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miniscm.c
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miniscm.c
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/*
* ---------- Mini-Scheme Interpreter Version 0.85 ----------
*
* coded by Atsushi Moriwaki (11/5/1989)
*
* E-MAIL : moriwaki@kurims.kurims.kyoto-u.ac.jp
*
* THIS SOFTWARE IS IN THE PUBLIC DOMAIN
* ------------------------------------
* This software is completely free to copy, modify and/or re-distribute.
* But I would appreciate it if you left my name on the code as the author.
*
*/
/*--
*
* This version has been modified by Chris Pressey.
* current version is 0.85p1 (as yet unreleased)
*
* This version has been modified by R.C. Secrist.
*
* Mini-Scheme is now maintained by Akira KIDA.
*
* This is a revised and modified version by Akira KIDA.
* current version is 0.85k4 (15 May 1994)
*
* Please send suggestions, bug reports and/or requests to:
* <SDI00379@niftyserve.or.jp>
*--
*/
/*
* Here is System declaration.
* Please define exactly one symbol in the following section.
*/
/* #define LSC */ /* LightSpeed C for Macintosh */
/* #define LSC4 */ /* THINK C version 4.0 for Macintosh */
/* #define MPW2 */ /* Macintosh Programmer's Workshop v2.0x */
/* #define BSD */ /* 4.x BSD */
/* #define MSC */ /* Microsoft C Compiler v.4.00 - 7.00 */
/* #define TURBOC */ /* Turbo C compiler v.2.0, or TC++ 1.0 */
/* #define SYSV */ /* System-V, or POSIX */
/* #define VAXC */ /* VAX/VMS VAXC 2.x or later */ /* (automatic) */
#ifdef __BORLANDC__ /* Borland C++ - MS-DOS */
#define TURBOC
#endif
#ifdef __TURBOC__ /* Turbo C V1.5 - MS-DOS */
#define TURBOC
#endif
#ifdef mips /* DECstation running OSF/1 */
#define BSD
#endif
#ifdef __osf__ /* Alpha AXP running OSF/1 */
#define BSD
#endif
#ifdef __DECC /* Alpha AXP running VMS */
#define VAXC
#endif
#ifdef _AIX /* RS/6000 running AIX */
#define BSD
#endif
/*
* Define or undefine following symbols as you need.
*/
/* #define VERBOSE */ /* define this if you want verbose GC */
#define AVOID_HACK_LOOP /* define this if your compiler is poor
* enougth to complain "do { } while (0)"
* construction.
*/
#define USE_SETJMP /* undef this if you do not want to use setjmp() */
#define USE_QQUOTE /* undef this if you do not need quasiquote */
#define USE_MACRO /* undef this if you do not need macro */
#ifdef USE_QQUOTE
/*--
* If your machine can't support "forward single quotation character"
* i.e., '`', you may have trouble to use backquote.
* So use '^' in place of '`'.
*/
# define BACKQUOTE '`'
#endif
/*
* Basic memory allocation units
*/
#ifdef TURBOC /* rcs */
#define CELL_SEGSIZE 2048
#define CELL_NSEGMENT 100
#define STR_SEGSIZE 2048
#define STR_NSEGMENT 100
#else
#define CELL_SEGSIZE 5000 /* # of cells in one segment */
#define CELL_NSEGMENT 100 /* # of segments for cells */
#define STR_SEGSIZE 2500 /* bytes of one string segment */
#define STR_NSEGMENT 100 /* # of segments for strings */
#endif
#define banner "Hello, This is Mini-Scheme Interpreter Version 0.85p1.\n"
#include <stdio.h>
#include <ctype.h>
#ifdef USE_SETJMP
#include <setjmp.h>
#endif
/* System dependency */
#ifdef LSC
#include <strings.h>
#include <unix.h>
#define malloc(x) NewPtr((long)(x))
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 5
#endif
#ifdef LSC4
#include <string.h>
#include <stdlib.h>
#define malloc(x) NewPtr((long)(x))
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 5
#endif
#ifdef MPW2
#include <strings.h>
#include <memory.h>
#define malloc(x) NewPtr((long)(x))
#define prompt "> [enter at next line]\n"
#define InitFile "init.scm"
#define FIRST_CELLSEGS 5
#endif
#ifdef BSD
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 10
#endif
#ifdef MSC
#include <string.h>
#include <stdlib.h>
#include <malloc.h>
#include <process.h>
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 3
#endif
#ifdef TURBOC
#include <string.h>
#include <stdlib.h>
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 3
#endif
#ifdef SYSV
#include <string.h>
#include <malloc.h>
#if __STDC__
# include <stdlib.h>
#endif
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 10
#endif
#ifdef VAXC
#include <string.h>
#include <stdlib.h>
#define prompt "> "
#define InitFile "init.scm"
#define FIRST_CELLSEGS 10
#endif
#ifdef __GNUC__
/*
* If we use gcc, AVOID_HACK_LOOP is unnecessary
*/
#undef AVOID_HACK_LOOP
#endif
#ifndef FIRST_CELLSEGS
#error Please define your system type.
/*
* We refrain this to raise an error anyway even if on pre-ANSI system.
*/
error Please define your system type.
#endif
/* cell structure */
struct cell {
unsigned short _flag;
union {
struct {
char *_svalue;
short _keynum;
} _string;
struct {
long _ivalue;
} _number;
struct {
struct cell *_car;
struct cell *_cdr;
} _cons;
} _object;
};
typedef struct cell *pointer;
#define T_STRING 1 /* 0000000000000001 */
#define T_NUMBER 2 /* 0000000000000010 */
#define T_SYMBOL 4 /* 0000000000000100 */
#define T_SYNTAX 8 /* 0000000000001000 */
#define T_PROC 16 /* 0000000000010000 */
#define T_PAIR 32 /* 0000000000100000 */
#define T_CLOSURE 64 /* 0000000001000000 */
#define T_CONTINUATION 128 /* 0000000010000000 */
#ifdef USE_MACRO
# define T_MACRO 256 /* 0000000100000000 */
#endif
#define T_PROMISE 512 /* 0000001000000000 */
#define T_ATOM 16384 /* 0100000000000000 */ /* only for gc */
#define CLRATOM 49151 /* 1011111111111111 */ /* only for gc */
#define MARK 32768 /* 1000000000000000 */
#define UNMARK 32767 /* 0111111111111111 */
/* macros for cell operations */
#define type(p) ((p)->_flag)
#define isstring(p) (type(p)&T_STRING)
#define strvalue(p) ((p)->_object._string._svalue)
#define keynum(p) ((p)->_object._string._keynum)
#define isnumber(p) (type(p)&T_NUMBER)
#define ivalue(p) ((p)->_object._number._ivalue)
#define ispair(p) (type(p)&T_PAIR)
#define car(p) ((p)->_object._cons._car)
#define cdr(p) ((p)->_object._cons._cdr)
#define issymbol(p) (type(p)&T_SYMBOL)
#define symname(p) strvalue(car(p))
#define hasprop(p) (type(p)&T_SYMBOL)
#define symprop(p) cdr(p)
#define issyntax(p) (type(p)&T_SYNTAX)
#define isproc(p) (type(p)&T_PROC)
#define syntaxname(p) strvalue(car(p))
#define syntaxnum(p) keynum(car(p))
#define procnum(p) ivalue(p)
#define isclosure(p) (type(p)&T_CLOSURE)
#ifdef USE_MACRO
# define ismacro(p) (type(p)&T_MACRO)
#endif
#define closure_code(p) car(p)
#define closure_env(p) cdr(p)
#define iscontinuation(p) (type(p)&T_CONTINUATION)
#define cont_dump(p) cdr(p)
#define ispromise(p) (type(p)&T_PROMISE)
#define setpromise(p) type(p) |= T_PROMISE
#define isatom(p) (type(p)&T_ATOM)
#define setatom(p) type(p) |= T_ATOM
#define clratom(p) type(p) &= CLRATOM
#define ismark(p) (type(p)&MARK)
#define setmark(p) type(p) |= MARK
#define clrmark(p) type(p) &= UNMARK
#define caar(p) car(car(p))
#define cadr(p) car(cdr(p))
#define cdar(p) cdr(car(p))
#define cddr(p) cdr(cdr(p))
#define cadar(p) car(cdr(car(p)))
#define caddr(p) car(cdr(cdr(p)))
#define cadaar(p) car(cdr(car(car(p))))
#define cadddr(p) car(cdr(cdr(cdr(p))))
#define cddddr(p) cdr(cdr(cdr(cdr(p))))
/* arrays for segments */
pointer cell_seg[CELL_NSEGMENT];
int last_cell_seg = -1;
char *str_seg[STR_NSEGMENT];
int str_seglast = -1;
/* We use 4 registers. */
pointer args; /* register for arguments of function */
pointer envir; /* stack register for current environment */
pointer code; /* register for current code */
pointer dump; /* stack register for next evaluation */
struct cell _NIL;
pointer NIL = &_NIL; /* special cell representing empty cell */
struct cell _T;
pointer T = &_T; /* special cell representing #t */
struct cell _F;
pointer F = &_F; /* special cell representing #f */
pointer oblist = &_NIL; /* pointer to symbol table */
pointer global_env; /* pointer to global environment */
/* global pointers to special symbols */
pointer LAMBDA; /* pointer to syntax lambda */
pointer QUOTE; /* pointer to syntax quote */
#ifdef USE_QQUOTE
pointer QQUOTE; /* pointer to symbol quasiquote */
pointer UNQUOTE; /* pointer to symbol unquote */
pointer UNQUOTESP; /* pointer to symbol unquote-splicing */
#endif
pointer free_cell = &_NIL; /* pointer to top of free cells */
long fcells = 0; /* # of free cells */
FILE *infp; /* input file */
FILE *outfp; /* output file */
#ifdef USE_SETJMP
jmp_buf error_jmp;
#endif
char gc_verbose; /* if gc_verbose is not zero, print gc status */
int quiet = 0; /* if not zero, print banner, prompt, results */
int all_errors_fatal = 0; /* if not zero, every error is a FatalError */
/* allocate new cell segment */
alloc_cellseg(n)
int n;
{
register pointer p;
register long i;
register int k;
for (k = 0; k < n; k++) {
if (last_cell_seg >= CELL_NSEGMENT - 1)
return k;
p = (pointer) malloc(CELL_SEGSIZE * sizeof(struct cell));
if (p == (pointer) 0)
return k;
cell_seg[++last_cell_seg] = p;
fcells += CELL_SEGSIZE;
for (i = 0; i < CELL_SEGSIZE - 1; i++, p++) {
type(p) = 0;
car(p) = NIL;
cdr(p) = p + 1;
}
type(p) = 0;
car(p) = NIL;
cdr(p) = free_cell;
free_cell = cell_seg[last_cell_seg];
}
return n;
}
/* allocate new string segment */
alloc_strseg(n)
int n;
{
register char *p;
register long i;
register int k;
for (k = 0; k < n; k++) {
if (str_seglast >= STR_NSEGMENT)
return k;
p = (char *) malloc(STR_SEGSIZE * sizeof(char));
if (p == (char *) 0)
return k;
str_seg[++str_seglast] = p;
for (i = 0; i < STR_SEGSIZE; i++)
*p++ = (char) (-1);
}
return n;
}
/* initialization of Mini-Scheme */
init_scheme()
{
register pointer i;
if (alloc_cellseg(FIRST_CELLSEGS) != FIRST_CELLSEGS)
FatalError("Unable to allocate initial cell segments");
if (!alloc_strseg(1))
FatalError("Unable to allocate initial string segments");
#ifdef VERBOSE
gc_verbose = 1;
#else
gc_verbose = 0;
#endif
init_globals();
}
/* get new cell. parameter a, b is marked by gc. */
pointer get_cell(a, b)
register pointer a, b;
{
register pointer x;
if (free_cell == NIL) {
gc(a, b);
if (free_cell == NIL)
#ifdef USE_SETJMP
if (!alloc_cellseg(1)) {
args = envir = code = dump = NIL;
gc(NIL, NIL);
if (free_cell != NIL)
Error("run out of cells --- rerurn to top level");
else
FatalError("run out of cells --- unable to recover cells");
}
#else
if (!alloc_cellseg(1))
FatalError("run out of cells --- unable to recover cells");
#endif
}
x = free_cell;
free_cell = cdr(x);
--fcells;
return (x);
}
/* get new cons cell */
pointer cons(a, b)
register pointer a, b;
{
register pointer x = get_cell(a, b);
type(x) = T_PAIR;
car(x) = a;
cdr(x) = b;
return (x);
}
/* get number atom */
pointer mk_number(num)
register long num;
{
register pointer x = get_cell(NIL, NIL);
type(x) = (T_NUMBER | T_ATOM);
ivalue(x) = num;
return (x);
}
/* allocate name to string area */
char *store_string(name)
char *name;
{
register char *q;
register short i;
long len, remain;
/* first check name has already listed */
for (i = 0; i <= str_seglast; i++)
for (q = str_seg[i]; *q != (char) (-1); ) {
if (!strcmp(q, name))
goto FOUND;
while (*q++)
; /* get next string */
}
len = strlen(name) + 2;
remain = (long) STR_SEGSIZE - ((long) q - (long) str_seg[str_seglast]);
if (remain < len) {
if (!alloc_strseg(1))
FatalError("run out of string area");
q = str_seg[str_seglast];
}
strcpy(q, name);
FOUND:
return (q);
}
/* get new string */
pointer mk_string(str)
char *str;
{
register pointer x = get_cell(NIL, NIL);
strvalue(x) = store_string(str);
type(x) = (T_STRING | T_ATOM);
keynum(x) = (short) (-1);
return (x);
}
/* get new symbol */
pointer mk_symbol(name)
char *name;
{
register pointer x;
/* fisrt check oblist */
for (x = oblist; x != NIL; x = cdr(x))
if (!strcmp(name, symname(car(x))))
break;
if (x != NIL)
return (car(x));
else {
x = cons(mk_string(name), NIL);
type(x) = T_SYMBOL;
oblist = cons(x, oblist);
return (x);
}
}
/* make symbol or number atom from string */
pointer mk_atom(q)
char *q;
{
char c, *p;
p = q;
if (!isdigit(c = *p++)) {
if ((c != '+' && c != '-') || !isdigit(*p))
return (mk_symbol(q));
}
for ( ; (c = *p) != 0; ++p)
if (!isdigit(c))
return (mk_symbol(q));
return (mk_number(atol(q)));
}
/* make constant */
pointer mk_const(name)
char *name;
{
long x;
char tmp[256];
if (!strcmp(name, "t"))
return (T);
else if (!strcmp(name, "f"))
return (F);
else if (*name == 'o') {/* #o (octal) */
sprintf(tmp, "0%s", &name[1]);
sscanf(tmp, "%lo", (unsigned long int *)&x);
return (mk_number(x));
} else if (*name == 'd') { /* #d (decimal) */
sscanf(&name[1], "%ld", &x);
return (mk_number(x));
} else if (*name == 'x') { /* #x (hex) */
sprintf(tmp, "0x%s", &name[1]);
sscanf(tmp, "%lx", (unsigned long int *)&x);
return (mk_number(x));
} else
return (NIL);
}
/* ========== garbage collector ========== */
/*--
* We use algorithm E (Kunuth, The Art of Computer Programming Vol.1,
* sec.3.5) for marking.
*/
mark(a)
pointer a;
{
register pointer t, q, p;
E1: t = (pointer) 0;
p = a;
E2: setmark(p);
E3: if (isatom(p))
goto E6;
E4: q = car(p);
if (q && !ismark(q)) {
setatom(p);
car(p) = t;
t = p;
p = q;
goto E2;
}
E5: q = cdr(p);
if (q && !ismark(q)) {
cdr(p) = t;
t = p;
p = q;
goto E2;
}
E6: if (!t)
return;
q = t;
if (isatom(q)) {
clratom(q);
t = car(q);
car(q) = p;
p = q;
goto E5;
} else {
t = cdr(q);
cdr(q) = p;
p = q;
goto E6;
}
}
/* garbage collection. parameter a, b is marked. */
gc(a, b)
register pointer a, b;
{
register pointer p;
register short i;
register long j;
if (gc_verbose)
printf("gc...");
/* mark system globals */
mark(oblist);
mark(global_env);
/* mark current registers */
mark(args);
mark(envir);
mark(code);
mark(dump);
/* mark variables a, b */
mark(a);
mark(b);
/* garbage collect */
clrmark(NIL);
fcells = 0;
free_cell = NIL;
for (i = 0; i <= last_cell_seg; i++) {
for (j = 0, p = cell_seg[i]; j < CELL_SEGSIZE; j++, p++) {
if (ismark(p))
clrmark(p);
else {
type(p) = 0;
cdr(p) = free_cell;
car(p) = NIL;
free_cell = p;
++fcells;
}
}
}
if (gc_verbose)
printf(" done %ld cells are recovered.\n", fcells);
}
/* ========== Rootines for Reading ========== */
#define TOK_LPAREN 0
#define TOK_RPAREN 1
#define TOK_DOT 2
#define TOK_ATOM 3
#define TOK_QUOTE 4
#define TOK_COMMENT 5
#define TOK_DQUOTE 6
#ifdef USE_QQUOTE
# define TOK_BQUOTE 7
# define TOK_COMMA 8
# define TOK_ATMARK 9
#endif
#define TOK_SHARP 10
#define LINESIZE 1024
char linebuff[LINESIZE];
char strbuff[256];
char *currentline = linebuff;
char *endline = linebuff;
/* get new character from input file */
int inchar()
{
if (currentline >= endline) { /* input buffer is empty */
if (feof(infp)) {
fclose(infp);
infp = stdin;
if (!quiet)
printf(prompt);
}
strcpy(linebuff, "\n");
if (fgets(currentline = linebuff, LINESIZE, infp) == NULL)
if (infp == stdin) {
if (!quiet)
fprintf(stderr, "Good-bye\n");
exit(0);
}
endline = linebuff + strlen(linebuff);
}
return (*currentline++);
}
/* clear input buffer */
clearinput()
{
currentline = endline = linebuff;
}
/* back to standard input */
flushinput()
{
if (infp != stdin) {
fclose(infp);
infp = stdin;
}
clearinput();
}
/* back character to input buffer */
backchar()
{
currentline--;
}
/* read chacters to delimiter */
char *readstr(delim)
char *delim;
{
char *p = strbuff;
while (isdelim(delim, (*p++ = inchar())))
;
backchar();
*--p = '\0';
return (strbuff);
}
/* read string expression "xxx...xxx" */
char *readstrexp()
{
char c, *p = strbuff;
for (;;) {
if ((c = inchar()) != '"')
*p++ = c;
else if (p > strbuff && *(p - 1) == '\\')
*(p - 1) = '"';
else {
*p = '\0';
return (strbuff);
}
}
}
/* check c is delimiter */
isdelim(s, c)
char *s;
char c;
{
while (*s)
if (*s++ == c)
return (0);
return (1);
}
/* skip white characters */
skipspace()
{
while (isspace(inchar()))
;
backchar();
}
/* get token */
token()
{
skipspace();
switch (inchar()) {
case '(':
return (TOK_LPAREN);
case ')':
return (TOK_RPAREN);
case '.':
return (TOK_DOT);
case '\'':
return (TOK_QUOTE);
case ';':
return (TOK_COMMENT);
case '"':
return (TOK_DQUOTE);
#ifdef USE_QQUOTE
case BACKQUOTE:
return (TOK_BQUOTE);
case ',':
if (inchar() == '@')
return (TOK_ATMARK);
else {
backchar();
return (TOK_COMMA);
}
#endif
case '#':
return (TOK_SHARP);
default:
backchar();
return (TOK_ATOM);
}
}
/* ========== Rootines for Printing ========== */
#define ok_abbrev(x) (ispair(x) && cdr(x) == NIL)
strunquote(p, s)
char *p;
char *s;
{
*p++ = '"';
for ( ; *s; ++s) {
if (*s == '"') {
*p++ = '\\';
*p++ = '"';
} else if (*s == '\n') {
*p++ = '\\';
*p++ = 'n';
} else
*p++ = *s;
}
*p++ = '"';
*p = '\0';
}
/* print atoms */
int printatom(l, f)
pointer l;
int f;
{
char *p;
if (l == NIL)
p = "()";
else if (l == T)
p = "#t";
else if (l == F)
p = "#f";
else if (isnumber(l)) {
p = strbuff;
sprintf(p, "%ld", ivalue(l));
} else if (isstring(l)) {
if (!f)
p = strvalue(l);
else {
p = strbuff;
strunquote(p, strvalue(l));
}
} else if (issymbol(l))
p = symname(l);
else if (isproc(l)) {
p = strbuff;
sprintf(p, "#<PROCEDURE %ld>", procnum(l));
#ifdef USE_MACRO
} else if (ismacro(l)) {
p = "#<MACRO>";
#endif
} else if (isclosure(l))
p = "#<CLOSURE>";
else if (iscontinuation(l))
p = "#<CONTINUATION>";
if (f < 0)
return strlen(p);
fputs(p, outfp);
return 0;
}
/* ========== Rootines for Evaluation Cycle ========== */
/* make closure. c is code. e is environment */
pointer mk_closure(c, e)
register pointer c, e;
{
register pointer x = get_cell(c, e);
type(x) = T_CLOSURE;
car(x) = c;
cdr(x) = e;
return (x);
}
/* make continuation. */
pointer mk_continuation(d)
register pointer d;
{
register pointer x = get_cell(NIL, d);
type(x) = T_CONTINUATION;
cont_dump(x) = d;
return (x);
}
/* reverse list -- make new cells */
pointer reverse(a)
register pointer a; /* a must be checked by gc */
{
register pointer p = NIL;
for ( ; ispair(a); a = cdr(a))
p = cons(car(a), p);
return (p);
}
/* reverse list --- no make new cells */
pointer non_alloc_rev(term, list)
pointer term, list;
{
register pointer p = list, result = term, q;
while (p != NIL) {
q = cdr(p);
cdr(p) = result;
result = p;
p = q;
}
return (result);
}
/* append list -- make new cells */
pointer append(a, b)
register pointer a, b;
{
register pointer p = b, q;
if (a != NIL) {
a = reverse(a);
while (a != NIL) {
q = cdr(a);
cdr(a) = p;
p = a;
a = q;
}
}
return (p);
}
/* equivalence of atoms */
eqv(a, b)
register pointer a, b;
{
if (isstring(a)) {
if (isstring(b))
return (strvalue(a) == strvalue(b));
else
return (0);
} else if (isnumber(a)) {
if (isnumber(b))
return (ivalue(a) == ivalue(b));
else
return (0);
} else
return (a == b);
}
/* true or false value macro */
#define istrue(p) ((p) != NIL && (p) != F)
#define isfalse(p) ((p) == NIL || (p) == F)
/* Error macro */
#ifdef AVOID_HACK_LOOP
# define BEGIN {
# define END }
#else
/*
* I believe this is better, but some compiler complains....
*/
# define BEGIN do {
# define END } while (0)
#endif
#define Error_0(s) BEGIN \
args = cons(mk_string((s)), NIL); \
operator = (short)OP_ERR0; \
return T; END
#define Error_1(s, a) BEGIN \
args = cons((a), NIL); \
args = cons(mk_string((s)), args); \
operator = (short)OP_ERR0; \
return T; END
/* control macros for Eval_Cycle */
#define s_goto(a) BEGIN \
operator = (short)(a); \