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With inspiration from other libraries
/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.runtime;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.IntBuffer;
/**
* Wrapper for {@link ByteBuffer} / {@link CharBuffer} / {@link IntBuffer}.
*
* Because Java lacks generics on primitive types, these three types
* do not share an interface, so we have to write one manually.
*/
public class CodePointBuffer {
public enum Type {
BYTE,
CHAR,
INT
}
private final Type type;
private final ByteBuffer byteBuffer;
private final CharBuffer charBuffer;
private final IntBuffer intBuffer;
private CodePointBuffer(Type type, ByteBuffer byteBuffer, CharBuffer charBuffer, IntBuffer intBuffer) {
this.type = type;
this.byteBuffer = byteBuffer;
this.charBuffer = charBuffer;
this.intBuffer = intBuffer;
}
public static CodePointBuffer withBytes(ByteBuffer byteBuffer) {
return new CodePointBuffer(Type.BYTE, byteBuffer, null, null);
}
public static CodePointBuffer withChars(CharBuffer charBuffer) {
return new CodePointBuffer(Type.CHAR, null, charBuffer, null);
}
public static CodePointBuffer withInts(IntBuffer intBuffer) {
return new CodePointBuffer(Type.INT, null, null, intBuffer);
}
public int position() {
switch (type) {
case BYTE:
return byteBuffer.position();
case CHAR:
return charBuffer.position();
case INT:
return intBuffer.position();
}
throw new UnsupportedOperationException("Not reached");
}
public void position(int newPosition) {
switch (type) {
case BYTE:
byteBuffer.position(newPosition);
break;
case CHAR:
charBuffer.position(newPosition);
break;
case INT:
intBuffer.position(newPosition);
break;
}
}
public int remaining() {
switch (type) {
case BYTE:
return byteBuffer.remaining();
case CHAR:
return charBuffer.remaining();
case INT:
return intBuffer.remaining();
}
throw new UnsupportedOperationException("Not reached");
}
public int get(int offset) {
switch (type) {
case BYTE:
return byteBuffer.get(offset);
case CHAR:
return charBuffer.get(offset);
case INT:
return intBuffer.get(offset);
}
throw new UnsupportedOperationException("Not reached");
}
Type getType() {
return type;
}
int arrayOffset() {
switch (type) {
case BYTE:
return byteBuffer.arrayOffset();
case CHAR:
return charBuffer.arrayOffset();
case INT:
return intBuffer.arrayOffset();
}
throw new UnsupportedOperationException("Not reached");
}
byte[] byteArray() {
assert type == Type.BYTE;
return byteBuffer.array();
}
char[] charArray() {
assert type == Type.CHAR;
return charBuffer.array();
}
int[] intArray() {
assert type == Type.INT;
return intBuffer.array();
}
public static Builder builder(int initialBufferSize) {
return new Builder(initialBufferSize);
}
public static class Builder {
private Type type;
private ByteBuffer byteBuffer;
private CharBuffer charBuffer;
private IntBuffer intBuffer;
private int prevHighSurrogate;
private Builder(int initialBufferSize) {
type = Type.BYTE;
byteBuffer = ByteBuffer.allocate(initialBufferSize);
charBuffer = null;
intBuffer = null;
prevHighSurrogate = -1;
}
Type getType() {
return type;
}
ByteBuffer getByteBuffer() {
return byteBuffer;
}
CharBuffer getCharBuffer() {
return charBuffer;
}
IntBuffer getIntBuffer() {
return intBuffer;
}
public CodePointBuffer build() {
switch (type) {
case BYTE:
byteBuffer.flip();
break;
case CHAR:
charBuffer.flip();
break;
case INT:
intBuffer.flip();
break;
}
return new CodePointBuffer(type, byteBuffer, charBuffer, intBuffer);
}
private static int roundUpToNextPowerOfTwo(int i) {
int nextPowerOfTwo = 32 - Integer.numberOfLeadingZeros(i - 1);
return (int) Math.pow(2, nextPowerOfTwo);
}
public void ensureRemaining(int remainingNeeded) {
switch (type) {
case BYTE:
if (byteBuffer.remaining() < remainingNeeded) {
int newCapacity = roundUpToNextPowerOfTwo(byteBuffer.capacity() + remainingNeeded);
ByteBuffer newBuffer = ByteBuffer.allocate(newCapacity);
byteBuffer.flip();
newBuffer.put(byteBuffer);
byteBuffer = newBuffer;
}
break;
case CHAR:
if (charBuffer.remaining() < remainingNeeded) {
int newCapacity = roundUpToNextPowerOfTwo(charBuffer.capacity() + remainingNeeded);
CharBuffer newBuffer = CharBuffer.allocate(newCapacity);
charBuffer.flip();
newBuffer.put(charBuffer);
charBuffer = newBuffer;
}
break;
case INT:
if (intBuffer.remaining() < remainingNeeded) {
int newCapacity = roundUpToNextPowerOfTwo(intBuffer.capacity() + remainingNeeded);
IntBuffer newBuffer = IntBuffer.allocate(newCapacity);
intBuffer.flip();
newBuffer.put(intBuffer);
intBuffer = newBuffer;
}
break;
}
}
public void append(CharBuffer utf16In) {
ensureRemaining(utf16In.remaining());
if (utf16In.hasArray()) {
appendArray(utf16In);
} else {
// TODO
throw new UnsupportedOperationException("TODO");
}
}
private void appendArray(CharBuffer utf16In) {
assert utf16In.hasArray();
switch (type) {
case BYTE:
appendArrayByte(utf16In);
break;
case CHAR:
appendArrayChar(utf16In);
break;
case INT:
appendArrayInt(utf16In);
break;
}
}
private void appendArrayByte(CharBuffer utf16In) {
assert prevHighSurrogate == -1;
char[] in = utf16In.array();
int inOffset = utf16In.arrayOffset() + utf16In.position();
int inLimit = utf16In.arrayOffset() + utf16In.limit();
byte[] outByte = byteBuffer.array();
int outOffset = byteBuffer.arrayOffset() + byteBuffer.position();
while (inOffset < inLimit) {
char c = in[inOffset];
if (c <= 0xFF) {
outByte[outOffset] = (byte)(c & 0xFF);
} else {
utf16In.position(inOffset - utf16In.arrayOffset());
byteBuffer.position(outOffset - byteBuffer.arrayOffset());
if (!Character.isHighSurrogate(c)) {
byteToCharBuffer(utf16In.remaining());
appendArrayChar(utf16In);
return;
} else {
byteToIntBuffer(utf16In.remaining());
appendArrayInt(utf16In);
return;
}
}
inOffset++;
outOffset++;
}
utf16In.position(inOffset - utf16In.arrayOffset());
byteBuffer.position(outOffset - byteBuffer.arrayOffset());
}
private void appendArrayChar(CharBuffer utf16In) {
assert prevHighSurrogate == -1;
char[] in = utf16In.array();
int inOffset = utf16In.arrayOffset() + utf16In.position();
int inLimit = utf16In.arrayOffset() + utf16In.limit();
char[] outChar = charBuffer.array();
int outOffset = charBuffer.arrayOffset() + charBuffer.position();
while (inOffset < inLimit) {
char c = in[inOffset];
if (!Character.isHighSurrogate(c)) {
outChar[outOffset] = c;
} else {
utf16In.position(inOffset - utf16In.arrayOffset());
charBuffer.position(outOffset - charBuffer.arrayOffset());
charToIntBuffer(utf16In.remaining());
appendArrayInt(utf16In);
return;
}
inOffset++;
outOffset++;
}
utf16In.position(inOffset - utf16In.arrayOffset());
charBuffer.position(outOffset - charBuffer.arrayOffset());
}
private void appendArrayInt(CharBuffer utf16In) {
char[] in = utf16In.array();
int inOffset = utf16In.arrayOffset() + utf16In.position();
int inLimit = utf16In.arrayOffset() + utf16In.limit();
int[] outInt = intBuffer.array();
int outOffset = intBuffer.arrayOffset() + intBuffer.position();
while (inOffset < inLimit) {
char c = in[inOffset];
inOffset++;
if (prevHighSurrogate != -1) {
if (Character.isLowSurrogate(c)) {
outInt[outOffset] = Character.toCodePoint((char) prevHighSurrogate, c);
outOffset++;
prevHighSurrogate = -1;
} else {
// Dangling high surrogate
outInt[outOffset] = prevHighSurrogate;
outOffset++;
if (Character.isHighSurrogate(c)) {
prevHighSurrogate = c & 0xFFFF;
} else {
outInt[outOffset] = c & 0xFFFF;
outOffset++;
prevHighSurrogate = -1;
}
}
} else if (Character.isHighSurrogate(c)) {
prevHighSurrogate = c & 0xFFFF;
} else {
outInt[outOffset] = c & 0xFFFF;
outOffset++;
}
}
if (prevHighSurrogate != -1) {
// Dangling high surrogate
outInt[outOffset] = prevHighSurrogate & 0xFFFF;
outOffset++;
}
utf16In.position(inOffset - utf16In.arrayOffset());
intBuffer.position(outOffset - intBuffer.arrayOffset());
}
private void byteToCharBuffer(int toAppend) {
byteBuffer.flip();
// CharBuffers hold twice as much per unit as ByteBuffers, so start with half the capacity.
CharBuffer newBuffer = CharBuffer.allocate(Math.max(byteBuffer.remaining() + toAppend, byteBuffer.capacity() / 2));
while (byteBuffer.hasRemaining()) {
newBuffer.put((char) (byteBuffer.get() & 0xFF));
}
type = Type.CHAR;
byteBuffer = null;
charBuffer = newBuffer;
}
private void byteToIntBuffer(int toAppend) {
byteBuffer.flip();
// IntBuffers hold four times as much per unit as ByteBuffers, so start with one quarter the capacity.
IntBuffer newBuffer = IntBuffer.allocate(Math.max(byteBuffer.remaining() + toAppend, byteBuffer.capacity() / 4));
while (byteBuffer.hasRemaining()) {
newBuffer.put(byteBuffer.get() & 0xFF);
}
type = Type.INT;
byteBuffer = null;
intBuffer = newBuffer;
}
private void charToIntBuffer(int toAppend) {
charBuffer.flip();
// IntBuffers hold two times as much per unit as ByteBuffers, so start with one half the capacity.
IntBuffer newBuffer = IntBuffer.allocate(Math.max(charBuffer.remaining() + toAppend, charBuffer.capacity() / 2));
while (charBuffer.hasRemaining()) {
newBuffer.put(charBuffer.get() & 0xFFFF);
}
type = Type.INT;
charBuffer = null;
intBuffer = newBuffer;
}
}
}