macro

4 files changed, 63 insertions, 6 deletions

diff --git a/src/interp.c b/src/interp.c
index e5e9167..5e181a8 100644
--- a/src/interp.c
+++ b/src/interp.c
@@ -52,10 +52,12 @@ void Interp_init(Interp *self) {
     Interp_add_primitive(self, "function", primitive_function);
     Interp_add_primitive(self, "defun", primitive_defun);
     Interp_add_primitive(self, "defvar", primitive_defvar);
+    Interp_add_primitive(self, "defmacro", primitive_defmacro);
     Interp_add_primitive(self, "funcall", primitive_funcall);
     Interp_add_primitive(self, "apply", primitive_apply);
     Interp_add_primitive(self, "quote", primitive_quote);
     Interp_add_primitive(self, "quasiquote", primitive_quasi);
+    Interp_add_primitive(self, "macroexpand-1", primitive_macroexpand1);
 
     Interp_add_userfunc(self, "eval", lisp_eval);
     Interp_add_userfunc(self, "show", builtin_show);
@@ -223,6 +225,16 @@ const char* lisp_to_string(Interp *interp, SExpRef val) {
     return sb.buf;
 }
 
+SExpRef lisp_macroexpand1(Interp *interp, SExpRef macro, SExpRef args) {
+    SExpRef fn = new_lambda(interp, REF(macro)->macro.args, REF(macro)->macro.body, interp->top_level);
+    PUSH_REG(fn);
+    SExpRef ret = lisp_apply(interp, fn, args);
+    POP_REG();
+    return ret;
+error:
+    return new_error(interp, "macroexpand: syntax error.\n");
+}
+
 void lisp_defun(Interp *interp, const char *name, SExpRef val) {
     SExpRef binding = REF(interp->top_level)->env.bindings;
     while (REF(binding)->type != kNilSExp) {
@@ -264,7 +276,7 @@ SExpRef lisp_setq(Interp *interp, const char *name, SExpRef val) {
         while (REF(binding)->type != kNilSExp) {
             if (strcmp(name, REF(REF(binding)->binding.name)->str) == 0) {
                 REF(binding)->binding.value = val;
-                return NIL;
+                return val;
             }
             binding = REF(binding)->binding.next;
         }
@@ -455,14 +467,22 @@ SExpRef lisp_eval(Interp *interp, SExpRef sexp) {
             }
         }
         SExpRef fn = lisp_lookup_func(interp, symbol);
-        if (!ERRORP(fn)) {
+        if (ERRORP(fn)) {
+            ret = new_error(interp, "eval: \"%s\" is not a primitive, function, or macro.\n", symbol);
+            goto end;
+        }
+        if (VALTYPE(fn) == kFuncSExp || VALTYPE(fn) == kUserFuncSExp) {
             SExpRef args = CDR(sexp);
             ret = primitive_funcall(interp, CONS(fn, args));
             goto end;
+        } else if (VALTYPE(fn) == kMacroSExp) {
+            SExpRef args = CDR(sexp);
+            SExpRef newast = lisp_macroexpand1(interp, fn, args);
+            PUSH_REG(newast);
+            ret = EVAL(newast);
+            POP_REG();
+            goto end;
         }
-        // TODO: macro / func
-        ret = new_error(interp, "eval: \"%s\" is not a primitive, function, or macro.\n", symbol);
-        goto end;
     }
     ret = new_error(interp, "eval: unknown syntax.\n");
 end:
@@ -500,6 +520,14 @@ SExpRef new_lambda(Interp *interp, SExpRef param, SExpRef body, SExpRef env) {
     return ret;
 }
 
+SExpRef new_macro(Interp *interp, SExpRef param, SExpRef body) {
+    SExpRef ret = new_sexp(interp);
+    REF(ret)->type = kMacroSExp;
+    REF(ret)->macro.args = param;
+    REF(ret)->macro.body = body;
+    return ret;
+}
+
 SExpRef new_binding(Interp *interp, SExpRef sym, SExpRef val) {
     SExpRef ret = new_sexp(interp);
     REF(ret)->type = kBindingSExp;
diff --git a/src/interp.h b/src/interp.h
index 1eaa920..b7b3025 100644
--- a/src/interp.h
+++ b/src/interp.h
@@ -60,6 +60,7 @@ void Interp_add_userfunc(Interp *self, const char *name, LispUserFunc fn);
 #define PUSH_REG(_x) { interp->reg = CONS((_x), interp->reg); }
 #define POP_REG() { interp->reg = CDR(interp->reg);  }
 
+SExpRef lisp_macroexpand1(Interp *interp, SExpRef macro, SExpRef args);
 SExpRef lisp_reverse(Interp *interp, SExpRef lst);
 void lisp_defun(Interp *interp, const char *name, SExpRef val);
 void lisp_defvar(Interp *interp, const char *name, SExpRef val);
@@ -95,6 +96,7 @@ SExpRef new_env(Interp *ctx);
 SExpRef new_binding(Interp *ctx, SExpRef name, SExpRef val);
 SExpRef new_userfunc(Interp *interp, LispUserFunc val);
 SExpRef new_lambda(Interp *interp, SExpRef param, SExpRef body, SExpRef env);
+SExpRef new_macro(Interp *interp, SExpRef param, SExpRef body);
 SExpRef new_list1(Interp *ctx, SExpRef e1);
 SExpRef new_list2(Interp *ctx, SExpRef e1, SExpRef e2);
 SExpRef new_list3(Interp *ctx, SExpRef e1, SExpRef e2, SExpRef e3);
diff --git a/src/primitives.c b/src/primitives.c
index 8290a01..266a8b7 100644
--- a/src/primitives.c
+++ b/src/primitives.c
@@ -165,6 +165,21 @@ SExpRef primitive_defun(Interp *interp, SExpRef args) {
 error:
     return new_error(interp, "defun: syntax error.\n");
 }
+SExpRef primitive_defmacro(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) < 3) goto error;
+    if (CAR(interp->stack).idx != interp->top_level.idx) {
+        return new_error(interp, "defmacro: macros can only be defined in top level.\n");
+    }
+    SExpRef name = CAR(args);
+    if (VALTYPE(name) != kSymbolSExp) goto error;
+    SExpRef param = CADR(args);
+    SExpRef body = CDDR(args);
+    SExpRef macro = new_macro(interp, param, body);
+    lisp_defun(interp, REF(name)->str, macro);
+    return name;
+error:
+    return new_error(interp, "defmacro: syntax error.\n");
+}
 
 SExpRef primitive_defvar(Interp *interp, SExpRef args) {
     if (lisp_length(interp, args) != 2) goto error;
@@ -231,6 +246,17 @@ SExpRef primitive_quote(Interp *interp, SExpRef args) {
     return CAR(args);
 }
 
+SExpRef primitive_macroexpand1(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) != 1) goto error;
+    args = CAR(args);
+    if (VALTYPE(CAR(args)) != kSymbolSExp) goto error;
+    SExpRef macro = lisp_lookup_func(interp, REF(CAR(args))->str);
+    if (VALTYPE(macro) != kMacroSExp) goto error;
+    return lisp_macroexpand1(interp, macro, CDR(args));
+error:
+    return new_error(interp, "macroexpand-1: syntax error.\n");
+}
+
 SExpRef primitive_apply(Interp *interp, SExpRef args) {
     if (lisp_length(interp, args) != 2) goto error;
     args = lisp_eval_args(interp, args);
@@ -293,7 +319,6 @@ static SExpRef quasi_on_list(Interp *interp, SExpRef lst) {
     return lisp_reverse(interp, newlst);
 }
 
-
 SExpRef primitive_quasi(Interp *interp, SExpRef args) {
     if (lisp_length(interp, args) != 1) return new_error(interp, "quasiquote: syntax error.\n");
     bool slicing;
diff --git a/src/primitives.h b/src/primitives.h
index 4f481af..0e6f061 100644
--- a/src/primitives.h
+++ b/src/primitives.h
@@ -12,7 +12,9 @@ SExpRef primitive_while(Interp *interp, SExpRef sexp);
 SExpRef primitive_lambda(Interp *interp, SExpRef sexp);
 SExpRef primitive_defun(Interp *interp, SExpRef sexp);
 SExpRef primitive_defvar(Interp *interp, SExpRef sexp);
+SExpRef primitive_defmacro(Interp *interp, SExpRef sexp);
 SExpRef primitive_function(Interp *interp, SExpRef sexp);
+SExpRef primitive_macroexpand1(Interp *interp, SExpRef sexp);
 SExpRef primitive_funcall(Interp *interp, SExpRef sexp);
 SExpRef primitive_apply(Interp *interp, SExpRef sexp);
 SExpRef primitive_quote(Interp *interp, SExpRef sexp);