UNIX — универсальная среда программирования - Брайан Керниган
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}
fpecatch() /* catch floating point exceptions */
{
execerror("floating point exception", (char*)0);
}
warning(s, t) /* print warning message */
char *s, *t;
{
fprintf(stderr. "%s: %s", progname, s);
if (t && *t)
fprintf(stderr, " %s , t);
fprintf(stderr, " near line %dn", lineno);
}
3.2.2 makefile
hoc2: hoc.o
cc hoc.o -o hoc2
3.3 hoc3
3.3.1 makefile
YFLAGS = -d # force creation of y.tab.h
OBJS = hoc.o init.o math.o symbol.o # abbreviation
hoc3: $(OBJS)
cc $(OBJS) -lm -o hoc3
hoc.o: hoc.h
init.o symbol.o: hoc.h y.tab.h
pr:
@pr hoc.y hoc.h init.c math.c symbol.c makefile
clean:
rm -f $(OBJS) y.tab.[ch]
3.3.2 hoc.h
typedef struct Symbol { /* symbol table entry */
char *name;
short type; /* VAR, BLTIN, UNDEF */
union {
double val; /* if VAR */
double (*ptr)(); /* if BLTIN */
} u;
struct Symbol *next; /* to link to another */
} Symbol;
Symbol *install(), *lookup();
3.3.3 hoc.y
%{
#include "hoc.h"
extern double Pow();
%}
%union {
double val; /* actual value */
Symbol *sym; /* symbol table pointer */
}
%token <val> NUMBER
%token <sym> VAR BLTIN UNDEF
%type <val> expr asgn
%right '=' %left '+' '-'
%left '*' '/'
%left UNARYMINUS
%right /* exponentiation */
%%
list: /* nothing */
| list 'n'
| list asgn 'n'
| list expr 'n' { printf("t%.8gn", $2); }
| list error 'n' { yyerrok; }
;
asgn: VAR '=' expr { $$=$1->u.val=$3; $1->type = VAR; }
;
expr: NUMBER
| VAR { if ($l->type == UNDEF)
execerror("undefined variable", $1->name);
$$ = $1->u.val;
}
| asgn
| BLTIN '(' expr ')' { $$ = (*($1->u.ptr))($3); }
| expr '+' expr { $$ = $1 + $3; }
| expr '-' expr { $$ = $1 - $3; }
| expr '*' expr { $$ = $1 * $3; }
| expr '/' expr {
if ($3 == 0.0)
execerror("division by zero", "");
$$ = $1 / $3;
}
| expr '^' expr { $$ = Pow($1, $3); }
| '(' expr ')' { $$ = $2; }
| '-' expr %prec UNARYMINUS { $$ = -$2; }
;
%%
/* end of grammar */
#include <stdio.h>
#include <ctype.h>
char *progname;
int lineno = 1;
#include <signal.h>
#include <setjmp.h>
jmp_buf begin;
main(argc, argv) /* hoc3 */
char *argv[];
{
int fpecatch();
progname = argv[0];
init();
setjmp(begin);
signal(SIGFPE, fpecatch);
yyparse();
}
yylex() /* hoc3 */
{
int c;
while ((c=getchar()) == ' ' || c == 't')
;
if (c == EOF)
return 0;
if (c == '.' || isdigit(c)) {
/* number */
ungetc(c, stdin);
scanf("%lf", &yylval.val);
return NUMBER;
}
if (isalpha(c)) {
Symbol *s;
char sbuf[100], *p = sbuf;
do {
*p++ = c;
} while ((c=getchar()) != EOF && isalnum(c));
ungetc(c, stdin);
*p = ' ';
if ((s=lookup(sbuf)) == 0)
s = install(sbuf, UNDEF, 0.0);
yylval.sym = s;
return s->type == UNDEF ? VAR : s->type;
}
if (c == 'n')
lineno++;
return c;
}
yyerror(s)
char *s;
{
warning(s, (char *)0);
}
execerror(s, t) /* recover from run-time error */
char *s, *t;
{
warning(s, t);
longjmp(begin, 0);
}
fpecatch() /* catch floating point exceptions */
execerror("floating point exception", (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 %dn", lineno);
}
3.3.4 init.c
#include "hoc.h"
#include "y.tab.h"
#include <math.h>
extern double Log(), Log10(), Exp(), Sqrt(), integer();
static struct { /* Constants */
char *name;
double eval;
} consts[] = {
"PI", 3.14159265358979323846,
"E", 2.71828182845904523536,
"GAMMA", 0.57721566490153286060, /* Euler */
"DEG", 57.29577951308232087680, /* deg/radian */
"PHI", 1.61803398874989484820, /* golden ratio */
0, 0
};
static struct { /* Built-ins */
char *name;
double (*func)();
} builtins[] = {
"sin", sin,
"cos", cos,
"atan", atan,
"log", Log, /* checks argument */
"log10", Log10, /* checks argument */
"exp", Exp, /* checks argument */
"sqrt", Sqrt, /* checks argument */
"int", integer,
"abs", fabs,
0, 0
};
init() /* install constants and built-ins in table */
{
int i;
Symbol *s;
for (i = 0; consts[i].name; i++)
install(consts[i].name, VAR, consts[i].eval);
for (i = 0; builtins[i].name; i++) {
s = install(builtins[i].name, BLTIN, 0.0);
s->u.ptr = builtins[i].func;
}
}
3.3.5 math.c
#include <math.h>
#include <errno.h>
extern int errno;
double errcheck();
double Log(x)
double x;
{
return errcheck(log(x), "log");
}
double Log10(x)
double x;
{
return errcheck(log10(x), "log10");
}
double Sqrt(x)
double x;
{
return errcheck(sqrt(x), "sqrt");
}
double Exp(x)
double x;
{
return errcheck(exp(x), "exp");
}
double Pow(x, y)
double x, y;
return errcheck(pow(x,y), "exponentiation");
}
double integer(x)
double x;
{
return (double)(long)x;
}
double errcheck(d, s) /* check result of library call */
double d;
char *s;
{
if (errno == EDOM) {
errno = 0;
execerror(s, "argument out of domain");
}
else if (errno == ERANGE) {
errno = 0;
execerror(s, "result out of range");
}
return d;
}
3.3.6 symbol.c
#include "hoc.h"
#include "y.tab.h"
static Symbol *symlist = 0; /* symbol table: linked list */
Symbol *lookup(s) /* find s in symbol table */
char *s;
{
Symbol *sp;
for (sp = symlist; sp != (Symbol*)0; sp = sp->next)
if (strcmp(sp->name, s) == 0)
return sp;
return 0; /* 0 ==> not found */
}
Symbol *install(s, t, d) /* install s in symbol table */
char *s;
int t;
double d;
Symbol *sp;
char *emalloc();
sp = (Symbol*)emalloc(sizeof(Symbol));
sp->name = emalloc(strlen(s)+1); /* +1 for ' ' */
strcpy(sp->name, s);
sp->type = t;
sp->u.val = d;
sp->next = symlist; /* put at front of list */
symlist = sp;
return sp;
}
char *emalloc(n) /* check return from malloc */
unsigned n;
{
char *p, *malloc();
p = malloc(n);
if (p == 0)
execerror("out of memory", (char*)0);
return p;
}
3.4 hoc3 с lex
3.4.1. hoc.h
typedef struct Symbol { /* symbol table entry */
char *name;
short type; /* VAR, BLTIN, UNDEF */
union {
double val; /* if VAR */
double (*ptr)(); /* if BLTIN */
} u;
struct Symbol *next; /* to link to another */
} Symbol;
Symbol *install(), *lookup();
3.4.2 hoc.y
%{
#include "hoc.h"
extern double Pow();
%}
%union {
double val; /* actual value */
Symbol *sym; /* symbol table pointer */
}
%token <val> NUMBER
%token <sym> VAR BLTIN UNDEF
%type <val> expr asgn
%right '='
%left '+' '-'
%left '*' '/'
%left UNARYMINUS
%right '^' /* exponentiation */
%%
list: /* nothing */
