Package org.sentrysoftware.jawk.ext

Class StdinExtension

java.lang.Object

org.sentrysoftware.jawk.ext.AbstractExtension

org.sentrysoftware.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

Author:

Danny Daglas

Constructor Summary

Constructors

Constructor	Description
StdinExtension()

Method Summary

Modifier and Type	Method	Description
String[]	extensionKeywords()	All the extended keywords supported by this extension.
String	getExtensionName()	getExtensionName.
void	init(VariableManager vm, JRT jrt, AwkSettings settings)	Called after the creation and before normal processing of the extension, pass in the Jawk Runtime Manager and the Variable Manager once.
Object	invoke(String keyword, Object[] args)	Invoke extension as a method.

Methods inherited from class org.sentrysoftware.jawk.ext.AbstractExtension

getAssocArrayParameterPositions

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.sentrysoftware.jawk.ext.JawkExtension

getAssocArrayParameterPositions

Constructor Details

StdinExtension

public StdinExtension()

Method Details

init

public void init(VariableManager vm,
 JRT jrt,
 AwkSettings settings)

Called after the creation and before normal processing of the extension, pass in the Jawk Runtime Manager and the Variable Manager once.

It is guaranteed init() is called before invoke() is called.

Specified by:

init in interface JawkExtension

Overrides:

init in class AbstractExtension

Parameters:

vm - Reference to the Variable Manager

jrt - Reference to the Runtime

settings - Reference to the settings

getExtensionName

public String getExtensionName()

getExtensionName.

Specified by:

getExtensionName in interface JawkExtension

Returns:

name of the extension package.

extensionKeywords

public String[] extensionKeywords()

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

Returns:

the list of keywords the extension provides support for

invoke

public Object invoke(String keyword,
 Object[] args)

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.