/* l2xiexpr.c  LTX2X interpreter parsing routines for expressions      */
/*  This code is partly based on algorithms presented by Ronald Mak in */
/*  "Writing Compilers & Interpreters", John Wiley & Sons, 1991        */

#include <stdio.h>
#include "l2xicmon.h"
#include "l2xierr.h"
#include "l2xiscan.h"
#include "l2xisymt.h"
#include "l2xiprse.h"
#include "l2xiidbg.h"
#ifndef l2xicpr_h
#include "l2xicpr.h"           /* extern token code lists */
#endif

/* EXTERNALS */

extern TOKEN_CODE token;
extern char token_string[];
extern char word_string[];
extern LITERAL literal;

extern SYMTAB_NODE_PTR symtab_display[];
extern int level;

 /* built-in constants */
extern SYMTAB_NODE_PTR false_idp, true_idp, unknown_idp;
extern SYMTAB_NODE_PTR conste_idp, pi_idp, undef_idp;
extern SYMTAB_NODE_PTR day_idp, month_idp, year_idp;

/* FORWARDS */
TYPE_STRUCT_PTR expression(), simple_expression(), term(), factor(),
               function_call();
TYPE_STRUCT_PTR simple_factor();
TYPE_STRUCT_PTR index_list();


/* MACROS */

/* integer_operands(tp1, tp2) TRUE if both are integer, else FALSE         */
#define integer_operands(tp1, tp2) ((tp1 == integer_typep) && \
                                   (tp2 == integer_typep))

/* real_operands(tp1, tp2)  TRUE if one or both operands are real, and     */
/*                          the other is integer, else FALSE               */
#define real_operands(tp1, tp2) (((tp1 == real_typep) &&      \
                                 ((tp2 == real_typep) ||     \
                                  (tp2 == integer_typep)))   \
                                        ||                   \
                                 ((tp2 == real_typep) &&     \
                                   ((tp1 == real_typep) ||   \
                                    (tp1 == integer_typep))))

/* boolean_operands(tp1, tp2) TRUE if both are boolean, else FALSE         */
#define boolean_operands(tp1, tp2) ((tp1 == boolean_typep) &&  \
                                   (tp2 == boolean_typep))

/* logical_operands(tp1, tp2) TRUE if both are logical/boolean, else FALSE    */
#define logical_operands(tp1, tp2) ((tp1 == boolean_typep || tp1 == logical_typep) &&  \
                                   (tp2 == boolean_typep || tp2 == logical_typep))

/* string_operands(tp1, tp2) TRUE iff both are string */
#define string_operands(tp1, tp2) ((tp1 == string_typep ||         \
                                   tp1->form == STRING_FORM) &&   \
                                  (tp2 == string_typep ||         \
                                   tp2->form == STRING_FORM))

/* NEW undef_types(tp1, tp2) TRUE if either is undefined, else FALSE */
#define undef_types(tp1, tp2) ((tp1 == any_typep) || \
                              (tp2 == any_typep))

/* NEW is_undef(tp1) TRUE if undefined, else FALSE */
#define is_undef(tp1) (tp1 == any_typep)

/* NEW set_undef(tp1)  sets tp1 to be an undef */
#define set_undef(tp1) tp1 = any_typep

/***************************************************************************/
/* expression() Process an expression consisting of a simple expression,   */
/*              optionally followed by a relational operator and a         */
/*              second simple expression.                                  */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR expression()
{
 TYPE_STRUCT_PTR result_tp, tp2;
 entry_debug("expression");

 /* first simple expression */
 result_tp = simple_expression();

 /* if operator, process following expression */
 if (token_in(rel_op_list)) {
   result_tp = base_type(result_tp);
   /* second expression */
   get_token();
   tp2 = base_type(simple_expression());
   check_rel_op_types(result_tp, tp2);
   result_tp = logical_typep;
 }

 exit_debug("expression");
 return(result_tp);
}                                                        /* end expression */
/***************************************************************************/



/***************************************************************************/
/* simple_expression() Process a simple expression                         */
/*                     consisting of terms seperated by +, -, OR, XXOR     */
/*                     operators. There may be an initial unary operator   */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR simple_expression()
{
 TOKEN_CODE op;                   /* operator token */
 TYPE_STRUCT_PTR result_tp, tp2;
 BOOLEAN saw_unary_op = FALSE;
 entry_debug("simple_expression");

 /* remember intial unary op */
 if ((token == PLUS) || (token == MINUS)) {
   saw_unary_op = TRUE;
   get_token();
 }

 /* first term */
 result_tp = term();

 /* if there was a unary operator, check its type for integer or real. */
 if (saw_unary_op && (base_type(result_tp) != integer_typep) &&
                     (result_tp != real_typep)) error(INCOMPATIBLE_TYPES);

 /* loop to process subsequent terms seperated by operators */
 while (token_in(add_op_list)) {
   op = token;
   result_tp = base_type(result_tp);

   get_token();
   tp2 = base_type(term());    /* next term */
   if (undef_types(result_tp, tp2)) {
     set_undef(result_tp);
   }
   else {
   switch (op) {
     case PLUS:  {
       /* integer op integer -> integer */
       if (integer_operands(result_tp, tp2))  result_tp = integer_typep;
       /* numbers -> real, */
       else if (real_operands(result_tp, tp2)) result_tp = real_typep;
       /* string concatenation */
       else if (string_operands(result_tp, tp2)) result_tp = string_typep;
       else {
         error(INCOMPATIBLE_TYPES);
         result_tp = &dummy_type;
       }
       break;
     }
     case MINUS: {
       /* integer op integer -> integer */
       if (integer_operands(result_tp, tp2))  result_tp = integer_typep;
       /* otherwise numbers -> real, else error */
       else if (real_operands(result_tp, tp2)) result_tp = real_typep;
       else {
         error(INCOMPATIBLE_TYPES);
         result_tp = &dummy_type;
       }
       break;
     }
     case OR:
     case XXOR: {
       /* boolean OR boolean -> boolean */
       if (!logical_operands(result_tp, tp2)) {
         error(INCOMPATIBLE_TYPES);
         result_tp = &dummy_type;
         break;
       }
       result_tp = logical_typep;
       break;
     }
     case XLIKE: {
        /* string LIKE string -> boolean */
       if (!string_operands(result_tp, tp2)) {
         error(INCOMPATIBLE_TYPES);
         result_tp = &dummy_type;
         break;
       }
       result_tp = logical_typep;
       break;
     }
   } /* end switch */
 }
 } /* end while */

 exit_debug("simple_expression");
 return(result_tp);
}                                                 /* end simple_expression */
/***************************************************************************/



/***************************************************************************/
/* term() Process a term                                                   */
/*                     consisting of factors seperated by                  */
/*                     *, /, DIV, MOD, or AND                              */
/*                     operators.                                          */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR term()
{
 TOKEN_CODE op;                   /* operator token */
 TYPE_STRUCT_PTR result_tp, tp2;
 entry_debug("term");

 /* first factor */
 result_tp = factor();

 /* loop to process subsequent factors seperated by operators */
 while (token_in(mult_op_list)) {
   op = token;
   result_tp = base_type(result_tp);

   get_token();
   tp2 = base_type(factor());    /* next factor */
   if (undef_types(result_tp, tp2)) {
     set_undef(result_tp);
   }
   else {
   switch (op) {
     case STAR: {
       /* integer op integer -> integer */
       if (integer_operands(result_tp, tp2))  result_tp = integer_typep;
       /* otherwise numbers -> real, else error */
       else if (real_operands(result_tp, tp2)) result_tp = real_typep;
       else {
         error(INCOMPATIBLE_TYPES);
         result_tp = &dummy_type;
       }
       break;
     }
     case SLASH: {
       /* number op number -> real */
       if ((!real_operands(result_tp, tp2)) &&
           (!integer_operands(result_tp, tp2))) {
         error(INCOMPATIBLE_TYPES);
       }
       result_tp = real_typep;
       break;
     }
     case DIV:
     case MOD: {
       /* integer op integer -> integer */
       if (!integer_operands(result_tp, tp2)) error(INCOMPATIBLE_TYPES);
       result_tp = integer_typep;
       break;
     }
     case AND: {
       /* boolean op boolean -> boolean */
       if (!logical_operands(result_tp, tp2)) {
         error(INCOMPATIBLE_TYPES);
         result_tp = logical_typep;
         break;
       }
     }
   } /* end switch */
 }
 } /* end while */

 exit_debug("term");
 return(result_tp);
}                                                              /* end term */
/***************************************************************************/



/***************************************************************************/
/* factor()    Process an EXPRESS factor                                   */
/*             simple_factor [ ** simple_factor ]                          */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR factor()
{
 TOKEN_CODE op;                   /* operator token */
 TYPE_STRUCT_PTR result_tp, tp2;
 entry_debug("factor");

 /* first factor */
 result_tp = simple_factor();

 op = token;
 if (op == STARSTAR) {
   result_tp = base_type(result_tp);
   get_token();
   tp2 = base_type(simple_factor());
   if (undef_types(result_tp, tp2)) {
     set_undef(result_tp);
   }
   else if (integer_operands(result_tp, tp2)) result_tp = integer_typep;
   else if (real_operands(result_tp, tp2)) result_tp = real_typep;
   else {
     error(INCOMPATIBLE_TYPES);
     result_tp = &dummy_type;
   }
 }

 exit_debug("factor");
 return(result_tp);
}                                                            /* end FACTOR */
/***************************************************************************/



/***************************************************************************/
/* simple_factor() Process a simple factor                                 */
/*                     a variable, a number, NOT factor, a                 */
/*                     parenthesized expression, or an interval expression */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR simple_factor()
{
 TYPE_STRUCT_PTR tp;
 TYPE_STRUCT_PTR tp1, tp2;
 TOKEN_CODE op;
 entry_debug("simple_factor");

 if (token_in(constant_list)) {             /* language defined constant */
   switch (token) {
     case XFALSE : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(false_idp);
       tp = logical_typep;
       break;
     }
     case XTRUE : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(true_idp);
       tp = logical_typep;
       break;
     }
     case XUNKNOWN : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(unknown_idp);
       tp = logical_typep;
       break;
     }
     case XCONST_E : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(conste_idp);
       tp = real_typep;
       break;
     }
     case XPI : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(pi_idp);
       tp = real_typep;
       break;
     }
     case QUERY_CHAR : {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(undef_idp);
       set_undef(tp);
       break;
     }
     case THE_DAY: {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(day_idp);
       tp = integer_typep;
       break;
     }
     case THE_MONTH: {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(month_idp);
       tp = integer_typep;
       break;
     }
     case THE_YEAR: {
       change_crunched_token(IDENTIFIER);
       crunch_symtab_node_ptr(year_idp);
       tp = integer_typep;
       break;
     }
     default : {
       error(UNIMPLEMENTED_CONSTANT);
       tp = &dummy_type;
       break;
     }
   }  /* end switch */
   get_token();
   exit_debug("factor at defined constants");
   return(tp);
 }  /* end of language defined constants */

 switch (token) {
   case IDENTIFIER: {
     SYMTAB_NODE_PTR idp;

     search_and_find_all_symtab(idp);
     switch (idp->defn.key) {
       case FUNC_DEFN: {
         crunch_symtab_node_ptr(idp);
         get_token();
         tp = routine_call(idp,TRUE);
         break;
       }
       case PROC_DEFN: {
         error(INVALID_IDENTIFIER_USAGE);
         get_token();
         actual_parm_list(idp,FALSE);
         tp = &dummy_type;
         break;
       }
       case CONST_DEFN: {
         crunch_symtab_node_ptr(idp);
         get_token();
         tp = idp->typep;
         break;
       }
       default: {
         tp = variable(idp, EXPR_USE);
         break;
       }
     } /* end switch */
     break;
   }
   case NUMBER_LITERAL: {
     SYMTAB_NODE_PTR np;

     np = search_symtab(token_string, symtab_display[1]);
     if (np == NULL) np = enter_symtab(token_string, symtab_display[1]);

     if (literal.type == INTEGER_LIT ) {
       tp = np->typep = integer_typep;
       np->defn.info.constant.value.integer = literal.value.integer;
     }
     else {         /* a real literal */
       tp = np->typep = real_typep;
       np->defn.info.constant.value.real = literal.value.real;
     }
     crunch_symtab_node_ptr(np);
     get_token();
     break;
   }
   case STRING_LITERAL: {
     SYMTAB_NODE_PTR np;
     int length = strlen(literal.value.string);

     np = search_symtab(token_string, symtab_display[1]);
     if (np == NULL) np = enter_symtab(token_string, symtab_display[1]);
     np->typep = tp = make_string_typep(length);
     np->info = alloc_bytes(length + 1);
     strcpy(np->info, literal.value.string);
     crunch_symtab_node_ptr(np);
     get_token();
     break;
   }
   case NOT: {
     get_token();
     tp = simple_factor();
     break;
   }
   case LPAREN: {
     get_token();
     tp = expression();

     if_token_get_else_error(RPAREN, MISSING_RPAREN);
     break;
   }
   case LBRACE: {   /* interval expression {expr op var op expr} */
     get_token();
     tp1 = simple_expression();
     op = token;
     if (op != LT && op != LE) {
       error(EXPECTED_INTERVAL_OP);
     }
     get_token();
     tp = simple_expression();
     check_rel_op_types(tp1, tp);
     op = token;
     if (op != LT && op != LE) {
       error(EXPECTED_INTERVAL_OP);
     }
     get_token();
     tp2 = simple_expression();
     check_rel_op_types(tp, tp2);
     if_token_get_else_error(RBRACE, MISSING_RBRACE);
     tp = logical_typep;
     break;
   }
   default: {
     error(INVALID_EXPRESSION);
     tp = &dummy_type;
     break;
   }
 } /* end switch */

 exit_debug("simple_factor");
 return(tp);

}                                                     /* end SIMPLE_FACTOR */
/***************************************************************************/



/***************************************************************************/
/* variable(var_idp, use) Process a variable                               */
/*                     consisting of                                       */
/*                     a simple id, an array id with subscripts,           */
/*                     or an entity id with attributes                     */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR variable(var_idp, use)
SYMTAB_NODE_PTR var_idp;                  /* var id */
USE use;                                  /* how variable is used */
{
 TYPE_STRUCT_PTR tp = var_idp->typep;
 DEFN_KEY defn_key = var_idp->defn.key;
 TYPE_STRUCT_PTR array_subscript_list();
 TYPE_STRUCT_PTR entity_attr();
 entry_debug("variable");

 crunch_symtab_node_ptr(var_idp);

 /* check the definition of the variable */
 switch (defn_key) {
   case VAR_DEFN:
   case VALPARM_DEFN:
   case VARPARM_DEFN:
   case FUNC_DEFN:
   case UNDEFINED: {
     break;
   }
   default: {
     tp = &dummy_type;
     error(INVALID_IDENTIFIER_USAGE);
     break;
   }
 } /* end switch */

 get_token();

 /* there must not be a parameter list, but parse for one anyway */
 if (token == LPAREN) {
   error(UNEXPECTED_TOKEN);
   actual_parm_list(var_idp, FALSE);
   exit_debug("variable (unexpected parm list)");
   return(tp);
 }

 /* subscripts or fields? */
 while ((token == LBRACKET) || (token == PERIOD)) {
   if (token == PERIOD) {
     tp = entity_attr(tp);
   }
   else {
     if (var_idp->typep == string_typep ||
         var_idp->typep->form == STRING_FORM) { /* substring op */
       tp = index_list(tp);
     }
     else {                                     /* aggregate index */
       tp = array_subscript_list(tp);
     }
   }
 }

 exit_debug("variable");
 return(tp);

}                                                          /* end variable */
/***************************************************************************/



/***************************************************************************/
/* index_list(tp) Process a (pair of) subscript v                          */
/*                     '[' <int_expr> [ ':' <int_expr> ] ']'               */
/* return a pointer to the type structure                                  */
/*  at entry: token is opening [                                           */
/*  at exit: token is after closing ]                                      */

TYPE_STRUCT_PTR index_list(tp)
TYPE_STRUCT_PTR tp;                 /* type of var just before opening [ */
{
 TYPE_STRUCT_PTR ss1_tp, ss2_tp;
 entry_debug("index_list (l2xiexpr.c)");

           /* check on var type */
 if (tp == string_typep || tp->form == STRING_FORM) {  /* OK */
   ;
 }
 else {
   error(UNEXPECTED_TOKEN);
 }

    /* do first expression */
 get_token();
 ss1_tp = expression();
 if (ss1_tp != integer_typep) error(INCOMPATIBLE_TYPES);

 if (token == COLON) {           /* do second expression */
   get_token();
   ss2_tp = expression();
   if (ss2_tp != integer_typep) error(INCOMPATIBLE_TYPES);
 }

 if_token_get_else_error(RBRACKET, MISSING_RBRACKET);
 exit_debug("index_list");
 return(tp);

}                                                        /* end INDEX_LIST */
/***************************************************************************/


/***************************************************************************/
/* array_subscript_list(tp) Process a list of subscripts                   */
/*                     [ <expr>, <expr>, ... ]                             */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR array_subscript_list(tp)
TYPE_STRUCT_PTR tp;
{
 TYPE_STRUCT_PTR index_tp, elmt_tp, ss_tp;

 /* loop to process the list */
 do {
   if (tp->form == ARRAY_FORM) {
     index_tp = tp->info.array.index_typep;
     elmt_tp = tp->info.array.elmt_typep;
     get_token();
     ss_tp = expression();

     /* check assignment compatibility */
     if (!is_assign_type_compatible(index_tp, ss_tp)) error(INCOMPATIBLE_TYPES);
     tp = elmt_tp;
   }
   else if (tp->form == BAG_FORM ||
            tp->form == LIST_FORM ||
            tp->form == SET_FORM) {
     index_tp = tp->info.dynagg.index_typep;
     elmt_tp = tp->info.dynagg.elmt_typep;
     get_token();
     ss_tp = expression();

     /* check assignment compatibility */
     if (!is_assign_type_compatible(index_tp, ss_tp)) error(INCOMPATIBLE_TYPES);
     tp = elmt_tp;
   }
   else {
     error(TOO_MANY_SUBSCRIPTS);
     while ((token != RBRACKET) && (!token_in(statement_end_list))) {
       get_token();
     }
   }
 } while (token == COMMA); /* end do */

 if_token_get_else_error(RBRACKET, MISSING_RBRACKET);
 return(tp);

}                                              /* end array_subscript_list */
/***************************************************************************/


/***************************************************************************/
/* entity_attr(tp) Process an entity attribute                             */
/*                     .  <attr-variable>                                  */
/* return a pointer to the type structure                                  */

TYPE_STRUCT_PTR entity_attr(tp)
TYPE_STRUCT_PTR tp;
{
 SYMTAB_NODE_PTR attr_idp;

 get_token();

 if ((token == IDENTIFIER) && (tp->form == ENTITY_FORM)) {
   search_this_symtab(attr_idp, tp->info.entity.attribute_symtab);

   crunch_symtab_node_ptr(attr_idp);
   get_token();
   if (attr_idp != NULL) return(attr_idp->typep);
   else {
     error(INVALID_ATTRIBUTE);
     return(&dummy_type);
   }
 }
 else {
   get_token();
   error(INVALID_ATTRIBUTE);
   return(&dummy_type);
 }

}                                                       /* end entity_attr */
/***************************************************************************/




/* TYPE COMPATIBILITY */


/***************************************************************************/
/* check_rel_op_types(tp1, tp2) Check operand types of a relational         */
/*                             operator                                    */

check_rel_op_types(tp1, tp2)
TYPE_STRUCT_PTR tp1;
TYPE_STRUCT_PTR tp2;
{

 /* identical scalar or enumeration types */
 if ((tp1 == tp2) &&
     ((tp1->form == SCALAR_FORM) || (tp1->form == ENUM_FORM))) {
   return;
 }

 /* one integer and one real */
 if (((tp1 == integer_typep) && (tp2 == real_typep)) ||
     ((tp2 == integer_typep) && (tp1 == real_typep))) {
   return;
 }

 /* two arbitrary strings */
 if (string_operands(tp1, tp2)) {
   return;
 }

 /* for the IN operator */
 /* tp2 is a dynamic aggregate, tp1 is the elmt type */
 if (is_dynagg(tp2)) {
   if (tp1 == tp2->info.dynagg.elmt_typep) {
     return;
   }
 }

 error(INCOMPATIBLE_TYPES);
}                                                /* end check_rel_op_types */
/***************************************************************************/


/***************************************************************************/
/* is_assign_type_compatible(tp1, tp2) Check if a value of type tp2        */
/*                               can be assigned to a variable of type tp1 */
/*                            (i.e. tp1 := tp2)                            */
/* return TRUE if types assignment compatible, else FALSE                  */

BOOLEAN is_assign_type_compatible(tp1, tp2)
TYPE_STRUCT_PTR tp1;
TYPE_STRUCT_PTR tp2;
{

 tp1 = base_type(tp1);
 tp2 = base_type(tp2);

 if (tp1 == tp2) return(TRUE);
 if (is_undef(tp2)) {
   compile_warning(ASSIGN_TO_UNDEF);
   return(TRUE);
 }

 /* real := integer */
 if ((tp1 == real_typep) && (tp2 == integer_typep)) return(TRUE);

 if (string_operands(tp1, tp2)) return(TRUE);

 /* incompatible */
 return(FALSE);

}                                         /* end is_assign_type_compatible */
/***************************************************************************/


/***************************************************************************/
/* base_type(tp)  Return the range type of a subrange type                 */

TYPE_STRUCT_PTR base_type(tp)
TYPE_STRUCT_PTR tp;
{
 return((tp->form == SUBRANGE_FORM)
                  ? tp->info.subrange.range_typep
                  : tp);
}                                                         /* end base_type */
/***************************************************************************/

You are viewing proxied material from ftp.icm.edu.pl. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.