org.jawk.ext
Class StdinExtension

java.lang.Object
  org.jawk.ext.AbstractExtension
      org.jawk.ext.StdinExtension

All Implemented Interfaces:

JawkExtension

public class StdinExtension
extends AbstractExtension
implements JawkExtension

Enable stdin processing in Jawk, to be used in conjunction with the -ni parameter. Since normal input processing is turned off via -ni, this is provided to enable a way to read input from stdin.

To use:

 StdinGetline() == 1 { print "--> " $0 }
 

The extension functions are as follows:

• StdinHasInput -
  Returns 1 when StdinGetline() does not block (i.e., when input is available or upon an EOF), 0 otherwise.
  Parameters:
  • none
  Returns:
  • 1 when StdinGetline() does not block, 0 otherwise.

• StdinGetline -
  Retrieve a line of input from stdin. The operation will block until input is available, EOF, or an IO error.
  Parameters:
  • none
  Returns:
  • 1 upon successful read of a line of input from stdin, 0 upon an EOF, and -1 when an IO error occurs.

• StdinBlock -
  Block until a call to StdinGetline() would not block. Parameters:
  • chained block function - optional
  Returns:
  • "Stdin" if this block object is triggered

Field Summary

Fields inherited from class org.jawk.ext.AbstractExtension

jrt, vm

Constructor Summary

StdinExtension()

Method Summary

java.lang.String[]	extensionKeywords() All the extended keywords supported by this extension.
java.lang.String	getExtensionName() The name of the extension package.
java.lang.Object	invoke(java.lang.String keyword, java.lang.Object[] args) Invoke extension as a method.

Methods inherited from class org.jawk.ext.AbstractExtension

checkNumArgs, getAssocArrayParameterPositions, init, toAwkString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jawk.ext.JawkExtension

getAssocArrayParameterPositions, init

Constructor Detail

StdinExtension

public StdinExtension()
               throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getExtensionName

public java.lang.String getExtensionName()

Description copied from interface: JawkExtension

The name of the extension package.

Specified by:

getExtensionName in interface JawkExtension

extensionKeywords

public java.lang.String[] extensionKeywords()

Description copied from interface: JawkExtension

All the extended keywords supported by this extension.

Note: Jawk will throw a runtime exception if the keyword collides with any other keyword in the system, extension or otherwise.

Specified by:

extensionKeywords in interface JawkExtension

invoke

public java.lang.Object invoke(java.lang.String keyword,
                               java.lang.Object[] args)

Description copied from interface: JawkExtension

Invoke extension as a method.

Specified by:

invoke in interface JawkExtension

Parameters:

keyword - The extension keyword.

args - Arguments to the extension.

Returns:

The return value (result) of the extension.