org.codehaus.commons.compiler

Interface IClassBodyEvaluator

All Superinterfaces:

ICookable

All Known Subinterfaces:

IExpressionEvaluator, IScriptEvaluator

All Known Implementing Classes:

ClassBodyEvaluator, ClassBodyEvaluator, ExpressionEvaluator, ExpressionEvaluator, ScriptEvaluator, ScriptEvaluator

public interface IClassBodyEvaluator
extends ICookable

Parses a class body and returns it as a Class object ready for use with java.lang.reflect.

Example:

   import java.util.*;

   static private int a = 1;
   private int b = 2;

   public void func(int c, int d) {
       return func2(c, d);
   }

   private static void func2(int e, int f) {
       return e * f;
   }
 

To set up an IClassBodyEvaluator object, proceed as follows:

1. Create an IClassBodyEvaluator-implementing class.
2. Configure the IClassBodyEvaluator by calling any of the following methods:
• setDefaultImports(String[])
• setClassName(String)
• setExtendedClass(Class)
• setImplementedInterfaces(Class[])
• ICookable.setParentClassLoader(ClassLoader)
3. Call any of the ICookable.cook(String, java.io.Reader) methods to scan, parse, compile and load the class body into the JVM.

To compile a class body and immediately instantiate an object, the createInstance(Reader) methods can be used.

The generated class may optionally extend/implement a given type; the returned instance can safely be type-cast to that optionalBaseType.

Example:

 public interface Foo {
     int bar(int a, int b);
 }
 ...
 IClassBodyEvaluator cbe = CompilerFactoryFactory.getDefaultCompilerFactory(). newClassBodyEvaluator();
 Foo f = (Foo) ClassBodyEvaluator.createFastClassBodyEvaluator(
     new Scanner(null, new StringReader("public int bar(int a, int b) { return a + b; }")),
     Foo.class,                  // Base type to extend/implement
     (ClassLoader) null          // Use current thread's context class loader
 );
 System.out.println("1 + 2 = " + f.bar(1, 2));
 

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_CLASS_NAME Default name for the generated class.

Fields inherited from interface org.codehaus.commons.compiler.ICookable

BOOT_CLASS_LOADER, SYSTEM_PROPERTY_SOURCE_DEBUGGING_DIR, SYSTEM_PROPERTY_SOURCE_DEBUGGING_ENABLE

Method Summary

Modifier and Type	Method and Description
Object	createInstance(Reader reader) Scans, parses and compiles a class body from the tokens delivered by the the given Reader, then creates and returns an instance of that class.
Class<?>	getClazz() Returns the loaded Class.
void	setClassName(String className) Sets the name of the generated class.
void	setDefaultImports(String[] optionalDefaultImports) "Default imports" add to the system import "java.lang", i.e. the evaluator may refer to classes imported by default imports without having to explicitly declare IMPORT statements.
void	setExtendedClass(Class<?> optionalExtendedClass) Sets a particular superclass that the generated class will extend.
void	setExtendedType(Class<?> optionalExtendedClass) Deprecated. Use setExtendedClass(Class) instead
void	setImplementedInterfaces(Class<?>[] implementedInterfaces) Sets a particular set of interfaces that the generated class will implement.
void	setImplementedTypes(Class<?>[] implementedInterfaces) Deprecated. Use setImplementedInterfaces(Class[]) instead

Methods inherited from interface org.codehaus.commons.compiler.ICookable

cook, cook, cook, cook, cook, cook, cook, cook, cookFile, cookFile, cookFile, cookFile, setCompileErrorHandler, setDebuggingInformation, setParentClassLoader, setWarningHandler

Field Detail

DEFAULT_CLASS_NAME

static final String DEFAULT_CLASS_NAME

Default name for the generated class.

See Also:

Constant Field Values

Method Detail

setDefaultImports

void setDefaultImports(@Nullable
                       String[] optionalDefaultImports)

"Default imports" add to the system import "java.lang", i.e. the evaluator may refer to classes imported by default imports without having to explicitly declare IMPORT statements.

Notice that JDK 5 "static imports" are also supported, as shown here:

     sc.setDefaultImports(new String[] {
         "java.util.Map",                          // Single type import
         "java.io.*",                              // Type-import-on-demand
         "static java.util.Collections.EMPTY_MAP", // Single static import
         "static java.util.Collections.*",         // Static-import-on-demand
     });
 

setClassName

void setClassName(String className)

Sets the name of the generated class. Defaults to DEFAULT_CLASS_NAME. In most cases, there is no need to set this name, because the generated class is loaded into its own ClassLoader where its name cannot collide with classes generated by other evaluators.

One reason to use this function is to have a class name in a non-default package, which can be relevant when types and members with DEFAULT accessibility are accessed.

setExtendedClass

void setExtendedClass(@Nullable
                      Class<?> optionalExtendedClass)

Sets a particular superclass that the generated class will extend. If optionalExtendedClass is null, the generated class will extend Object.

The usual reason to set a base class for an evaluator is that the generated class can directly access the superclass's (non-private) members.

setExtendedType

@Deprecated
void setExtendedType(@Nullable
                                  Class<?> optionalExtendedClass)

Deprecated. Use setExtendedClass(Class) instead

setImplementedInterfaces

void setImplementedInterfaces(Class<?>[] implementedInterfaces)

Sets a particular set of interfaces that the generated class will implement.

setImplementedTypes

@Deprecated
void setImplementedTypes(Class<?>[] implementedInterfaces)

Deprecated. Use setImplementedInterfaces(Class[]) instead

getClazz

Class<?> getClazz()

Returns the loaded Class.

This method must only be called after exactly one of the ICookable.cook(String, java.io.Reader) methods was called.

createInstance

Object createInstance(Reader reader)
               throws CompileException,
                      IOException

Scans, parses and compiles a class body from the tokens delivered by the the given Reader, then creates and returns an instance of that class.

Parameters:

reader - Source of class body tokens

Returns:

An object that extends the optionalExtendedType and implements the given implementedTypes

Throws:

CompileException

IOException