harec

commit 10060824bc60fb02d532cffdf8fb0a989aff391a
parent 553c994eadc52936d2a65f367c522de9646643c8
Author: Drew DeVault <sir@cmpwn.com>
Date:   Sun, 31 Jan 2021 16:06:00 -0500

Implement context-defined array lengths

Diffstat:
M
include/ast.h
 | 
1
+
M
include/lex.h
 | 
1
+
M
include/types.h
 | 
2
+-
M
rt/abort.ha
 | 
2
+-
M
src/check.c
 | 
40
++++++++++++++++++++++++++++++++++++----
M
src/lex.c
 | 
1
+
M
src/parse.c
 | 
7
+++++++

7 files changed, 48 insertions(+), 6 deletions(-)
diff --git a/include/ast.h b/include/ast.h
@@ -27,6 +27,7 @@ struct ast_imports {
 struct ast_list_type {
 	struct ast_expression *length; // NULL for slices and unbounded arrays
 	struct ast_type *members;
+	bool contextual;
 };
 
 struct ast_enum_field {
diff --git a/include/lex.h b/include/lex.h
@@ -11,6 +11,7 @@ enum lexical_token {
 	T_ATTR_NORETURN,
 	T_ATTR_SYMBOL,
 	T_ATTR_TEST,
+	T_UNDERSCORE,
 	T_ABORT,
 	T_ALLOC,
 	T_APPEND,
diff --git a/include/types.h b/include/types.h
@@ -49,7 +49,7 @@ struct type_alias {
 };
 
 struct type_array {
-	size_t length; // SIZE_UNDEFINED for [*] or slices
+	size_t length; // SIZE_UNDEFINED for [*] and slices
 	const struct type *members;
 };
 
diff --git a/rt/abort.ha b/rt/abort.ha
@@ -7,7 +7,7 @@ export @noreturn @symbol("rt.abort") fn _abort(msg: str) void = {
 };
 
 // See include/gen.h
-const reasons: [3]str = [
+const reasons: [_]str = [
 	"slice or array access out of bounds",	// 0
 	"type assertion failed",		// 1
 	"allocation failed",			// 2
diff --git a/src/check.c b/src/check.c
@@ -376,7 +376,10 @@ check_expr_binding(struct context *ctx,
 			++ctx->id;
 		}
 
-		if (type) {
+		bool context = abinding->type
+			&& abinding->type->storage == TYPE_STORAGE_ARRAY
+			&& abinding->type->array.contextual;
+		if (type && !context) {
 			// If the type is defined in advance, we can insert the
 			// object into the scope early, which is required for
 			// self-referencing objects.
@@ -391,9 +394,21 @@ check_expr_binding(struct context *ctx,
 
 		check_expression(ctx, abinding->initializer, initializer, type);
 
-		if (!type) {
-			type = type_store_lookup_with_flags(ctx->store,
-				initializer->result, abinding->flags);
+		if (context) {
+			expect(&aexpr->loc,
+				initializer->result->storage == TYPE_STORAGE_ARRAY,
+				"Cannot infer array length from non-array type");
+			expect(&aexpr->loc,
+				initializer->result->array.members == type->array.members,
+				"Initializer is not assignable to binding type");
+			type = initializer->result;
+		}
+
+		if (context || !type) {
+			if (!type) {
+				type = type_store_lookup_with_flags(ctx->store,
+					initializer->result, abinding->flags);
+			}
 
 			if (!abinding->is_static) {
 				binding->object = scope_insert(ctx->scope,
@@ -1581,12 +1596,29 @@ check_global(struct context *ctx,
 
 	const struct type *type = type_store_lookup_atype(
 			ctx->store, agdecl->type);
+	bool context = agdecl->type->storage == TYPE_STORAGE_ARRAY
+			&& agdecl->type->array.contextual;
 
 	// TODO: Free initialier
 	struct expression *initializer =
 		xcalloc(1, sizeof(struct expression));
 	check_expression(ctx, agdecl->init, initializer, type);
 
+	if (context) {
+		expect(&agdecl->init->loc,
+			initializer->result->storage == TYPE_STORAGE_ARRAY,
+			"Cannot infer array length from non-array type");
+		expect(&agdecl->init->loc,
+			initializer->result->array.members == type->array.members,
+			"Initializer is not assignable to binding type");
+		type = initializer->result;
+
+		// Update type of object (drops const, hack!)
+		struct scope_object *obj = (struct scope_object *)scope_lookup(
+				ctx->scope, &agdecl->ident);
+		obj->type = type;
+	}
+
 	expect(&agdecl->init->loc,
 		type_is_assignable(type, initializer->result),
 		"Constant type is not assignable from initializer type");
diff --git a/src/lex.c b/src/lex.c
@@ -20,6 +20,7 @@ static const char *tokens[] = {
 	[T_ATTR_NORETURN] = "@noreturn",
 	[T_ATTR_SYMBOL] = "@symbol",
 	[T_ATTR_TEST] = "@test",
+	[T_UNDERSCORE] = "_",
 	[T_ABORT] = "abort",
 	[T_ALLOC] = "alloc",
 	[T_APPEND] = "append",
diff --git a/src/parse.c b/src/parse.c
@@ -631,6 +631,13 @@ parse_type(struct lexer *lexer)
 			want(lexer, T_RBRACKET, NULL);
 			type->array.members = parse_type(lexer);
 			break;
+		case T_UNDERSCORE:
+			type->storage = TYPE_STORAGE_ARRAY;
+			type->array.length = NULL;
+			type->array.contextual = true;
+			want(lexer, T_RBRACKET, NULL);
+			type->array.members = parse_type(lexer);
+			break;
 		default:
 			type->storage = TYPE_STORAGE_ARRAY;
 			unlex(lexer, &tok);