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/*
* Environment.java
*
* Copyright (C) 2002-2006 Peter Graves
* $Id$
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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.
*
* As a special exception, the copyright holders of this library give you
* permission to link this library with independent modules to produce an
* executable, regardless of the license terms of these independent
* modules, and to copy and distribute the resulting executable under
* terms of your choice, provided that you also meet, for each linked
* independent module, the terms and conditions of the license of that
* module. An independent module is a module which is not derived from
* or based on this library. If you modify this library, you may extend
* this exception to your version of the library, but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*/
package org.armedbear.lisp;
import java.io.Serializable;
import static org.armedbear.lisp.Lisp.*;
public final class Environment extends LispObject implements Serializable
{
Binding vars;
FunctionBinding lastFunctionBinding;
private Binding blocks;
private Binding tags;
public boolean inactive; //default value: false == active
public Environment() {}
public Environment(Environment parent)
{
if (parent != null)
{
vars = parent.vars;
lastFunctionBinding = parent.lastFunctionBinding;
blocks = parent.blocks;
tags = parent.tags;
}
}
// Construct a new Environment extending parent with the specified symbol-
// value binding.
public Environment(Environment parent, Symbol symbol, LispObject value)
{
this(parent);
vars = new Binding(symbol, value, vars);
}
@Override
public LispObject typeOf()
{
return Symbol.ENVIRONMENT;
}
@Override
public LispObject classOf()
{
return BuiltInClass.ENVIRONMENT;
}
@Override
public LispObject typep(LispObject type)
{
if (type == Symbol.ENVIRONMENT)
return T;
if (type == BuiltInClass.ENVIRONMENT)
return T;
return super.typep(type);
}
public boolean isEmpty()
{
if (lastFunctionBinding != null)
return false;
if (vars != null)
{
for (Binding binding = vars; binding != null; binding = binding.next)
if (!binding.specialp)
return false;
}
return true;
}
public void bind(Symbol symbol, LispObject value)
{
vars = new Binding(symbol, value, vars);
}
public void rebind(Symbol symbol, LispObject value)
{
Binding binding = getBinding(symbol);
binding.value = value;
}
public LispObject lookup(LispObject symbol, Binding binding) {
while (binding != null) {
if (binding.symbol == symbol)
return binding.value;
binding = binding.next;
}
return null;
}
public LispObject lookup(LispObject symbol)
{
return lookup(symbol, vars);
}
public Binding getBinding(LispObject symbol) {
return getBinding(symbol, vars);
}
public Binding getBinding(LispObject symbol, Binding binding) {
while (binding != null) {
if (binding.symbol == symbol)
return binding;
binding = binding.next;
}
return null;
}
// Function bindings.
public void addFunctionBinding(LispObject name, LispObject value)
{
lastFunctionBinding =
new FunctionBinding(name, value, lastFunctionBinding);
}
public LispObject lookupFunction(LispObject name)
{
FunctionBinding binding = lastFunctionBinding;
if (name instanceof Symbol)
{
while (binding != null)
{
if (binding.name == name)
return binding.value;
binding = binding.next;
}
// Not found in environment.
return name.getSymbolFunction();
}
if (name instanceof Cons)
{
while (binding != null)
{
if (binding.name.equal(name))
return binding.value;
binding = binding.next;
}
}
return null;
}
public void addBlock(LispObject symbol, LispObject block)
{
blocks = new Binding(symbol, this, block, blocks);
}
public LispObject lookupBlock(LispObject symbol)
{
Binding binding = blocks;
while (binding != null)
{
if (binding.symbol == symbol)
return binding.value;
binding = binding.next;
}
return null;
}
public Binding getBlockBinding(LispObject block)
{
Binding binding = blocks;
while (binding != null)
{
if (binding.symbol == block)
return binding;
binding = binding.next;
}
return null;
}
public void addTagBinding(LispObject tag, LispObject code)
{
tags = new Binding(tag, this, code, tags);
}
public Binding getTagBinding(LispObject tag)
{
Binding binding = tags;
while (binding != null)
{
if (binding.symbol.eql(tag))
return binding;
binding = binding.next;
}
return null;
}
// Returns body with declarations removed.
public LispObject processDeclarations(LispObject body)
{
LispObject bodyAndDecls = parseBody(body, false);
LispObject specials = parseSpecials(bodyAndDecls.NTH(1));
for (; specials != NIL; specials = specials.cdr())
declareSpecial(checkSymbol(specials.car()));
return bodyAndDecls.car();
}
public void declareSpecial(Symbol var)
{
vars = new Binding(var, null, vars);
vars.specialp = true;
}
/** Return true if a symbol is declared special.
*
* If there is no binding in the current (lexical) environment,
* the current dynamic environment (thread) is checked.
*/
public boolean isDeclaredSpecial(Symbol var)
{
Binding binding = getBinding(var);
return (binding != null) ? binding.specialp :
(LispThread.currentThread().getSpecialBinding(var) != null);
}
@Override
public String printObject()
{
return unreadableString("ENVIRONMENT");
}
// ### make-environment
public static final Primitive MAKE_ENVIRONMENT =
new Primitive("make-environment", PACKAGE_SYS, true,
"&optional parent-environment")
{
@Override
public LispObject execute()
{
return new Environment();
}
@Override
public LispObject execute(LispObject arg)
{
if (arg == NIL)
return new Environment();
return new Environment(checkEnvironment(arg));
}
};
// ### environment-add-macro-definition
public static final Primitive ENVIRONMENT_ADD_MACRO_DEFINITION =
new Primitive("environment-add-macro-definition", PACKAGE_SYS, true,
"environment name expander")
{
@Override
public LispObject execute(LispObject first, LispObject second,
LispObject third)
{
Environment env = checkEnvironment(first);
LispObject name = second;
LispObject expander = third;
env.addFunctionBinding(name, expander);
return env;
}
};
// ### environment-add-function-definition
public static final Primitive ENVIRONMENT_ADD_FUNCTION_DEFINITION =
new Primitive("environment-add-function-definition", PACKAGE_SYS, true,
"environment name lambda-expression")
{
@Override
public LispObject execute(LispObject first, LispObject second,
LispObject third)
{
checkEnvironment(first).addFunctionBinding(second, third);
return first;
}
};
// ### environment-add-symbol-binding
public static final Primitive ENVIRONMENT_ADD_SYMBOL_BINDING =
new Primitive("environment-add-symbol-binding", PACKAGE_SYS, true,
"environment symbol value")
{
@Override
public LispObject execute(LispObject first, LispObject second,
LispObject third)
{
checkEnvironment(first).bind(checkSymbol(second), third);
return first;
}
};
// ### empty-environment-p
private static final Primitive EMPTY_ENVIRONMENT_P =
new Primitive("empty-environment-p", PACKAGE_SYS, true, "environment")
{
@Override
public LispObject execute(LispObject arg)
{
return checkEnvironment(arg).isEmpty() ? T : NIL;
}
};
// ### environment-variables
private static final Primitive ENVIRONMENT_VARS =
new Primitive("environment-variables", PACKAGE_SYS, true, "environment")
{
@Override
public LispObject execute(LispObject arg)
{
Environment env = checkEnvironment(arg);
LispObject result = NIL;
for (Binding binding = env.vars; binding != null; binding = binding.next)
if (!binding.specialp)
result = result.push(new Cons(binding.symbol, binding.value));
return result.nreverse();
}
};
// ### environment-all-variables
private static final Primitive ENVIRONMENT_ALL_VARS =
new Primitive("environment-all-variables", PACKAGE_SYS, true, "environment")
{
@Override
public LispObject execute(LispObject arg)
{
Environment env = checkEnvironment(arg);
LispObject result = NIL;
for (Binding binding = env.vars;
binding != null; binding = binding.next)
if (binding.specialp)
result = result.push(binding.symbol);
else
result = result.push(new Cons(binding.symbol, binding.value));
return result.nreverse();
}
};
// ### environment-all-functions
private static final Primitive ENVIRONMENT_ALL_FUNS =
new Primitive("environment-all-functions", PACKAGE_SYS, true, "environment")
{
@Override
public LispObject execute(LispObject arg)
{
Environment env = checkEnvironment(arg);
LispObject result = NIL;
for (FunctionBinding binding = env.lastFunctionBinding;
binding != null; binding = binding.next)
result = result.push(new Cons(binding.name, binding.value));
return result.nreverse();
}
};
}
