/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* JFlex 1.4.3 *
* Copyright (C) 1998-2009 Gerwin Klein <lsf@jflex.de> *
* All rights reserved. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License. See the file *
* COPYRIGHT for more information. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License along *
* with this program; if not, write to the Free Software Foundation, Inc., *
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
* *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
package JFlex;
/**
* Encapsulates an action in the specification.
*
* It stores the Java code as String together with a priority (line number in the specification).
*
* @author Gerwin Klein
* @version JFlex 1.4.3, $Revision: 433 $, $Date: 2009-01-31 19:52:34 +1100 (Sat, 31 Jan 2009) $
*/
final public class Action {
/** A normal action */
public final static int NORMAL = 0;
/** Action of a lookahead expression r1/r2 with fixed length r1 */
public final static int FIXED_BASE = 1;
/** Action of a lookahead expression r1/r2 with fixed length r2 */
public final static int FIXED_LOOK = 2;
/** Action of a lookahead expression r1/r2 with a finite choice of
* fixed lengths in r2 */
public final static int FINITE_CHOICE = 3;
/** Action of a general lookahead expression */
public final static int GENERAL_LOOK = 4;
/** Action of the 2nd forward pass for lookahead */
public final static int FORWARD_ACTION = 5;
/** Action of the backward pass for lookahead */
public final static int BACKWARD_ACTION = 6;
/**
* The Java code this Action represents
*/
String content;
/**
* The priority (i.e. line number in the specification) of this Action.
*/
int priority;
/**
* Which kind of action this is.
* (normal, <code>a/b</code> with fixed length a, fixed length b, etc)
*/
private int kind = NORMAL;
/** The length of the lookahead (if fixed) */
private int len;
/** The entry state of the corresponding forward DFA (if general lookahead) */
private int entryState;
/**
* Creates a new Action object with specified content and line number.
*
* @param content java code
* @param priority line number
*/
public Action(String content, int priority) {
this.content = content.trim();
this.priority = priority;
}
/**
* Creates a new Action object of the specified kind. Only
* accepts FORWARD_ACTION or BACKWARD_ACTION.
*
* @param kind the kind of action
*
* @see #FORWARD_ACTION
* @see #BACKWARD_ACTION
*/
public Action(int kind) {
if (kind != FORWARD_ACTION && kind != BACKWARD_ACTION)
throw new GeneratorException();
this.content = "";
this.priority = Integer.MAX_VALUE;
this.kind = kind;
}
/**
* Compares the priority value of this Action with the specified action.
*
* @param other the other Action to compare this Action with.
*
* @return this Action if it has higher priority - the specified one, if not.
*/
public Action getHigherPriority(Action other) {
if (other == null) return this;
// the smaller the number the higher the priority
if (other.priority > this.priority)
return this;
else
return other;
}
/**
* Returns the String representation of this object.
*
* @return string representation of the action
*/
public String toString() {
return "Action (priority "+priority+", lookahead "+kind+") :" +
Out.NL+content; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
}
/**
* Returns <code>true</code> iff the parameter is an
* Action with the same content as this one.
*
* @param a the object to compare this Action with
* @return true if the action strings are equal
*/
public boolean isEquiv(Action a) {
return this == a ||
(this.content.equals(a.content) &&
this.kind == a.kind &&
this.len == a.len &&
this.entryState == a.entryState);
}
/**
* Calculate hash value.
*
* @return a hash value for this Action
*/
public int hashCode() {
return content.hashCode();
}
/**
* Test for equality to another object.
*
* This action equals another object if the other
* object is an equivalent action.
*
* @param o the other object.
*
* @see Action#isEquiv(Action)
*/
public boolean equals(Object o) {
if (o instanceof Action)
return isEquiv((Action) o);
else
return false;
}
/**
* Return true iff this is action belongs to a general lookahead rule.
*
* @return true if this actions belongs to a general lookahead rule.
*/
public boolean isGenLookAction() {
return kind == GENERAL_LOOK;
}
/**
* Return true if code for this is action should be emitted, false
* if it is a BACK/FORWARD lookahead action.
*
* @return true if code should be emitted for this action.
*/
public boolean isEmittable() {
return kind != BACKWARD_ACTION && kind != FORWARD_ACTION;
}
/**
* Return kind of lookahead.
*/
public int lookAhead() {
return kind;
}
/**
* Sets the lookahead kind and data for this action
*
* @param kind which kind of lookahead it is
* @param data the length for fixed length look aheads.
*
*/
public void setLookAction(int kind, int data) {
this.kind = kind;
this.len = data;
}
/**
* The length of the lookahead or base if this is a fixed length
* lookahead action.
*/
public int getLookLength() {
return len;
}
/**
* Return the corresponding entry state for the forward DFA (if this
* is a general lookahead expression)
*
* @return the forward DFA entry state (+1 is the backward DFA)
*/
public int getEntryState() {
return entryState;
}
/**
* Set the corresponding entry state for the forward DFA of this action
* (if this is a general lookahead expression)
*
* @param the entry state for the forward DFA of this action
*/
public void setEntryState(int entryState) {
this.entryState = entryState;
}
public Action copyChoice(int length) {
Action a = new Action(this.content, this.priority);
a.setLookAction(FINITE_CHOICE, length);
return a;
}
/**
* String representation of the lookahead kind of this action.
*
* @return the string representation
*/
public String lookString() {
switch (kind) {
case NORMAL: return "";
case BACKWARD_ACTION: return "LOOK_BACK";
case FIXED_BASE: return "FIXED_BASE";
case FIXED_LOOK: return "FIXED_LOOK";
case FINITE_CHOICE: return "FINITE_CHOICE";
case FORWARD_ACTION: return "LOOK_FORWARD";
case GENERAL_LOOK: return "LOOK_ACTION";
default: return "unknown lookahead type";
}
}
}