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3.1 hoc1

3.1.1 makefile

hoc1: hoc.o

      cc hoc.o -o hoc1

3.1.2 hoc.y

%{

#define YYSTYPE double /* data type of yacc stack */

%}

%token NUMBER

%left '+' /* left associative, same precedence */

%left '*' '/' /* left assoc., higher precedence */

%%

list : /* nothing */

 | list '\n'

 | list expr '\n' { printf("\t%.8g\n", $2); }

 ;

expr: NUMBER { $$ = $1; }

 | expr '+' expr { $$ = $1 + $3; }

 | expr '-' expr { $$ = $1 - $3; }

 | expr '*' expr { $$ = $1 * $3; }

 | expr '/' expr { $$ = $1 / $3; }

 | '(' expr ')' { $$ = $2; }

 ;

%%

/* end of grammar */

#include

#include

char *progname; /* for error messages */

int lineno = 1;

main(argc, argv) /* hoc1 */

 char *argv[];

{

 progname = argv[0];

 yyparse();

}

yylex() /* hoc1 */

{

 int c;

 while ((c=getchar()) == ' ' || c == '\t')

  ;

 if (c == EOF)

  return 0;

 if (c == '.' || isdigit(c)) { /* number */

  ungetc(c, stdin);

 scanf("%lf", &yylval);

 return NUMBER;

 if (c == '\n')

  lineno++;

 return c;

}

yyerror(s) /* called for yacc syntax error */

 char *s;

{

 warning(s, (char*)0);

}

warning(s, t) /* print warning message */

 char *s, *t;

{

 fprintf(stderr, "%s: %s", progname, s);

 if (t)

  fprintf(stderr, " %s", t);

 fprintf(stderr, " near line %d\n", lineno);

}

3.1.3 hoc1.y , версия 1.5

%{

#define YYSTYPE double /* data type of yacc stack */

%}

%token NUMBER

%left '-' '+'

%left '*' '/'

%left UNARYMINUS

%%

list: /* nothing */

 | list '\n'

 | list expr '\n' { printf("\t%.8g\n", $2); }

 ;

expr: NUMBER { $$ = $1; }

 | expr '+' expr { $$ = $1 + $3; }

 | expr '-' expr { $$ = $1 - $3; }

 | expr '*' expr { $$ = $1 * $3; }

 | expr '/' expr { $$ = $1 / $3; }

 | '-' expr %prec UNARYMINUS { $$ = -$2; } /* new */

 | '(' expr ')' { $$ = $2; }

 ;

%%

/* end of grammar */

#include

#include

char *progname; /* for error messages */

int lineno = 1;

main(argc, argv) /* hoc1 */

 char *argv[];

{

 progname = argv[0];

 yyparse();

}

yylex() /* hoc1 */

{

 int c;

 while ((c=getchar()) == ' ' || с == '\t')

  ;

 if (c == EOF)

  return 0;

 if (c == '.' || isdigit(c)) { /* number */

  ungetc(c, stdin);

  scanf("%lf", &yylval);

  return NUMBER;

 }

 if (c == '\n')

  lineno++;

 return c;

}

yyerror(s)

 char *s;

{

 warning(s, (char *)0);

}

warning(s, t)

 char *s, *t;

{

 fprintf(stderr, "%s: %s", progname, s);

 if (t && *t)

  fprintf(stderr, "%s", t);

 fprintf(stderr, " near line %d\n", lineno);

}

3.2 hoc2

3.2.1 hoc.y

%{

double mem[26]; /* memory for variables 'a'..'z' */

%}

%union { /* stack type */

 double val; /* actual value */