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tisp.c
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tisp.c
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/* zlib License
*
* Copyright (c) 2017-2022 Ed van Bruggen
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
#include <ctype.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <limits.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "tisp.h"
#define BETWEEN(X, A, B) ((A) <= (X) && (X) <= (B))
#define LEN(X) (sizeof(X) / sizeof((X)[0]))
/* functions */
static void hash_add(Hash ht, char *key, Val val);
/* utility functions */
/* return named string for each type */
/* TODO loop through each type bit to print */
char *
type_str(TspType t)
{
switch (t) {
case TSP_NONE: return "Void";
case TSP_NIL: return "Nil";
case TSP_INT: return "Int";
case TSP_DEC: return "Dec";
case TSP_RATIO: return "Ratio";
case TSP_STR: return "Str";
case TSP_SYM: return "Sym";
case TSP_PRIM: return "Prim";
case TSP_FORM: return "Form";
case TSP_FUNC: return "Func";
case TSP_MACRO: return "Macro";
case TSP_PAIR: return "Pair";
default:
if (t == TSP_EXPR)
return "Expr";
if (t == TSP_RATIONAL)
return "Rational";
if (t & TSP_NUM)
return "Num";
return "Invalid";
}
}
/* check if character can be a part of a symbol */
static int
issym(char c)
{
return BETWEEN(c, 'a', 'z') || BETWEEN(c, 'A', 'Z') ||
BETWEEN(c, '0', '9') || strchr("_+-*/=<>!?$&^#@:~", c);
}
/* check if character is start of a number */
/* TODO only if -/+ is not followed by a delim */
static int
isnum(char *str)
{
return isdigit(*str) || (*str == '.' && isdigit(str[1])) ||
((*str == '-' || *str == '+') && (isdigit(str[1]) || str[1] == '.'));
}
/* check if character is a symbol delimiter */
static char
isdelim(int c)
{
/* add .{}[]`', */
return isspace(c) || c == '(' || c == ')' || c == '"' || c == ';';
}
/* skip over comments and white space */
/* TODO support mac/windows line endings */
static void
skip_ws(Tsp st, int skipnl)
{
const char *s = skipnl ? " \t\n" : " \t";
while (tsp_fget(st) && (strchr(s, tsp_fget(st)) || tsp_fget(st) == ';')) {
st->filec += strspn(st->file+st->filec, s); /* skip white space */
for (; tsp_fget(st) == ';'; tsp_finc(st)) /* skip comments until newline */
st->filec += strcspn(st->file+st->filec, "\n") - !skipnl;
}
}
/* count number of parenthesis */
static int
count_parens(char *s, int len)
{
int count = 0;
for (int i = 0; i < len && s[i]; i++)
if (s[i] == '(')
count++;
else if (s[i] == ')')
count--;
return count;
}
/* get length of list, if improper list return -1 */
int
list_len(Val v)
{
int len = 0;
for (; v->t == TSP_PAIR; v = cdr(v))
len++;
return nilp(v) ? len : -1;
}
/* check if two values are equal */
static int
vals_eq(Val a, Val b)
{
if (a->t & TSP_NUM && b->t & TSP_NUM) { /* NUMBERs */
if (num(a) != num(b) || den(a) != den(b))
return 0;
return 1;
}
if (a->t != b->t)
return 0;
if (a->t == TSP_PAIR) /* PAIR */
return vals_eq(car(a), car(b)) && vals_eq(cdr(a), cdr(b));
/* TODO function var names should not matter in comparison */
if (a->t & (TSP_FUNC | TSP_MACRO)) /* FUNCTION, MACRO */
return vals_eq(a->v.f.args, b->v.f.args) &&
vals_eq(a->v.f.body, b->v.f.body);
if (a != b) /* PRIMITIVE, STRING, SYMBOL, NIL, VOID */
return 0;
return 1;
}
/* reduce fraction by modifying supplied numerator and denominator */
static void
frac_reduce(int *num, int *den)
{
int a = abs(*num), b = abs(*den), c = a % b;
while (c > 0) {
a = b;
b = c;
c = a % b;
}
*num = *num / b;
*den = *den / b;
}
/* hash map */
/* return hashed number based on key */
static uint32_t
hash(char *key)
{
uint32_t h = 0;
char c;
while (h < UINT32_MAX && (c = *key++))
h = h * 33 + c;
return h;
}
/* create new empty hash table with given capacity */
static Hash
hash_new(size_t cap, Hash next)
{
if (cap < 1) return NULL;
Hash ht = malloc(sizeof(struct Hash));
if (!ht) perror("; malloc"), exit(1);
ht->size = 0;
ht->cap = cap;
ht->items = calloc(cap, sizeof(struct Entry));
if (!ht->items) perror("; calloc"), exit(1);
ht->next = next;
return ht;
}
/* get entry in one hash table for the key */
static Entry
entry_get(Hash ht, char *key)
{
int i = hash(key) % ht->cap;
char *s;
while ((s = ht->items[i].key)) {
if (!strcmp(s, key))
break;
if (++i == ht->cap)
i = 0;
}
return &ht->items[i]; /* returns entry if found or empty one to be filled */
}
/* get value of given key in each hash table */
static Val
hash_get(Hash ht, char *key)
{
Entry e;
for (; ht; ht = ht->next) {
e = entry_get(ht, key);
if (e->key)
return e->val;
}
return NULL;
}
/* enlarge the hash table to ensure algorithm's efficiency */
static void
hash_grow(Hash ht)
{
int i, ocap = ht->cap;
Entry oitems = ht->items;
ht->cap *= 2;
ht->items = calloc(ht->cap, sizeof(struct Entry));
if (!ht->items) perror("; calloc"), exit(1);
for (i = 0; i < ocap; i++) /* repopulate new hash table with old values */
if (oitems[i].key)
hash_add(ht, oitems[i].key, oitems[i].val);
free(oitems);
}
/* create new key and value pair to the hash table */
static void
hash_add(Hash ht, char *key, Val val)
{
Entry e = entry_get(ht, key);
e->val = val;
if (!e->key) {
e->key = key;
ht->size++;
if (ht->size > ht->cap / 2) /* grow table if it is more than half full */
hash_grow(ht);
}
}
/* add each binding args[i] -> vals[i] */
/* args and vals are both lists */
/* TODO don't return anything in hash_extend since it's modifying ht */
static Hash
hash_extend(Hash ht, Val args, Val vals)
{
Val arg, val;
for (; !nilp(args); args = cdr(args), vals = cdr(vals)) {
if (args->t == TSP_PAIR) {
arg = car(args);
val = car(vals);
} else {
arg = args;
val = vals;
}
if (arg->t != TSP_SYM)
tsp_warnf("expected symbol for argument of function"
" definition, recieved %s", type_str(arg->t));
hash_add(ht, arg->v.s, val);
if (args->t != TSP_PAIR)
break;
}
return ht;
}
/* make types */
Val
mk_val(TspType t)
{
Val ret = malloc(sizeof(struct Val));
if (!ret) perror("; malloc"), exit(1);
ret->t = t;
return ret;
}
Val
mk_int(int i)
{
Val ret = mk_val(TSP_INT);
num(ret) = i;
den(ret) = 1;
return ret;
}
Val
mk_dec(double d)
{
Val ret = mk_val(TSP_DEC);
num(ret) = d;
den(ret) = 1;
return ret;
}
Val
mk_rat(int num, int den)
{
Val ret;
if (den == 0)
tsp_warn("division by zero");
frac_reduce(&num, &den);
if (den < 0) { /* simplify so only numerator is negative */
den = abs(den);
num = -num;
}
if (den == 1) /* simplify into integer if denominator is 1 */
return mk_int(num);
ret = mk_val(TSP_RATIO);
ret->v.n.num = num;
ret->v.n.den = den;
return ret;
}
/* TODO combine mk_str and mk_sym */
Val
mk_str(Tsp st, char *s)
{
Val ret;
if ((ret = hash_get(st->strs, s)))
return ret;
ret = mk_val(TSP_STR);
ret->v.s = strndup(s, strlen(s));
if (!ret->v.s) perror("; strndup"), exit(1);
hash_add(st->strs, s, ret);
return ret;
}
Val
mk_sym(Tsp st, char *s)
{
Val ret;
if ((ret = hash_get(st->syms, s)))
return ret;
ret = mk_val(TSP_SYM);
ret->v.s = strndup(s, strlen(s));
if (!ret->v.s) perror("; strndup"), exit(1);
hash_add(st->syms, s, ret);
return ret;
}
Val
mk_prim(TspType t, Prim pr, char *name)
{
Val ret = mk_val(t);
ret->v.pr.name = name;
ret->v.pr.pr = pr;
return ret;
}
Val
mk_func(TspType t, char *name, Val args, Val body, Hash env)
{
Val ret = mk_val(t);
ret->v.f.name = name;
ret->v.f.args = args;
ret->v.f.body = body;
ret->v.f.env = env;
return ret;
}
Val
mk_pair(Val a, Val b)
{
Val ret = mk_val(TSP_PAIR);
car(ret) = a;
cdr(ret) = b;
return ret;
}
Val
mk_list(Tsp st, int n, ...)
{
Val lst, cur;
va_list argp;
va_start(argp, n);
lst = mk_pair(va_arg(argp, Val), st->nil);
for (cur = lst; n > 1; n--, cur = cdr(cur))
cdr(cur) = mk_pair(va_arg(argp, Val), st->nil);
va_end(argp);
return lst;
}
/* read */
/* read first character of number to determine sign */
static int
read_sign(Tsp st)
{
switch (tsp_fget(st)) {
case '-': tsp_finc(st); return -1;
case '+': tsp_finc(st); return 1;
default: return 1;
}
}
/* return read integer */
static int
read_int(Tsp st)
{
int ret = 0;
for (; tsp_fget(st) && isdigit(tsp_fget(st)); tsp_finc(st))
ret = ret * 10 + tsp_fget(st) - '0';
return ret;
}
/* return read scientific notation */
static Val
read_sci(Tsp st, double val, int isint)
{
if (tolower(tsp_fget(st)) != 'e')
goto finish;
tsp_finc(st);
double sign = read_sign(st) == 1 ? 10.0 : 0.1;
for (int expo = read_int(st); expo--; val *= sign) ;
finish:
if (isint)
return mk_int(val);
return mk_dec(val);
}
/* return read number */
static Val
read_num(Tsp st)
{
int sign = read_sign(st);
int num = read_int(st);
size_t oldc;
switch (tsp_fget(st)) {
case '/':
if (!isnum(st->file + ++st->filec))
tsp_warn("incorrect ratio format, no denominator found");
return mk_rat(sign * num, read_sign(st) * read_int(st));
case '.':
tsp_finc(st);
oldc = st->filec;
double d = (double) read_int(st);
int size = st->filec - oldc;
while (size--)
d /= 10.0;
return read_sci(st, sign * (num+d), 0);
default:
return read_sci(st, sign * num, 1);
}
}
/* return character for escape */
static char
esc_char(char c)
{
switch (c) {
case 'n': return '\n';
case 't': return '\t';
case '\n': return ' ';
case '\\':
case '"':
default: return c;
}
}
/* replace all encoded escape characters in string with their actual character */
static char *
esc_str(char *s, int len)
{
char *pos, *ret = malloc((len+1) * sizeof(char));
if (!ret) perror("; malloc"), exit(1);
for (pos = ret; pos-ret < len; pos++, s++)
*pos = (*s == '\\') ? esc_char(*(++s)) : *s;
*pos = '\0';
return ret;
}
/* return read string */
static Val
read_str(Tsp st)
{
int len = 0;
char *s = st->file + ++st->filec; /* skip starting open quote */
for (; tsp_fget(st) != '"'; tsp_finc(st), len++)
if (!tsp_fget(st))
tsp_warn("reached end before closing double quote");
else if (tsp_fget(st) == '\\' && tsp_fgetat(st, -1) != '\\')
tsp_finc(st); /* skip over break condition */
tsp_finc(st); /* skip last closing quote */
return mk_str(st, esc_str(s, len));
}
/* return read symbol */
static Val
read_sym(Tsp st)
{
int n = 1, i = 0;
char *sym = malloc(n);
for (; tsp_fget(st) && issym(tsp_fget(st)); tsp_finc(st)) {
if (!sym) perror("; alloc"), exit(1);
sym[i++] = tsp_fget(st);
if (i == n) {
n *= 2;
sym = realloc(sym, n);
}
}
sym[i] = '\0';
return mk_sym(st, sym);
}
/* return read string containing a list */
/* TODO read pair after as well, allow lambda((x) (* x 2))(4) */
static Val
read_pair(Tsp st, char endchar)
{
Val a, b;
skip_ws(st, 1);
if (tsp_fget(st) == endchar)
return tsp_finc(st), st->nil;
/* TODO simplify read_pair by supporting (. x) => x */
if (!(a = tisp_read(st)))
return NULL;
skip_ws(st, 1);
if (!tsp_fget(st))
tsp_warnf("reached end before closing '%c'", endchar);
if (tsp_fget(st) == '.' && isdelim(tsp_fgetat(st,1))) {
tsp_finc(st);
if (!(b = tisp_read(st)))
return NULL;
skip_ws(st, 1);
if (tsp_fget(st) != endchar)
tsp_warnf("did not find closing '%c'", endchar);
tsp_finc(st);
skip_ws(st, 1);
} else {
if (!(b = read_pair(st, endchar)))
return NULL;
}
return mk_pair(a, b);
}
/* reads given string returning its tisp value */
Val
tisp_read(Tsp st)
{
char *prefix[] = {
"'", "quote",
"`", "quasiquote",
",@", "unquote-splice", /* always check before , */
",", "unquote",
"@", "Func",
};
skip_ws(st, 1);
if (strlen(st->file+st->filec) == 0) /* empty list */
return st->none;
if (isnum(st->file+st->filec)) /* number */
return read_num(st);
/* TODO support | for symbols */
if (tsp_fget(st) == '"') /* strings */
return read_str(st);
for (int i = 0; i < LEN(prefix); i += 2) { /* character prefix */
if (!strncmp(st->file+st->filec, prefix[i], strlen(prefix[i]))) {
Val v;
tsp_fincn(st, strlen(prefix[i]));
if (!(v = tisp_read(st)))
return NULL;
return mk_list(st, 2, mk_sym(st, prefix[i+1]), v);
}
}
if (issym(tsp_fget(st))) /* symbols */
return read_sym(st);
if (tsp_fget(st) == '(') /* list */
return tsp_finc(st), read_pair(st, ')');
tsp_warnf("could not read given input '%c'", st->file[st->filec]);
}
/* return string containing contents of file name */
char *
tisp_read_file(char *fname)
{
char buf[BUFSIZ], *file = NULL;
int len = 0, n, fd, parens = 0;
if (!fname) /* read from stdin if no file given */
fd = 0;
else if ((fd = open(fname, O_RDONLY)) < 0)
tsp_warnf("could not find file '%s'", fname);
while ((n = read(fd, buf, sizeof(buf))) > 0) {
file = realloc(file, len + n + 1);
if (!file) perror("; realloc"), exit(1);
memcpy(file + len, buf, n);
len += n;
file[len] = '\0';
if (fd == 0 && !(parens += count_parens(buf, n)))
break;
}
if (fd) /* close file if not stdin */
close(fd);
if (n < 0)
tsp_warnf("could not read file '%s'", fname);
return file;
}
/* read given file name returning its tisp value */
Val
tisp_parse_file(Tsp st, char *fname)
{
Val ret = mk_pair(st->none, st->nil);
Val v, last = ret;
char *file = st->file;
size_t filec = st->filec;
if (!(st->file = tisp_read_file(fname)))
return ret;
for (st->filec = 0; tsp_fget(st) && (v = tisp_read(st)); last = cdr(last))
cdr(last) = mk_pair(v, st->nil);
free(st->file);
st->file = file;
st->filec = filec;
return cdr(ret);
}
/* eval */
/* evaluate each element of list */
Val
tisp_eval_list(Tsp st, Hash env, Val v)
{
Val cur = mk_pair(NULL, st->none);
Val ret = cur, ev;
for (; !nilp(v); v = cdr(v), cur = cdr(cur)) {
if (v->t != TSP_PAIR) {
if (!(ev = tisp_eval(st, env, v)))
return NULL;
cdr(cur) = ev;
return cdr(ret);
}
if (!(ev = tisp_eval(st, env, car(v))))
return NULL;
cdr(cur) = mk_pair(ev, st->none);
}
cdr(cur) = st->nil;
return cdr(ret);
}
/* evaluate all elements of list returning last */
Val
tisp_eval_seq(Tsp st, Hash env, Val v)
{
Val ret = st->none;
for (; v->t == TSP_PAIR; v = cdr(v))
if (!(ret = tisp_eval(st, env, car(v))))
return NULL;
return nilp(v) ? ret : tisp_eval(st, env, v);
}
static void
prepend_bt(Tsp st, Hash env, Val f)
{
if (!f->v.f.name) /* no need to record anonymous functions */
return;
for (; env->next; env = env->next) ; /* bt var located at base env */
Entry e = entry_get(env, "bt");
if (e->val->t == TSP_PAIR && car(e->val)->t == TSP_SYM &&
!strncmp(f->v.f.name, car(e->val)->v.s, strlen(car(e->val)->v.s)))
return; /* don't record same function on recursion */
e->val = mk_pair(mk_sym(st, f->v.f.name), e->val);
}
/* evaluate procedure f with arguments */
static Val
eval_proc(Tsp st, Hash env, Val f, Val args)
{
Val ret;
Hash e;
/* evaluate function and primitive arguments before being passed */
if (f->t & (TSP_FUNC|TSP_PRIM))
if (!(args = tisp_eval_list(st, env, args)))
return NULL;
switch (f->t) {
case TSP_FORM:
case TSP_PRIM:
return (*f->v.pr.pr)(st, env, args);
case TSP_FUNC:
case TSP_MACRO:
tsp_arg_num(args, f->v.f.name ? f->v.f.name : "anon",
list_len(f->v.f.args));
e = hash_new(8, f->v.f.env);
/* TODO call hash_extend in hash_new to know new hash size */
if (!(hash_extend(e, f->v.f.args, args)))
return NULL;
if (!(ret = tisp_eval_seq(st, e, f->v.f.body)))
return prepend_bt(st, env, f), NULL;
if (f->t == TSP_MACRO)
ret = tisp_eval(st, env, ret);
return ret;
default:
tsp_warnf("attempt to evaluate non procedural type %s", type_str(f->t));
}
}
/* evaluate given value */
Val
tisp_eval(Tsp st, Hash env, Val v)
{
Val f;
switch (v->t) {
case TSP_SYM:
if (!(f = hash_get(env, v->v.s)))
tsp_warnf("could not find symbol %s", v->v.s);
return f;
case TSP_PAIR:
if (!(f = tisp_eval(st, env, car(v))))
return NULL;
return eval_proc(st, env, f, cdr(v));
case TSP_STR: /* TODO string interpolation */
default:
return v;
}
}
/* print */
/* main print function */
void
tisp_print(FILE *f, Val v)
{
switch (v->t) {
case TSP_NONE:
fputs("Void", f);
break;
case TSP_NIL:
fputs("Nil", f);
break;
case TSP_INT:
fprintf(f, "%d", (int)num(v));
break;
case TSP_DEC:
fprintf(f, "%.15g", num(v));
if (num(v) == (int)num(v))
fprintf(f, ".0");
break;
case TSP_RATIO:
fprintf(f, "%d/%d", (int)num(v), (int)den(v));
break;
case TSP_STR:
case TSP_SYM:
fputs(v->v.s, f);
break;
case TSP_FUNC:
case TSP_MACRO:
fprintf(f, "#<%s%s%s>", /* if proc name is not null print it */
v->t == TSP_FUNC ? "function" : "macro",
v->v.pr.name ? ":" : "",
v->v.pr.name ? v->v.pr.name : "");
break;
case TSP_PRIM:
fprintf(f, "#<primitive:%s>", v->v.pr.name);
break;
case TSP_FORM:
fprintf(f, "#<form:%s>", v->v.pr.name);
break;
case TSP_PAIR:
putc('(', f);
tisp_print(f, car(v));
for (v = cdr(v); !nilp(v); v = cdr(v)) {
if (v->t == TSP_PAIR) {
putc(' ', f);
tisp_print(f, car(v));
} else {
fputs(" . ", f);
tisp_print(f, v);
break;
}
}
putc(')', f);
break;
default:
fprintf(stderr, "; tisp: could not print value type %s\n", type_str(v->t));
}
}
/* primitives */
/* return first element of list */
static Val
prim_car(Tsp st, Hash env, Val args)
{
tsp_arg_num(args, "car", 1);
tsp_arg_type(car(args), "car", TSP_PAIR);
return caar(args);
}
/* return elements of a list after the first */
static Val
prim_cdr(Tsp st, Hash env, Val args)
{
tsp_arg_num(args, "cdr", 1);
tsp_arg_type(car(args), "cdr", TSP_PAIR);
return cdar(args);
}
/* return new pair */
static Val
prim_cons(Tsp st, Hash env, Val args)
{
tsp_arg_num(args, "cons", 2);
return mk_pair(car(args), cadr(args));
}
/* do not evaluate argument */
static Val
form_quote(Tsp st, Hash env, Val args)
{
tsp_arg_num(args, "quote", 1);
return car(args);
}
/* evaluate argument given */
static Val
prim_eval(Tsp st, Hash env, Val args)
{
Val v;
tsp_arg_num(args, "eval", 1);
return (v = tisp_eval(st, st->global, car(args))) ? v : st->none;
}
/* test equality of all values given */
static Val
prim_eq(Tsp st, Hash env, Val args)
{
if (nilp(args))
return st->t;
for (; !nilp(cdr(args)); args = cdr(args))
if (!vals_eq(car(args), cadr(args)))
return st->nil;
return st->t;
}
/* evaluates all expressions if their conditions are met */
static Val
form_cond(Tsp st, Hash env, Val args)
{
Val v, cond;
for (v = args; !nilp(v); v = cdr(v))
if (!(cond = tisp_eval(st, env, caar(v))))
return NULL;
else if (!nilp(cond)) /* TODO incorporate else directly into cond */
return tisp_eval_seq(st, env, cdar(v));
return st->none;
}
/* return type of tisp value */
static Val
prim_typeof(Tsp st, Hash env, Val args)
{
tsp_arg_num(args, "typeof", 1);
return mk_str(st, type_str(car(args)->t));
}
/* TODO rename get to getattr like python ? */
/* get a property of given value */
static Val
prim_get(Tsp st, Hash env, Val args)
{
Val v, prop;
tsp_arg_num(args, "get", 2);
v = car(args), prop = cadr(args);
tsp_arg_type(prop, "get", TSP_SYM);
switch (v->t) {
case TSP_FORM:
case TSP_PRIM:
if (!strncmp(prop->v.s, "name", 4))
return mk_sym(st, v->v.pr.name);
break;
case TSP_FUNC:
case TSP_MACRO:
if (!strncmp(prop->v.s, "name", 4))
return mk_sym(st, v->v.f.name ? v->v.f.name : "anon");
if (!strncmp(prop->v.s, "body", 4))
return v->v.f.body;
if (!strncmp(prop->v.s, "args", 4))
return v->v.f.args;
break;
case TSP_INT:
case TSP_RATIO:
if (!strncmp(prop->v.s, "numerator", 9))
return mk_int(v->v.n.num);
if (!strncmp(prop->v.s, "denominator", 9))
return mk_int(v->v.n.den);
break;
case TSP_PAIR: /* TODO get nth element if number */
if (!strncmp(prop->v.s, "car", 3))
return v->v.p.car;
if (!strncmp(prop->v.s, "cdr", 3))
return v->v.p.cdr;
break;
case TSP_STR:
case TSP_SYM:
if (!strncmp(prop->v.s, "len", 3))
return mk_int(strlen(v->v.s));
default: break;
}
tsp_warnf("get: can not access %s from type %s",
prop->v.s, type_str(v->t));
}
/* creates new tisp function */
static Val
form_Func(Tsp st, Hash env, Val args)
{
Val params, body;
tsp_arg_min(args, "Func", 1);
if (nilp(cdr(args))) { /* if only 1 argument is given, auto fill func parameters */
params = mk_pair(mk_sym(st, "it"), st->nil);
body = args;
} else {
params = car(args);
body = cdr(args);
}
return mk_func(TSP_FUNC, NULL, params, body, env);
}
/* creates new tisp defined macro */
static Val
form_Macro(Tsp st, Hash env, Val args)
{
tsp_arg_min(args, "Macro", 1);
Val ret = form_Func(st, env, args);
ret->t = TSP_MACRO;
return ret;
}
/* creates new variable of given name and value
* if pair is given as name of variable, creates function with the car as the
* function name and the cdr the function arguments */
/* TODO if var not func error if more than 2 args */
static Val
form_def(Tsp st, Hash env, Val args)
{
Val sym, val;
tsp_arg_min(args, "def", 1);
if (car(args)->t == TSP_PAIR) { /* create function if given argument list */
sym = caar(args); /* first element of argument list is function name */
if (sym->t != TSP_SYM)
tsp_warnf("def: incorrect format,"
" expected symbol for function name, received %s",
type_str(sym->t));
val = mk_func(TSP_FUNC, sym->v.s, cdar(args), cdr(args), env);
} else if (car(args)->t == TSP_SYM) { /* create variable */
sym = car(args); /* if only symbol given, make it self evaluating */
val = nilp(cdr(args)) ? sym : tisp_eval(st, env, cadr(args));
} else tsp_warn("def: incorrect format, no variable name found");
if (!val)
return NULL;
/* set procedure name if it was previously anonymous */
if (val->t & (TSP_FUNC|TSP_MACRO) && !val->v.f.name)
val->v.f.name = sym->v.s;
hash_add(env, sym->v.s, val);
return st->none;
}
/* set symbol to new value */
static Val
form_set(Tsp st, Hash env, Val args)
{
Val val;
Hash h;
Entry e = NULL;
tsp_arg_num(args, "set!", 2);
tsp_arg_type(car(args), "set!", TSP_SYM);
if (!(val = tisp_eval(st, env, cadr(args))))
return NULL;
/* find first occurrence of symbol */
for (h = env; h; h = h->next) {
e = entry_get(h, car(args)->v.s);
if (e->key)
break;
}
if (!e || !e->key)
tsp_warnf("set!: variable %s is not defined", car(args)->v.s);
if (e->val->t == TSP_PRIM) /* TODO hard code other values */
tsp_warnf("set!: can not modify %s, is primitive procedure", e->val->v.pr.name);
e->val = val;
return val;
}
/* TODO fix crashing if try to undefine builtin */
static Val
form_undefine(Tsp st, Hash env, Val args)
{
tsp_arg_min(args, "undefine!", 1);
tsp_arg_type(car(args), "undefine!", TSP_SYM);
for (Hash h = env; h; h = h->next) {