From 41bb75cea1821ad2b676fdbb4847ce5441f00f42 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Wed, 13 Nov 2019 14:35:26 -0500
Subject: evaluating default arguments

---
 cgen.c   | 24 +++++++++++++++++++++---
 main.c   |  3 ++-
 test.toc |  9 ++++++++-
 types.c  | 24 ++++++++++++++++++++++--
 4 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/cgen.c b/cgen.c
index 956fd83..0e27220 100644
--- a/cgen.c
+++ b/cgen.c
@@ -982,8 +982,14 @@ static bool cgen_expr_pre(CGenerator *g, Expression *e) {
 		break;
 	case EXPR_CALL: {
 		if (!cgen_expr_pre(g, e->call.fn)) return false;
-		arr_foreach(e->call.arg_exprs, Expression, arg)
-			if (!cgen_expr_pre(g, arg)) return false;
+		int i = 0;
+		bool *constant = e->call.fn->type.fn.constant;
+		arr_foreach(e->call.arg_exprs, Expression, arg) {
+			if (!constant || !constant[i]) {
+				if (!cgen_expr_pre(g, arg)) return false;
+			}
+			i++;
+		}
 		if (cgen_uses_ptr(&e->type)) {
 			e->call.c.id = g->ident_counter++;
 			if (!cgen_type_pre(g, &e->type, e->where)) return false;
@@ -1078,6 +1084,18 @@ static bool cgen_expr_pre(CGenerator *g, Expression *e) {
 			return false;
 		break;
 	case EXPR_VAL:
+		if (!cgen_val_pre(g, e->val, &e->type, e->where))
+			return false;
+		if (!cgen_type_pre(g, &e->type, e->where)) return false;
+		e->val_c_id = g->ident_counter++;
+		cgen_write(g, " ");
+		cgen_ident_id(g, e->val_c_id);
+		if (!cgen_type_post(g, &e->type, e->where)) return false;
+		cgen_write(g, " = ");
+		if (!cgen_val(g, e->val, &e->type, e->where))
+			return false;
+		cgen_write(g, ";");
+		cgen_nl(g);
 		break;
 	case EXPR_LITERAL_INT:
 	case EXPR_LITERAL_FLOAT:
@@ -1399,7 +1417,7 @@ static bool cgen_expr(CGenerator *g, Expression *e) {
 		cgen_ident_id(g, e->slice.c.id);
 		break;
 	case EXPR_VAL:
-		assert(!*"Value expressions cannot be cgenerated!!!");
+		cgen_ident_id(g, e->val_c_id);
 		break;
 	}
 	return true;
diff --git a/main.c b/main.c
index 1378718..a7a0888 100644
--- a/main.c
+++ b/main.c
@@ -1,8 +1,9 @@
 /* 
 TODO:
+evaluate default arguments
+make sure they're only evaluated once
 compile time arguments + out parameters (in C)
 double check that val_get_ptr is being used everywhere it should be
-evaluate default arguments
 compile-time arguments for out parameter functions
 compile-time arguments for functions returning tuples
 deal with x, y @= fn(x: int, y @ int){}
diff --git a/test.toc b/test.toc
index 8e52b1b..dda957a 100644
--- a/test.toc
+++ b/test.toc
@@ -22,15 +22,22 @@ puti @= fn(x: int) {
 // 	f.z += 43.2;
 // };
 
-f @= fn(x @ int) i: int {
+f @= fn(x @ int = 3+5) i: int {
   i = x;
 };
+g @= fn(x, y : (int, int) = (3+5, 4+9)) i: int {
+  i = x + y;
+};
+
 
 main @= fn() {
 	 puti(f(313));
 	 puti(f(128));
 	 puti(f(231));
 	 puti(f(100+213));
+	 puti(f());
+	 puti(g());
+
 };
 // b := bar();
 
diff --git a/types.c b/types.c
index 00f72e8..dcfbfd8 100644
--- a/types.c
+++ b/types.c
@@ -254,6 +254,15 @@ static bool type_of_fn(Typer *tr, Expression *e, Type *t) {
 				}
 			}
 		}
+		if (decl->flags & DECL_HAS_EXPR) {
+			Value val;
+			if (!eval_expr(tr->evalr, &decl->expr, &val)) {
+				info_print(decl->where, "Was trying to evaluate default arguments (which must be constants!)");
+				return false;
+			}
+			decl->expr.kind = EXPR_VAL;
+			decl->expr.val = val;
+		}
 		for (size_t i = 0; i < arr_len(decl->idents); i++) {
 			Type *param_type = typer_arr_add(tr, &t->fn.types);
 			*param_type = decl->type;
@@ -1050,6 +1059,7 @@ static bool types_expr(Typer *tr, Expression *e) {
 				
 				arr_foreach(fn_decl->params, Declaration, param) {
 					bool is_required = !(param->flags & DECL_HAS_EXPR);
+					long ident_idx = 0;
 					arr_foreach(param->idents, Identifier, ident) {
 						if (index == i) {
 							if (is_required) {
@@ -1058,9 +1068,18 @@ static bool types_expr(Typer *tr, Expression *e) {
 								free(s);
 								return false;
 							} else {
-								new_args[i] = param->expr;
+								assert(param->expr.kind == EXPR_VAL); /* evaluated in type_of_fn */
+								new_args[i].kind = EXPR_VAL;
+								new_args[i].flags = param->expr.flags;
+								new_args[i].type = param->type.kind == TYPE_TUPLE
+									? param->type.tuple[ident_idx]
+									: param->type;
+								new_args[i].val = param->type.kind == TYPE_TUPLE
+									? param->expr.val.tuple[ident_idx]
+									: param->expr.val;
 							}
 						}
+						ident_idx++;
 						index++;
 					}
 				}
@@ -1449,7 +1468,8 @@ static bool types_expr(Typer *tr, Expression *e) {
 		t->tuple = NULL;
 		arr_foreach(e->tuple, Expression, x) {
 			Type *x_type = typer_arr_add(tr, &t->tuple);
-			types_expr(tr, x);
+			if (!types_expr(tr, x))
+				return false;
 			*x_type = x->type;
 		}
 		break;
-- 
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