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The core parser functionality. This may be all you need.
/*
* Copyright (C) 2007-2010 Júlio Vilmar Gesser.
* Copyright (C) 2011, 2013-2023 The JavaParser Team.
*
* This file is part of JavaParser.
*
* JavaParser can be used either under the terms of
* a) the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* b) the terms of the Apache License
*
* You should have received a copy of both licenses in LICENCE.LGPL and
* LICENCE.APACHE. Please refer to those files for details.
*
* JavaParser 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 Lesser General Public License for more details.
*/
package com.github.javaparser;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* {@link Provider} un-escaping unicode escape sequences in the input sequence.
*/
public class UnicodeEscapeProcessingProvider implements Provider {
private static final char LF = '\n';
private static final char CR = '\r';
private static final char BACKSLASH = '\\';
private static final int EOF = -1;
private char[] _data;
/**
* The number of characters in {@link #_data}.
*/
private int _len = 0;
/**
* The position in {@link #_data} where to read the next source character from.
*/
private int _pos = 0;
private boolean _backslashSeen;
private final LineCounter _inputLine = new LineCounter();
private final LineCounter _outputLine = new LineCounter();
private final PositionMappingBuilder _mappingBuilder = new PositionMappingBuilder(_outputLine, _inputLine);
private Provider _input;
/**
* Creates a {@link UnicodeEscapeProcessingProvider}.
*/
public UnicodeEscapeProcessingProvider(Provider input) {
this(2048, input);
}
/**
* Creates a {@link UnicodeEscapeProcessingProvider}.
*/
public UnicodeEscapeProcessingProvider(int bufferSize, Provider input) {
_input = input;
_data = new char[bufferSize];
}
/**
* The {@link LineCounter} of the input file.
*/
public LineCounter getInputCounter() {
return _inputLine;
}
/**
* The {@link LineCounter} of the output file.
*/
public LineCounter getOutputCounter() {
return _outputLine;
}
@Override
public int read(char[] buffer, final int offset, int len) throws IOException {
int pos = offset;
int stop = offset + len;
while (pos < stop) {
int ch = _outputLine.process(nextOutputChar());
if (ch < 0) {
if (pos == offset) {
// Nothing read yet, this is the end of the stream.
return EOF;
}
break;
}
_mappingBuilder.update();
buffer[pos++] = (char) ch;
}
return pos - offset;
}
@Override
public void close() throws IOException {
_input.close();
}
/**
* Produces the next un-escaped character to be written to the output.
*
* @return The next character or {@code -1} if no more characters are available.
*/
private int nextOutputChar() throws IOException {
int next = nextInputChar();
switch(next) {
case EOF:
return EOF;
case BACKSLASH:
{
if (_backslashSeen) {
return clearBackSlashSeen(next);
}
return backSlashSeen();
}
default:
{
// An arbitrary character.
return clearBackSlashSeen(next);
}
}
}
private int clearBackSlashSeen(int next) {
_backslashSeen = false;
return next;
}
private int backSlashSeen() throws IOException {
_backslashSeen = true;
int next = nextInputChar();
switch(next) {
case EOF:
// End of file after backslash produces the backslash itself.
return BACKSLASH;
case 'u':
{
return unicodeStartSeen();
}
default:
{
pushBack(next);
return BACKSLASH;
}
}
}
private int unicodeStartSeen() throws IOException {
int uCnt = 1;
while (true) {
int next = nextInputChar();
switch(next) {
case EOF:
{
pushBackUs(uCnt);
return BACKSLASH;
}
case 'u':
{
uCnt++;
continue;
}
default:
{
return readDigits(uCnt, next);
}
}
}
}
private int readDigits(int uCnt, int next3) throws IOException {
int digit3 = digit(next3);
if (digit3 < 0) {
pushBack(next3);
pushBackUs(uCnt);
return BACKSLASH;
}
int next2 = nextInputChar();
int digit2 = digit(next2);
if (digit2 < 0) {
pushBack(next2);
pushBack(next3);
pushBackUs(uCnt);
return BACKSLASH;
}
int next1 = nextInputChar();
int digit1 = digit(next1);
if (digit1 < 0) {
pushBack(next1);
pushBack(next2);
pushBack(next3);
pushBackUs(uCnt);
return BACKSLASH;
}
int next0 = nextInputChar();
int digit0 = digit(next0);
if (digit0 < 0) {
pushBack(next0);
pushBack(next1);
pushBack(next2);
pushBack(next3);
pushBackUs(uCnt);
return BACKSLASH;
}
int ch = digit3 << 12 | digit2 << 8 | digit1 << 4 | digit0;
return clearBackSlashSeen(ch);
}
private void pushBackUs(int cnt) {
for (int n = 0; n < cnt; n++) {
pushBack('u');
}
}
private static int digit(int ch) {
if (ch >= '0' && ch <= '9') {
return ch - '0';
}
if (ch >= 'A' && ch <= 'F') {
return 10 + ch - 'A';
}
if (ch >= 'a' && ch <= 'f') {
return 10 + ch - 'a';
}
return -1;
}
/**
* Processes column/line information from the input file.
*
* @return The next character or {@code -1} if no more input is available.
*/
private int nextInputChar() throws IOException {
int result = nextBufferedChar();
return _inputLine.process(result);
}
/**
* Retrieves the next un-escaped character from the buffered {@link #_input}.
*
* @return The next character or {@code -1} if no more input is available.
*/
private int nextBufferedChar() throws IOException {
while (isBufferEmpty()) {
int direct = fillBuffer();
if (direct < 0) {
return EOF;
}
}
return _data[_pos++];
}
private boolean isBufferEmpty() {
return _pos >= _len;
}
private int fillBuffer() throws IOException {
_pos = 0;
int direct = _input.read(_data, 0, _data.length);
if (direct != 0) {
_len = direct;
}
return direct;
}
private void pushBack(int ch) {
if (ch < 0) {
return;
}
if (isBufferEmpty()) {
_pos = _data.length;
_len = _data.length;
} else if (_pos == 0) {
if (_len == _data.length) {
// Buffer is completely full, no push possible, enlarge buffer.
char[] newData = new char[_data.length + 1024];
_len = newData.length;
_pos = newData.length - _data.length;
System.arraycopy(_data, 0, newData, _pos, _data.length);
_data = newData;
} else {
// Move contents to the right.
int cnt = _len - _pos;
_pos = _data.length - _len;
_len = _data.length;
System.arraycopy(_data, 0, _data, _pos, cnt);
}
}
_data[--_pos] = (char) ch;
}
/**
* The {@link PositionMapping} being built during processing the file.
*/
public PositionMapping getPositionMapping() {
return _mappingBuilder.getMapping();
}
/**
* An algorithm mapping {@link Position} form two corresponding files.
*/
public static final class PositionMapping {
private final List _deltas = new ArrayList<>();
/**
* Creates a {@link UnicodeEscapeProcessingProvider.PositionMapping}.
*/
public PositionMapping() {
super();
}
/**
* Whether this is the identity transformation.
*/
public boolean isEmpty() {
return _deltas.isEmpty();
}
void add(int line, int column, int lineDelta, int columnDelta) {
_deltas.add(new DeltaInfo(line, column, lineDelta, columnDelta));
}
/**
* Looks up the {@link PositionUpdate} for the given Position.
*/
public PositionUpdate lookup(Position position) {
int result = Collections.binarySearch(_deltas, position);
if (result >= 0) {
return _deltas.get(result);
}
int insertIndex = -result - 1;
if (insertIndex == 0) {
// Before the first delta info, identity mapping.
return PositionUpdate.NONE;
}
return _deltas.get(insertIndex - 1);
}
/**
* Algorithm updating a {@link Position} from one file to a
* {@link Position} in a corresponding file.
*/
public static interface PositionUpdate {
/**
* The identity position mapping.
*/
PositionUpdate NONE = new PositionUpdate() {
@Override
public int transformLine(int line) {
return line;
}
@Override
public int transformColumn(int column) {
return column;
}
@Override
public Position transform(Position pos) {
return pos;
}
};
/**
* Maps the given line to an original line.
*/
int transformLine(int line);
/**
* Maps the given column to an original column.
*/
int transformColumn(int column);
/**
* The transformed position.
*/
default Position transform(Position pos) {
int line = pos.line;
int column = pos.column;
int transformedLine = transformLine(line);
int transformedColumn = transformColumn(column);
return new Position(transformedLine, transformedColumn);
}
}
private static final class DeltaInfo extends Position implements PositionUpdate {
/**
* The offset to add to the {@link #line} and all following source
* positions up to the next {@link PositionUpdate}.
*/
private final int _lineDelta;
/**
* The offset to add to the {@link #column} and all following
* source positions up to the next {@link PositionUpdate}.
*/
private final int _columnDelta;
/**
* Creates a {@link PositionUpdate}.
*/
public DeltaInfo(int line, int column, int lineDelta, int columnDelta) {
super(line, column);
_lineDelta = lineDelta;
_columnDelta = columnDelta;
}
@Override
public int transformLine(int sourceLine) {
return sourceLine + _lineDelta;
}
@Override
public int transformColumn(int sourceColumn) {
return sourceColumn + _columnDelta;
}
@Override
public String toString() {
return "(" + line + ", " + column + ": " + _lineDelta + ", " + _columnDelta + ")";
}
}
/**
* Transforms the given {@link Position}.
*/
public Position transform(Position pos) {
return lookup(pos).transform(pos);
}
/**
* Transforms the given {@link Range}.
*/
public Range transform(Range range) {
Position begin = transform(range.begin);
Position end = transform(range.end);
if (begin == range.begin && end == range.end) {
// No change.
return range;
}
return new Range(begin, end);
}
}
private static final class PositionMappingBuilder {
private LineCounter _left;
private LineCounter _right;
private final PositionMapping _mapping = new PositionMapping();
private int _lineDelta = 0;
private int _columnDelta = 0;
/**
* Creates a {@link PositionMappingBuilder}.
*
* @param left The source {@link LineCounter}.
* @param right The target {@link LineCounter}.
*/
public PositionMappingBuilder(LineCounter left, LineCounter right) {
_left = left;
_right = right;
update();
}
/**
* The built {@link PositionMapping}.
*/
public PositionMapping getMapping() {
return _mapping;
}
public void update() {
int lineDelta = _right.getLine() - _left.getLine();
int columnDelta = _right.getColumn() - _left.getColumn();
if (lineDelta != _lineDelta || columnDelta != _columnDelta) {
_mapping.add(_left.getLine(), _left.getColumn(), lineDelta, columnDelta);
_lineDelta = lineDelta;
_columnDelta = columnDelta;
}
}
}
/**
* Processor keeping track of the current line and column in a stream of
* incoming characters.
*
* @see #process(int)
*/
public static final class LineCounter {
/**
* Whether {@link #CR} has been seen on the input as last character.
*/
private boolean _crSeen;
private int _line = 1;
private int _column = 1;
/**
* Creates a {@link UnicodeEscapeProcessingProvider.LineCounter}.
*/
public LineCounter() {
super();
}
/**
* The line of the currently processed input character.
*/
public int getLine() {
return _line;
}
/**
* The column of the currently processed input character.
*/
public int getColumn() {
return _column;
}
/**
* The current position.
*/
public Position getPosition() {
return new Position(getLine(), getColumn());
}
/**
* Analyzes the given character for line feed.
*/
public int process(int ch) {
switch(ch) {
case EOF:
{
break;
}
case CR:
{
incLine();
_crSeen = true;
break;
}
case LF:
{
// CR LF does only count as a single line terminator.
if (_crSeen) {
_crSeen = false;
} else {
incLine();
}
break;
}
default:
{
_crSeen = false;
_column++;
}
}
return ch;
}
private void incLine() {
_line++;
_column = 1;
}
}
}