8230531: API Doc for CharsetEncoder.maxBytesPerChar() should be clearer about BOMs
Reviewed-by: martin, alanb
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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#warn This file is preprocessed before being compiled
package java.nio.charset;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.BufferOverflowException;
import java.nio.BufferUnderflowException;
import java.lang.ref.WeakReference;
import java.nio.charset.CoderMalfunctionError; // javadoc
import java.util.Arrays;
/**
* An engine that can transform a sequence of $itypesPhrase$ into a sequence of
* $otypesPhrase$.
*
* <a id="steps"></a>
*
* <p> The input $itype$ sequence is provided in a $itype$ buffer or a series
* of such buffers. The output $otype$ sequence is written to a $otype$ buffer
* or a series of such buffers. $A$ $coder$ should always be used by making
* the following sequence of method invocations, hereinafter referred to as $a$
* <i>$coding$ operation</i>:
*
* <ol>
*
* <li><p> Reset the $coder$ via the {@link #reset reset} method, unless it
* has not been used before; </p></li>
*
* <li><p> Invoke the {@link #$code$ $code$} method zero or more times, as
* long as additional input may be available, passing {@code false} for the
* {@code endOfInput} argument and filling the input buffer and flushing the
* output buffer between invocations; </p></li>
*
* <li><p> Invoke the {@link #$code$ $code$} method one final time, passing
* {@code true} for the {@code endOfInput} argument; and then </p></li>
*
* <li><p> Invoke the {@link #flush flush} method so that the $coder$ can
* flush any internal state to the output buffer. </p></li>
*
* </ol>
*
* Each invocation of the {@link #$code$ $code$} method will $code$ as many
* $itype$s as possible from the input buffer, writing the resulting $otype$s
* to the output buffer. The {@link #$code$ $code$} method returns when more
* input is required, when there is not enough room in the output buffer, or
* when $a$ $coding$ error has occurred. In each case a {@link CoderResult}
* object is returned to describe the reason for termination. An invoker can
* examine this object and fill the input buffer, flush the output buffer, or
* attempt to recover from $a$ $coding$ error, as appropriate, and try again.
*
* <a id="ce"></a>
*
* <p> There are two general types of $coding$ errors. If the input $itype$
* sequence is $notLegal$ then the input is considered <i>malformed</i>. If
* the input $itype$ sequence is legal but cannot be mapped to a valid
* $outSequence$ then an <i>unmappable character</i> has been encountered.
*
* <a id="cae"></a>
*
* <p> How $a$ $coding$ error is handled depends upon the action requested for
* that type of error, which is described by an instance of the {@link
* CodingErrorAction} class. The possible error actions are to {@linkplain
* CodingErrorAction#IGNORE ignore} the erroneous input, {@linkplain
* CodingErrorAction#REPORT report} the error to the invoker via
* the returned {@link CoderResult} object, or {@linkplain CodingErrorAction#REPLACE
* replace} the erroneous input with the current value of the
* replacement $replTypeName$. The replacement
*
#if[encoder]
* is initially set to the $coder$'s default replacement, which often
* (but not always) has the initial value $defaultReplName$;
#end[encoder]
#if[decoder]
* has the initial value $defaultReplName$;
#end[decoder]
*
* its value may be changed via the {@link #replaceWith($replFQType$)
* replaceWith} method.
*
* <p> The default action for malformed-input and unmappable-character errors
* is to {@linkplain CodingErrorAction#REPORT report} them. The
* malformed-input error action may be changed via the {@link
* #onMalformedInput(CodingErrorAction) onMalformedInput} method; the
* unmappable-character action may be changed via the {@link
* #onUnmappableCharacter(CodingErrorAction) onUnmappableCharacter} method.
*
* <p> This class is designed to handle many of the details of the $coding$
* process, including the implementation of error actions. $A$ $coder$ for a
* specific charset, which is a concrete subclass of this class, need only
* implement the abstract {@link #$code$Loop $code$Loop} method, which
* encapsulates the basic $coding$ loop. A subclass that maintains internal
* state should, additionally, override the {@link #implFlush implFlush} and
* {@link #implReset implReset} methods.
*
* <p> Instances of this class are not safe for use by multiple concurrent
* threads. </p>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*
* @see ByteBuffer
* @see CharBuffer
* @see Charset
* @see Charset$OtherCoder$
*/
public abstract class Charset$Coder$ {
private final Charset charset;
private final float average$ItypesPerOtype$;
private final float max$ItypesPerOtype$;
private $replType$ replacement;
private CodingErrorAction malformedInputAction
= CodingErrorAction.REPORT;
private CodingErrorAction unmappableCharacterAction
= CodingErrorAction.REPORT;
// Internal states
//
private static final int ST_RESET = 0;
private static final int ST_CODING = 1;
private static final int ST_END = 2;
private static final int ST_FLUSHED = 3;
private int state = ST_RESET;
private static String stateNames[]
= { "RESET", "CODING", "CODING_END", "FLUSHED" };
/**
* Initializes a new $coder$. The new $coder$ will have the given
* $otypes-per-itype$ and replacement values.
*
* @param cs
* The charset that created this $coder$
*
* @param average$ItypesPerOtype$
* A positive float value indicating the expected number of
* $otype$s that will be produced for each input $itype$
*
* @param max$ItypesPerOtype$
* A positive float value indicating the maximum number of
* $otype$s that will be produced for each input $itype$
*
* @param replacement
* The initial replacement; must not be {@code null}, must have
* non-zero length, must not be longer than max$ItypesPerOtype$,
* and must be {@linkplain #isLegalReplacement legal}
*
* @throws IllegalArgumentException
* If the preconditions on the parameters do not hold
*/
{#if[encoder]?protected:private}
Charset$Coder$(Charset cs,
float average$ItypesPerOtype$,
float max$ItypesPerOtype$,
$replType$ replacement)
{
this.charset = cs;
// Use !(a > 0.0f) rather than (a <= 0.0f) to exclude NaN values
if (!(average$ItypesPerOtype$ > 0.0f))
throw new IllegalArgumentException("Non-positive "
+ "average$ItypesPerOtype$");
// Use !(a > 0.0f) rather than (a <= 0.0f) to exclude NaN values
if (!(max$ItypesPerOtype$ > 0.0f))
throw new IllegalArgumentException("Non-positive "
+ "max$ItypesPerOtype$");
if (average$ItypesPerOtype$ > max$ItypesPerOtype$)
throw new IllegalArgumentException("average$ItypesPerOtype$"
+ " exceeds "
+ "max$ItypesPerOtype$");
this.replacement = replacement;
this.average$ItypesPerOtype$ = average$ItypesPerOtype$;
this.max$ItypesPerOtype$ = max$ItypesPerOtype$;
replaceWith(replacement);
}
/**
* Initializes a new $coder$. The new $coder$ will have the given
* $otypes-per-itype$ values and its replacement will be the
* $replTypeName$ $defaultReplName$.
*
* @param cs
* The charset that created this $coder$
*
* @param average$ItypesPerOtype$
* A positive float value indicating the expected number of
* $otype$s that will be produced for each input $itype$
*
* @param max$ItypesPerOtype$
* A positive float value indicating the maximum number of
* $otype$s that will be produced for each input $itype$
*
* @throws IllegalArgumentException
* If the preconditions on the parameters do not hold
*/
protected Charset$Coder$(Charset cs,
float average$ItypesPerOtype$,
float max$ItypesPerOtype$)
{
this(cs,
average$ItypesPerOtype$, max$ItypesPerOtype$,
$defaultRepl$);
}
/**
* Returns the charset that created this $coder$.
*
* @return This $coder$'s charset
*/
public final Charset charset() {
return charset;
}
/**
* Returns this $coder$'s replacement value.
*
* @return This $coder$'s current replacement,
* which is never {@code null} and is never empty
*/
public final $replType$ replacement() {
#if[decoder]
return replacement;
#end[decoder]
#if[encoder]
return Arrays.copyOf(replacement, replacement.$replLength$);
#end[encoder]
}
/**
* Changes this $coder$'s replacement value.
*
* <p> This method invokes the {@link #implReplaceWith implReplaceWith}
* method, passing the new replacement, after checking that the new
* replacement is acceptable. </p>
*
* @param newReplacement The new replacement; must not be
* {@code null}, must have non-zero length,
#if[decoder]
* and must not be longer than the value returned by the
* {@link #max$ItypesPerOtype$() max$ItypesPerOtype$} method
#end[decoder]
#if[encoder]
* must not be longer than the value returned by the
* {@link #max$ItypesPerOtype$() max$ItypesPerOtype$} method, and
* must be {@link #isLegalReplacement legal}
#end[encoder]
*
* @return This $coder$
*
* @throws IllegalArgumentException
* If the preconditions on the parameter do not hold
*/
public final Charset$Coder$ replaceWith($replType$ newReplacement) {
if (newReplacement == null)
throw new IllegalArgumentException("Null replacement");
int len = newReplacement.$replLength$;
if (len == 0)
throw new IllegalArgumentException("Empty replacement");
if (len > max$ItypesPerOtype$)
throw new IllegalArgumentException("Replacement too long");
#if[decoder]
this.replacement = newReplacement;
#end[decoder]
#if[encoder]
if (!isLegalReplacement(newReplacement))
throw new IllegalArgumentException("Illegal replacement");
this.replacement = Arrays.copyOf(newReplacement, newReplacement.$replLength$);
#end[encoder]
implReplaceWith(this.replacement);
return this;
}
/**
* Reports a change to this $coder$'s replacement value.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by $coder$s that require notification of changes to
* the replacement. </p>
*
* @param newReplacement The replacement value
*/
protected void implReplaceWith($replType$ newReplacement) {
}
#if[encoder]
private WeakReference<CharsetDecoder> cachedDecoder = null;
/**
* Tells whether or not the given byte array is a legal replacement value
* for this encoder.
*
* <p> A replacement is legal if, and only if, it is a legal sequence of
* bytes in this encoder's charset; that is, it must be possible to decode
* the replacement into one or more sixteen-bit Unicode characters.
*
* <p> The default implementation of this method is not very efficient; it
* should generally be overridden to improve performance. </p>
*
* @param repl The byte array to be tested
*
* @return {@code true} if, and only if, the given byte array
* is a legal replacement value for this encoder
*/
public boolean isLegalReplacement(byte[] repl) {
WeakReference<CharsetDecoder> wr = cachedDecoder;
CharsetDecoder dec = null;
if ((wr == null) || ((dec = wr.get()) == null)) {
dec = charset().newDecoder();
dec.onMalformedInput(CodingErrorAction.REPORT);
dec.onUnmappableCharacter(CodingErrorAction.REPORT);
cachedDecoder = new WeakReference<CharsetDecoder>(dec);
} else {
dec.reset();
}
ByteBuffer bb = ByteBuffer.wrap(repl);
CharBuffer cb = CharBuffer.allocate((int)(bb.remaining()
* dec.maxCharsPerByte()));
CoderResult cr = dec.decode(bb, cb, true);
return !cr.isError();
}
#end[encoder]
/**
* Returns this $coder$'s current action for malformed-input errors.
*
* @return The current malformed-input action, which is never {@code null}
*/
public CodingErrorAction malformedInputAction() {
return malformedInputAction;
}
/**
* Changes this $coder$'s action for malformed-input errors.
*
* <p> This method invokes the {@link #implOnMalformedInput
* implOnMalformedInput} method, passing the new action. </p>
*
* @param newAction The new action; must not be {@code null}
*
* @return This $coder$
*
* @throws IllegalArgumentException
* If the precondition on the parameter does not hold
*/
public final Charset$Coder$ onMalformedInput(CodingErrorAction newAction) {
if (newAction == null)
throw new IllegalArgumentException("Null action");
malformedInputAction = newAction;
implOnMalformedInput(newAction);
return this;
}
/**
* Reports a change to this $coder$'s malformed-input action.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by $coder$s that require notification of changes to
* the malformed-input action. </p>
*
* @param newAction The new action
*/
protected void implOnMalformedInput(CodingErrorAction newAction) { }
/**
* Returns this $coder$'s current action for unmappable-character errors.
*
* @return The current unmappable-character action, which is never
* {@code null}
*/
public CodingErrorAction unmappableCharacterAction() {
return unmappableCharacterAction;
}
/**
* Changes this $coder$'s action for unmappable-character errors.
*
* <p> This method invokes the {@link #implOnUnmappableCharacter
* implOnUnmappableCharacter} method, passing the new action. </p>
*
* @param newAction The new action; must not be {@code null}
*
* @return This $coder$
*
* @throws IllegalArgumentException
* If the precondition on the parameter does not hold
*/
public final Charset$Coder$ onUnmappableCharacter(CodingErrorAction
newAction)
{
if (newAction == null)
throw new IllegalArgumentException("Null action");
unmappableCharacterAction = newAction;
implOnUnmappableCharacter(newAction);
return this;
}
/**
* Reports a change to this $coder$'s unmappable-character action.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by $coder$s that require notification of changes to
* the unmappable-character action. </p>
*
* @param newAction The new action
*/
protected void implOnUnmappableCharacter(CodingErrorAction newAction) { }
/**
* Returns the average number of $otype$s that will be produced for each
* $itype$ of input. This heuristic value may be used to estimate the size
* of the output buffer required for a given input sequence.
*
* @return The average number of $otype$s produced
* per $itype$ of input
*/
public final float average$ItypesPerOtype$() {
return average$ItypesPerOtype$;
}
/**
* Returns the maximum number of $otype$s that will be produced for each
* $itype$ of input. This value may be used to compute the worst-case size
* of the output buffer required for a given input sequence. This value
* accounts for any necessary content-independent prefix or suffix
#if[encoder]
* $otype$s, such as byte-order marks.
#end[encoder]
#if[decoder]
* $otype$s.
#end[decoder]
*
* @return The maximum number of $otype$s that will be produced per
* $itype$ of input
*/
public final float max$ItypesPerOtype$() {
return max$ItypesPerOtype$;
}
/**
* $Code$s as many $itype$s as possible from the given input buffer,
* writing the results to the given output buffer.
*
* <p> The buffers are read from, and written to, starting at their current
* positions. At most {@link Buffer#remaining in.remaining()} $itype$s
* will be read and at most {@link Buffer#remaining out.remaining()}
* $otype$s will be written. The buffers' positions will be advanced to
* reflect the $itype$s read and the $otype$s written, but their marks and
* limits will not be modified.
*
* <p> In addition to reading $itype$s from the input buffer and writing
* $otype$s to the output buffer, this method returns a {@link CoderResult}
* object to describe its reason for termination:
*
* <ul>
*
* <li><p> {@link CoderResult#UNDERFLOW} indicates that as much of the
* input buffer as possible has been $code$d. If there is no further
* input then the invoker can proceed to the next step of the
* <a href="#steps">$coding$ operation</a>. Otherwise this method
* should be invoked again with further input. </p></li>
*
* <li><p> {@link CoderResult#OVERFLOW} indicates that there is
* insufficient space in the output buffer to $code$ any more $itype$s.
* This method should be invoked again with an output buffer that has
* more {@linkplain Buffer#remaining remaining} $otype$s. This is
* typically done by draining any $code$d $otype$s from the output
* buffer. </p></li>
*
* <li><p> A {@linkplain CoderResult#malformedForLength
* malformed-input} result indicates that a malformed-input
* error has been detected. The malformed $itype$s begin at the input
* buffer's (possibly incremented) position; the number of malformed
* $itype$s may be determined by invoking the result object's {@link
* CoderResult#length() length} method. This case applies only if the
* {@linkplain #onMalformedInput malformed action} of this $coder$
* is {@link CodingErrorAction#REPORT}; otherwise the malformed input
* will be ignored or replaced, as requested. </p></li>
*
* <li><p> An {@linkplain CoderResult#unmappableForLength
* unmappable-character} result indicates that an
* unmappable-character error has been detected. The $itype$s that
* $code$ the unmappable character begin at the input buffer's (possibly
* incremented) position; the number of such $itype$s may be determined
* by invoking the result object's {@link CoderResult#length() length}
* method. This case applies only if the {@linkplain #onUnmappableCharacter
* unmappable action} of this $coder$ is {@link
* CodingErrorAction#REPORT}; otherwise the unmappable character will be
* ignored or replaced, as requested. </p></li>
*
* </ul>
*
* In any case, if this method is to be reinvoked in the same $coding$
* operation then care should be taken to preserve any $itype$s remaining
* in the input buffer so that they are available to the next invocation.
*
* <p> The {@code endOfInput} parameter advises this method as to whether
* the invoker can provide further input beyond that contained in the given
* input buffer. If there is a possibility of providing additional input
* then the invoker should pass {@code false} for this parameter; if there
* is no possibility of providing further input then the invoker should
* pass {@code true}. It is not erroneous, and in fact it is quite
* common, to pass {@code false} in one invocation and later discover that
* no further input was actually available. It is critical, however, that
* the final invocation of this method in a sequence of invocations always
* pass {@code true} so that any remaining un$code$d input will be treated
* as being malformed.
*
* <p> This method works by invoking the {@link #$code$Loop $code$Loop}
* method, interpreting its results, handling error conditions, and
* reinvoking it as necessary. </p>
*
*
* @param in
* The input $itype$ buffer
*
* @param out
* The output $otype$ buffer
*
* @param endOfInput
* {@code true} if, and only if, the invoker can provide no
* additional input $itype$s beyond those in the given buffer
*
* @return A coder-result object describing the reason for termination
*
* @throws IllegalStateException
* If $a$ $coding$ operation is already in progress and the previous
* step was an invocation neither of the {@link #reset reset}
* method, nor of this method with a value of {@code false} for
* the {@code endOfInput} parameter, nor of this method with a
* value of {@code true} for the {@code endOfInput} parameter
* but a return value indicating an incomplete $coding$ operation
*
* @throws CoderMalfunctionError
* If an invocation of the $code$Loop method threw
* an unexpected exception
*/
public final CoderResult $code$($Itype$Buffer in, $Otype$Buffer out,
boolean endOfInput)
{
int newState = endOfInput ? ST_END : ST_CODING;
if ((state != ST_RESET) && (state != ST_CODING)
&& !(endOfInput && (state == ST_END)))
throwIllegalStateException(state, newState);
state = newState;
for (;;) {
CoderResult cr;
try {
cr = $code$Loop(in, out);
} catch (BufferUnderflowException x) {
throw new CoderMalfunctionError(x);
} catch (BufferOverflowException x) {
throw new CoderMalfunctionError(x);
}
if (cr.isOverflow())
return cr;
if (cr.isUnderflow()) {
if (endOfInput && in.hasRemaining()) {
cr = CoderResult.malformedForLength(in.remaining());
// Fall through to malformed-input case
} else {
return cr;
}
}
CodingErrorAction action = null;
if (cr.isMalformed())
action = malformedInputAction;
else if (cr.isUnmappable())
action = unmappableCharacterAction;
else
assert false : cr.toString();
if (action == CodingErrorAction.REPORT)
return cr;
if (action == CodingErrorAction.REPLACE) {
if (out.remaining() < replacement.$replLength$)
return CoderResult.OVERFLOW;
out.put(replacement);
}
if ((action == CodingErrorAction.IGNORE)
|| (action == CodingErrorAction.REPLACE)) {
// Skip erroneous input either way
in.position(in.position() + cr.length());
continue;
}
assert false;
}
}
/**
* Flushes this $coder$.
*
* <p> Some $coder$s maintain internal state and may need to write some
* final $otype$s to the output buffer once the overall input sequence has
* been read.
*
* <p> Any additional output is written to the output buffer beginning at
* its current position. At most {@link Buffer#remaining out.remaining()}
* $otype$s will be written. The buffer's position will be advanced
* appropriately, but its mark and limit will not be modified.
*
* <p> If this method completes successfully then it returns {@link
* CoderResult#UNDERFLOW}. If there is insufficient room in the output
* buffer then it returns {@link CoderResult#OVERFLOW}. If this happens
* then this method must be invoked again, with an output buffer that has
* more room, in order to complete the current <a href="#steps">$coding$
* operation</a>.
*
* <p> If this $coder$ has already been flushed then invoking this method
* has no effect.
*
* <p> This method invokes the {@link #implFlush implFlush} method to
* perform the actual flushing operation. </p>
*
* @param out
* The output $otype$ buffer
*
* @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
* {@link CoderResult#OVERFLOW}
*
* @throws IllegalStateException
* If the previous step of the current $coding$ operation was an
* invocation neither of the {@link #flush flush} method nor of
* the three-argument {@link
* #$code$($Itype$Buffer,$Otype$Buffer,boolean) $code$} method
* with a value of {@code true} for the {@code endOfInput}
* parameter
*/
public final CoderResult flush($Otype$Buffer out) {
if (state == ST_END) {
CoderResult cr = implFlush(out);
if (cr.isUnderflow())
state = ST_FLUSHED;
return cr;
}
if (state != ST_FLUSHED)
throwIllegalStateException(state, ST_FLUSHED);
return CoderResult.UNDERFLOW; // Already flushed
}
/**
* Flushes this $coder$.
*
* <p> The default implementation of this method does nothing, and always
* returns {@link CoderResult#UNDERFLOW}. This method should be overridden
* by $coder$s that may need to write final $otype$s to the output buffer
* once the entire input sequence has been read. </p>
*
* @param out
* The output $otype$ buffer
*
* @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
* {@link CoderResult#OVERFLOW}
*/
protected CoderResult implFlush($Otype$Buffer out) {
return CoderResult.UNDERFLOW;
}
/**
* Resets this $coder$, clearing any internal state.
*
* <p> This method resets charset-independent state and also invokes the
* {@link #implReset() implReset} method in order to perform any
* charset-specific reset actions. </p>
*
* @return This $coder$
*
*/
public final Charset$Coder$ reset() {
implReset();
state = ST_RESET;
return this;
}
/**
* Resets this $coder$, clearing any charset-specific internal state.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by $coder$s that maintain internal state. </p>
*/
protected void implReset() { }
/**
* $Code$s one or more $itype$s into one or more $otype$s.
*
* <p> This method encapsulates the basic $coding$ loop, $coding$ as many
* $itype$s as possible until it either runs out of input, runs out of room
* in the output buffer, or encounters $a$ $coding$ error. This method is
* invoked by the {@link #$code$ $code$} method, which handles result
* interpretation and error recovery.
*
* <p> The buffers are read from, and written to, starting at their current
* positions. At most {@link Buffer#remaining in.remaining()} $itype$s
* will be read, and at most {@link Buffer#remaining out.remaining()}
* $otype$s will be written. The buffers' positions will be advanced to
* reflect the $itype$s read and the $otype$s written, but their marks and
* limits will not be modified.
*
* <p> This method returns a {@link CoderResult} object to describe its
* reason for termination, in the same manner as the {@link #$code$ $code$}
* method. Most implementations of this method will handle $coding$ errors
* by returning an appropriate result object for interpretation by the
* {@link #$code$ $code$} method. An optimized implementation may instead
* examine the relevant error action and implement that action itself.
*
* <p> An implementation of this method may perform arbitrary lookahead by
* returning {@link CoderResult#UNDERFLOW} until it receives sufficient
* input. </p>
*
* @param in
* The input $itype$ buffer
*
* @param out
* The output $otype$ buffer
*
* @return A coder-result object describing the reason for termination
*/
protected abstract CoderResult $code$Loop($Itype$Buffer in,
$Otype$Buffer out);
/**
* Convenience method that $code$s the remaining content of a single input
* $itype$ buffer into a newly-allocated $otype$ buffer.
*
* <p> This method implements an entire <a href="#steps">$coding$
* operation</a>; that is, it resets this $coder$, then it $code$s the
* $itype$s in the given $itype$ buffer, and finally it flushes this
* $coder$. This method should therefore not be invoked if $a$ $coding$
* operation is already in progress. </p>
*
* @param in
* The input $itype$ buffer
*
* @return A newly-allocated $otype$ buffer containing the result of the
* $coding$ operation. The buffer's position will be zero and its
* limit will follow the last $otype$ written.
*
* @throws IllegalStateException
* If $a$ $coding$ operation is already in progress
*
* @throws MalformedInputException
* If the $itype$ sequence starting at the input buffer's current
* position is $notLegal$ and the current malformed-input action
* is {@link CodingErrorAction#REPORT}
*
* @throws UnmappableCharacterException
* If the $itype$ sequence starting at the input buffer's current
* position cannot be mapped to an equivalent $otype$ sequence and
* the current unmappable-character action is {@link
* CodingErrorAction#REPORT}
*/
public final $Otype$Buffer $code$($Itype$Buffer in)
throws CharacterCodingException
{
int n = (int)(in.remaining() * average$ItypesPerOtype$());
$Otype$Buffer out = $Otype$Buffer.allocate(n);
if ((n == 0) && (in.remaining() == 0))
return out;
reset();
for (;;) {
CoderResult cr = in.hasRemaining() ?
$code$(in, out, true) : CoderResult.UNDERFLOW;
if (cr.isUnderflow())
cr = flush(out);
if (cr.isUnderflow())
break;
if (cr.isOverflow()) {
n = 2*n + 1; // Ensure progress; n might be 0!
$Otype$Buffer o = $Otype$Buffer.allocate(n);
out.flip();
o.put(out);
out = o;
continue;
}
cr.throwException();
}
out.flip();
return out;
}
#if[decoder]
/**
* Tells whether or not this decoder implements an auto-detecting charset.
*
* <p> The default implementation of this method always returns
* {@code false}; it should be overridden by auto-detecting decoders to
* return {@code true}. </p>
*
* @return {@code true} if, and only if, this decoder implements an
* auto-detecting charset
*/
public boolean isAutoDetecting() {
return false;
}
/**
* Tells whether or not this decoder has yet detected a
* charset <i>(optional operation)</i>.
*
* <p> If this decoder implements an auto-detecting charset then at a
* single point during a decoding operation this method may start returning
* {@code true} to indicate that a specific charset has been detected in
* the input byte sequence. Once this occurs, the {@link #detectedCharset
* detectedCharset} method may be invoked to retrieve the detected charset.
*
* <p> That this method returns {@code false} does not imply that no bytes
* have yet been decoded. Some auto-detecting decoders are capable of
* decoding some, or even all, of an input byte sequence without fixing on
* a particular charset.
*
* <p> The default implementation of this method always throws an {@link
* UnsupportedOperationException}; it should be overridden by
* auto-detecting decoders to return {@code true} once the input charset
* has been determined. </p>
*
* @return {@code true} if, and only if, this decoder has detected a
* specific charset
*
* @throws UnsupportedOperationException
* If this decoder does not implement an auto-detecting charset
*/
public boolean isCharsetDetected() {
throw new UnsupportedOperationException();
}
/**
* Retrieves the charset that was detected by this
* decoder <i>(optional operation)</i>.
*
* <p> If this decoder implements an auto-detecting charset then this
* method returns the actual charset once it has been detected. After that
* point, this method returns the same value for the duration of the
* current decoding operation. If not enough input bytes have yet been
* read to determine the actual charset then this method throws an {@link
* IllegalStateException}.
*
* <p> The default implementation of this method always throws an {@link
* UnsupportedOperationException}; it should be overridden by
* auto-detecting decoders to return the appropriate value. </p>
*
* @return The charset detected by this auto-detecting decoder,
* or {@code null} if the charset has not yet been determined
*
* @throws IllegalStateException
* If insufficient bytes have been read to determine a charset
*
* @throws UnsupportedOperationException
* If this decoder does not implement an auto-detecting charset
*/
public Charset detectedCharset() {
throw new UnsupportedOperationException();
}
#end[decoder]
#if[encoder]
private boolean canEncode(CharBuffer cb) {
if (state == ST_FLUSHED)
reset();
else if (state != ST_RESET)
throwIllegalStateException(state, ST_CODING);
CodingErrorAction ma = malformedInputAction();
CodingErrorAction ua = unmappableCharacterAction();
try {
onMalformedInput(CodingErrorAction.REPORT);
onUnmappableCharacter(CodingErrorAction.REPORT);
encode(cb);
} catch (CharacterCodingException x) {
return false;
} finally {
onMalformedInput(ma);
onUnmappableCharacter(ua);
reset();
}
return true;
}
/**
* Tells whether or not this encoder can encode the given character.
*
* <p> This method returns {@code false} if the given character is a
* surrogate character; such characters can be interpreted only when they
* are members of a pair consisting of a high surrogate followed by a low
* surrogate. The {@link #canEncode(java.lang.CharSequence)
* canEncode(CharSequence)} method may be used to test whether or not a
* character sequence can be encoded.
*
* <p> This method may modify this encoder's state; it should therefore not
* be invoked if an <a href="#steps">encoding operation</a> is already in
* progress.
*
* <p> The default implementation of this method is not very efficient; it
* should generally be overridden to improve performance. </p>
*
* @param c
* The given character
*
* @return {@code true} if, and only if, this encoder can encode
* the given character
*
* @throws IllegalStateException
* If $a$ $coding$ operation is already in progress
*/
public boolean canEncode(char c) {
CharBuffer cb = CharBuffer.allocate(1);
cb.put(c);
cb.flip();
return canEncode(cb);
}
/**
* Tells whether or not this encoder can encode the given character
* sequence.
*
* <p> If this method returns {@code false} for a particular character
* sequence then more information about why the sequence cannot be encoded
* may be obtained by performing a full <a href="#steps">encoding
* operation</a>.
*
* <p> This method may modify this encoder's state; it should therefore not
* be invoked if an encoding operation is already in progress.
*
* <p> The default implementation of this method is not very efficient; it
* should generally be overridden to improve performance. </p>
*
* @param cs
* The given character sequence
*
* @return {@code true} if, and only if, this encoder can encode
* the given character without throwing any exceptions and without
* performing any replacements
*
* @throws IllegalStateException
* If $a$ $coding$ operation is already in progress
*/
public boolean canEncode(CharSequence cs) {
CharBuffer cb;
if (cs instanceof CharBuffer)
cb = ((CharBuffer)cs).duplicate();
else
cb = CharBuffer.wrap(cs.toString());
return canEncode(cb);
}
#end[encoder]
private void throwIllegalStateException(int from, int to) {
throw new IllegalStateException("Current state = " + stateNames[from]
+ ", new state = " + stateNames[to]);
}
}