*: revert GC-safe API, turn to conservative GC

GC-safe API is inconvenient, essentially operating on a stack machine.
No variables available, just Push/Pop etc...

main.c

@@ -9,7 +9,6 @@
 
 static void
 repl(struct VM *vm, int pos, FILE* stream) {
-  int ref = pos++;
   struct SexpReader r = {.pkgMapping = Nil};
   int errCode = 0;
 
@@ -18,23 +17,21 @@ repl(struct VM *vm, int pos, FILE* stream) {
       printf("%d #> ", i);
     }
 
-    Obj exp = sexpRead(vm, pos, &r, stream, &errCode);
+    Obj exp = sexpRead(&r, stream, &errCode);
     if (errCode != 0) {
       break;
     }
 
     /* printf("before macro expand =="); */
     /* sexpWrite(stdout, exp); */
 
-    vmSet(vm, ref, exp);
-    exp = macroExpand(vm, pos, ref);
+    exp = macroExpand(vm, pos, exp);
 
     /* printf("after macro expand =="); */
     /* sexpWrite(stdout, exp); */
     /* printf("\n"); */
 
-    vmSet(vm, ref, exp);
-    Obj res = eval(vm, pos, ref);
+    Obj res = eval(vm, pos, exp);
 
     if (stream == stdin) {
       sexpWrite(stdout, res);

src/bootstrap_test.c

@@ -5,28 +5,23 @@
 #include "reader.h"
 #include "vm.h"
 
-extern Obj reverse(struct VM *vm, int pos, int O);
+extern Obj reverse(Obj exp);
 
 void readFileAsSexp(void *pc, Obj val, struct VM *vm, int pos) {
   Obj path = vmGet(vm, 1);
   Obj pkg = vmGet(vm, 2);
-
   struct SexpReader r = {.pkgMapping = Nil, .selfPath = toCStr(stringStr(pkg))};
   strBuf pathStr = stringStr(path);
   FILE* f = fopen(toCStr(pathStr), "r");
   int errCode = 0;
-
-  int ret = pos++;
-  vmSet(vm, ret, Nil);
-  int v = pos++;
+  Obj ret = Nil;
   while(errCode == 0) {
-    vmSet(vm, v, sexpRead(vm, pos, &r, f, &errCode));
-    vmSet(vm, ret, vmCons(vm, v, ret));
+    Obj v = sexpRead(&r, f, &errCode);
+    ret = cons(v, ret);
   }
   fclose(f);
-
-  Obj tmp = reverse(vm, pos, ret);
-  vmReturn(vm, tmp);
+  ret = reverse(ret);
+  vmReturn(vm, ret);
 }
 
 void writeSexpToFile(void *pc, Obj val, struct VM *vm, int pos) {
@@ -51,9 +46,7 @@ int main(int argc, char *argv[]) {
 
   // (load "lib/bootstrap.cora" "")  to generate the new init.bc and compile.bc
   char *s = "../lib/bootstrap.cora";
-  int tmp = pos++;
-  vmSet(vm, tmp, cons(intern("load"), cons(makeString(s, strlen(s)), cons(makeString("", 0), Nil))));
-  eval(vm, pos, tmp);
+  eval(vm, pos, cons(intern("load"), cons(makeString(s, strlen(s)), cons(makeString("", 0), Nil))));
 
   // Check the new generated bytecode can be load successfully
   loadByteCode(vm, pos, cstr("./init.bc"));

src/builtin.c

@@ -49,23 +49,18 @@ primLoad(struct VM *vm, int pos, str path, str pkg) {
 
   struct SexpReader r = {.pkgMapping = Nil, .selfPath = pkg.str};
   int err = 0;
-  Obj ast = sexpRead(vm, pos, &r, in, &err);
-  int ref = pos++;
+  Obj ast = sexpRead(&r, in, &err);
   while(err == 0) {
-
     /* printf("========================================= read == \n"); */
     /* sexpWrite(stdout, ast); */
     /* printf("\n"); */
-
-    vmSet(vm, ref, ast);
-    Obj exp = macroExpand(vm, pos, ref);
+    Obj exp = macroExpand(vm, pos, ast);
 
     /* printObj(stdout, exp); */
     /* printf("\n"); */
 
-    vmSet(vm, ref, exp);
-    eval(vm, pos, ref);
-    ast = sexpRead(vm, pos, &r, in, &err);
+    eval(vm, pos, exp);
+    ast = sexpRead(&r, in, &err);
   }
   fclose(in);
 }
@@ -541,7 +536,7 @@ loadByteCode(struct VM *vm, int pos, str path) {
   }
   struct SexpReader r = {.pkgMapping = Nil, .selfPath = ""};
   int err = 0;
-  Obj ast = sexpRead(vm, pos, &r, in, &err);
+  Obj ast = sexpRead(&r, in, &err);
   while(ast != Nil) {
     /* printf("========================================= read == \n"); */
     Obj code = car(ast);
@@ -557,11 +552,11 @@ loadByteCode(struct VM *vm, int pos, str path) {
 
 
 Obj
-eval(struct VM *vm, int pos, Ref exp) {
+eval(struct VM *vm, int pos, Obj exp) {
   // call (cora/lib/compile.cc exp) to generate the bytecode
   Obj compile = symbolGet(makeSymbol("cora/lib/compile.cc"));
   vmPush(vm, pos++, compile);
-  vmPush(vm, pos++, vmRef(vm, exp));
+  vmPush(vm, pos++, exp);
   Obj res = vmCall(vm, pos, 2);
 
   /* printf("the byte code is ===\n"); */
@@ -578,12 +573,12 @@ eval(struct VM *vm, int pos, Ref exp) {
 }
 
 Obj
-macroExpand(struct VM *vm, int pos, Ref exp) {
+macroExpand(struct VM *vm, int pos, Obj exp) {
   Obj val = symbolGet(symMacroExpand);
   if (val == Nil || val == Undef) {
-    return vmRef(vm, exp);
+    return exp;
   }
   vmPush(vm, pos++, val);
-  vmPush(vm, pos++, vmRef(vm, exp));
+  vmPush(vm, pos++, exp);
   return vmCall(vm, pos, 2);
 }

src/eval_test.c

@@ -183,10 +183,8 @@ TestEvalBasic() {
     struct SexpReader r = {.pkgMapping = Nil};
     FILE* f = fmemopen(c->input, strlen(c->input), "r");
     int errCode;
-    Obj s = sexpRead(vm, pos, &r, f, &errCode);
-    int ref = pos++;
-    vmSet(vm, ref, s);
-    Obj res = eval(vm, pos, ref);
+    Obj s = sexpRead(&r, f, &errCode);
+    Obj res = eval(vm, pos, s);
 
     char output[512];
     memset(output, 0, 512);
@@ -328,7 +326,6 @@ TestTryCatch() {
   /* char *pkgName = "cora/init"; */
   /* eval(vm, cons(intern("import"), cons(makeString(pkgName, strlen(pkgName)), Nil))); */
 
-  int ref = pos++;
   for (int i=0; i<sizeof(cases)/sizeof(struct testCase); i++) {
     struct testCase *c = &cases[i];
 
@@ -337,11 +334,9 @@ TestTryCatch() {
     struct SexpReader r = {.pkgMapping = Nil};
     FILE* f = fmemopen(c->input, strlen(c->input), "r");
     int errCode;
-    Obj s = sexpRead(vm, pos, &r, f, &errCode);
-    vmSet(vm, ref, s);
-    Obj exp = macroExpand(vm, pos, ref);
-    vmSet(vm, ref, exp);
-    Obj res = eval(vm, pos, ref);
+    Obj s = sexpRead(&r, f, &errCode);
+    Obj exp = macroExpand(vm, pos, s);
+    Obj res = eval(vm, pos, exp);
 
     char output[512];
     memset(output, 0, 512);

src/reader.c

@@ -1,6 +1,5 @@
 #include "reader.h"
 #include "types.h"
-#include "vm.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -55,21 +54,21 @@ peekFirstChar(FILE *in) {
 }
 
 static Obj
-readCons(struct VM *vm, int pos, struct SexpReader *r, FILE *in, int *errCode) {
+readCons(struct SexpReader *r, FILE *in, int *errCode) {
   int c = getc(in);
   if (c == ')') {
     // read the empty list
     return Nil;
   }
 
   ungetc(c, in);
-  Obj hd = sexpRead(vm, pos, r, in, errCode);
+  Obj hd = sexpRead(r, in, errCode);
 
   c = peekFirstChar(in);
   ungetc(c, in);
 
   /* read list */
-  Obj tl = readCons(vm, pos, r, in, errCode);
+  Obj tl = readCons(r, in, errCode);
 
   /* printf("read cdr"); */
   /* printObj(cdr); */
@@ -97,38 +96,31 @@ readCons(struct VM *vm, int pos, struct SexpReader *r, FILE *in, int *errCode) {
 }
 
 Obj
-reverse(struct VM *vm, int pos, int O) {
-  const int RET = pos++;
-  const int TMP = pos++;
-  vmSet(vm, RET, Nil);
-  while(vmRef(vm, O) != Nil) {
-    vmSet(vm, TMP, vmCar(vm, O));
-    vmSet(vm, RET, vmCons(vm, TMP, RET));
-    vmSet(vm, O, vmCdr(vm, O));
+reverse(Obj o) {
+  Obj ret = Nil;
+  while (o != Nil) {
+    ret = cons(car(o), ret);
+    o = cdr(o);
   }
-  return vmRef(vm, RET);
+  return ret;
 }
 
 static Obj
-readListMacro(struct VM *vm, int pos, struct SexpReader *r, FILE *in, int *errCode) {
-  const int hd = pos;
-  vmPush(vm, pos++, intern("list"));
-  const int ret = pos;
-  vmPush(vm, pos++, Nil);
-  const int o = pos++;
+readListMacro(struct SexpReader *r, FILE *in, int *errCode) {
+  Obj hd = intern("list");
+  Obj ret = Nil;
   char b = peekFirstChar(in);
   while (b != EOF && b != ']') {
     if (b == '.') {
-      vmSet(vm, hd, intern("list-rest"));
+      hd = intern("list-rest");
     } else {
       ungetc(b, in);
-      vmSet(vm, o, sexpRead(vm, pos, r, in, errCode));
-      vmSet(vm, ret, vmCons(vm, o, ret));
+      Obj o = sexpRead(r, in, errCode);
+      ret = cons(o, ret);
     }
     b = peekFirstChar(in);
   }
-  vmSet(vm, ret, reverse(vm, pos, ret));
-  return vmCons(vm, hd, ret);
+  return cons(hd, reverse(ret));
 }
 
 static Obj
@@ -151,7 +143,7 @@ readNumber(FILE *in) {
 }
 
 Obj
-sexpRead(struct VM *vm, int pos, struct SexpReader* r, FILE *in, int *errCode) {
+sexpRead(struct SexpReader* r, FILE *in, int *errCode) {
   int c;
   int i;
   char buffer[512];
@@ -167,18 +159,18 @@ sexpRead(struct VM *vm, int pos, struct SexpReader* r, FILE *in, int *errCode) {
 
   // read quote
   if (c == '\'') {
-    Obj o = sexpRead(vm, pos, r, in, errCode);
+    Obj o = sexpRead( r, in, errCode);
     return cons(symQuote, cons(o, Nil));
   }
 
   // read the empty list or pair
   if (c == '(')	{
-    return readCons(vm, pos, r, in, errCode);
+    return readCons(r, in, errCode);
   }
 
   // read list macro
   if (c == '[') {
-    return readListMacro(vm, pos, r, in, errCode);
+    return readListMacro( r, in, errCode);
   }
 
   // read a string

src/reader.h

@@ -10,11 +10,9 @@ struct SexpReader {
   char *selfPath;
 };
 
-Obj sexpRead(struct VM *vm, int pos, struct SexpReader *r, FILE *in, int *errCode);
+Obj sexpRead(struct SexpReader *r, FILE *in, int *errCode);
 void sexpWrite(FILE *out, Obj obj);
 
-/* Obj reverse(Obj o); */
-
 void printObj(FILE* f, Obj o);
 
 #endif

src/reader_test.c

@@ -6,15 +6,13 @@
 
 static void
 TestReadSexp() {
-  struct VM *vm = newVM();
-  int pos = 0;
   char buffer[] = "(a b c)";
   /* char buffer[] = "(a)"; */
   FILE *stream = fmemopen(buffer, strlen(buffer), "r");
 
   struct SexpReader reader = {.pkgMapping = Nil};
   int errCode;
-  Obj o = sexpRead(vm, pos, &reader, stream, &errCode);
+  Obj o = sexpRead(&reader, stream, &errCode);
 
   /* Obj r = cons(intern("a"), cons(intern("b"), cons(intern("c"), Nil))); */
   Obj z = cons(intern("a"), cons(intern("b"), cons(intern("c"), Nil)));
@@ -39,19 +37,17 @@ TestImport() {
   char buffer[] = "(@import \"std/cora/basic\" xxx)\n(xxx.yyy 42)";
   FILE *stream = fmemopen(buffer, strlen(buffer), "r");
 
-  struct VM *vm = newVM();
-  int pos = 0;
   struct SexpReader r = {.pkgMapping = Nil};
   int errCode;
-  Obj o = sexpRead(vm, pos, &r, stream, &errCode);
+  Obj o = sexpRead(&r, stream, &errCode);
   Obj pathStr = makeString("std/cora/basic", 14);
   Obj s = cons(intern("import"), cons(pathStr, Nil));
   assert(eq(o, s));
   /* printObj(stdout, r.pkgMapping); */
   /* printf("\n"); */
   assert(eq(r.pkgMapping, cons(cons(intern("xxx"), pathStr), Nil)));
 
-  Obj x = sexpRead(vm, pos, &r, stream, &errCode);
+  Obj x = sexpRead(&r, stream, &errCode);
   /* printObj(stdout, x); */
   /* printf("\n"); */
   assert(eq(car(x), intern("std/cora/basic.yyy")));

src/vm.c

@@ -655,16 +655,6 @@ vmReturn(struct VM *vm, Obj val) {
   opExit(NULL, val, vm, 0);
 }
 
-void
-vmSet(struct VM* vm, int ref, Obj val) {
-  vm->stack[ref] = val;
-}
-
-Obj
-vmRef(struct VM *vm, int ref) {
-  return vm->stack[ref];
-}
-
 void
 vmPush(struct VM *vm, int pos, Obj val) {
   vm->stack[pos] = val;
@@ -686,18 +676,3 @@ vmCall(struct VM *vm, int pos, int n) {
   makeTheCall(NULL, Nil, vm, pos);
   return vm->result;
 }
-
-Obj
-vmCar(struct VM *vm, int ref) {
-  return car(vm->stack[ref]);
-}
-
-Obj
-vmCdr(struct VM *vm, int ref) {
-  return cdr(vm->stack[ref]);
-}
-
-Obj
-vmCons(struct VM *vm, int r1, int r2) {
-  return cons(vm->stack[r1], vm->stack[r2]);
-}