Add first lisp bits

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 152 insertions, 0 deletions

diff --git a/src/lisp/ao_lisp_eval.c b/src/lisp/ao_lisp_eval.c
new file mode 100644
index 00000000..531e3b72
--- /dev/null
+++ b/src/lisp/ao_lisp_eval.c
@@ -0,0 +1,152 @@
+/*
+ * 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include "ao_lisp.h"
+
+/*
+ * Non-recursive eval
+ *
+ * Plan: walk actuals, construct formals
+ *
+ * stack >  save  > actuals > actual_1
+ *           v         v
+ *	   formals     .    > actual_2
+ */
+
+static struct ao_lisp_cons	*stack;
+static struct ao_lisp_cons	*actuals;
+static struct ao_lisp_cons	*formals;
+static struct ao_lisp_cons	*formals_tail;
+static uint8_t been_here;
+
+ao_lisp_poly
+ao_lisp_eval(ao_lisp_poly v)
+{
+	struct ao_lisp_cons	*formal;
+	int			cons = 0;
+
+	if (!been_here) {
+		been_here = 1;
+		ao_lisp_root_add(&ao_lisp_cons_type, &stack);
+		ao_lisp_root_add(&ao_lisp_cons_type, &actuals);
+		ao_lisp_root_add(&ao_lisp_cons_type, &formals);
+		ao_lisp_root_add(&ao_lisp_cons_type, &formals_tail);
+	}
+	stack = 0;
+	actuals = 0;
+	formals = 0;
+	formals_tail = 0;
+	for (;;) {
+
+		/* Build stack frames for each list */
+		while (ao_lisp_poly_type(v) == AO_LISP_CONS) {
+			if (v == AO_LISP_NIL)
+				break;
+
+			/* Push existing frame on the stack */
+			if (cons++) {
+				struct ao_lisp_cons *frame;
+
+				frame = ao_lisp_cons(ao_lisp_cons_poly(actuals), formals);
+				stack = ao_lisp_cons(ao_lisp_cons_poly(frame), stack);
+			}
+			actuals = ao_lisp_poly_cons(v);
+			formals = NULL;
+			formals_tail = NULL;
+			v = actuals->car;
+
+			printf("start: stack"); ao_lisp_cons_print(stack); printf("\n");
+			printf("start: actuals"); ao_lisp_cons_print(actuals); printf("\n");
+			printf("start: formals"); ao_lisp_cons_print(formals); printf("\n");
+		}
+
+		/* Evaluate primitive types */
+
+		switch (ao_lisp_poly_type(v)) {
+		case AO_LISP_INT:
+		case AO_LISP_STRING:
+			break;
+		case AO_LISP_ATOM:
+			v = ao_lisp_poly_atom(v)->val;
+			break;
+		}
+
+		for (;;) {
+			printf("add formal: "); ao_lisp_poly_print(v); printf("\n");
+
+			formal = ao_lisp_cons(v, NULL);
+			if (formals_tail)
+				formals_tail->cdr = formal;
+			else
+				formals = formal;
+			formals_tail = formal;
+			actuals = actuals->cdr;
+
+			printf("formals: ");
+			ao_lisp_cons_print(formals);
+			printf("\n");
+			printf("actuals: ");
+			ao_lisp_cons_print(actuals);
+			printf("\n");
+
+			/* Process all of the arguments */
+			if (actuals) {
+				v = actuals->car;
+				printf ("actual: "); ao_lisp_poly_print(v); printf("\n");
+				break;
+			}
+
+			v = formals->car;
+
+			/* Evaluate the resulting list */
+			if (ao_lisp_poly_type(v) == AO_LISP_BUILTIN) {
+				struct ao_lisp_builtin *b = ao_lisp_poly_builtin(v);
+
+				v = b->func(formals->cdr);
+
+				printf ("eval: ");
+				ao_lisp_cons_print(formals);
+				printf(" -> ");
+				ao_lisp_poly_print(v);
+				printf ("\n");
+			} else {
+				printf ("invalid eval\n");
+			}
+
+			if (--cons) {
+				struct ao_lisp_cons	*frame;
+
+				/* Pop the previous frame off the stack */
+				frame = ao_lisp_poly_cons(stack->car);
+				actuals = ao_lisp_poly_cons(frame->car);
+				formals = frame->cdr;
+
+				/* Recompute the tail of the formals list */
+				for (formal = formals; formal->cdr != NULL; formal = formal->cdr);
+				formals_tail = formal;
+
+				stack = stack->cdr;
+				printf("stack pop: stack"); ao_lisp_cons_print(stack); printf("\n");
+				printf("stack pop: actuals"); ao_lisp_cons_print(actuals); printf("\n");
+				printf("stack pop: formals"); ao_lisp_cons_print(formals); printf("\n");
+			} else {
+				printf("done func\n");
+				break;
+			}
+		}
+		if (!cons)
+			break;
+	}
+	return v;
+}