ExecutionContext (Scripturian 1.1.10)

java.lang.Object
- com.threecrickets.scripturian.ExecutionContext

```
public class ExecutionContext
extends Object
```
Encapsulates context for an Executable.
You should always release() an execution context when done using it.
An execution context is not in itself thread-safe. However, it supports two use cases with different threading behavior.
The first occurs when Executable.execute(ExecutionContext, Object, ExecutionController) is callable by concurrent threads. In this case, each thread should create its own execution context, and the context in such cases is essentially thread-unique. Just be aware that if your executable spawns threads, they would need to coordinate access to the context if they need it.
The second occurs when Executable.makeEnterable(Object, ExecutionContext, Object, ExecutionController) is called, and then Executable.enter(Object, String, Object...) is callable by concurrent threads. In this case, all invoking threads share the same execution context. Because the context is immutable (internally makeImmutable() is called), it is "thread-safe" to the extent that you better not try to modify it. Otherwise, an IllegalStateException is thrown.

Author:

Tal Liron

Field Summary

Fields
Modifier and Type	Field and Description
`protected Executable`	`enterableExecutable` Non-null if this context is enterable.
`protected Object`	`enteringKey` Non-null if this context is enterable.

Constructor Summary

Constructors
Constructor and Description
`ExecutionContext()` Constructor.
`ExecutionContext(Writer writer)` Constructor.
`ExecutionContext(Writer writer, Writer errorWriter)` Constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addAdapter(LanguageAdapter languageAdapter)` Sets a language adapter as a user of this context.
`static void`	`disconnect()` Makes sure there is no execution context associated with this thread.
`Object`	`enter(String entryPointName, Object... arguments)` Enters the executable at a stored, named location, via the last language adapter that used this context.
`LanguageAdapter`	`getAdapter()` The last language adapter used by the context.
`Map<String,Object>`	`getAttributes()` General-purpose attributes.
`static ExecutionContext`	`getCurrent()` The execution context set for this thread.
`Executable`	`getEnterableExecutable()` Non-null if this context is enterable.
`Writer`	`getErrorWriter()` The standard error set for executables using this context.
`Writer`	`getErrorWriterOrDefault()` The standard error set for executables using this context.
`List<URI>`	`getLibraryLocations()` Locations where language adapters might search for extra libraries.
`Map<String,Object>`	`getServices()` Services exposed to executables using this context.
`Writer`	`getWriter()` The standard output set for executables using this context.
`Writer`	`getWriterOrDefault()` The standard output set for executables using this context.
`boolean`	`isImmutable()` Immutable contexts will throw an `IllegalStateException` whenever an attempt is made to change them.
`ExecutionContext`	`makeCurrent()` Sets this execution context for this thread.
`void`	`makeImmutable()` Makes this context immutable.
`void`	`release()` Calls `LanguageAdapter.releaseContext(ExecutionContext)` on all adapters that have used this context.
`Writer`	`setErrorWriter(Writer writer)` The standard error set for executables using this context.
`Writer`	`setWriter(Writer writer)` The standard output set for executables using this context.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - enterableExecutable
```
protected Executable enterableExecutable
```
    Non-null if this context is enterable.
  - enteringKey
```
protected Object enteringKey
```
    Non-null if this context is enterable.
- Constructor Detail
  - ExecutionContext
```
public ExecutionContext()
```
    Constructor.
  - ExecutionContext
```
public ExecutionContext(Writer writer)
```
    Constructor.
    
    Parameters:
    
    writer - The standard output set for executables using this context
  - ExecutionContext
```
public ExecutionContext(Writer writer,
                        Writer errorWriter)
```
    Constructor.
    
    Parameters:
    
    writer - The standard output set for executables using this context
    
    errorWriter - The standard error set for executables using this context
- Method Detail
  - getCurrent
```
public static ExecutionContext getCurrent()
```
    The execution context set for this thread.
    
    Returns:
    
    An execution context or null
    
    See Also:
    
    makeCurrent(), disconnect()
  - disconnect
```
public static void disconnect()
```
    Makes sure there is no execution context associated with this thread.
    
    See Also:
    
    makeCurrent(), getCurrent()
  - getAttributes
```
public Map<String,Object> getAttributes()
```
    General-purpose attributes. Useful for configuring special language features not supported by the context. Additionally, language adapters and other components along the execution chain might use this to store contextual state.
    Immutable contexts will return an unmodifiable map.
    
    Returns:
    
    The attributes
    
    See Also:
    
    isImmutable()
  - getLibraryLocations
```
public List<URI> getLibraryLocations()
```
    Locations where language adapters might search for extra libraries. The exact use varies per language adapter. "Location" URIs are often filesystem directory paths, but some adapters might support paths to specific library files and network URLs.
    Immutable contexts will return an unmodifiable list.
    
    Returns:
    
    The library locations
    
    See Also:
    
    File.toURI()
  - getServices
```
public Map<String,Object> getServices()
```
    Services exposed to executables using this context.
    Immutable contexts will return an unmodifiable map.
    
    Returns:
    
    The exposed services
    
    See Also:
    
    isImmutable()
  - getWriter
```
public Writer getWriter()
```
    The standard output set for executables using this context.
    
    Returns:
    
    The writer or null
  - getWriterOrDefault
```
public Writer getWriterOrDefault()
```
    The standard output set for executables using this context.
    
    Returns:
    
    The writer or the default writer
  - setWriter
```
public Writer setWriter(Writer writer)
```
    The standard output set for executables using this context.
    
    Parameters:
    
    writer - The writer
    
    Returns:
    
    The previous writer or null
  - getErrorWriter
```
public Writer getErrorWriter()
```
    The standard error set for executables using this context.
    
    Returns:
    
    The error writer or null
  - getErrorWriterOrDefault
```
public Writer getErrorWriterOrDefault()
```
    The standard error set for executables using this context.
    
    Returns:
    
    The error writer or the default error writer
  - setErrorWriter
```
public Writer setErrorWriter(Writer writer)
```
    The standard error set for executables using this context.
    
    Parameters:
    
    writer - The writer
    
    Returns:
    
    The previous error writer or null
  - getAdapter
```
public LanguageAdapter getAdapter()
```
    The last language adapter used by the context.
    
    Returns:
    
    The language adapter or null
  - addAdapter
```
public void addAdapter(LanguageAdapter languageAdapter)
```
    Sets a language adapter as a user of this context. The adapter will then get a chance to release contextual state when release() is called.
    
    Parameters:
    
    languageAdapter - The language adapter
    
    See Also:
    
    LanguageAdapter.releaseContext(ExecutionContext)
  - getEnterableExecutable
```
public Executable getEnterableExecutable()
```
    Non-null if this context is enterable.
    
    Returns:
    
    The enterable executable or null
    
    See Also:
    
    enter(String, Object...), Executable.makeEnterable(Object, ExecutionContext, Object, ExecutionController)
  - isImmutable
```
public boolean isImmutable()
```
    Immutable contexts will throw an IllegalStateException whenever an attempt is made to change them.
    
    Returns:
    
    True if immutable
  - enter
```
public Object enter(String entryPointName,
                    Object... arguments)
             throws ParsingException,
                    ExecutionException,
                    NoSuchMethodException
```
    Enters the executable at a stored, named location, via the last language adapter that used this context. According to the language, the entry point can be a function, method, lambda, closure, etc.
    The context must have been previously made enterable by a call to Executable.makeEnterable(Object, ExecutionContext, Object, ExecutionController) .
    
    Parameters:
    
    entryPointName - The name of the entry point
    
    arguments - Optional state to pass to the entry point
    
    Returns:
    
    State returned from the entry point or null
    
    Throws:
    
    ParsingException - In case of a parsing error
    
    ExecutionException - In case of an execution error
    
    NoSuchMethodException - In case the entry point does not exist
    
    See Also:
    
    getEnterableExecutable(), getAdapter()
  - makeImmutable
```
public void makeImmutable()
```
    Makes this context immutable. Any attempt to change it will result in an IllegalStateException.
    Calling this method more than once will have no effect. Once made immutable, execution contexts cannot become mutable again.
  - makeCurrent
```
public ExecutionContext makeCurrent()
```
    Sets this execution context for this thread.
    
    Returns:
    
    The previous current execution context or null
    
    See Also:
    
    getCurrent(), disconnect()
  - release
```
public void release()
```
    Calls LanguageAdapter.releaseContext(ExecutionContext) on all adapters that have used this context.
    After this call, any attempt to access the context will result in an IllegalStateException.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class ExecutionContext

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

enterableExecutable

enteringKey

Constructor Detail

ExecutionContext

ExecutionContext

ExecutionContext

Method Detail

getCurrent

disconnect

getAttributes

getLibraryLocations

getServices

getWriter

getWriterOrDefault

setWriter

getErrorWriter

getErrorWriterOrDefault

setErrorWriter

getAdapter

addAdapter

getEnterableExecutable

isImmutable

enter

makeImmutable

makeCurrent

release

toString