UNIX — универсальная среда программирования - Брайан Керниган
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Закладка:
d1 = pop();
d1.val = Pow(d1.val, d2.val);
push(d1);
}
assign() /* assign top value to next value */
{
Datum d1, d2;
d1= pop();
d2 = pop();
if (d1.sym->type != VAR && d1.sym->type != UNDEF)
execerror("assignment to non-variable", d1.sym->name);
d1.sym->u.val = d2.val;
d1.sym->type = VAR;
push(d2);
}
print() /* pop top value from stack, print it */
{
Datum d;
d = pop();
printf("t%8gn", d.val);
}
Inst *code(f) /* install one instruction or operand */
Inst f;
{
Inst *oprogp = progp;
if (progp >= &eprog[NPROG])
execerror("program too big", (char*)0);
*progp++ = f;
return oprogp;
}
execute(p) /* run the machine */
Inst *p;
{
for (pc = p; *pc != STOP; )
(*(*pc++))();
}
3.5.2 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();
typedef union Datum { /* interpreter stack type */
double val;
Symbol *sym;
} Datum;
extern Datum pop();
typedef int (*Inst)(); /* machine instruction */
#define STOP (Inst)0
extern Inst prog[];
extern eval(), add(), sub(), mul(), div(), negate(), power();
extern assign(), bltin(), varpush(), constpush(), print();
3.5.3 hoc.y
%{
#include "hoc.h"
#define code2(c1,c2) code(c1); code(c2)
#define code3(c1,c2,c3) code(c1); code(c2); code(c3)
%}
%union {
Symbol *sym; /* symbol table pointer */
Inst *inst; /* machine instruction */
}
%token <sym> NUMBER VAR BLTIN UNDEF
%right '='
%left '+' '-'
%left '*' '/'
%left UNARYMINUS
%right '^' /* exponentiation */
%%
list: /* nothing */
| list 'n'
| list asgn 'n' { code2(pop, STOP); return 1; }
| list expr 'n' { code2(print, STOP); return 1; }
| list error 'n' { yyerrok; }
;
asgn: VAR '=' expr { code3(varpush,(Inst)$1.assign); }
;
expr: NUMBER { code2(constpush, (Inst)$1); }
| VAR { code3(varpush, (Inst)$1, eval); }
| asgn
| BLTIN '(' expr ')' { code2(bltin, (Inst)$1->u.ptr); }
| '(' expr ')'
| expr '+' expr { code(add); }
| expr '-' expr { code(sub); }
| expr '*' expr { code(mul); }
| expr '/' expr { code(div); }
| expr '^' expr { code(power); }
| '-' expr %prec UNARYMINUS { code(negate); }
;
%%
/* 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) /* hoc4 */
char *argv[];
{
int fpecatch();
progname = argv[0];
init();
setjmp(begin);
signal(SIGFPE, fpecatch);
for (initcode(); yyparse(); initcode())
execute(prog);
return 0;
}
static int c; /* global for use by warning() */
yylex() /* hoc4 */
{
while ((c=getchar()) == ' ' || с == 't')
;
if (c == EOF)
return 0;
if (c == '.' || isdigit(c)) { /* number */
double d;
ungetc(c, stdin);
scanf ("%lf", &d);
yylval.sym = install("", NUMBER, d);
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);
while (c != 'n' && с != EOF)
с = getchar(); /* flush rest of input line */
}
3.5.4 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;
}
}
3.5.5. makefile
YFLAGS = -d
OBJS = hoc.o code.o init.o math.o symbol.o
hoc4: $(OBJS)
cc $(OBJS) -lm -o hoc4
hoc.o code.o init.o symbol.o: hoc.h
code.o init.o symbol.o: x.tab.h
x.tab.h: y.tab.h
-cmp -s x.tab.h y.tab.h || cp y.tab.h x.tab.h
pr: hoc.y hoc.h code.c init.c math.c symbol.c
@pr $?
@touch pr
clean:
rm -f $(OBJS) [xy].tab.[ch]
3.5.6. 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;
}
3.5.7 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();
