - /** - * Resets the peek pointer to the "read" pointer. - */ - void resetPeek(); - - /** - * Advances the read pointer to the peek pointer -- so if the "peek" - * function was called, "read" will now return the character after - * the last peeked character. - */ - void consumePeek(); - - /** - * Moves the read cursor to the next non-whitespace character. Returns - * false, if the end of the stream was reached. - * - * @return false if the end of the stream was reached, false othrwise. - */ - bool consumeWhitespace(); - - /** - * Creates a new CharReader located at the same position as this CharReader - * instance, yet the new CharReader can be used independently of this - * CharReader. Use the "commit" function of the returned CharReader to - * copy the state of the forked CharReaderFork to this CharReader. - * - * @return a CharReaderFork instance positioned at the same location as this - * CharReader instance. - */ - CharReaderFork fork(); - - /** - * Returns true if there are no more characters as the stream was - * closed. - * - * @return true if there is no more data. - */ - bool atEnd() const { return buffer->atEnd(readCursor.cursor); } - - /** - * Returns the current line (starting with one). - * - * @return the current line number. - */ - uint32_t getLine() const { return readCursor.line; } - - /** - * Returns the current column (starting with one). - * - * @return the current column number. - */ - uint32_t getColumn() const { return readCursor.column; } - - /** - * Returns the current byte offset of the read cursor. - * - * @return the byte position within the stream. - */ - size_t getOffset() const { return buffer->offset(readCursor.cursor); }; - - /** - * Returns the line the read cursor currently is in, but at most the - * given number of characters in the form of a Context structure. - */ - Context getContext(ssize_t maxSize); -}; - -/** - * A CharReaderFork is returned whenever the "fork" function of the CharReader - * class is used. Its "commit" function can be used to move the underlying - * CharReader instance to the location of the CharReaderFork instance. Otherwise - * the read location of the underlying CharReader is left unchanged. - */ -class CharReaderFork : public CharReader { -private: - friend CharReader; - - /** - * The reader cursor of the underlying CharReader instance. - */ - CharReader::Cursor &parentReadCursor; - - /** - * The peek cursor of the underlying CharReader instance. - */ - CharReader::Cursor &parentPeekCursor; - - /** - * Constructor of the CharReaderFork class. - * - * @param buffer is a reference at the parent Buffer instance. - * @param parentPeekCursor is a reference at the parent read cursor. - * @param parentPeekCursor is a reference at the parent peek cursor. - * @param coherent specifies whether the char reader cursors are initialized - * coherently. - */ - CharReaderFork(std::shared_ptr<Buffer> buffer, - CharReader::Cursor &parentReadCursor, - CharReader::Cursor &parentPeekCursor, bool coherent); - -public: - /** - * Moves the read and peek cursor of the parent CharReader to the location - * of the read and peek cursor in the fork. - */ - void commit(); -}; -} - -/** - * Alias of the commonly used CharReader class. - */ -using CharReader = utils::CharReader; - -} - -#endif /* _OUSIA_CHAR_READER_HPP_ */ - |