Package org.esa.snap.core.gpf.descriptor.template

Class TemplateEngine<C>

java.lang.Object

org.esa.snap.core.gpf.descriptor.template.TemplateEngine<C>

public abstract class TemplateEngine<C>
extends Object

A template engine represents an abstraction over concrete scripting engines. The currently supported scripting engines are Apache Velocity and Javascript.

Field Summary

Fields

Modifier and Type	Field	Description
protected TemplateContext<C>	context
protected TemplateContext<C>	lastContext
protected ToolAdapterOperatorDescriptor	operatorDescriptor

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	TemplateEngine(ToolAdapterOperatorDescriptor descriptor)

Method Summary

Modifier and Type	Method	Description
static TemplateEngine	createInstance(ToolAdapterOperatorDescriptor descriptor, TemplateType templateType)	Creates an instance of a template engine, of the given type, for the given descriptor.
static TemplateEngine	createInstance(ToolAdapterOperatorDescriptor descriptor, TemplateType templateType, boolean stateful)	Creates an instance of a template engine.
abstract String	execute(Template template, Map<String,Object> parameters)	Processes the given template.
TemplateContext<C>	getContext()	Returns the last execution context.
List<String>	getLines(Template template, Map<String,Object> parameters)	Returns the contents of the processed template as a list of strings (lines).
Path	getTemplateBasePath()	Returns the absolute path of the template file.
abstract TemplateType	getType()	Returns the type of the template.
abstract void	parse(Template template)	Parses the given template without processing it.

Methods inherited from class java.lang.Object

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

Field Detail

operatorDescriptor

protected ToolAdapterOperatorDescriptor operatorDescriptor

context

protected TemplateContext<C> context

lastContext

protected TemplateContext<C> lastContext

Constructor Detail

TemplateEngine

protected TemplateEngine(ToolAdapterOperatorDescriptor descriptor)

Method Detail

createInstance

public static TemplateEngine createInstance(ToolAdapterOperatorDescriptor descriptor,
                                            TemplateType templateType,
                                            boolean stateful)

Creates an instance of a template engine.

Parameters:

descriptor - The operator descriptor

templateType - The template type

stateful - If true, the scripting engine will be singleton-like.

Returns:

the template engine

parse

public abstract void parse(Template template)
                    throws TemplateException

Parses the given template without processing it. This method should be used for verifying the syntactical correctness of the template.

Parameters:

template - The template to parse

Throws:

TemplateException - in case of an exception during parsing of the template

getType

public abstract TemplateType getType()

Returns the type of the template. Can be either TemplateType.VELOCITY or TemplateType.JAVASCRIPT

getContext

public TemplateContext<C> getContext()

Returns the last execution context. The execution context would contain transformed parameter values.

createInstance

public static TemplateEngine createInstance(ToolAdapterOperatorDescriptor descriptor,
                                            TemplateType templateType)

Creates an instance of a template engine, of the given type, for the given descriptor.

Parameters:

descriptor - The descriptor for which to create the engine

templateType - The template type

Returns:

An instance of a template engine

execute

public abstract String execute(Template template,
                               Map<String,Object> parameters)
                        throws TemplateException

Processes the given template.

Parameters:

template - The template to be processed

parameters - Parameters to be passed to the template.

Returns:

If everything ok, the transformed template

Throws:

TemplateException - in case of an exception during processing of the template

getLines

public List<String> getLines(Template template,
                             Map<String,Object> parameters)
                      throws TemplateException

Returns the contents of the processed template as a list of strings (lines).

Parameters:

template - The template to be processed

parameters - Parameters to be passed to the template engine

Returns:

A list of strings representing the lines of the processed template

Throws:

TemplateException - in case of an exception during processing of the template

getTemplateBasePath

public Path getTemplateBasePath()

Returns the absolute path of the template file.