Package org.metricshub.jawk.ext

Class StdinExtension

java.lang.Object

org.metricshub.jawk.ext.AbstractExtension

org.metricshub.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

Field Summary

Fields

Modifier and Type	Field	Description
static final StdinExtension	INSTANCE

Constructor Summary

Constructors

Constructor	Description
StdinExtension()

Method Summary

Modifier and Type	Method	Description
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.
BlockObject	stdinBlockFunction(Object... args)
Object	stdinGetlineFunction()
int	stdinHasInputFunction()

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

getExtensionFunctions

Methods inherited from class java.lang.Object

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

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

getExtensionFunctions

Field Details

INSTANCE

public static final StdinExtension INSTANCE

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()

Description copied from class: AbstractExtension

getExtensionName.

Specified by:

getExtensionName in interface JawkExtension

Overrides:

getExtensionName in class AbstractExtension

Returns:

name of the extension package.

stdinHasInputFunction

public int stdinHasInputFunction()

stdinGetlineFunction

public Object stdinGetlineFunction()

stdinBlockFunction

public BlockObject stdinBlockFunction(Object... args)