/* C code supplied at the beginning of the file.  */

%{

#include <stdio.h>
#include <string.h>

extern int  yylexlinenum;                   /* these are in YYlex      */
extern char *yytext;                        /* current token           */


%}

/* Keywords and reserved words begin here.  */

%union{                                     /* this is the data union  */
   char   name[128];                       /* names                   */
}

/*-------------------- the reserved words -----------------------------*/

%token PERIOD
%token NEWLINE
%token POSITIONAL

%token VERB
%token ADVERB

%token PROPER_NOUN
%token NOUN

%token DECLARATIVE
%token CONDITIONAL


%type  <name> declarative
%type  <name> verb_phrase
%type  <name> noun_phrase
%type  <name> position_phrase
%type  <name> adverb

%type  <name> POSITIONAL VERB ADVERB PROPER_NOUN
%type  <name> NOUN DECLARATIVE CONDITIONAL

%%

sentence_list : sentence
             | sentence_list NEWLINE sentence
             ;


sentence : verb_phrase noun_phrase position_phrase adverb period
          {
            printf("I understand that sentence.\n");
            printf("VP = %s \n",$1);
            printf("NP = %s \n",$2);
            printf("PP = %s \n",$3);
            printf("AD = %s \n",$4);
          }
        | { yyerror("That's a strange sentence !!");  }
        ;

position_phrase : POSITIONAL  declarative PROPER_NOUN
                 {
                   sprintf($$,"%s %s %s",$1,$2,$3);
                 }
               | /* empty */ { strcpy($$,""); }
               ;


verb_phrase : VERB { strcpy($$,$1); strcat($$," "); }
           | adverb VERB
             {
               sprintf($$,"%s %s",$1,$2);
             }
           ;

adverb : ADVERB      { strcpy($$,$1); }
      | /* empty */ { strcpy($$,""); }
      ;

noun_phrase : DECLARATIVE NOUN
             {
               sprintf($$,"%s %s",$1,$2);
             }
           | CONDITIONAL declarative NOUN
                 {
                   sprintf($$,"%s %s %s",$1,$2,$3);
                 }
           | NOUN { strcpy($$,$1); strcat($$," "); }
           ;

declarative : DECLARATIVE { strcpy($$,$1); }
           | /* empty */ { strcpy($$,""); }
           ;

period : /* empty */
      | PERIOD
      ;


%%

/* Supplied main() and yyerror() functions.  */

int main(int argc, char *argv[])
{
 yyparse();   /* parse the file          */
 return(0);
}

int yyerror(char *message)
{
 extern FILE *yyout;

 fprintf(yyout,"\nError at line %5d. (%s) \n",
                    yylexlinenum,message);
}