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:
  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-casted 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 Details

  • Method Details

    • setDefaultImports

      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.

      Notice that JDK 5 "static imports" are also supported, as shown in the following example.

      Example:

           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)
      Set 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(Class optionalExtendedClass)
      Set a particular superclass that the generated class will extend. If null is passed, the generated class will extend Object.

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

    • setExtendedType

      @Deprecated void setExtendedType(Class optionalExtendedClass)
      Deprecated.
    • setImplementedInterfaces

      void setImplementedInterfaces(Class[] implementedInterfaces)
      Set a particular set of interfaces that the generated class will implement.
    • setImplementedTypes

      @Deprecated void setImplementedTypes(Class[] implementedInterfaces)
      Deprecated.
    • 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