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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#ifndef ARCHETYPE_INTERPRETER
#define ARCHETYPE_INTERPRETER
#include "glk/archetype/expression.h"
#include "common/stream.h"
namespace Glk {
namespace Archetype {
enum DesiredType { LVALUE, RVALUE, NAME };
typedef ExprNode ResultType;
struct ContextType {
int sender, self, each, message;
ContextType() : sender(0), self(0), each(0), message(0) {}
};
extern int MainObject;
extern void interpreter_init();
/**
* A short wrapper to NewDynStr which basically uses the stack as temporary string storage.
* If you want to use a string constructor expression as an argument, call this function,
* since it does not take strings by reference but by value. Expensive on the stack but
* only briefly; it saves cluttering eval_expr
*/
extern StringPtr MakeNewDynStr(const String &s);
/**
* Given a string message, returns its number in the Vocabulary list, or -1 if it was not found.
* At present, it simply uses a very inefficient O(N) lookup. If speed begins to become a
* consideration, this can be changed.
* @param message message to find number of
* @returns the number of the message in the Vocabulary list.
*/
extern int find_message(const String &message);
/**
* Converts a scalar expression node to a target type. Deals primarily with numeric -> string
* or string -> numeric conversions in their many incarnations.
* @param target_type type to convert to
* @param the_scalar scalar to convert
*/
extern bool convert_to(AclType target_type, ResultType &the_scalar);
/**
* Used to initialize previously unused result records. Does not expect that there might be
* a string pointer lurking within.
*/
extern void undefine(ResultType &result);
/**
* To be used on temporary result variables after their usefulness is finished. Like 'undefine' above,
* except that it is used only for results that have actually been used - in other words, results with
* their "kind" field set properly.
*/
extern void cleanup(ResultType &result);
/**
* Does an rvalue-like copy from r2 to r1
*/
extern void copy_result(ResultType &r1, const ResultType &r2);
/**
* Compares two result nodes according to the given operator.
* @returns true if they can; false if they cannot
*/
extern bool result_compare(short comparison, ResultType &r1, ResultType &r2);
/**
* Given the result of an LVALUE evaluation and a result to assign to the attribute,
* performs the assignment if possible.
* @param target hopefully points to attribute to receive assignment
* @param value Result to assign
* @returns Returns true if the assignment was successful; false otherwise
*/
extern bool assignment(ResultType &target, ResultType &value);
/**
* Writes the given result to screen w/o terminating it with a newline
*/
extern void write_result(ResultType &result);
/**
* For purposes of debugging.
* Strings are enclosed in double quotes.
* Messages are enclosed in single quotes.
* Quote literals are preceded by >>
*/
extern void display_result(ResultType &result);
/**
* Given an expression tree, displays the thing on screen.
*/
extern void display_expr(ExprTree the_tree);
/**
* Loads a game into memory from a binary input file. Checks for errors
* in the header or incompatible versions.
* @param f_in Input file
*/
extern bool load_game(Common::ReadStream *f_in);
} // End of namespace Archetype
} // End of namespace Glk
#endif
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