Interface IClassBodyEvaluator

All Superinterfaces:
ICookable
All Known Implementing Classes:
ClassBodyEvaluator, ClassBodyEvaluator

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-cast to that baseType.

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

    • setParentClassLoader

      void setParentClassLoader(@Nullable ClassLoader parentClassLoader)
      The "parent class loader" is used to load referenced classes. Useful values are:
      System.getSystemClassLoader() The running JVM's class path
      Thread.currentThread().getContextClassLoader() or null The class loader effective for the invoking thread
      ClassLoaders.BOOTCLASSPATH_CLASS_LOADER The running JVM's boot class path

      The parent class loader defaults to the current thread's context class loader.

    • setDebuggingInformation

      void setDebuggingInformation(boolean debugSource, boolean debugLines, boolean debugVars)
      Determines what kind of debugging information is included in the generates classes. The default is typically "-g:none".
    • setCompileErrorHandler

      void setCompileErrorHandler(@Nullable ErrorHandler compileErrorHandler)
      Installs an ErrorHandler which is invoked during compilation on each error. (By default, the compilation throws a CompileException on the first error and terminates.)

      If the given ErrorHandler throws a CompileException, then the compilation terminates and the exception is propagated.

      If the given ErrorHandler does not throw a CompileException but completes normally, then the compilation may or may not continue, depending on the error. Iff the compilation completes normally but errors were reported, then it will throw a CompileException indicating the number of errors.

      In other words: The ErrorHandler may throw a CompileException or not, but the compilation will definitely throw a CompileException if one or more compile errors have occurred.

      Parameters:
      compileErrorHandler - null to restore the default behavior (throwing a CompileException)
    • setWarningHandler

      void setWarningHandler(@Nullable WarningHandler warningHandler)
      By default, warnings are discarded, but an application my install a custom WarningHandler.
      Parameters:
      warningHandler - null to indicate that no warnings be issued
    • setDefaultImports

      void setDefaultImports(String... defaultImports)
      "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(
               "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
           );
    • getDefaultImports

      String[] getDefaultImports()
      Returns:
      The default imports that were previously configured with setDefaultImports(String...)
    • 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<?> extendedClass)
      Sets a particular superclass that the generated class will extend. If extendedClass 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<?> extendedClass)
      Deprecated.
    • setImplementedInterfaces

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

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

      Class<?> getClazz()
      Returns:
      The generated Class
      Throws:
      IllegalStateException - This IClassBodyEvaluator is not yet cooked
    • 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 extendedType and implements the given implementedTypes
      Throws:
      CompileException
      IOException