Брайан Керниган - UNIX — универсальная среда программирования

{

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 '\0' */

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;

}

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();

%{

#include "hoc.h"

extern double Pow();

%}

%union {

double val; /* actual value */

Symbol *sym; /* symbol table pointer */

}

%token NUMBER

%token VAR BLTIN UNDEF

%type expr asgn

%right '='

%left '+' '-'

%left '*' '/'

%left UNARYMINUS

%right '^' /* exponentiation */

%%

list: /* nothing */

| list '\n'

| list asgn '\n'

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

| list error '\n' { yyerrok; }

;

asgn: VAR '=' expr { $$=$1->u.val=$3; $1->type = VAR; }

;

expr: NUMBER

| VAR {

if ($1->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

#include

char *progname;

int lineno = 1;

#include

jmp_buf begin;

main(argc, argv) /* hoc3 */

char *argv[];

{

progname = argv[0];

init();

setjmp(begin);

yyparse();

}

yyerror(s)

char *s;

{

warning(s, (char *)0);

}

execerror(s, t)

char *s, *t;

{

warning(s, t);

longjmp(begin, 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);

}

#include "hoc.h"

#include "y.tab.h"

#include

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;

}

}

%{

#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]; }

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

#include

#include

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;

}

#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 '\0' */

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;

}

#include "hoc.h"

#include "y.tab.h"

#define NSTACK 256

static Datum stack[NSTACK]; /* the stack */

static Datum *stackp; /* next free spot on stack */

#define NPROG 2000

Inst prog[NPROG]; /* the machine */

Inst *progp; /* next free spot for code generation */

Inst *pc; /* program counter during execution */

initcode() /* initialize for code generation */

{

stackp = stack;

progp = prog;

}

push(d) /* push d onto stack */

Datum d;

{

if (stackp >= &stack[NSTACK])

execerror("stack overflow", (char*)0);

*stackp++ = d;