package org.codehaus.plexus.util;
/*
* Copyright The Codehaus Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import org.codehaus.plexus.util.reflection.Reflector;
import org.codehaus.plexus.util.reflection.ReflectorException;
import java.io.FilterReader;
import java.io.IOException;
import java.io.PushbackReader;
import java.io.Reader;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
/**
* A FilterReader which interpolates keyword values into a character stream.
* Keywords are recognized when enclosed between starting and ending delimiter
* strings. The keywords themselves, and their values, are fetched from a Map
* supplied to the constructor.
* <p>
* When a possible keyword token is recognized (by detecting the starting and
* ending token delimiters):
* </p>
* <ul>
* <li>if the enclosed string is found in the keyword Map, the delimiters and
* the keyword are effectively replaced by the keyword's value;</li>
* <li>if the enclosed string is found in the keyword Map, but its value has
* zero length, then the token (delimiters and keyword) is effectively removed
* from the character stream;</li>
* <li>if the enclosed string is <em>not</em> found in the keyword Map, then
* no substitution is made; the token text is passed through unaltered.</li>
* </ul>
* <p>
* A token in the incoming character stream may be <em>escaped</em> by
* prepending an "escape sequence" which is specified to the constructor. An
* escaped token is passed through as written, with the escape sequence removed.
* This allows things which would look like tokens to be read literally rather
* than interpolated.
* </p>
*
* @author jdcasey Created on Feb 3, 2005
*
* @see InterpolationFilterReader
* @see org.codehaus.plexus.interpolation
*/
public class LineOrientedInterpolatingReader
extends FilterReader
{
public static final String DEFAULT_START_DELIM = "${";
public static final String DEFAULT_END_DELIM = "}";
public static final String DEFAULT_ESCAPE_SEQ = "\\";
private static final char CARRIAGE_RETURN_CHAR = '\r';
private static final char NEWLINE_CHAR = '\n';
private final PushbackReader pushbackReader;
private final Map<String, Object> context;
private final String startDelim;
private final String endDelim;
private final String escapeSeq;
private final int minExpressionSize;
private final Reflector reflector;
private int lineIdx = -1;
private String line;
/**
* Construct an interpolating Reader, specifying token delimiters and the
* escape sequence.
*
* @param reader the Reader to be filtered.
* @param context keyword/value pairs for interpolation.
* @param startDelim character sequence which (possibly) begins a token.
* @param endDelim character sequence which ends a token.
* @param escapeSeq
*/
public LineOrientedInterpolatingReader( Reader reader, Map<String, ?> context, String startDelim, String endDelim,
String escapeSeq )
{
super( reader );
this.startDelim = startDelim;
this.endDelim = endDelim;
this.escapeSeq = escapeSeq;
// Expressions have to be at least this size...
this.minExpressionSize = startDelim.length() + endDelim.length() + 1;
this.context = Collections.unmodifiableMap( context );
this.reflector = new Reflector();
if ( reader instanceof PushbackReader )
{
this.pushbackReader = (PushbackReader) reader;
}
else
{
this.pushbackReader = new PushbackReader( reader, 1 );
}
}
/**
* Filters a Reader using the default escape sequence "\".
*
* @param reader the Reader to be filtered.
* @param context keyword/value pairs for interpolation.
* @param startDelim the character sequence which (possibly) begins a token.
* @param endDelim the character sequence which ends a token.
*/
public LineOrientedInterpolatingReader( Reader reader, Map<String, ?> context, String startDelim, String endDelim )
{
this( reader, context, startDelim, endDelim, DEFAULT_ESCAPE_SEQ );
}
/**
* Filters a Reader using the default escape sequence "\" and token
* delimiters "${", "}".
*
* @param reader the Reader to be filtered.
* @param context keyword/value pairs for interpolation.
*/
public LineOrientedInterpolatingReader( Reader reader, Map<String, ?> context )
{
this( reader, context, DEFAULT_START_DELIM, DEFAULT_END_DELIM, DEFAULT_ESCAPE_SEQ );
}
public int read() throws IOException
{
if ( line == null || lineIdx >= line.length() )
{
readAndInterpolateLine();
}
int next = -1;
if ( line != null && lineIdx < line.length() )
{
next = line.charAt( lineIdx++ );
}
return next;
}
public int read( char[] cbuf, int off, int len ) throws IOException
{
int fillCount = 0;
for ( int i = off; i < off + len; i++ )
{
int next = read();
if ( next > -1 )
{
cbuf[i] = (char) next;
}
else
{
break;
}
fillCount++;
}
if ( fillCount == 0 )
{
fillCount = -1;
}
return fillCount;
}
public long skip( long n ) throws IOException
{
long skipCount = 0;
for ( long i = 0; i < n; i++ )
{
int next = read();
if ( next < 0 )
{
break;
}
skipCount++;
}
return skipCount;
}
private void readAndInterpolateLine() throws IOException
{
String rawLine = readLine();
if(rawLine != null)
{
Set expressions = parseForExpressions( rawLine );
Map evaluatedExpressions = evaluateExpressions( expressions );
String interpolated = replaceWithInterpolatedValues( rawLine, evaluatedExpressions );
if ( interpolated != null && interpolated.length() > 0 )
{
line = interpolated;
lineIdx = 0;
}
}
else
{
line = null;
lineIdx = -1;
}
}
/*
* Read one line from the wrapped Reader. A line is a sequence of characters
* ending in CRLF, CR, or LF. The terminating character(s) will be included
* in the returned line.
*/
private String readLine() throws IOException
{
StringBuilder lineBuffer = new StringBuilder( 40 ); // half of the "normal" line maxsize
int next;
boolean lastWasCR = false;
while ( ( next = pushbackReader.read() ) > -1 )
{
char c = (char) next;
if ( c == CARRIAGE_RETURN_CHAR )
{
lastWasCR = true;
lineBuffer.append( c );
}
else if ( c == NEWLINE_CHAR )
{
lineBuffer.append( c );
break; // end of line.
}
else if ( lastWasCR )
{
pushbackReader.unread( c );
break;
}
else
{
lineBuffer.append( c );
}
}
if ( lineBuffer.length() < 1 )
{
return null;
}
else
{
return lineBuffer.toString();
}
}
private String replaceWithInterpolatedValues( String rawLine, Map evaluatedExpressions )
{
String result = rawLine;
for ( Object o : evaluatedExpressions.entrySet() )
{
Map.Entry entry = (Map.Entry) o;
String expression = (String) entry.getKey();
String value = String.valueOf( entry.getValue() );
result = findAndReplaceUnlessEscaped( result, expression, value );
}
return result;
}
private Map evaluateExpressions( Set expressions )
{
Map<String, Object> evaluated = new TreeMap<String,Object>();
for ( Object expression : expressions )
{
String rawExpression = (String) expression;
String realExpression =
rawExpression.substring( startDelim.length(), rawExpression.length() - endDelim.length() );
String[] parts = realExpression.split( "\\." );
if ( parts.length > 0 )
{
Object value = context.get( parts[0] );
if ( value != null )
{
for ( int i = 1; i < parts.length; i++ )
{
try
{
value = reflector.getObjectProperty( value, parts[i] );
if ( value == null )
{
break;
}
}
catch ( ReflectorException e )
{
// TODO: Fix this! It should report, but not interrupt.
e.printStackTrace();
break;
}
}
evaluated.put( rawExpression, value );
}
}
}
return evaluated;
}
private Set parseForExpressions( String rawLine )
{
Set<String> expressions = new HashSet<String>();
if ( rawLine != null )
{
int placeholder = -1;
do
{
// find the beginning of the next expression.
int start = findDelimiter( rawLine, startDelim, placeholder );
// if we can't find a start-delimiter, then there is no valid expression. Ignore everything else.
if ( start < 0 )
{
// no expression found.
break;
}
// find the end of the next expression.
int end = findDelimiter( rawLine, endDelim, start + 1 );
// if we can't find an end-delimiter, then this is not a valid expression. Ignore it.
if ( end < 0 )
{
// no VALID expression found.
break;
}
// if we reach this point, we have a valid start and end position, which
// means we have a valid expression. So, we add it to the set of
// expressions in need of evaluation.
expressions.add( rawLine.substring( start, end + endDelim.length() ) );
// increment the placeholder so we can look beyond this expression.
placeholder = end + 1;
} while ( placeholder < rawLine.length() - minExpressionSize );
}
return expressions;
}
private int findDelimiter( String rawLine, String delimiter, int lastPos )
{
int placeholder = lastPos;
int position;
do
{
position = rawLine.indexOf( delimiter, placeholder );
if ( position < 0 )
{
break;
}
else
{
int escEndIdx = rawLine.indexOf( escapeSeq, placeholder ) + escapeSeq.length();
if ( escEndIdx > escapeSeq.length() - 1 && escEndIdx == position )
{
placeholder = position + 1;
position = -1;
}
}
} while ( position < 0 && placeholder < rawLine.length() - endDelim.length() );
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// use length() - endDelim.length() b/c otherwise there is nothing left to search.
return position;
}
private String findAndReplaceUnlessEscaped(String rawLine, String search, String replace)
{
StringBuilder lineBuffer = new StringBuilder( (int) ( rawLine.length() * 1.5 ) );
int lastReplacement = -1;
do
{
int nextReplacement = rawLine.indexOf( search, lastReplacement + 1 );
if(nextReplacement > -1)
{
if(lastReplacement < 0)
{
lastReplacement = 0;
}
lineBuffer.append( rawLine.substring( lastReplacement, nextReplacement ) );
int escIdx = rawLine.indexOf( escapeSeq, lastReplacement + 1 );
if(escIdx > -1 && escIdx + escapeSeq.length() == nextReplacement)
{
lineBuffer.setLength( lineBuffer.length() - escapeSeq.length() );
lineBuffer.append( search );
}
else
{
lineBuffer.append( replace );
}
lastReplacement = nextReplacement + search.length();
}
else
{
break;
}
}
while(lastReplacement > -1);
if( lastReplacement < rawLine.length() )
{
lineBuffer.append( rawLine.substring( lastReplacement ) );
}
return lineBuffer.toString();
}
}