/*
* Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package java.nio.charset;
import java.lang.ref.
WeakReference;
import java.nio.*;
import java.util.
Map;
import java.util.
HashMap;
/**
* A description of the result state of a coder.
*
* <p> A charset coder, that is, either a decoder or an encoder, consumes bytes
* (or characters) from an input buffer, translates them, and writes the
* resulting characters (or bytes) to an output buffer. A coding process
* terminates for one of four categories of reasons, which are described by
* instances of this class:
*
* <ul>
*
* <li><p> <i>Underflow</i> is reported when there is no more input to be
* processed, or there is insufficient input and additional input is
* required. This condition is represented by the unique result object
* {@link #UNDERFLOW}, whose {@link #isUnderflow() isUnderflow} method
* returns <tt>true</tt>. </p></li>
*
* <li><p> <i>Overflow</i> is reported when there is insufficient room
* remaining in the output buffer. This condition is represented by the
* unique result object {@link #OVERFLOW}, whose {@link #isOverflow()
* isOverflow} method returns <tt>true</tt>. </p></li>
*
* <li><p> A <i>malformed-input error</i> is reported when a sequence of
* input units is not well-formed. Such errors are described by instances of
* this class whose {@link #isMalformed() isMalformed} method returns
* <tt>true</tt> and whose {@link #length() length} method returns the length
* of the malformed sequence. There is one unique instance of this class for
* all malformed-input errors of a given length. </p></li>
*
* <li><p> An <i>unmappable-character error</i> is reported when a sequence
* of input units denotes a character that cannot be represented in the
* output charset. Such errors are described by instances of this class
* whose {@link #isUnmappable() isUnmappable} method returns <tt>true</tt> and
* whose {@link #length() length} method returns the length of the input
* sequence denoting the unmappable character. There is one unique instance
* of this class for all unmappable-character errors of a given length.
* </p></li>
*
* </ul>
*
* <p> For convenience, the {@link #isError() isError} method returns <tt>true</tt>
* for result objects that describe malformed-input and unmappable-character
* errors but <tt>false</tt> for those that describe underflow or overflow
* conditions. </p>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*/
public class
CoderResult {
private static final int
CR_UNDERFLOW = 0;
private static final int
CR_OVERFLOW = 1;
private static final int
CR_ERROR_MIN = 2;
private static final int
CR_MALFORMED = 2;
private static final int
CR_UNMAPPABLE = 3;
private static final
String[]
names
= { "UNDERFLOW", "OVERFLOW", "MALFORMED", "UNMAPPABLE" };
private final int
type;
private final int
length;
private
CoderResult(int
type, int
length) {
this.
type =
type;
this.
length =
length;
}
/**
* Returns a string describing this coder result.
*
* @return A descriptive string
*/
public
String toString() {
String nm =
names[
type];
return
isError() ?
nm + "[" +
length + "]" :
nm;
}
/**
* Tells whether or not this object describes an underflow condition.
*
* @return <tt>true</tt> if, and only if, this object denotes underflow
*/
public boolean
isUnderflow() {
return (
type ==
CR_UNDERFLOW);
}
/**
* Tells whether or not this object describes an overflow condition.
*
* @return <tt>true</tt> if, and only if, this object denotes overflow
*/
public boolean
isOverflow() {
return (
type ==
CR_OVERFLOW);
}
/**
* Tells whether or not this object describes an error condition.
*
* @return <tt>true</tt> if, and only if, this object denotes either a
* malformed-input error or an unmappable-character error
*/
public boolean
isError() {
return (
type >=
CR_ERROR_MIN);
}
/**
* Tells whether or not this object describes a malformed-input error.
*
* @return <tt>true</tt> if, and only if, this object denotes a
* malformed-input error
*/
public boolean
isMalformed() {
return (
type ==
CR_MALFORMED);
}
/**
* Tells whether or not this object describes an unmappable-character
* error.
*
* @return <tt>true</tt> if, and only if, this object denotes an
* unmappable-character error
*/
public boolean
isUnmappable() {
return (
type ==
CR_UNMAPPABLE);
}
/**
* Returns the length of the erroneous input described by this
* object <i>(optional operation)</i>.
*
* @return The length of the erroneous input, a positive integer
*
* @throws UnsupportedOperationException
* If this object does not describe an error condition, that is,
* if the {@link #isError() isError} does not return <tt>true</tt>
*/
public int
length() {
if (!
isError())
throw new
UnsupportedOperationException();
return
length;
}
/**
* Result object indicating underflow, meaning that either the input buffer
* has been completely consumed or, if the input buffer is not yet empty,
* that additional input is required.
*/
public static final
CoderResult UNDERFLOW
= new
CoderResult(
CR_UNDERFLOW, 0);
/**
* Result object indicating overflow, meaning that there is insufficient
* room in the output buffer.
*/
public static final
CoderResult OVERFLOW
= new
CoderResult(
CR_OVERFLOW, 0);
private static abstract class
Cache {
private
Map<
Integer,
WeakReference<
CoderResult>>
cache = null;
protected abstract
CoderResult create(int
len);
private synchronized
CoderResult get(int
len) {
if (
len <= 0)
throw new
IllegalArgumentException("Non-positive length");
Integer k = new
Integer(
len);
WeakReference<
CoderResult>
w;
CoderResult e = null;
if (
cache == null) {
cache = new
HashMap<
Integer,
WeakReference<
CoderResult>>();
} else if ((
w =
cache.
get(
k)) != null) {
e =
w.
get();
}
if (
e == null) {
e =
create(
len);
cache.
put(
k, new
WeakReference<
CoderResult>(
e));
}
return
e;
}
}
private static
Cache malformedCache
= new
Cache() {
public
CoderResult create(int
len) {
return new
CoderResult(
CR_MALFORMED,
len);
}};
/**
* Static factory method that returns the unique object describing a
* malformed-input error of the given length.
*
* @param length
* The given length
*
* @return The requested coder-result object
*/
public static
CoderResult malformedForLength(int
length) {
return
malformedCache.
get(
length);
}
private static
Cache unmappableCache
= new
Cache() {
public
CoderResult create(int
len) {
return new
CoderResult(
CR_UNMAPPABLE,
len);
}};
/**
* Static factory method that returns the unique result object describing
* an unmappable-character error of the given length.
*
* @param length
* The given length
*
* @return The requested coder-result object
*/
public static
CoderResult unmappableForLength(int
length) {
return
unmappableCache.
get(
length);
}
/**
* Throws an exception appropriate to the result described by this object.
*
* @throws BufferUnderflowException
* If this object is {@link #UNDERFLOW}
*
* @throws BufferOverflowException
* If this object is {@link #OVERFLOW}
*
* @throws MalformedInputException
* If this object represents a malformed-input error; the
* exception's length value will be that of this object
*
* @throws UnmappableCharacterException
* If this object represents an unmappable-character error; the
* exceptions length value will be that of this object
*/
public void
throwException()
throws
CharacterCodingException
{
switch (
type) {
case
CR_UNDERFLOW: throw new
BufferUnderflowException();
case
CR_OVERFLOW: throw new
BufferOverflowException();
case
CR_MALFORMED: throw new
MalformedInputException(
length);
case
CR_UNMAPPABLE: throw new
UnmappableCharacterException(
length);
default:
assert false;
}
}
}