// Copyright 2000-2005 the Contributors, as shown in the revision logs.
// Licensed under the Apache Public Source License 2.0 ("the License").
// You may not use this file except in compliance with the License.

package org.ibex.js;

/**
 *  Constants for the various JavaScript ByteCode operations.
 *
 *  Each instruction is an opcode and an optional literal literal;
 *  some Tokens are also valid; see Tokens.java
 */
interface ByteCodes {

    /** push the literal onto the stack */
    public static final byte LITERAL = -2;

    /** push a new array onto the stack with length equal to the literal */
    public static final byte ARRAY = -3;         

    /** push an empty object onto the stack */
    public static final byte OBJECT = -4;        

    /** create a new instance; literal is a reference to the corresponding ForthBlock */
    public static final byte NEWFUNCTION = -5;      

    /** if given a non-null argument declare its argument in the current scope and push
        it to the stack, else, declares the element on the top of the stack and leaves it
        there */
    //public static final byte DECLARE = -6;       

    /** push a reference to the current scope onto the stack */
    public static final byte GLOBALSCOPE = -7;

    /** if given a null literal pop two elements off the stack; push stack[-1].get(stack[top])
        else pop one element off the stack, push stack[top].get(literal) */
    public static final byte GET = -8;           

    /** push stack[-1].get(stack[top]) */
    public static final byte GET_PRESERVE = -9; 

    /** pop two elements off the stack; stack[-2].put(stack[-1], stack[top]); push stack[top] */
    public static final byte PUT = -10;           

    /** literal is a relative address; pop stacktop and jump if the value is true */
    public static final byte JT = -11;           

    /** literal is a relative address; pop stacktop and jump if the value is false */
    public static final byte JF = -12;           

    /** literal is a relative address; jump to it */
    public static final byte JMP = -13;          

    /** discard the top stack element */
    static public final byte POP = -14;          

    /** pop element; call stack[top](stack[-n], stack[-n+1]...) where n is the number of args to the function */
    public static final byte CALL = -15;         

    /** pop an element; push a JS.JSArray containing the keys of the popped element */
    public static final byte PUSHKEYS = -16;     

    /** push the top element down so that (arg) elements are on top of it; all other elements retain ordering */
    public static final byte SWAP = -17;         

    /** execute the bytecode block pointed to by the literal in a fresh scope with parentScope==THIS */
    public static final byte NEWSCOPE = -18;        

    /** execute the bytecode block pointed to by the literal in a fresh scope with parentScope==THIS */
    public static final byte OLDSCOPE = -19;

    /** push a copy of the top stack element */
    public static final byte DUP = -20;          

    /** a NOP; confers a label upon the following instruction */
    public static final byte LABEL = -21;          

    /** execute the ForthBlock pointed to by the literal until BREAK encountered; push TRUE onto the stack for the first iteration
     *  and FALSE for all subsequent iterations */
    public static final byte LOOP = -22;        
     
    /** similar effect a a GET followed by a CALL */
    public static final byte CALLMETHOD = -23;

    /** finish a finally block and carry out whatever instruction initiated the finally block */
    public static final byte FINALLY_DONE = -24;
    
    /** finish a finally block and carry out whatever instruction initiated the finally block */
    public static final byte MAKE_GRAMMAR = -25;
    
    // FEATURE: Document these and NEWSCOPE/OLDSCOPE/TOPSCOPE changes
    public static final byte SCOPEGET = -26;
    public static final byte SCOPEPUT = -27;    
    
    public static final String[] bytecodeToString = new String[] {
        "", "", "LITERAL", "ARRAY", "OBJECT", "NEWFUNCTION", "DECLARE", "GLOBALSCOPE",
        "GET", "GET_PRESERVE", "PUT", "JT", "JF", "JMP", "POP", "CALL", "PUSHKEYS",
        "SWAP", "NEWSCOPE", "OLDSCOPE", "DUP", "LABEL", "LOOP", "CALLMETHOD",
        "FINALLY_DONE", "MAKE_GRAMMAR", "SCOPEGET", "SCOPEPUT"
    };
}