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package org.codehaus.jackson.io;
import java.io.*;
/**
* Since JDK does not come with UTF-32/UCS-4, let's implement a simple
* decoder to use.
*/
public final class UTF32Reader
extends BaseReader
{
final boolean mBigEndian;
/**
* Although input is fine with full Unicode set, Java still uses
* 16-bit chars, so we may have to split high-order chars into
* surrogate pairs.
*/
char mSurrogate = NULL_CHAR;
/**
* Total read character count; used for error reporting purposes
*/
int mCharCount = 0;
/**
* Total read byte count; used for error reporting purposes
*/
int mByteCount = 0;
/*
////////////////////////////////////////
// Life-cycle
////////////////////////////////////////
*/
public UTF32Reader(IOContext ctxt,
InputStream in, byte[] buf, int ptr, int len,
boolean isBigEndian)
{
super(ctxt, in, buf, ptr, len);
mBigEndian = isBigEndian;
}
/*
////////////////////////////////////////
// Public API
////////////////////////////////////////
*/
public int read(char[] cbuf, int start, int len)
throws IOException
{
// Already EOF?
if (mBuffer == null) {
return -1;
}
if (len < 1) {
return len;
}
// Let's then ensure there's enough room...
if (start < 0 || (start+len) > cbuf.length) {
reportBounds(cbuf, start, len);
}
len += start;
int outPtr = start;
// Ok, first; do we have a surrogate from last round?
if (mSurrogate != NULL_CHAR) {
cbuf[outPtr++] = mSurrogate;
mSurrogate = NULL_CHAR;
// No need to load more, already got one char
} else {
/* Note: we'll try to avoid blocking as much as possible. As a
* result, we only need to get 4 bytes for a full char.
*/
int left = (mLength - mPtr);
if (left < 4) {
if (!loadMore(left)) { // (legal) EOF?
return -1;
}
}
}
main_loop:
while (outPtr < len) {
int ptr = mPtr;
int ch;
if (mBigEndian) {
ch = (mBuffer[ptr] << 24) | ((mBuffer[ptr+1] & 0xFF) << 16)
| ((mBuffer[ptr+2] & 0xFF) << 8) | (mBuffer[ptr+3] & 0xFF);
} else {
ch = (mBuffer[ptr] & 0xFF) | ((mBuffer[ptr+1] & 0xFF) << 8)
| ((mBuffer[ptr+2] & 0xFF) << 16) | (mBuffer[ptr+3] << 24);
}
mPtr += 4;
// Does it need to be split to surrogates?
// (also, we can and need to verify illegal chars)
if (ch > 0xFFFF) { // need to split into surrogates?
if (ch > LAST_VALID_UNICODE_CHAR) {
reportInvalid(ch, outPtr-start,
"(above "+Integer.toHexString(LAST_VALID_UNICODE_CHAR)+") ");
}
ch -= 0x10000; // to normalize it starting with 0x0
cbuf[outPtr++] = (char) (0xD800 + (ch >> 10));
// hmmh. can this ever be 0? (not legal, at least?)
ch = (0xDC00 | (ch & 0x03FF));
// Room for second part?
if (outPtr >= len) { // nope
mSurrogate = (char) ch;
break main_loop;
}
}
cbuf[outPtr++] = (char) ch;
if (mPtr >= mLength) {
break main_loop;
}
}
len = outPtr - start;
mCharCount += len;
return len;
}
/*
////////////////////////////////////////
// Internal methods
////////////////////////////////////////
*/
private void reportUnexpectedEOF(int gotBytes, int needed)
throws IOException
{
int bytePos = mByteCount + gotBytes;
int charPos = mCharCount;
throw new CharConversionException("Unexpected EOF in the middle of a 4-byte UTF-32 char: got "
+gotBytes+", needed "+needed
+", at char #"+charPos+", byte #"+bytePos+")");
}
private void reportInvalid(int value, int offset, String msg)
throws IOException
{
int bytePos = mByteCount + mPtr - 1;
int charPos = mCharCount + offset;
throw new CharConversionException("Invalid UTF-32 character 0x"
+Integer.toHexString(value)
+msg+" at char #"+charPos+", byte #"+bytePos+")");
}
/**
* @param available Number of "unused" bytes in the input buffer
*
* @return True, if enough bytes were read to allow decoding of at least
* one full character; false if EOF was encountered instead.
*/
private boolean loadMore(int available)
throws IOException
{
mByteCount += (mLength - available);
// Bytes that need to be moved to the beginning of buffer?
if (available > 0) {
if (mPtr > 0) {
for (int i = 0; i < available; ++i) {
mBuffer[i] = mBuffer[mPtr+i];
}
mPtr = 0;
}
mLength = available;
} else {
/* Ok; here we can actually reasonably expect an EOF,
* so let's do a separate read right away:
*/
mPtr = 0;
int count = mIn.read(mBuffer);
if (count < 1) {
mLength = 0;
if (count < 0) { // -1
freeBuffers(); // to help GC?
return false;
}
// 0 count is no good; let's err out
reportStrangeStream();
}
mLength = count;
}
/* Need at least 4 bytes; if we don't get that many, it's an
* error.
*/
while (mLength < 4) {
int count = mIn.read(mBuffer, mLength, mBuffer.length - mLength);
if (count < 1) {
if (count < 0) { // -1, EOF... no good!
freeBuffers(); // to help GC?
reportUnexpectedEOF(mLength, 4);
}
// 0 count is no good; let's err out
reportStrangeStream();
}
mLength += count;
}
return true;
}
}
