/*******************************************************************************
* Copyright (c) 2001, 2005 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Jens Lukowski/Innoopract - initial renaming/restructuring
*
*******************************************************************************/
package org.eclipse.wst.xml.core.internal.contenttype;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import org.eclipse.core.resources.IStorage;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.wst.sse.core.internal.encoding.CodedIO;
import org.eclipse.wst.sse.core.internal.encoding.EncodingMemento;
import org.eclipse.wst.sse.core.internal.encoding.IResourceCharsetDetector;
public abstract class AbstractResourceEncodingDetector implements IResourceCharsetDetector {
protected EncodingMemento fEncodingMemento;
protected boolean fHeaderParsed;
protected Reader fReader;
/**
*
*/
public AbstractResourceEncodingDetector() {
super();
}
/**
* Note: once this instance is created, trace info still needs to be
* appended by caller, depending on the context its created.
*/
private void createEncodingMemento(String detectedCharsetName) {
fEncodingMemento = new EncodingMemento();
fEncodingMemento.setJavaCharsetName(getAppropriateJavaCharset(detectedCharsetName));
fEncodingMemento.setDetectedCharsetName(detectedCharsetName);
// TODO: if detectedCharset and spec default is
// null, need to use "work
// bench based" defaults.
fEncodingMemento.setAppropriateDefault(getSpecDefaultEncoding());
}
/**
* convience method all subclasses can use (but not override)
*
* @param detectedCharsetName
* @param reason
*/
final protected void createEncodingMemento(String detectedCharsetName, String reason) {
createEncodingMemento(detectedCharsetName);
}
/**
* convience method all subclasses can use (but not override)
*/
final protected void ensureInputSet() {
if (fReader == null) {
throw new IllegalStateException("input must be set before use"); //$NON-NLS-1$
}
}
/**
* This method can return null, if invalid charset name (in which case
* "appropriateDefault" should be used, if a name is really need for some
* "save anyway" cases).
*
* @param detectedCharsetName
* @return
*/
private String getAppropriateJavaCharset(String detectedCharsetName) {
String result = null;
// 1. Check explicit mapping overrides from
// property file -- its here we pick up "rules" for cases
// that are not even in Java
result = CodedIO.checkMappingOverrides(detectedCharsetName);
// 2. Use the "canonical" name from JRE mappings
// Note: see Charset JavaDoc, the name you get one
// with can be alias,
// the name you get back is "standard" name.
Charset javaCharset = null;
try {
javaCharset = Charset.forName(detectedCharsetName);
} catch (UnsupportedCharsetException e) {
// only set invalid, if result is same as detected -- they won't
// be equal if
// overridden
if (result != null && result.equals(detectedCharsetName)) {
fEncodingMemento.setInvalidEncoding(detectedCharsetName);
}
} catch (IllegalCharsetNameException e) {
// only set invalid, if result is same as detected -- they won't
// be equal if
// overridden
if (result != null && result.equals(detectedCharsetName)) {
fEncodingMemento.setInvalidEncoding(detectedCharsetName);
}
}
// give priority to java cononical name, if present
if (javaCharset != null) {
result = javaCharset.name();
// but still allow overrides
result = CodedIO.checkMappingOverrides(result);
}
return result;
}
public String getEncoding() throws IOException {
return getEncodingMemento().getDetectedCharsetName();
}
// to ensure consist overall rules used, we'll mark as
// final,
// and require subclasses to provide certain pieces of
// the
// implementation
public EncodingMemento getEncodingMemento() throws IOException {
ensureInputSet();
if (!fHeaderParsed) {
parseInput();
// we keep track of if header's already been
// parse, so can make
// multiple 'get' calls, without causing
// reparsing.
fHeaderParsed = true;
// Note: there is a "hidden assumption" here
// that an empty
// string in content should be treated same as
// not present.
}
if (fEncodingMemento == null) {
handleSpecDefault();
}
if (fEncodingMemento == null) {
// safty net
fEncodingMemento = new NullMemento();
}
return fEncodingMemento;
}
/**
* This is to return a default encoding -- as specified by an industry
* content type spec -- when not present in the stream, for example, XML
* specifies UTF-8, JSP specifies ISO-8859-1. This method should return
* null if there is no such "spec default".
*/
abstract public String getSpecDefaultEncoding();
public EncodingMemento getSpecDefaultEncodingMemento() {
resetAll();
EncodingMemento result = null;
String enc = getSpecDefaultEncoding();
if (enc != null) {
createEncodingMemento(enc, EncodingMemento.DEFAULTS_ASSUMED_FOR_EMPTY_INPUT);
fEncodingMemento.setAppropriateDefault(enc);
result = fEncodingMemento;
}
return result;
}
private void handleSpecDefault() {
String encodingName;
encodingName = getSpecDefaultEncoding();
if (encodingName != null) {
//createEncodingMemento(encodingName,
// EncodingMemento.USED_CONTENT_TYPE_DEFAULT);
fEncodingMemento = new EncodingMemento();
fEncodingMemento.setJavaCharsetName(encodingName);
fEncodingMemento.setAppropriateDefault(encodingName);
}
}
/**
* Every subclass must provide a way to parse the input. This method has
* several critical responsibilities:
* <li>set the fEncodingMemento field appropriately, according to the
* results of the parse of fReader.</li>
* <li>set fHarderParsed to true, to avoid wasted re-parsing.</li>
*/
abstract protected void parseInput() throws IOException;
/**
*
*/
protected void resetAll() {
fReader = null;
fHeaderParsed = false;
fEncodingMemento = null;
}
/**
*
*/
public void set(InputStream inputStream) {
resetAll();
fReader = new ByteReader(inputStream);
try {
fReader.mark(CodedIO.MAX_MARK_SIZE);
} catch (IOException e) {
// impossible, since we know ByteReader
// supports marking
throw new Error(e);
}
}
/**
*
*/
public void set(IStorage iStorage) throws CoreException {
resetAll();
InputStream inputStream = iStorage.getContents();
InputStream resettableStream = new BufferedInputStream(inputStream, CodedIO.MAX_BUF_SIZE);
resettableStream.mark(CodedIO.MAX_MARK_SIZE);
set(resettableStream);
// TODO we'll need to "remember" IFile, or
// get its (or its project's) settings, in case
// those are needed to handle cases when the
// encoding is not in the file stream.
}
/**
* Note: this is not part of interface to help avoid confusion ... it
* expected this Reader is a well formed character reader ... that is, its
* all ready been determined to not be a unicode marked input stream. And,
* its assumed to be in the correct position, at position zero, ready to
* read first character.
*/
public void set(Reader reader) {
resetAll();
fReader = reader;
if (!fReader.markSupported()) {
fReader = new BufferedReader(fReader);
}
try {
fReader.mark(CodedIO.MAX_MARK_SIZE);
} catch (IOException e) {
// impossble, since we just checked if markable
throw new Error(e);
}
}
}