classUtils.javassist.expr
Class ExprEditor

java.lang.Object
  extended by classUtils.javassist.expr.ExprEditor

public class ExprEditor
extends java.lang.Object

A translator of method bodies.

The users can define a subclass of this class to customize how to modify a method body. The overall architecture is similar to the strategy pattern.

If instrument() is called in CtMethod, the method body is scanned from the beginning to the end. Whenever an expression, such as a method call and a new expression (object creation), is found, edit() is called in ExprEdit. edit() can inspect and modify the given expression. The modification is reflected on the original method body. If edit() does nothing, the original method body is not changed.

The following code is an example:

This code inspects all method calls appearing in the method represented by cm and it prints the names and the line numbers of the methods declared in class Point. This code does not modify the body of the method represented by cm. If the method body must be modified, call replace() in MethodCall.

See Also:
CompileTimeClass.instrument(ExprEditor), CtMethod.instrument(ExprEditor), CtConstructor.instrument(ExprEditor), MethodCall, NewExpr, FieldAccess, CodeConverter

Constructor Summary
ExprEditor()
          Default constructor.
 
Method Summary
 boolean doit(CompileTimeClass clazz, MethodInfo minfo)
          Undocumented method.
 void edit(Cast c)
          Edits an expression for explicit type casting (overridable).
 void edit(FieldAccess f)
          Edits a field-access expression (overridable).
 void edit(Handler h)
          Edits a catch clause (overridable).
 void edit(Instanceof i)
          Edits an instanceof expression (overridable).
 void edit(MethodCall m)
          Edits a method call (overridable).
 void edit(NewExpr e)
          Edits a new expression (overridable).
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ExprEditor

public ExprEditor()
Default constructor. It does nothing.

Method Detail

doit

public boolean doit(CompileTimeClass clazz,
                    MethodInfo minfo)
             throws CannotCompileException
Undocumented method. Do not use; internal-use only.

Throws:
CannotCompileException

edit

public void edit(NewExpr e)
          throws CannotCompileException
Edits a new expression (overridable). The default implementation performs nothing.

Parameters:
e - the new expression creating an object.
Throws:
CannotCompileException

edit

public void edit(MethodCall m)
          throws CannotCompileException
Edits a method call (overridable). The default implementation performs nothing.

Throws:
CannotCompileException

edit

public void edit(FieldAccess f)
          throws CannotCompileException
Edits a field-access expression (overridable). Field access means both read and write. The default implementation performs nothing.

Throws:
CannotCompileException

edit

public void edit(Instanceof i)
          throws CannotCompileException
Edits an instanceof expression (overridable). The default implementation performs nothing.

Throws:
CannotCompileException

edit

public void edit(Cast c)
          throws CannotCompileException
Edits an expression for explicit type casting (overridable). The default implementation performs nothing.

Throws:
CannotCompileException

edit

public void edit(Handler h)
          throws CannotCompileException
Edits a catch clause (overridable). The default implementation performs nothing.

Throws:
CannotCompileException