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/*******************************************************************************
* Copyright (c) 2009 Luaj.org. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
******************************************************************************/
package org.luaj.vm2;
/**
* String buffer for use in string library methods, optimized for production
* of StrValue instances.
*
* The buffer can begin initially as a wrapped {@link LuaValue}
* and only when concatenation actually occurs are the bytes first copied.
*
* To convert back to a {@link LuaValue} again,
* the function {@link Buffer#value()} is used.
* @see LuaValue
* @see LuaValue#buffer()
* @see LuaString
*/
public final class Buffer {
/** Default capacity for a buffer: 64 */
private static final int DEFAULT_CAPACITY = 64;
/** Shared static array with no bytes */
private static final byte[] NOBYTES = {};
/** Bytes in this buffer */
private byte[] bytes;
/** Length of this buffer */
private int length;
/** Offset into the byte array */
private int offset;
/** Value of this buffer, when not represented in bytes */
private LuaValue value;
/**
* Create buffer with default capacity
* @see #DEFAULT_CAPACITY
*/
public Buffer() {
this(DEFAULT_CAPACITY);
}
/**
* Create buffer with specified initial capacity
* @param initialCapacity the initial capacity
*/
public Buffer( int initialCapacity ) {
bytes = new byte[ initialCapacity ];
length = 0;
offset = 0;
value = null;
}
/**
* Create buffer with specified initial value
* @param value the initial value
*/
public Buffer(LuaValue value) {
bytes = NOBYTES;
length = offset = 0;
this.value = value;
}
/**
* Get buffer contents as a {@link LuaValue}
* @return value as a {@link LuaValue}, converting as necessary
*/
public LuaValue value() {
return value != null? value: this.tostring();
}
/**
* Set buffer contents as a {@link LuaValue}
* @param value value to set
*/
public Buffer setvalue(LuaValue value) {
bytes = NOBYTES;
offset = length = 0;
this.value = value;
return this;
}
/**
* Convert the buffer to a {@link LuaString}
* @return the value as a {@link LuaString}
*/
public final LuaString tostring() {
realloc( length, 0 );
return LuaString.valueOf( bytes, offset, length );
}
/**
* Convert the buffer to a Java String
* @return the value as a Java String
*/
public String tojstring() {
return value().tojstring();
}
/**
* Convert the buffer to a Java String
* @return the value as a Java String
*/
public String toString() {
return tojstring();
}
/**
* Append a single byte to the buffer.
* @return {@code this} to allow call chaining
*/
public final Buffer append( byte b ) {
makeroom( 0, 1 );
bytes[ offset + length++ ] = b;
return this;
}
/**
* Append a {@link LuaValue} to the buffer.
* @return {@code this} to allow call chaining
*/
public final Buffer append( LuaValue val ) {
append( val.strvalue() );
return this;
}
/**
* Append a {@link LuaString} to the buffer.
* @return {@code this} to allow call chaining
*/
public final Buffer append( LuaString str ) {
final int n = str.m_length;
makeroom( 0, n );
str.copyInto( 0, bytes, offset + length, n );
length += n;
return this;
}
/**
* Append a Java String to the buffer.
* The Java string will be converted to bytes using the UTF8 encoding.
* @return {@code this} to allow call chaining
* @see LuaString#encodeToUtf8(char[], int, byte[], int)
*/
public final Buffer append( String str ) {
char[] c = str.toCharArray();
final int n = LuaString.lengthAsUtf8( c );
makeroom( 0, n );
LuaString.encodeToUtf8( c, c.length, bytes, offset + length );
length += n;
return this;
}
/** Concatenate this buffer onto a {@link LuaValue}
* @param lhs the left-hand-side value onto which we are concatenating {@code this}
* @return {@link Buffer} for use in call chaining.
*/
public Buffer concatTo(LuaValue lhs) {
return setvalue(lhs.concat(value()));
}
/** Concatenate this buffer onto a {@link LuaString}
* @param lhs the left-hand-side value onto which we are concatenating {@code this}
* @return {@link Buffer} for use in call chaining.
*/
public Buffer concatTo(LuaString lhs) {
return value!=null&&!value.isstring()? setvalue(lhs.concat(value)): prepend(lhs);
}
/** Concatenate this buffer onto a {@link LuaNumber}
*
* The {@link LuaNumber} will be converted to a string before concatenating.
* @param lhs the left-hand-side value onto which we are concatenating {@code this}
* @return {@link Buffer} for use in call chaining.
*/
public Buffer concatTo(LuaNumber lhs) {
return value!=null&&!value.isstring()? setvalue(lhs.concat(value)): prepend(lhs.strvalue());
}
/** Concatenate bytes from a {@link LuaString} onto the front of this buffer
* @param s the left-hand-side value which we will concatenate onto the front of {@code this}
* @return {@link Buffer} for use in call chaining.
*/
public Buffer prepend(LuaString s) {
int n = s.m_length;
makeroom( n, 0 );
System.arraycopy( s.m_bytes, s.m_offset, bytes, offset-n, n );
offset -= n;
length += n;
value = null;
return this;
}
/** Ensure there is enough room before and after the bytes.
* @param nbefore number of unused bytes which must precede the data after this completes
* @param nafter number of unused bytes which must follow the data after this completes
*/
public final void makeroom( int nbefore, int nafter ) {
if ( value != null ) {
LuaString s = value.strvalue();
value = null;
length = s.m_length;
offset = nbefore;
bytes = new byte[nbefore+length+nafter];
System.arraycopy(s.m_bytes, s.m_offset, bytes, offset, length);
} else if ( offset+length+nafter > bytes.length || offset