Merge branch 'master' of ssh://git.gag.com/scm/git/fw/altos

1 files changed, 208 insertions, 0 deletions

diff --git a/src/scheme/ao_scheme_lambda.c b/src/scheme/ao_scheme_lambda.c
new file mode 100644
index 00000000..ec6f858c
--- /dev/null
+++ b/src/scheme/ao_scheme_lambda.c
@@ -0,0 +1,208 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao_scheme.h"
+
+int
+lambda_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_scheme_lambda);
+}
+
+void
+lambda_mark(void *addr)
+{
+	struct ao_scheme_lambda	*lambda = addr;
+
+	ao_scheme_poly_mark(lambda->code, 0);
+	ao_scheme_poly_mark(lambda->frame, 0);
+}
+
+void
+lambda_move(void *addr)
+{
+	struct ao_scheme_lambda	*lambda = addr;
+
+	ao_scheme_poly_move(&lambda->code, 0);
+	ao_scheme_poly_move(&lambda->frame, 0);
+}
+
+const struct ao_scheme_type ao_scheme_lambda_type = {
+	.size = lambda_size,
+	.mark = lambda_mark,
+	.move = lambda_move,
+	.name = "lambda",
+};
+
+void
+ao_scheme_lambda_write(ao_poly poly)
+{
+	struct ao_scheme_lambda	*lambda = ao_scheme_poly_lambda(poly);
+	struct ao_scheme_cons	*cons = ao_scheme_poly_cons(lambda->code);
+
+	printf("(");
+	printf("%s", ao_scheme_args_name(lambda->args));
+	while (cons) {
+		printf(" ");
+		ao_scheme_poly_write(cons->car);
+		cons = ao_scheme_poly_cons(cons->cdr);
+	}
+	printf(")");
+}
+
+ao_poly
+ao_scheme_lambda_alloc(struct ao_scheme_cons *code, int args)
+{
+	struct ao_scheme_lambda	*lambda;
+	ao_poly			formal;
+	struct ao_scheme_cons	*cons;
+
+	formal = ao_scheme_arg(code, 0);
+	while (formal != AO_SCHEME_NIL) {
+		switch (ao_scheme_poly_type(formal)) {
+		case AO_SCHEME_CONS:
+			cons = ao_scheme_poly_cons(formal);
+			if (ao_scheme_poly_type(cons->car) != AO_SCHEME_ATOM)
+				return ao_scheme_error(AO_SCHEME_INVALID, "formal %p is not atom", cons->car);
+			formal = cons->cdr;
+			break;
+		case AO_SCHEME_ATOM:
+			formal = AO_SCHEME_NIL;
+			break;
+		default:
+			return ao_scheme_error(AO_SCHEME_INVALID, "formal %p is not atom", formal);
+		}
+	}
+
+	ao_scheme_cons_stash(0, code);
+	lambda = ao_scheme_alloc(sizeof (struct ao_scheme_lambda));
+	code = ao_scheme_cons_fetch(0);
+	if (!lambda)
+		return AO_SCHEME_NIL;
+
+	lambda->type = AO_SCHEME_LAMBDA;
+	lambda->args = args;
+	lambda->code = ao_scheme_cons_poly(code);
+	lambda->frame = ao_scheme_frame_mark(ao_scheme_frame_current);
+	DBGI("build frame: "); DBG_POLY(lambda->frame); DBG("\n");
+	DBG_STACK();
+	return ao_scheme_lambda_poly(lambda);
+}
+
+ao_poly
+ao_scheme_do_lambda(struct ao_scheme_cons *cons)
+{
+	return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_LAMBDA);
+}
+
+ao_poly
+ao_scheme_do_nlambda(struct ao_scheme_cons *cons)
+{
+	return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_NLAMBDA);
+}
+
+ao_poly
+ao_scheme_do_macro(struct ao_scheme_cons *cons)
+{
+	return ao_scheme_lambda_alloc(cons, AO_SCHEME_FUNC_MACRO);
+}
+
+ao_poly
+ao_scheme_lambda_eval(void)
+{
+	struct ao_scheme_lambda	*lambda = ao_scheme_poly_lambda(ao_scheme_v);
+	struct ao_scheme_cons	*cons = ao_scheme_poly_cons(ao_scheme_stack->values);
+	struct ao_scheme_cons	*code = ao_scheme_poly_cons(lambda->code);
+	ao_poly			formals;
+	struct ao_scheme_frame	*next_frame;
+	int			args_wanted;
+	ao_poly			varargs = AO_SCHEME_NIL;
+	int			args_provided;
+	int			f;
+	struct ao_scheme_cons	*vals;
+
+	DBGI("lambda "); DBG_POLY(ao_scheme_lambda_poly(lambda)); DBG("\n");
+
+	args_wanted = 0;
+	for (formals = ao_scheme_arg(code, 0);
+	     ao_scheme_is_pair(formals);
+	     formals = ao_scheme_poly_cons(formals)->cdr)
+		++args_wanted;
+	if (formals != AO_SCHEME_NIL) {
+		if (ao_scheme_poly_type(formals) != AO_SCHEME_ATOM)
+			return ao_scheme_error(AO_SCHEME_INVALID, "bad lambda form");
+		varargs = formals;
+	}
+
+	/* Create a frame to hold the variables
+	 */
+	args_provided = ao_scheme_cons_length(cons) - 1;
+	if (varargs == AO_SCHEME_NIL) {
+		if (args_wanted != args_provided)
+			return ao_scheme_error(AO_SCHEME_INVALID, "need %d args, got %d", args_wanted, args_provided);
+	} else {
+		if (args_provided < args_wanted)
+			return ao_scheme_error(AO_SCHEME_INVALID, "need at least %d args, got %d", args_wanted, args_provided);
+	}
+
+	ao_scheme_poly_stash(1, varargs);
+	next_frame = ao_scheme_frame_new(args_wanted + (varargs != AO_SCHEME_NIL));
+	varargs = ao_scheme_poly_fetch(1);
+	if (!next_frame)
+		return AO_SCHEME_NIL;
+
+	/* Re-fetch all of the values in case something moved */
+	lambda = ao_scheme_poly_lambda(ao_scheme_v);
+	cons = ao_scheme_poly_cons(ao_scheme_stack->values);
+	code = ao_scheme_poly_cons(lambda->code);
+	formals = ao_scheme_arg(code, 0);
+	vals = ao_scheme_poly_cons(cons->cdr);
+
+	next_frame->prev = lambda->frame;
+	ao_scheme_frame_current = next_frame;
+	ao_scheme_stack->frame = ao_scheme_frame_poly(ao_scheme_frame_current);
+
+	for (f = 0; f < args_wanted; f++) {
+		struct ao_scheme_cons *arg = ao_scheme_poly_cons(formals);
+		DBGI("bind "); DBG_POLY(arg->car); DBG(" = "); DBG_POLY(vals->car); DBG("\n");
+		ao_scheme_frame_bind(next_frame, f, arg->car, vals->car);
+		formals = arg->cdr;
+		vals = ao_scheme_poly_cons(vals->cdr);
+	}
+	if (varargs) {
+		DBGI("bind "); DBG_POLY(varargs); DBG(" = "); DBG_POLY(ao_scheme_cons_poly(vals)); DBG("\n");
+		/*
+		 * Bind the rest of the arguments to the final parameter
+		 */
+		ao_scheme_frame_bind(next_frame, f, varargs, ao_scheme_cons_poly(vals));
+	} else {
+		/*
+		 * Mark the cons cells from the actuals as freed for immediate re-use, unless
+		 * the actuals point into the source function (nlambdas and macros), or if the
+		 * stack containing them was copied as a part of a continuation
+		 */
+		if (lambda->args == AO_SCHEME_FUNC_LAMBDA && !ao_scheme_stack_marked(ao_scheme_stack)) {
+			ao_scheme_stack->values = AO_SCHEME_NIL;
+			ao_scheme_cons_free(cons);
+		}
+	}
+	DBGI("eval frame: "); DBG_POLY(ao_scheme_frame_poly(next_frame)); DBG("\n");
+	DBG_STACK();
+	DBGI("eval code: "); DBG_POLY(code->cdr); DBG("\n");
+	return code->cdr;
+}