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/*
Ousía
Copyright (C) 2014, 2015 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/>.
*/
#include "BufferedCharReader.hpp"
namespace ousia {
// Constants used within the linebreak statemachine.
static const uint8_t LB_STATE_NONE = 0x00;
static const uint8_t LB_STATE_ONE = 0x01;
static const uint8_t LB_STATE_LF = 0x10;
static const uint8_t LB_STATE_CR = 0x20;
static const uint8_t LB_STATE_MASK_CNT = 0x0F;
static const uint8_t LB_STATE_MASK_TYPE = 0xF0;
/*******************************************************************************
* Struct BufferedCharReader::ReadCursor
******************************************************************************/
BufferedCharReader::ReadCursor::ReadCursor(const bool destructive) :
destructive(destructive)
{
reset();
}
void BufferedCharReader::ReadCursor::assign(const ReadCursor &cursor)
{
this->line = cursor.line;
this->column = cursor.column;
this->bufferElem = cursor.bufferElem;
this->bufferPos = cursor.bufferPos;
this->lbState = cursor.lbState;
}
void BufferedCharReader::ReadCursor::reset()
{
this->line = 1;
this->column = 1;
this->bufferElem = 0;
this->bufferPos = 0;
this->lbState = LB_STATE_NONE;
}
/*******************************************************************************
* Class BufferedCharReader
******************************************************************************/
BufferedCharReader::BufferedCharReader() :
readCursor(true), peekCursor(false)
{
reset();
}
void BufferedCharReader::reset()
{
readCursor.reset();
peekCursor.reset();
buffer.clear();
closed = false;
}
bool BufferedCharReader::feed(const std::string &data)
{
// Abort if the BufferedCharReader was closed
if (closed) {
return false;
}
// Append the data onto the queue
buffer.push_back(data);
return true;
}
void BufferedCharReader::close()
{
closed = true;
}
bool BufferedCharReader::substituteLinebreaks(ReadCursor *cursor, char *c)
{
// Handle line breaks, inserts breakes after the following character
// combinations: \n, \r, \n\r, \r\n TODO: Change behaviour to \n, \n\r, \r\n
if ((*c == '\n') || (*c == '\r')) {
// Determine the type of the current linebreak character
const uint8_t type = (*c == '\n') ? LB_STATE_LF : LB_STATE_CR;
// Read the last count and the last type from the state
const uint8_t lastCount = cursor->lbState & LB_STATE_MASK_CNT;
const uint8_t lastType = cursor->lbState & LB_STATE_MASK_TYPE;
// Set the current linebreak type and counter in the state
cursor->lbState = ((lastCount + 1) & 1) | type;
// If either this is the first instance of this character or the same
// return character is repeated
if (!lastCount || (lastType == type)) {
*c = '\n';
return true;
}
return false;
}
// Find the state
cursor->lbState = LB_STATE_NONE;
return true;
}
bool BufferedCharReader::readCharacterAtCursor(ReadCursor *cursor,
char *c)
{
bool hasChar = false;
while (!hasChar) {
// Abort if the current buffer element does not point to a valid entry
// in the buffer -- we must wait until another data block has been fed
// into the buffer
if (cursor->bufferElem >= buffer.size()) {
return false;
}
// Fetch the current element the peek pointer points to
const std::string &data = buffer[cursor->bufferElem];
// Handle the "no data" case -- either in a destructive or
// non-destructive manner.
if (cursor->bufferPos >= data.length()) {
if (cursor->destructive) {
buffer.pop_front();
} else {
cursor->bufferElem++;
}
cursor->bufferPos = 0;
continue;
}
// Read the character, advance the buffer position
*c = *(data.data() + cursor->bufferPos);
cursor->bufferPos++;
// Substitute linebreaks with a single LF (0x0A)
hasChar = substituteLinebreaks(cursor, c);
}
// Update the position counter
if (*c == '\n') {
cursor->line++;
cursor->column = 1;
} else {
// Ignore UTF-8 continuation bytes
if (!((*c & 0x80) && !(*c & 0x40))) {
cursor->column++;
}
}
return true;
}
bool BufferedCharReader::peek(char *c)
{
return readCharacterAtCursor(&peekCursor, c);
}
bool BufferedCharReader::read(char *c)
{
resetPeek();
return readCharacterAtCursor(&readCursor, c);
}
void BufferedCharReader::consumePeek()
{
// Remove all no longer needed buffer elements
for (unsigned int i = 0; i < peekCursor.bufferElem; i++) {
buffer.pop_front();
}
peekCursor.bufferElem = 0;
// Copy the peek cursor to the read cursor
readCursor.assign(peekCursor);
}
void BufferedCharReader::resetPeek()
{
// Reset the peek cursor to the read cursor
peekCursor.assign(readCursor);
}
bool BufferedCharReader::atEnd()
{
if (closed) {
if (buffer.size() <= 0) {
return true;
} else if (buffer.size() == 1) {
return buffer[0].size() == readCursor.bufferPos;
}
}
return false;
}
}
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