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/* Lexer for formula answers
   Copyright (C) 1992-2000 Michigan State University

   The CAPA system 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.

   The CAPA system 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 the CAPA system; see the file COPYING.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.

   As a special exception, you have permission to link this program
   with the TtH/TtM library and distribute executables, as long as you
   follow the requirements of the GNU GPL in regard to all of the
   software in the executable aside from TtH/TtM.
*/

/* =========================================================== */
/*      capaFormulaLexer.c  created by Isaac Tsai @ Feb 1999   */
/* =========================================================== */

#include <ctype.h>    /* isspace() */
#include <stdio.h>    /* sscanf()  */
#include <string.h>   /* strlen() strcpy() */
#include "capaParser.h"
#define YYSTYPE  Symbol_p
#include "capaFormula.h"
#include "capaToken.h"

/* ---------------  Global variables ------------------------- */
extern      int         Func_idx;
extern      Symbol      FuncStack[MAX_FUNC_NEST];


extern      char        Fbuf[ONE_K];          /* lexer input buffer */
extern      int         Fidx;                 /* lexer input char index */

extern      Symbol_p    fml_lval;  /* lexical variable used in parser */

/* ---- Token value returned from this lexer ---------------- */

/* ---------------  Global variables ------------------------ */


/* scan a F_NUMBER token */
double
f_get_float()
{
  double   num; 
  int      ii=0, len;
  char     num_str[QUARTER_K];
  
  num_str[ii]=0;
  while( isspace(Fbuf[Fidx]) ) { Fidx++; }
  if( Fbuf[Fidx] == '+' || Fbuf[Fidx] == '-' ) {
    num_str[ii++] = Fbuf[Fidx++];
  }
  while( isdigit(Fbuf[Fidx]) || Fbuf[Fidx] == '.' ) {
      num_str[ii++] = Fbuf[Fidx++];
  }
  if( Fbuf[Fidx] == 'E' || Fbuf[Fidx] == 'e' ) {  /* a number followed immediately by e or E */
    if( Fbuf[Fidx+1] == '+' || Fbuf[Fidx+1] == '-' || isdigit(Fbuf[Fidx+1]) ) {  
    /* e or E followed immediately by a digit */
      num_str[ii++] = Fbuf[Fidx++];
      num_str[ii++] = Fbuf[Fidx++];
      while( isdigit(Fbuf[Fidx]) ) {
        num_str[ii++] = Fbuf[Fidx++];
      }
    }
  }
  num_str[ii] = 0; /* terminate the str */
  len = strlen(num_str);
  if(len > 0 ) {
    sscanf(num_str,"%lg", &num);
  } else {
    num = 1.0;
  }
  return (num);
}

char *
f_get_id()
{
  char    *var_p; 
  int      ii=0, len;
  char     id_str[QUARTER_K];
  
  id_str[ii]=0;
  while( isspace(Fbuf[Fidx]) ) { Fidx++; }
  if( isalpha( Fbuf[Fidx] ) ) {
    id_str[ii++] = Fbuf[Fidx++];
  }
  while( isalnum(Fbuf[Fidx]) || Fbuf[Fidx] == '_' ) {
      id_str[ii++] = Fbuf[Fidx++];
  }
  id_str[ii] = 0; /* terminate the str */
  len = strlen(id_str);
  var_p = (char *)capa_malloc( (len+1), sizeof(char));
  strcpy(var_p,id_str);
  return (var_p);
}

int
f_peek_next_token()
{
  int   idx;
  
  idx = Fidx;
  while( isspace(Fbuf[idx]) ) { idx++; }
  return (Fbuf[idx]); 
}


/* ======================================================= */

int
fml_lex()
{
  char    *id_p;
  int      c;
  
  if( Fbuf[Fidx] == 0 )  { /* printf("EoI\n"); */ return (EOF); }
  while( isspace(Fbuf[Fidx]) ) { Fidx++; }
  if( isalpha(Fbuf[Fidx]) ) {
    id_p = f_get_id();
    c = f_peek_next_token();
    if( c == '(' ) {
      (FuncStack[Func_idx]).s_type = FUNCTION_ID;
      (FuncStack[Func_idx]).s_name = id_p;
       Func_idx++;
       
       return (F_ID);
    } else {
      fml_lval = find_formula_id(id_p); capa_mfree((char *)id_p);
      if( fml_lval == NULL) {
        return (F_ERROR);
      } else {
        return (V_ID);
      }
    } 
  }
  if( isdigit(Fbuf[Fidx]) || Fbuf[Fidx] == '.' ) {
    
    fml_lval = (Symbol *) capa_malloc(1, sizeof(Symbol)); /* *** */
    fml_lval->s_real = f_get_float();
    fml_lval->s_type = R_CONSTANT;
    
    return (F_NUMBER);
  }
  if( Fbuf[Fidx] == '(' ) {
    Fidx++;
    return (F_LPAR);
  }
  if( Fbuf[Fidx] == ')' ) {
    Fidx++;
    return (F_RPAR);
  }
  if( Fbuf[Fidx] == '+' ) {
    Fidx++;
    return (F_PLUS);
  }
  if( Fbuf[Fidx] == '-' ) {
    Fidx++;
    return (F_MINUS);
  }
  if( Fbuf[Fidx] == '*' ) {
    Fidx++;
    return (F_MULT);
  }
  if( Fbuf[Fidx] == '/' ) {
    Fidx++;
    return (F_DIV);
  }
  if( Fbuf[Fidx] == '%' ) {
    Fidx++;
    return (F_MOD);
  }
  if( Fbuf[Fidx] == '^' ) {
    Fidx++;
    return (F_POW);
  }
  if( Fbuf[Fidx] == ',' ) {
    Fidx++;
    return (F_COMMA);
  }
  return (F_ERROR);
  
}