diff options
Diffstat (limited to 'src/core/utils/Buffer.hpp')
| -rw-r--r-- | src/core/utils/Buffer.hpp | 301 |
1 files changed, 0 insertions, 301 deletions
diff --git a/src/core/utils/Buffer.hpp b/src/core/utils/Buffer.hpp deleted file mode 100644 index 0dd0a25..0000000 --- a/src/core/utils/Buffer.hpp +++ /dev/null @@ -1,301 +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 Buffer.hpp - * - * Helper class which allows to read from an input source from multiple cursors. - * - * @author Andreas Stöckel (astoecke@techfak.uni-bielefeld.de) - */ - -#ifndef _OUSIA_BUFFER_HPP_ -#define _OUSIA_BUFFER_HPP_ - -#include <list> -#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 a pointer at the memory region to which the data should be - * writtern. - * @param size is the size of the - * @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. - */ - static constexpr size_t REQUEST_SIZE = 16 * 1024; - - /** - * 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(); - -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 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); - - // 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); - - /** - * 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. - * - * @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); - -// /** -// * Reads string from the ring buffer from the given cursor. -// * -// * @param cursor specifies the cursor from which the data should be read. -// * The cursor will be advanced by the specified number of bytes (or to the -// * end of the stream). -// * @param res is the vector into which the data should be read. Any already -// * present data will be overridden. -// * @param len is number of bytes that should be read from the buffer. -// * @return true if len bytes were read, false if less the len bytes have -// * been read because the end of the stream has been reached. -// */ -// bool read(CursorId cursor, std::vector<char> &res, size_t len); -}; - -} -} - -#endif /* _OUSIA_BUFFER_HPP_ */ - |