Big refactorHEADmaster

1 files changed, 177 insertions, 0 deletions

diff --git a/src/runtime/value/func.c b/src/runtime/value/func.c
new file mode 100644
index 0000000..af039eb
--- /dev/null
+++ b/src/runtime/value/func.c
@@ -0,0 +1,177 @@
+#include <lcq/pit/runtime/value/func.h>
+
+static pit_value free_vars(pit_runtime *rt, pit_value initial_bound, pit_value body) {
+    i64 expr_stack_reset = rt->expr_stack->next;
+    pit_value ret = PIT_NIL;
+    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, initial_bound, body)) < 0) {
+        pit_error(rt, "free variable search stack overflow");
+        return PIT_NIL;
+    }
+    while (rt->expr_stack->next > expr_stack_reset) {
+        pit_value boundscur, bound, cur;
+        if (pit_vec_pop(pit_value)(rt->expr_stack, &boundscur) < 0) {
+            pit_error(rt, "free variable search stack underflow");
+            return PIT_NIL;
+        }
+        bound = pit_value_cons_car(rt, boundscur);
+        cur = pit_value_cons_cdr(rt, boundscur);
+        if (pit_value_is_cons(rt, cur)) {
+            pit_value fsym = pit_value_cons_car(rt, cur);
+            bool is_symbol = pit_value_is_symbol(rt, fsym);
+            pit_value fargs = pit_value_cons_cdr(rt, cur);
+            if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "lambda")) {
+                pit_value new_bound = pit_value_list_append(rt, pit_value_cons_car(rt, fargs), bound);
+                fargs = pit_value_cons_cdr(rt, fargs);
+                while (fargs != PIT_NIL) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, new_bound, pit_value_cons_car(rt, fargs))) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                    fargs = pit_value_cons_cdr(rt, fargs);
+                }
+            } else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "quote")) {
+                /* don't look inside quote!
+                   if we add other special forms, make sure to consider them here if necessary! */
+            } else {
+                while (fargs != PIT_NIL) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, bound, pit_value_cons_car(rt, fargs))) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                    fargs = pit_value_cons_cdr(rt, fargs);
+                }
+                if (!is_symbol) {
+                    if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_cons(rt, bound, fsym)) < 0) {
+                        pit_error(rt, "free variable search stack overflow");
+                        return PIT_NIL;
+                    }
+                }
+            }
+        } else if (pit_value_is_symbol(rt, cur)) {
+            if (pit_value_list_contains_eq(rt, cur, bound) == PIT_NIL) {
+                ret = pit_value_cons(rt, cur, ret);
+            }
+        }
+    }
+    rt->expr_stack->next = expr_stack_reset;
+    return ret;
+}
+
+bool pit_value_is_func(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_FUNC);
+}
+bool pit_value_is_nativefunc(pit_runtime *rt, pit_value a) {
+    return pit_value_is_ref_heavy_sort(rt, a, PIT_VALUE_HEAVY_SORT_NATIVEFUNC);
+}
+pit_value pit_value_func_lambda(pit_runtime *rt, pit_value args, pit_value body) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for lambda"); return PIT_NIL; }
+    pit_value expanded = pit_macroexpand(rt, pit_value_cons(rt, pit_symtab_intern_cstr(rt, "progn"), body));
+    pit_value freevars = free_vars(rt, args, expanded);
+    pit_value env = PIT_NIL;
+    while (freevars != PIT_NIL) {
+        pit_value sym = pit_value_cons_car(rt, freevars);
+        pit_value cell = pit_symtab_get_value_cell(rt, sym);
+        env = pit_value_cons(rt, pit_value_cons(rt, sym, cell), env);
+        freevars = pit_value_cons_cdr(rt, freevars);
+    }
+    h->hsort = PIT_VALUE_HEAVY_SORT_FUNC;
+    pit_value arg_cells = PIT_NIL;
+    pit_value arg_rest_nm = PIT_NIL;
+    pit_value separator = pit_symtab_intern_cstr(rt, "&");
+    while (args != PIT_NIL) {
+        pit_value nm = pit_value_cons_car(rt, args);
+        if (pit_value_eq(nm, separator)) {
+            pit_value next_nm = pit_value_cons_car(rt, pit_value_cons_cdr(rt, args));
+            if (next_nm == PIT_NIL) { pit_error(rt, "invalid & in lambda list"); return PIT_NIL; }
+            arg_rest_nm = next_nm;
+            arg_cells = pit_value_cons(rt, next_nm, arg_cells);
+            break;
+        } else {
+            arg_cells = pit_value_cons(rt, nm, arg_cells);
+            args = pit_value_cons_cdr(rt, args);
+        }
+    }
+    arg_cells = pit_value_list_reverse(rt, arg_cells);
+    h->in.func.args = arg_cells;
+    h->in.func.arg_rest_nm = arg_rest_nm;
+    h->in.func.env = env;
+    h->in.func.body = expanded;
+    return ret;
+}
+pit_value pit_value_nativefunc_new_with_data(pit_runtime *rt, pit_nativefunc f, void *data) {
+    pit_value ret = pit_value_ref_heavy_new(rt);
+    pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, ret));
+    if (!h) { pit_error(rt, "failed to create new heavy value for nativefunc"); return PIT_NIL; }
+    h->hsort = PIT_VALUE_HEAVY_SORT_NATIVEFUNC;
+    h->in.nativefunc.f = f;
+    h->in.nativefunc.data = data;
+    return ret;
+}
+pit_value pit_value_nativefunc_new(pit_runtime *rt, pit_nativefunc f) {
+    return pit_value_nativefunc_new_with_data(rt, f, NULL);
+}
+pit_value pit_value_apply(pit_runtime *rt, pit_value f, pit_value args) {
+    char buf[256] = {0};
+    if (pit_value_is_symbol(rt, f)) {
+        f = pit_symtab_fget(rt, f);
+    }
+    /* if f is not a symbol, assume it is a func or nativefunc
+       most commonly, this happens when you funcall a variable
+       with a function in the value cell, e.g. passing a lambda to a function */
+    switch (pit_value_sort(f)) {
+    case PIT_VALUE_SORT_REF: {
+        pit_value_heavy *h = pit_value_ref_deref(rt, pit_value_as_ref(rt, f));
+        if (!h) { pit_error(rt, "bad ref"); return PIT_NIL; }
+        if (h->hsort == PIT_VALUE_HEAVY_SORT_FUNC) {
+            /* calling a Lisp function is simple! */
+            pit_value bound = PIT_NIL;
+            pit_value env = h->in.func.env;
+            while (env != PIT_NIL) { /* first, bind all entries in the closure */
+                pit_value b = pit_value_cons_car(rt, env);
+                pit_value nm = pit_value_cons_car(rt, b);
+                pit_symtab_bind(rt, nm, pit_value_cons_cdr(rt, b));
+                bound = pit_value_cons(rt, nm, bound);
+                env = pit_value_cons_cdr(rt, env);
+            }
+            pit_value anames = h->in.func.args;
+            while (anames != PIT_NIL) { /* bind all argument names to their values */
+                pit_value nm = pit_value_cons_car(rt, anames);
+                pit_value cell = pit_value_cell_new(rt, PIT_NIL);
+                if (h->in.func.arg_rest_nm != PIT_NIL && pit_value_eq(nm, h->in.func.arg_rest_nm)) {
+                    pit_value_cell_set(rt, cell, args, nm);
+                    pit_symtab_bind(rt, nm, cell);
+                    break;
+                } else {
+                    pit_value_cell_set(rt, cell, pit_value_cons_car(rt, args), nm);
+                    pit_symtab_bind(rt, nm, cell);
+                }
+                bound = pit_value_cons(rt, nm, bound);
+                args = pit_value_cons_cdr(rt, args);
+                anames = pit_value_cons_cdr(rt, anames);
+            }
+            pit_value ret = pit_eval(rt, h->in.func.body); /* evaluate the body */
+            while (bound != PIT_NIL) { /* unbind everything we bound earlier, in reverse */
+                pit_symtab_unbind(rt, pit_value_cons_car(rt, bound));
+                bound = pit_value_cons_cdr(rt, bound);
+            }
+            return ret;
+        } else if (h->hsort == PIT_VALUE_HEAVY_SORT_NATIVEFUNC) {
+            /* calling native functions is even simpler */
+            return h->in.nativefunc.f(rt, args, h->in.nativefunc.data);
+        } else {
+            i64 end = pit_dump(rt, buf, sizeof(buf) - 1, f, true);
+            buf[end] = 0;
+            pit_error(rt, "attempted to apply non-function ref: %s", buf);
+            return PIT_NIL;
+        }
+    }
+    default: {
+        i64 end = pit_dump(rt, buf, sizeof(buf) - 1, f, true);
+        buf[end] = 0;
+        pit_error(rt, "attempted to apply non-function value: %s", buf);
+        return PIT_NIL;
+    }
+    }
+}