org.mozilla.javascript.Arguments Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of rhino Show documentation
The Rhino JavaScript Engine for Java
The newest version!
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.javascript;

/**
 * This class implements the "arguments" object.
 *
 * See ECMA 10.1.8
 *
 * @see org.mozilla.javascript.NativeCall
 * @author Norris Boyd
 */
final class Arguments extends IdScriptableObject
{
    static final long serialVersionUID = 4275508002492040609L;

    private static final String FTAG = "Arguments";

    public Arguments(NativeCall activation)
    {
        this.activation = activation;

        Scriptable parent = activation.getParentScope();
        setParentScope(parent);
        setPrototype(ScriptableObject.getObjectPrototype(parent));

        args = activation.originalArgs;
        lengthObj = Integer.valueOf(args.length);

        NativeFunction f = activation.function;
        calleeObj = f;

        int version = f.getLanguageVersion();
        if (version <= Context.VERSION_1_3
            && version != Context.VERSION_DEFAULT)
        {
            callerObj = null;
        } else {
            callerObj = NOT_FOUND;
        }
    }

    @Override
    public String getClassName()
    {
        return FTAG;
    }

    private Object arg(int index) {
      if (index < 0 || args.length <= index) return NOT_FOUND;
      return args[index];
    }

    // the following helper methods assume that 0 < index < args.length

    private void putIntoActivation(int index, Object value) {
        String argName = activation.function.getParamOrVarName(index);
        activation.put(argName, activation, value);
    }

    private Object getFromActivation(int index) {
        String argName = activation.function.getParamOrVarName(index);
        return activation.get(argName, activation);
    }

    private void replaceArg(int index, Object value) {
      if (sharedWithActivation(index)) {
        putIntoActivation(index, value);
      }
      synchronized (this) {
        if (args == activation.originalArgs) {
          args = args.clone();
        }
        args[index] = value;
      }
    }

    private void removeArg(int index) {
      synchronized (this) {
        if (args[index] != NOT_FOUND) {
          if (args == activation.originalArgs) {
            args = args.clone();
          }
          args[index] = NOT_FOUND;
        }
      }
    }

    // end helpers

    @Override
    public boolean has(int index, Scriptable start)
    {
        if (arg(index) != NOT_FOUND) {
          return true;
        }
        return super.has(index, start);
    }

    @Override
    public Object get(int index, Scriptable start)
    {
      final Object value = arg(index);
      if (value == NOT_FOUND) {
        return super.get(index, start);
      } else {
        if (sharedWithActivation(index)) {
          return getFromActivation(index);
        } else {
          return value;
        }
      }
    }

    private boolean sharedWithActivation(int index)
    {
        NativeFunction f = activation.function;
        int definedCount = f.getParamCount();
        if (index < definedCount) {
            // Check if argument is not hidden by later argument with the same
            // name as hidden arguments are not shared with activation
            if (index < definedCount - 1) {
                String argName = f.getParamOrVarName(index);
                for (int i = index + 1; i < definedCount; i++) {
                    if (argName.equals(f.getParamOrVarName(i))) {
                        return false;
                    }
                }
            }
            return true;
        }
        return false;
    }

    @Override
    public void put(int index, Scriptable start, Object value)
    {
        if (arg(index) == NOT_FOUND) {
          super.put(index, start, value);
        } else {
          replaceArg(index, value);
        }
    }

    @Override
    public void delete(int index)
    {
        if (0 <= index && index < args.length) {
          removeArg(index);
        }
        super.delete(index);
    }

// #string_id_map#

    private static final int
        Id_callee           = 1,
        Id_length           = 2,
        Id_caller           = 3,

        MAX_INSTANCE_ID     = Id_caller;

    @Override
    protected int getMaxInstanceId()
    {
        return MAX_INSTANCE_ID;
    }

    @Override
    protected int findInstanceIdInfo(String s)
    {
        int id;
// #generated# Last update: 2010-01-06 05:48:21 ARST
        L0: { id = 0; String X = null; int c;
            int s_length = s.length();
            if (s_length==6) {
                c=s.charAt(5);
                if (c=='e') { X="callee";id=Id_callee; }
                else if (c=='h') { X="length";id=Id_length; }
                else if (c=='r') { X="caller";id=Id_caller; }
            }
            if (X!=null && X!=s && !X.equals(s)) id = 0;
            break L0;
        }
// #/generated#

        if (id == 0) return super.findInstanceIdInfo(s);

        int attr;
        switch (id) {
          case Id_callee:
            attr = calleeAttr;
            break;
          case Id_caller:
            attr = callerAttr;
            break;
          case Id_length:
            attr = lengthAttr;
            break;
          default: throw new IllegalStateException();
        }
        return instanceIdInfo(attr, id);
    }

// #/string_id_map#

    @Override
    protected String getInstanceIdName(int id)
    {
        switch (id) {
            case Id_callee: return "callee";
            case Id_length: return "length";
            case Id_caller: return "caller";
        }
        return null;
    }

    @Override
    protected Object getInstanceIdValue(int id)
    {
        switch (id) {
            case Id_callee: return calleeObj;
            case Id_length: return lengthObj;
            case Id_caller: {
                Object value = callerObj;
                if (value == UniqueTag.NULL_VALUE) { value = null; }
                else if (value == null) {
                    NativeCall caller = activation.parentActivationCall;
                    if (caller != null) {
                        value = caller.get("arguments", caller);
                    }
                }
                return value;
            }
        }
        return super.getInstanceIdValue(id);
    }

    @Override
    protected void setInstanceIdValue(int id, Object value)
    {
        switch (id) {
            case Id_callee: calleeObj = value; return;
            case Id_length: lengthObj = value; return;
            case Id_caller:
                callerObj = (value != null) ? value : UniqueTag.NULL_VALUE;
                return;
        }
        super.setInstanceIdValue(id, value);
    }

    @Override
    protected void setInstanceIdAttributes(int id, int attr)
    {
        switch (id) {
            case Id_callee: calleeAttr = attr; return;
            case Id_length: lengthAttr = attr; return;
            case Id_caller: callerAttr = attr; return;
        }
        super.setInstanceIdAttributes(id, attr);
    }

    @Override
    Object[] getIds(boolean getAll)
    {
        Object[] ids = super.getIds(getAll);
        if (args.length != 0) {
            boolean[] present = new boolean[args.length];
            int extraCount = args.length;
            for (int i = 0; i != ids.length; ++i) {
                Object id = ids[i];
                if (id instanceof Integer) {
                    int index = ((Integer)id).intValue();
                    if (0 <= index && index < args.length) {
                        if (!present[index]) {
                            present[index] = true;
                            extraCount--;
                        }
                    }
                }
            }
            if (!getAll) { // avoid adding args which were redefined to non-enumerable
              for (int i = 0; i < present.length; i++) {
                if (!present[i] && super.has(i, this)) {
                  present[i] = true;
                  extraCount--;
                }
              }
            }
            if (extraCount != 0) {
                Object[] tmp = new Object[extraCount + ids.length];
                System.arraycopy(ids, 0, tmp, extraCount, ids.length);
                ids = tmp;
                int offset = 0;
                for (int i = 0; i != args.length; ++i) {
                    if (present == null || !present[i]) {
                        ids[offset] = Integer.valueOf(i);
                        ++offset;
                    }
                }
                if (offset != extraCount) Kit.codeBug();
            }
        }
        return ids;
    }

    @Override
    protected ScriptableObject getOwnPropertyDescriptor(Context cx, Object id) {
      double d = ScriptRuntime.toNumber(id);
      int index = (int) d;
      if (d != index) {
        return super.getOwnPropertyDescriptor(cx, id);
      }
      Object value = arg(index);
      if (value == NOT_FOUND) {
        return super.getOwnPropertyDescriptor(cx, id);
      }
      if (sharedWithActivation(index)) {
        value = getFromActivation(index);
      }
      if (super.has(index, this)) { // the descriptor has been redefined
        ScriptableObject desc = super.getOwnPropertyDescriptor(cx, id);
        desc.put("value", desc, value);
        return desc;
      } else {
        Scriptable scope = getParentScope();
        if (scope == null) scope = this;
        return buildDataDescriptor(scope, value, EMPTY);
      }
    }

    @Override
    protected void defineOwnProperty(Context cx, Object id,
                                     ScriptableObject desc,
                                     boolean checkValid) {
      super.defineOwnProperty(cx, id, desc, checkValid);

      double d = ScriptRuntime.toNumber(id);
      int index = (int) d;
      if (d != index) return;

      Object value = arg(index);
      if (value == NOT_FOUND) return;

      if (isAccessorDescriptor(desc)) {
        removeArg(index);
        return;
      }

      Object newValue = getProperty(desc, "value");
      if (newValue == NOT_FOUND) return;

      replaceArg(index, newValue);

      if (isFalse(getProperty(desc, "writable"))) {
        removeArg(index);
      }
    }

// Fields to hold caller, callee and length properties,
// where NOT_FOUND value tags deleted properties.
// In addition if callerObj == NULL_VALUE, it tags null for scripts, as
// initial callerObj == null means access to caller arguments available
// only in JS <= 1.3 scripts
    private Object callerObj;
    private Object calleeObj;
    private Object lengthObj;

    private int callerAttr = DONTENUM;
    private int calleeAttr = DONTENUM;
    private int lengthAttr = DONTENUM;

    private NativeCall activation;

// Initially args holds activation.getOriginalArgs(), but any modification
// of its elements triggers creation of a copy. If its element holds NOT_FOUND,
// it indicates deleted index, in which case super class is queried.
    private Object[] args;
}