Package gnu.jel

Class OP

java.lang.Object
gnu.jel.OP
Direct Known Subclasses:
OPbinary, OPcall, OPcondtnl, OPload, OPunary
public abstract class OP
extends java.lang.Object
A tree node, representing an operation.

  • Field Summary

    Fields 
    Modifier and Type Field Description
    OP[] chi
    Holds references to children of this node
    int resID
    Holds type ID of the result of this OP
    java.lang.Class<?> resType
    Holds type of the result of this OP
    static java.lang.Class<?>[] specialTypes
    Classes of the special types by ID.
    static byte[] unwrapType
    Unwraps the type ID.

  • Constructor Summary

    Constructors 
    Constructor Description
    OP()  

  • Method Summary

    Modifier and Type Method Description
    abstract void compile​(ClassFile cf)
    Called to generate the code implementing this OP.
    abstract java.lang.Object eval()
    Called to evaluate this node and all its sub-nodes.
    static boolean isWidening​(int id1, java.lang.Class<?> c1, int id2, java.lang.Class<?> c2)
    Used to find out if the conversion t1->t2 is widening.
    static boolean isWidening​(java.lang.Class<?> c1, java.lang.Class<?> c2)
    Used to find out if the conversion t1->t2 is widening.
    protected static java.lang.Object narrow​(java.lang.Number val, int clsID)
    Narrows the value back to desired primitiva type.
    static int typeID​(java.lang.Class<?> c)
    Identifies the primitive type of the given class.
    static int typeIDObject​(java.lang.Object o)
    Identify the primitive type corresponding to the given reflection object.
    protected static java.lang.Number widen​(java.lang.Object o, int clsID)
    Makes widest possible representation of a value of Java primitive type.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • chi

      public OP[] chi
      Holds references to children of this node

    • resID

      public int resID
      Holds type ID of the result of this OP

    • resType

      public java.lang.Class<?> resType
      Holds type of the result of this OP

    • specialTypes

      public static final java.lang.Class<?>[] specialTypes
      Classes of the special types by ID.

      The frequently used types (those on which many operations are defined) are identified by an integer number. The advantage is the possibility to have almost completely table driven code generator.

      So, the special types are only special in the fact that except of the reference to their class object they are also identified by an integer number.

    • unwrapType

      public static final byte[] unwrapType
      Unwraps the type ID.

      That is all special types which are references are translated into 8.

  • Constructor Details

    • OP

      public OP()

  • Method Details

    • eval

      public abstract java.lang.Object eval() throws java.lang.Exception
      Called to evaluate this node and all its sub-nodes.

      Upon success this node is to be replaced by the constant node holding the returned object.

      Returns:
      an object to which this node evaluates
      Throws:
      java.lang.Exception

    • compile

      public abstract void compile​(ClassFile cf)
      Called to generate the code implementing this OP.
      Parameters:
      cf - class file with a new open method to write the code into.

    • typeID

      public static final int typeID​(java.lang.Class<?> c)
      Identifies the primitive type of the given class.
      Parameters:
      c - class to identify.
      Returns:
      id of the corresponding primitive type.

    • typeIDObject

      public static final int typeIDObject​(java.lang.Object o)
      Identify the primitive type corresponding to the given reflection object.
      Parameters:
      o - object to identify.
      Returns:
      id of the corresponding primitive type.

    • isWidening

      public static boolean isWidening​(int id1, java.lang.Class<?> c1, int id2, java.lang.Class<?> c2)
      Used to find out if the conversion t1->t2 is widening.
      Parameters:
      id1 - type ID to convert from
      c1 - class to convert from (used if id1==8)
      id2 - type ID to convert to
      c2 - class to convert to (used if id2==8)
      Returns:
      true if the given conversion is widening (can be done automatically)

    • isWidening

      public static boolean isWidening​(java.lang.Class<?> c1, java.lang.Class<?> c2)
      Used to find out if the conversion t1->t2 is widening.
      Parameters:
      c1 - class to convert from (used if id1==8)
      c2 - class to convert to (used if id2==8)
      Returns:
      true if the given conversion is widening (can be done automatically)

    • widen

      protected static java.lang.Number widen​(java.lang.Object o, int clsID)
      Makes widest possible representation of a value of Java primitive type.
      Parameters:
      o - reflection object, containing value to represent.
      clsID - ID of a type of this reflection object (to save lookup).
      Returns:
      Number, representing the given value.

    • narrow

      protected static java.lang.Object narrow​(java.lang.Number val, int clsID)
      Narrows the value back to desired primitiva type.
      Parameters:
      val - reflection object, containing value to narrow.
      clsID - ID of a type to narrow the given object into.
      Returns:
      narrowed reflection object.