// 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;
import org.ibex.util.*;

/** A JavaScript function, compiled into bytecode */
class JSFunction extends JS.Immutable implements ByteCodes, Tokens, Pausable {
    private static final JS[] emptyArgs = new JS[0];

    // Fields and Accessors ///////////////////////////////////////////////

    int numFormalArgs = 0;         ///< the number of formal arguments

    String sourceName;             ///< the source code file that this block was drawn from
    private int firstLine = -1;    ///< the first line of this script

    int[] line = new int[10];      ///< the line numbers
    int[] op = new int[10];        ///< the instructions
    Object[] arg = new Object[10]; ///< the arguments to the instructions
    int size = 0;                  ///< the number of instruction/argument pairs

    JSScope parentScope;           ///< the default scope to use as a parent scope when executing this


    // Public //////////////////////////////////////////////////////////////////////////////

    private Interpreter runner = null;
    public Object run(Object o) throws JSExn {
        if (runner == null) runner = new Interpreter(this, true, emptyArgs);
        Object ret = runner.run(o);
        if (runner.f == null) runner = null;
        return ret;
    }
    public void pause() throws NotPausableException {
        if (runner == null) throw new NotPausableException();
        runner.pause();
    }

    public JSFunction _cloneWithNewParentScope(JSScope s) {
        JSFunction ret = new JSFunction(sourceName, firstLine, s);
        // Reuse the same op, arg, line, and size variables for the new "instance" of the function
        // NOTE: Neither *this* function nor the new function should be modified after this call
        ret.op = this.op;
        ret.arg = this.arg;
        ret.line = this.line;
        ret.size = this.size;
        ret.numFormalArgs = this.numFormalArgs;
        return ret;
    }

    public JS call(JS method, JS[] args) throws JSExn {
        if (method != null) return super.call(method, args);
        return (JS)new Interpreter(this, false, args).run(null); }

    JSScope getParentScope() { return parentScope; }

    // Adding and Altering Bytecodes ///////////////////////////////////////////////////

    JSFunction(String sourceName, int firstLine, JSScope parentScope) {
        this.sourceName = sourceName;
        this.firstLine = firstLine;
        this.parentScope = parentScope;
    }

    int get(int pos) { return op[pos]; }
    Object getArg(int pos) { return arg[pos]; }
    void set(int pos, int op_, Object arg_) { op[pos] = op_; arg[pos] = arg_; }
    void set(int pos, Object arg_) { arg[pos] = arg_; }
    int pop() { size--; arg[size] = null; return op[size]; }
    void paste(JSFunction other) { for(int i=0; i<other.size; i++) add(other.line[i], other.op[i], other.arg[i]); }
    JSFunction add(int line, int op_) { return add(line, op_, null); }
    JSFunction add(int line, int op_, Object arg_) {
        if (size == op.length - 1) {
            int[] line2 = new int[op.length * 2]; System.arraycopy(this.line, 0, line2, 0, op.length); this.line = line2;
            Object[] arg2 = new Object[op.length * 2]; System.arraycopy(arg, 0, arg2, 0, arg.length); arg = arg2;
            int[] op2 = new int[op.length * 2]; System.arraycopy(op, 0, op2, 0, op.length); op = op2;
        }
        this.line[size] = line;
        op[size] = op_;
        arg[size] = arg_;
        size++;
        return this;
    }
    

    // Debugging //////////////////////////////////////////////////////////////////////

    String extendedToString() { return "[" + sourceName + ":" + firstLine + "]"; }

    String dump() { return dump(""); }
    private  String dump(String prefix) {
        StringBuffer sb = new StringBuffer(1024);
        sb.append("\n" + sourceName + ": " + firstLine + "\n");
        for (int i=0; i < size; i++) {
            sb.append(prefix);
            sb.append(i).append(" (").append(line[i]).append("): ");
            if (op[i] < 0) sb.append(bytecodeToString[-op[i]]);
            else sb.append(codeToString[op[i]]);
            sb.append(" ");
            sb.append(arg[i] == null ? "(no arg)" : arg[i] instanceof JS ? JSU.str((JS)arg[i]) : arg[i]);
            if((op[i] == JF || op[i] == JT || op[i] == JMP) && arg[i] != null && arg[i] instanceof Number) {
                sb.append(" jump to ").append(i+((Number) arg[i]).intValue());
            } else  if(op[i] == TRY) {
                int[] jmps = (int[]) arg[i];
                sb.append(" catch: ").append(jmps[0] < 0 ? "No catch block" : ""+(i+jmps[0]));
                sb.append(" finally: ").append(jmps[1] < 0 ? "No finally block" : ""+(i+jmps[1]));
            } else if(op[i] == NEWFUNCTION) {
                sb.append(((JSFunction) arg[i]).dump(prefix + "     "));
            } else if(op[i] == NEWSCOPE) {
                int n = ((JSNumber)arg[i]).toInt();
                sb.append(" base: " + (n>>>16) + " size: " + (n&0xffff));
            }
            sb.append("\n");
        }
        return sb.toString();
    } 


}