// -*- c-basic-offset: 2 -*-
/*
 *  This file is part of the KDE libraries
 *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
 *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 *  Boston, MA 02111-1307, USA.
 *
 *  $Id: interpreter.h,v 1.9 2002/03/05 23:13:28 rich Exp $
 */

#ifndef _KJS_INTERPRETER_H_
#define _KJS_INTERPRETER_H_

#include "value.h"
#include "object.h"
#include "types.h"

namespace KJS {

  class ContextImp;
  class ExecStateImp;
  class InterpreterImp;

  /**
   * Represents an execution context, as specified by section 10 of the ECMA
   * spec.
   *
   * An execution context contains information about the current state of the
   * script - the scope for variable lookup, the value of "this", etc. A new
   * execution context is entered whenever global code is executed (e.g. with
   * @ref Interpreter::evaluate()), a function is called (see @ref
   * Object::call()), or the builtin "eval" function is executed.
   *
   * Most inheritable functions in the KJS api take a @ref ExecState pointer as
   * their first parameter. This can be used to obtain a handle to the current
   * execution context.
   *
   * Note: Context objects are wrapper classes/smart pointers for the internal
   * KJS ContextImp type. When one context variable is assigned to another, it
   * is still referencing the same internal object.
   */
  class Context {
  public:
    Context(ContextImp *);
    Context(const Context &c);
    Context& operator=(const Context &c);
    virtual ~Context();

    bool isNull() const;
    ContextImp *imp() const;

    /**
     * Returns the scope chain for this execution context. This is used for
     * variable lookup, with the list being searched from start to end until a
     * variable is found.
     *
     * @return The execution context's scope chain
     */
    const List scopeChain() const;

    /**
     * Returns the variable object for the execution context. This contains a
     * property for each variable declared in the execution context.
     *
     * @return The execution context's variable object
     */
    Object variableObject() const;

    /**
     * Returns the "this" value for the execution context. This is the value
     * returned when a script references the special variable "this". It should
     * always be an Object, unless application-specific code has passed in a
     * different type.
     *
     * The object that is used as the "this" value depends on the type of
     * execution context - for global contexts, the global object is used. For
     * function objewcts, the value is given by the caller (e.g. in the case of
     * obj.func(), obj would be the "this" value). For code executed by the
     * built-in "eval" function, the this value is the same as the calling
     * context.
     *
     * @return The execution context's "this" value
     */
    Object thisValue() const;

    /**
     * Returns the context from which the current context was invoked. For
     * global code this will be a null context (i.e. one for which @ref
     * isNull() returns true). You should check @ref isNull() on the returned
     * value before calling any of it's methods.
     *
     * @return The calling execution context
     */
    const Context callingContext() const;
  private:
    ContextImp *rep;
  };

  /**
   * Interpreter objects can be used to evaluate ECMAScript code. Each
   * interpreter has a global object which is used for the purposes of code
   * evaluation, and also provides access to built-in properties such as
   * " Object" and "Number".
   */
  class Interpreter {
  public:
    /**
     * Creates a new interpreter. The supplied object will be used as the global
     * object for all scripts executed with this interpreter. During
     * constuction, all the standard properties such as "Object" and "Number"
     * will be added to the global object.
     *
     * Note: You should not use the same global object for multiple
     * interpreters.
     *
     * This is due do the fact that the built-in properties are set in the
     * constructor, and if these objects have been modified from another
     * interpreter (e.g. a script modifying String.prototype), the changes will
     * be overridden.
     *
     * @param global The object to use as the global object for this interpreter
     */
    Interpreter(const Object &global);
    /**
     * Creates a new interpreter. A global object will be created and
     * initialized with the standard global properties.
     */
    Interpreter();
    virtual ~Interpreter();

    /**
     * Returns the object that is used as the global object during all script
     * execution performed by this interpreter
     */
    Object globalObject() const;

    void initGlobalObject();

    /**
     * Returns the execution state object which can be used to execute
     * scripts using this interpreter at a the "global" level, i.e. one
     * with a execution context that has the global object as the "this"
     * value, and who's scope chain contains only the global object.
     *
     * Note: this pointer remains constant for the life of the interpreter
     * and should not be manually deleted.
     *
     * @return The interpreter global execution state object
     */
    ExecState *globalExec();

    /**
     * Parses the supplied ECMAScript code and checks for syntax errors.
     *
     * @param code The code to check
     * @return true if there were no syntax errors in the code, otherwise false
     */
    bool checkSyntax(const UString &code);

    /**
     * Evaluates the supplied ECMAScript code.
     *
     * Since this method returns a Completion, you should check the type of
     * completion to detect an error or before attempting to access the returned
     * value. For example, if an error occurs during script execution and is not
     * caught by the script, the completion type will be Throw.
     *
     * If the supplied code is invalid, a SyntaxError will be thrown.
     *
     * @param code The code to evaluate
     * @param thisV The value to pass in as the "this" value for the script
     * execution. This should either be Null() or an Object.
     * @return A completion object representing the result of the execution.
     */
    Completion evaluate(const UString &code, const Value &thisV = Value());

    /**
     * @internal
     *
     * Returns the implementation object associated with this interpreter.
     * Only useful for internal KJS operations.
     */
    InterpreterImp *imp();

    /**
     * Returns the builtin "Object" object. This is the object that was set
     * as a property of the global object during construction; if the property
     * is replaced by script code, this method will still return the original
     * object.
     *
     * @return The builtin "Object" object
     */
    Object builtinObject() const;

    /**
     * Returns the builtin "Function" object.
     */
    Object builtinFunction() const;

    /**
     * Returns the builtin "Array" object.
     */
    Object builtinArray() const;


    /**
     * Returns the builtin "Boolean" object.
     */
    Object builtinBoolean() const;

    /**
     * Returns the builtin "String" object.
     */
    Object builtinString() const;

    /**
     * Returns the builtin "Number" object.
     */
    Object builtinNumber() const;

    /**
     * Returns the builtin "Date" object.
     */
    Object builtinDate() const;

    /**
     * Returns the builtin "RegExp" object.
     */
    Object builtinRegExp() const;

    /**
     * Returns the builtin "Error" object.
     */
    Object builtinError() const;

    /**
     * Returns the builtin "Object.prototype" object.
     */
    Object builtinObjectPrototype() const;

    /**
     * Returns the builtin "Function.prototype" object.
     */
    Object builtinFunctionPrototype() const;

    /**
     * Returns the builtin "Array.prototype" object.
     */
    Object builtinArrayPrototype() const;

    /**
     * Returns the builtin "Boolean.prototype" object.
     */
    Object builtinBooleanPrototype() const;

    /**
     * Returns the builtin "String.prototype" object.
     */
    Object builtinStringPrototype() const;

    /**
     * Returns the builtin "Number.prototype" object.
     */
    Object builtinNumberPrototype() const;

    /**
     * Returns the builtin "Date.prototype" object.
     */
    Object builtinDatePrototype() const;

    /**
     * Returns the builtin "RegExp.prototype" object.
     */
    Object builtinRegExpPrototype() const;

    /**
     * Returns the builtin "Error.prototype" object.
     */
    Object builtinErrorPrototype() const;

    /**
     * The initial value of "Error" global property
     */
    Object builtinEvalError() const;
    Object builtinRangeError() const;
    Object builtinReferenceError() const;
    Object builtinSyntaxError() const;
    Object builtinTypeError() const;
    Object builtinURIError() const;

    Object builtinEvalErrorPrototype() const;
    Object builtinRangeErrorPrototype() const;
    Object builtinReferenceErrorPrototype() const;
    Object builtinSyntaxErrorPrototype() const;
    Object builtinTypeErrorPrototype() const;
    Object builtinURIErrorPrototype() const;

    enum CompatMode { NativeMode, IECompat, NetscapeCompat };
    /**
     * Call this to enable a compatibility mode with another browser.
     * (by default konqueror is in "native mode").
     * Currently, in KJS, this only changes the behaviour of Date::getYear()
     * which returns the full year under IE.
     */
    void setCompatMode(CompatMode mode);
    CompatMode compatMode() const;

    /**
     * Called by InterpreterImp during the mark phase of the garbage collector
     * Default implementation does nothing, this exist for classes that reimplement Interpreter.
     */
    virtual void mark() {}

    /**
     * Provides a way to distinguish derived classes.
     * Only useful if you reimplement Interpreter and if different kind of
     * interpreters are created in the same process.
     * The base class returns 0, the ECMA-bindings interpreter returns 1.
     */
    virtual int rtti() { return 0; }

#ifdef KJS_DEBUG_MEM
    /**
     * @internal
     */
    static void finalCheck();
#endif
  private:
    InterpreterImp *rep;

    /**
     * This constructor is not implemented, in order to prevent
     * copy-construction of Interpreter objects. You should always pass around
     * pointers to an interpreter instance instead.
     */
    Interpreter(const Interpreter&);

    /**
     * This constructor is not implemented, in order to prevent assignment of
     * Interpreter objects. You should always pass around pointers to an
     * interpreter instance instead.
     */
    Interpreter operator=(const Interpreter&);
  protected:
    virtual void virtual_hook( int id, void* data );
  };

  /**
   * Represents the current state of script execution. This object allows you
   * obtain a handle the interpreter that is currently executing the script,
   * and also the current execution state context.
   */
  class ExecState {
    friend class InterpreterImp;
    friend class FunctionImp;
    friend class GlobalFuncImp;
  public:
    virtual ~ExecState();

    /**
     * Returns the interpreter associated with this execution state
     *
     * @return The interpreter executing the script
     */
    Interpreter *interpreter() const;

    /**
     * Returns the execution context associated with this execution state
     *
     * @return The current execution state context
     */
    const Context context() const;

    void setException(const Value &e);
    void clearException();
    Value exception() const;
    bool hadException() const;

  private:
    ExecState(Interpreter *interp, ContextImp *con);
    ExecStateImp *rep;
  };

}; // namespace

#endif // _KJS_INTERPRETER_H_
