/*  $Id: parser.c,v 1.11 2002/02/01 15:05:01 jan Exp $

    Part of XPCE --- The SWI-Prolog GUI toolkit

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (C): 1985-2002, University of Amsterdam

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <h/kernel.h>
#include <h/lang.h>

NewClass(parser)
  Tokeniser	tokeniser;		/* The tokeniser */
  ChainTable	operators;		/* Operator table */
  HashTable	active;			/* Active symbols */
End;


Name openbracket;
Name closebracket;
Name comma;

static status	operatorParser(Parser p, Operator op);

static status
initialiseParserv(Parser p, Tokeniser t, int nops, Any *ops)
{ assign(p, tokeniser, t);
  assign(p, operators, newObject(ClassChainTable, EAV));

  for(; nops > 0; nops--, ops++)
    operatorParser(p, *ops);

  succeed;
}

		 /*******************************
		 *	   DECLARACTIONS	*
		 *******************************/

static status
operatorParser(Parser p, Operator op)
{ appendChainTable(p->operators, op->name, op);
  symbolTokeniser(p->tokeniser, op->name);

  succeed;
}


static status
activeParser(Parser p, Any token, Any msg)
{ if ( isFunction(msg) )
    msg = newObject(ClassQuoteFunction, msg, EAV);
  if ( isNil(p->active) )
    assign(p, active, newObject(ClassHashTable, EAV));

  return appendHashTable(p->active, token, msg);
}



		 /*******************************
		 *	OUTPUT GENERATION	*
		 *******************************/

static Any
getBuildTermParser(Parser p, Class class, int argc, Any *argv)
{ answer(answerObjectv(class, argc, argv));
}


		 /*******************************
		 *	      SPECIALS		*
		 *******************************/

#define MAX_ARGV 256

#define getTokenParser(p)	qadGetv((p)->tokeniser, NAME_token, 0, NULL)
#define ungetTokenParser(p, t)	qadSendv((p)->tokeniser, NAME_token, 1, &(t))
#define DCHAINCACHESIZE 10

static Chain DelimiterChainCache[DCHAINCACHESIZE];

static Chain
delimiterChain(Name d1, Name d2)
{ int i;
  Chain ch;

  for(i=0; i<DCHAINCACHESIZE; i++)
  { if ( (ch=DelimiterChainCache[i]) )
    { if ( ch->size == TWO &&
	   ch->head->value == d1 &&
	   ch->tail->value == d2 )
	return ch;
    } else
    { ch = DelimiterChainCache[i] = newObject(ClassChain, d1, d2, EAV);
      protectObject(ch);
      return ch;
    }
  }

  for(i=DCHAINCACHESIZE-1; i>0; i--)
    DelimiterChainCache[i] = DelimiterChainCache[i-1];

  ch = DelimiterChainCache[i] = newObject(ClassChain, d1, d2, EAV);
  protectObject(ch);
  return ch;
}


static Any
getListParser(Parser p, Name end, Name delimiter, Name functor)
{ Any argv[MAX_ARGV];
  int argc = 0;
  Any arg;
  Any token;
  Chain endterm;

  if ( isDefault(end) )
    end = closebracket;
  if ( isDefault(delimiter) )
    delimiter = comma;
  if ( notDefault(functor) )
    argv[argc++] = functor;

  if ( !(token = getTokenParser(p)) || token == EndOfFile )
    fail;
  if ( token == end )
    answer(getv(p, NAME_buildTerm, argc, argv));
  else
    ungetTokenParser(p, token);

  endterm = delimiterChain(end, delimiter);
					/* TBD: avoid this! */
  for(;;)
  { Any dl;

    TRY(arg = qadGetv(p, NAME_term, 1, (Any *)&endterm));
    argv[argc++] = arg;

    if ( !(dl = getTokenParser(p)) || dl == EndOfFile )
      fail;
    if ( dl == end )
      answer(getv(p, NAME_buildTerm, argc, argv));
    if ( isNil(delimiter) )
      ungetTokenParser(p, token);
  }
}


static Operator
prefix_op(Chain ch)
{ Cell cell;

  for_cell(cell, ch)
  { Operator o = cell->value;
    if ( o->left_priority == ZERO )
      return o;
  }

  fail;
}


static Operator
postfix_op(Chain ch)
{ Cell cell;

  for_cell(cell, ch)
  { Operator o = cell->value;
    if ( o->right_priority == ZERO )
      return o;
  }

  fail;
}


static Operator
infix_op(Chain ch)
{ Cell cell;

  for_cell(cell, ch)
  { Operator o = cell->value;
    if ( o->left_priority != ZERO && o->right_priority != ZERO )
      return o;
  }

  fail;
}


#define FAST_VALUES 10

typedef struct
{ Any	*values;
  Any	fast_values[FAST_VALUES];
  int	size;
  int	allocated;
} stack, *Stack;


static void
initStack(Stack s)
{ s->values = s->fast_values;
  s->size = 0;
  s->allocated = FAST_VALUES;
}


static void
pushStack(Stack s, Any v)
{ if ( s->size >= s->allocated )
  { int new = s->allocated * 2;

    if ( s->values == s->fast_values )
    { s->values = pceMalloc(sizeof(Any) * new);
      cpdata(s->values, s->fast_values, Any, s->size);
    } else
      s->values = pceRealloc(s->values, sizeof(Any) * new);
  }

  s->values[s->size++] = v;
}


static Any
popStack(Stack s)
{ return s->size > 0 ? s->values[--s->size] : FAIL;
}


static Any
peekStack(Stack s)
{ return s->size > 0 ? s->values[s->size-1] : FAIL;
}


static void
doneStack(Stack s)
{ if ( s->values != s->fast_values )
    pceFree(s->values);
}


static status
reduce(Parser p, Stack out, Stack side, int pri)
{ Operator o2;

  while( (o2=popStack(side)) && valInt(o2->priority) <= pri )
  { DEBUG(NAME_term, Cprintf("Reduce %s\n", pp(o2->name)));
    if ( o2->left_priority != ZERO && o2->right_priority != ZERO ) /* infix */
    { Any t, av[3];

      av[2] = popStack(out);
      av[1] = popStack(out);
      av[0] = o2->name;

      TRY(t = getv(p, NAME_buildTerm, 3, av));
      pushStack(out, t);
    } else				/* pre- or postfix */
    { Any t, av[2];

      av[1] = popStack(out);
      av[0] = o2->name;

      TRY(t = getv(p, NAME_buildTerm, 2, av));
      pushStack(out, t);
    }
  }

  succeed;
}


static int
modify(Parser p, int rmo, Stack out, Stack side, int pri)
{ Operator s, o2;
  Chain ops;

  if ( (s = peekStack(side)) && valInt(s->priority) < pri )
  { if ( s->left_priority == ZERO && rmo == 0 )	/* prefix */
    { rmo++;
      pushStack(out, s->name);
      popStack(side);
      DEBUG(NAME_term, Cprintf("Modify prefix %s --> name\n", pp(s->name)));
    } else if ( s->left_priority != ZERO && s->right_priority != ZERO &&
		rmo == 0 &&
		out->size > 0 &&
		(ops = getMemberHashTable((HashTable)p->operators, s->name)) &&
		(o2 = postfix_op(ops)) )
    { Any t, av[2];

      av[1] = popStack(out);
      av[0] = o2->name;
      t = getv(p, NAME_buildTerm, 2, av);

      rmo++;
      pushStack(out, t);
      popStack(side);
      DEBUG(NAME_term, Cprintf("Modify infix %s --> postfix\n", pp(s->name)));
    }
  }

  return rmo;
}



static Any
getTermParser(Parser p, Chain end)
{ Any token;
  Any active, rval;
  Function f;
  stack os, ss;
  Stack out = &os;
  Stack side = &ss;
  int rmo = 0;
  
  initStack(out);
  initStack(side);

  for(;;)
  { Chain ops;

    if ( !(token = getTokenParser(p)) )
      fail;
    if ( token == EndOfFile )
      goto exit;

					/* Active tokens */
    if ( notNil(p->active) && (active = getMemberHashTable(p->active, token)) )
    { if ( (f = checkType(active, TypeFunction, NIL)) &&
	   (rval = getForwardReceiverFunctionv(f, p, 1, &token)) )
	token = rval;
      else if ( instanceOfObject(active, ClassCode) )
      { forwardReceiverCodev(active, p, 1, &token);
	continue;
      }
    }

    if ( isName(token) && getPeekTokeniser(p->tokeniser) == toInt('(') )
    { Any t2;

      if ( (t2 = getTokenParser(p)) != openbracket )
	ungetTokenParser(p, t2);
      else
	TRY(token = get(p, NAME_list, closebracket, comma, token, EAV));
    }
					/* end detection */
    if ( notDefault(end) && memberChain(end, token) )
    { ungetTokenParser(p, token);
      goto exit;
    }

					/* operators */
    if ( isName(token) &&
	 (ops = getMemberHashTable((HashTable)p->operators, token)) )
    { Operator op;

      if ( (op = infix_op(ops)) )
      { DEBUG(NAME_term, Cprintf("Infix op %s\n", pp(token)));

	rmo = modify(p, rmo, out, side, valInt(op->left_priority));
	if ( rmo == 1 )
	{ TRY(reduce(p, out, side, valInt(op->left_priority)));
	  pushStack(side, op);
	  rmo--;
	  continue;
	}
      }
      if ( (op = postfix_op(ops)) )
      { DEBUG(NAME_term, Cprintf("Postfix op %s\n", pp(token)));

	rmo = modify(p, rmo, out, side, valInt(op->left_priority));
	if ( rmo == 1 )
	{ TRY(reduce(p, out, side, valInt(op->left_priority)));
	  pushStack(side, op);
	  continue;
	}
      }

      if ( rmo == 0 && (op = prefix_op(ops)) )
      { DEBUG(NAME_term, Cprintf("Prefix op %s\n", pp(token)));

	TRY(reduce(p, out, side, valInt(op->left_priority)));
	pushStack(side, op);
	continue;
      } 
    }

    if ( rmo == 0 )
    { rmo++;
      DEBUG(NAME_term, Cprintf("Pushing %s\n", pp(token)));
      pushStack(out, token);
    } else
    { send(p, NAME_syntaxError, CtoName("Operator expected"), EAV);
      fail;
    }
  }

exit:
  rmo = modify(p, rmo, out, side, 100000);
  TRY(reduce(p, out, side, 100000));
  
  DEBUG(NAME_term, Cprintf("out->size = %d; side->size = %d\n",
			   out->size == 1, side->size));

  if ( out->size == 1 && side->size == 0 )
    rval = popStack(out);
  else if ( out->size == 0 && side->size == 1 )
  { Operator op = popStack(side);

    rval = op->name;
  } else
  { send(p, NAME_syntaxError, CtoName("Unbalanced operators"), EAV);
    rval = FAIL;
  }

  doneStack(out);
  doneStack(side);

  return rval;
}


static Any
getParseParser(Parser p, Any input)
{ Any rval;
  Tokeniser t = p->tokeniser;
  Tokeniser t2 = getOpenTokeniser(t, input);
  
  addCodeReference(t);
  addCodeReference(input);
  if ( t2 != t )
    assign(p, tokeniser, t2);
  rval = getTermParser(p, DEFAULT);
  if ( t2 != t )
    assign(p, tokeniser, t);
  delCodeReference(input);
  delCodeReference(t);

  answer(rval);
}



		 /*******************************
		 *	 CLASS DECLARATION	*
		 *******************************/

/* Type declarations */

static char *T_buildTerm[] =
        { "class=class", "argument=unchecked ..." };
static char *T_list[] =
        { "end=[name]", "delimiter=[name]*", "functor=[name]" };
static char *T_active[] =
        { "token=any", "message=code|function" };
static char *T_initialise[] =
        { "tokeniser=tokeniser", "operators=operator..." };

/* Instance Variables */

static vardecl var_parser[] =
{ IV(NAME_tokeniser, "tokeniser", IV_BOTH,
     NAME_syntax, "Tokeniser used for this parser"),
  IV(NAME_operators, "chain_table", IV_BOTH,
     NAME_syntax, "Operator table for this parser"),
  IV(NAME_active, "hash_table*", IV_BOTH,
     NAME_syntax, "Active tokens")
};

/* Send Methods */

static senddecl send_parser[] =
{ SM(NAME_initialise, 2, T_initialise, initialiseParserv,
     DEFAULT, "Create from tokeniser and operators"),
  SM(NAME_active, 2, T_active, activeParser,
     NAME_syntax, "Declare token to call message"),
  SM(NAME_operator, 1, "operator=operator", operatorParser,
     NAME_syntax, "Declare operator for parser")
};

/* Get Methods */

static getdecl get_parser[] =
{ GM(NAME_buildTerm, 2, "object=unchecked", T_buildTerm, getBuildTermParser,
     NAME_build, "Create object from data read"),
  GM(NAME_list, 3, "object=unchecked", T_list, getListParser,
     NAME_parse, "Read terms upto end"),
  GM(NAME_parse, 1, "unchecked", "input=char_array|file|text_buffer", getParseParser,
     NAME_parse, "Open, read <-term and close"),
  GM(NAME_term, 1, "term=unchecked", "end=[chain]", getTermParser,
     NAME_parse, "Read next term")
};

/* Resources */

#define rc_parser NULL
/*
static classvardecl rc_parser[] =
{ 
};
*/

/* Class Declaration */

static Name parser_termnames[] = { NAME_tokeniser };

ClassDecl(parser_decls,
          var_parser, send_parser, get_parser, rc_parser,
          1, parser_termnames,
          "$Rev$");

status
makeClassParser(Class class)
{ declareClass(class, &parser_decls);
  delegateClass(class, NAME_tokeniser);

  openbracket = CtoName("(");
  closebracket = CtoName(")");
  comma = CtoName(",");

  succeed;
}
