/* -*- C++ -*- */
// $Id$

// ========================================================================
//
// = LIBRARY
//    orbsvcs/PSS
//
// = FILENAME
//    PSDL_Interpreter.h
//
// = AUTHOR
//    Priyanka Gontla <pgontla@doc.ece.uci.edu>
//
// ========================================================================

#ifndef TAO_PSDL_INTERPRETER_H
#define TAO_PSDL_INTERPRETER_H
#include /**/ "ace/pre.h"

#include "psdl_export.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

#include "tao/orbconf.h"
#include "ace/Synch.h"

class TAO_PSDL_Node;

class TAO_PSDL_Export TAO_PSDL_Interpreter
{
  // = TITLE
  //      TAO_PSDL_Interpreter is the superclass for all PSDL interpreters.
  //      Its build tree method invokes the yacc parser to parse a constraint
  //      or preference string.
protected:
  // = Initialization and termination methods.
  TAO_PSDL_Interpreter (void);
  // Constructor.

  ~TAO_PSDL_Interpreter (void);
  // Destructor.

  int build_tree (const char* constraints);
  // Using the Yacc generated parser, construct an expression tree
  // representing <nodes> from the tokens returned by it.

  static int is_empty_string (const char* str);

  TAO_PSDL_Node* root_;
  // The root of the expression tree, not equal to null if build_tree
  // successfully builds a tree from the constraints.
private:
  static TAO_SYNCH_MUTEX parserMutex__;
  // This mutex protects the <build_tree> method from reentrance.
};


// Functions we need for parsing.
extern int TAO_PSDL_yyparse (void *);
extern void yyrestart (FILE*);
extern int yylex (TAO_PSDL_Node **, void *);

// Have yylex read from the node string, not from stdin.
//#undef YY_INPUT
//#define YY_INPUT(b, r, ms) (r = TAO_Lex_String_Input::copy_into(b, ms))

class TAO_Lex_String_Input
{
  // = TITLE
  //   Have Lex read from a string and not from stdin. Essentially,
  //   the interpreter needs to call yylex() until EOF, and call
  //   TAO_Lex_String_Input::reset() with the new string, prior to
  //   calling yyparse.
public:
  static void reset (char* input_string);
  // Reset the lex input.

  static int copy_into (char* buf, int max_size);
  // Method lex will call to read from the input string.

private:

  static char* string_;
  static char* current_;
  static char* end_;
  // Pointers to keep track of the input string.
};

// The union used by lex and bison to build the Abstract Syntax Tree.
#define YYSTYPE TAO_PSDL_Node *

extern YYSTYPE yylval;
extern YYSTYPE yyval;

#include /**/ "ace/post.h"
#endif /* TAO_PSDL_INTERPRETER_H */