UNIX — универсальная среда программирования - Керниган Брайан Уилсон
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;
}
}
3.4.4. lex.l
%{
#include "hoc.h"
#include "y.tab.h"
extern int lineno;
%}
%%
[ t] { ; } /* skip blanks and tabs */
[0-9]+.?|[0-9][0-9]+ {
sscanf(yytext, "%lf", &yylval.val);
return NUMBER;
}
[a-zA-Z][a-zA-Z0-9]* {
Symbol *s;
if ((s=lookup(yytext)) == 0)
s = install(yytext, UNDEF, 0.0);
yylval.sym = s;
return s->type == UNDEF ? VAR : s->type;
}
n {
lineno++;
return 'n';
} /* everything else */
. { return yytext[0]; }
3.4.5 makefile
YFLAGS = -d
OBJS = hoc.o lex.o init.o math.o symbol.o
hoc3: $(OBJS)
cc $(OBJS) -lm -ll -o hoc3
hoc.o: hoc.h
lex.o init.o symbol.o: hoc.h y.tab.h
3.4.6 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;
}
3.4.7 symbol.c
#include "hoc.h"
#include "y.tab.h"
