org.codehaus.plexus.util
Class InterpolationFilterReader

java.lang.Object
  java.io.Reader
      java.io.FilterReader
          org.codehaus.plexus.util.InterpolationFilterReader

All Implemented Interfaces:

Closeable, Readable

public class InterpolationFilterReader
extends FilterReader

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.

When a possible keyword token is recognized (by detecting the starting and ending token delimiters):

• if the enclosed string is found in the keyword Map, the delimiters and the keyword are effectively replaced by the keyword's value;
• 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;
• if the enclosed string is not found in the keyword Map, then no substitution is made; the token text is passed through unaltered.

See Also:

LineOrientedInterpolatingReader, org.codehaus.plexus.interpolation

Field Summary

Fields inherited from class java.io.FilterReader

in

Fields inherited from class java.io.Reader

lock

Constructor Summary

InterpolationFilterReader(Reader in, Map variables)
Construct a Reader using the default interpolation delimiter tokens "${" and "}".

InterpolationFilterReader(Reader in, Map variables, String beginToken, String endToken)
Construct a Reader to interpolate values enclosed between the given delimiter tokens.

Method Summary

int	read() Returns the next character in the filtered stream, replacing tokens from the original stream.
int	read(char[] cbuf, int off, int len) Reads characters into a portion of an array.
long	skip(long n) Skips characters.

Methods inherited from class java.io.FilterReader

close, mark, markSupported, ready, reset

Methods inherited from class java.io.Reader

read, read

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

InterpolationFilterReader

public InterpolationFilterReader(Reader in,
                                 Map variables,
                                 String beginToken,
                                 String endToken)

Construct a Reader to interpolate values enclosed between the given delimiter tokens.

Parameters:

in - a Reader to be wrapped for interpolation.

variables - name/value pairs to be interpolated into the character stream.

beginToken - an interpolation target begins with this.

endToken - an interpolation target ends with this.

InterpolationFilterReader

public InterpolationFilterReader(Reader in,
                                 Map variables)

Construct a Reader using the default interpolation delimiter tokens "${" and "}".

Parameters:

in - a Reader to be wrapped for interpolation.

variables - name/value pairs to be interpolated into the character stream.

Method Detail

skip

public long skip(long n)
          throws IOException

Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.

Overrides:

skip in class FilterReader

Parameters:

n - The number of characters to skip

Returns:

the number of characters actually skipped

Throws:

IllegalArgumentException - If n is negative.

IOException - If an I/O error occurs

read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException

Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

Overrides:

read in class FilterReader

Parameters:

cbuf - Destination buffer to write characters to. Must not be null.

off - Offset at which to start storing characters.

len - Maximum number of characters to read.

Returns:

the number of characters read, or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

read

public int read()
         throws IOException

Returns the next character in the filtered stream, replacing tokens from the original stream.

Overrides:

read in class FilterReader

Returns:

the next character in the resulting stream, or -1 if the end of the resulting stream has been reached

Throws:

IOException - if the underlying stream throws an IOException during reading