org.apache.pig.scripting.js

Class JsScriptEngine

java.lang.Object

org.apache.pig.scripting.ScriptEngine

org.apache.pig.scripting.js.JsScriptEngine

public class JsScriptEngine
extends ScriptEngine

ScriptEngine implementation for JavaScript

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.scripting.ScriptEngine

ScriptEngine.SupportedScriptLang

Field Summary

Fields inherited from class org.apache.pig.scripting.ScriptEngine

NAMESPACE_SEPARATOR

Constructor Summary

Constructors

Constructor and Description
JsScriptEngine()

Method Summary

Methods

Modifier and Type	Method and Description
protected Object	eval(String expr)
static JsScriptEngine	getInstance()
protected Map<String,Object>	getParamsFromVariables() Returns a map from local variable names to their values
protected String	getScriptingLang() Gets ScriptEngine classname or keyword for the scripting language
Object	jsCall(String functionName, Object[] passedParams) call a javascript function
Object	jsEval(String name, Reader scriptReader) evaluate javascript from a reader
Object	jsEval(String name, String script) evaluate a javascript String
org.mozilla.javascript.Scriptable	jsNewArray(long size) creates a new javascript array
org.mozilla.javascript.Scriptable	jsNewObject() creates a new JavaScript object
void	jsPut(String name, Object value) put a value in the current scope
protected void	load(String name, InputStream script)
protected Map<String,List<PigStats>>	main(PigContext pigContext, String scriptFile) Actually runs the script file.
void	registerFunctions(String path, String namespace, PigContext pigContext) Registers scripting language functions as Pig functions with given namespace

Methods inherited from class org.apache.pig.scripting.ScriptEngine

getInstance, getJarPath, getPigStatsMap, getScriptAsStream, getSupportedScriptLang, run

Methods inherited from class java.lang.Object

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

Constructor Detail

JsScriptEngine

public JsScriptEngine()

Method Detail

getInstance

public static JsScriptEngine getInstance()

jsEval

public Object jsEval(String name,
            String script)

evaluate a javascript String

Parameters:

name - the name of the script (for error messages)

script - the content of the script

Returns:

the result

jsEval

public Object jsEval(String name,
            Reader scriptReader)

evaluate javascript from a reader

Parameters:

name - the name of the script (for error messages)

scriptReader - the content of the script

Returns:

the result

jsPut

public void jsPut(String name,
         Object value)

put a value in the current scope

Parameters:

name - the name of the variable

value - its value

jsCall

public Object jsCall(String functionName,
            Object[] passedParams)

call a javascript function

Parameters:

functionName - the name of the function

passedParams - the parameters to pass

Returns:

the result of the function

jsNewObject

public org.mozilla.javascript.Scriptable jsNewObject()

creates a new JavaScript object

Returns:

an empty object

jsNewArray

public org.mozilla.javascript.Scriptable jsNewArray(long size)

creates a new javascript array

Parameters:

size - the size of the array

Returns:

an empty array of the given size

eval

protected Object eval(String expr)

load

protected void load(String name,
        InputStream script)

main

protected Map<String,List<PigStats>> main(PigContext pigContext,
                              String scriptFile)
                                   throws IOException

Description copied from class: ScriptEngine

Actually runs the script file. This method will be implemented by individual script engines.

Specified by:

main in class ScriptEngine

Parameters:

pigContext - ScriptPigContext to run the script file

scriptFile - the file

Throws:

IOException

registerFunctions

public void registerFunctions(String path,
                     String namespace,
                     PigContext pigContext)
                       throws IOException

Description copied from class: ScriptEngine

Registers scripting language functions as Pig functions with given namespace

Specified by:

registerFunctions in class ScriptEngine

Parameters:

path - path of the script

namespace - namespace for the functions

pigContext - pigcontext to register functions to pig in the given namespace

Throws:

IOException

getParamsFromVariables

protected Map<String,Object> getParamsFromVariables()
                                             throws IOException

Description copied from class: ScriptEngine

Returns a map from local variable names to their values

Specified by:

getParamsFromVariables in class ScriptEngine

Throws:

IOException

getScriptingLang

protected String getScriptingLang()

Description copied from class: ScriptEngine

Gets ScriptEngine classname or keyword for the scripting language

Specified by:

getScriptingLang in class ScriptEngine