/*
 * TclException.java --
 *
 *	This file defines the TclException class used by Tcl to report
 *	generic script-level errors and exceptions.
 *
 * Copyright (c) 1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and
 * redistribution of this file, and for a DISCLAIMER OF ALL
 * WARRANTIES.
 * 
 * RCS: @(#) $Id: TclException.java,v 1.2 2000/04/03 14:09:11 mo Exp $
 *
 */

package tcl.lang;

/*
 * TclException is used to interrupt the Tcl script currently being
 * interpreted by the Tcl Interpreter. Usually, a TclException is thrown
 * to indicate a script level error, e.g.:
 *
 *	- A syntax error occurred in a script.
 *	- A unknown variable is referenced.
 *	- A unknown command is executed.
 *	- A command is passed incorrected.
 *
 * A TclException can also be thrown by Tcl control structure commands such
 * as "return" and "continue" to change the flow of control in
 * a Tcl script.
 *
 * A TclException is accompanied by two pieces of information: the error
 * message and the completion code. The error message is a string stored in
 * the interpreter result. After a TclException is thrown and caught, the
 * error message can be queried by Interp.getResult().
 *
 * The completion code indicates why the TclException is generated. It is
 * stored in the compCode field of this class.
 */

public class TclException extends Exception {

/*
 * Stores the completion code of a TclException.
 */

private int compCode;

/*
 * An index that indicates where an error occurs inside a Tcl
 * string. This is used to add the offending command into the stack
 * trace.
 *
 * A negative value means the location of the index is unknown.
 *
 * Currently this field is used only by the Jacl interpreter.
 */

protected int errIndex;


/*
 *----------------------------------------------------------------------
 *
 * TclException --
 *
 *	Create an TclException with the given error message and
 *	completion code and indicate the location of the error in a
 *	script.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The instance fields are initialized; the message is assigned to
 *	the interpreter's result if interp is non-null.
 *
 *----------------------------------------------------------------------
 */

protected
TclException(
    Interp interp,		// Current interpreter. May be null if unknown.
    String msg,			// Error message.
    int ccode,			// Completion code.
    int idx) 			// Error index.
{
    super(msg);
    if (ccode == TCL.OK) {
	throw new TclRuntimeError(
		"The reserved completion code TCL.OK (0) cannot be used " +
		"in TclException");
    }
    compCode = ccode;
    errIndex = idx;

    if (interp != null && msg != null) {
	interp.setResult(msg);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclException --
 *
 *	Create a TclException with the given completion code.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The instance fields are initialized.
 *
 *----------------------------------------------------------------------
 */

public
TclException(
    int ccode)			// Completion code.
{
    super();
    if (ccode == TCL.OK) {
	throw new TclRuntimeError(
		"The reserved completion code TCL.OK (0) cannot be used");
    }
    compCode = ccode;
    errIndex = -1;
}

/*
 *----------------------------------------------------------------------
 *
 * TclException --
 *
 *	Create an TclException with the given error message. The
 *	completion code is set to ERROR by default.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The instance fields are initialized; the message is assigned to
 *	the interpreter's result if interp is non-null.
 *
 *----------------------------------------------------------------------
 */

public
TclException(
    Interp interp,		// Current interpreter. May be null if unknown.
    String msg)			// Error message.
{
    this(interp, msg, TCL.ERROR, -1);
}

/*
 *----------------------------------------------------------------------
 *
 * TclException --
 *
 *	Create an TclException with the given error message and
 *	completion code.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The instance fields are initialized; the message is assigned to
 *	the interpreter's result if interp is non-null.
 *
 *----------------------------------------------------------------------
 */

public
TclException(
    Interp interp,		// Current interpreter. May be null if unknown.
    String msg,			// Error message.
    int ccode)			// Completion code.
{
    this(interp, msg, ccode, -1);
}

/*
 *----------------------------------------------------------------------
 *
 * getCompletionCode --
 *
 *	Returns the current completion code.
 *
 * Results:
 *	The int value of compCode.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

final public int 
getCompletionCode() 
{
    return compCode;
}

/*
 *----------------------------------------------------------------------
 *
 * setCompletionCode --
 *
 *	Sets the current completion code.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The completion code is changed.
 *
 *----------------------------------------------------------------------
 */

final void
setCompletionCode(
    int ccode)			// New completion code. 
{
    if (ccode == TCL.OK) {
	throw new TclRuntimeError(
		"The reserved completion code TCL.OK (0) cannot be used");
    }
    compCode = ccode;
}

} // end TclException

