parse: implement parsing of semicolon-delimited statement lists

bshell/parse/syntax/statement.c

@@ -1,15 +1,99 @@
 #include "../syntax.h"
 
+bool peek_statement(struct parse_ctx *ctx)
+{
+	if (peek_keyword_expr(ctx)) {
+		return true;
+	}
+
+	if (peek_arith_expr(ctx)) {
+		return true;
+	}
+
+	if (peek_command(ctx)) {
+		return true;
+	}
+
+	return false;
+}
+
 bool parse_statement(struct parse_ctx *ctx, struct ast_node **out)
 {
+	if (!peek_token(ctx)) {
+		/* error, or EOF */
+		return false;
+	}
+
+	bool unknown = true;
 	bool ok = false;
-	if (peek_arith_expr(ctx)) {
+	if (peek_keyword_expr(ctx)) {
-		ok = parse_arith_expr(ctx, out);
+		unknown = false;
+		ok = parse_keyword_expr(ctx, out);
+	}
+
+	if (!ok && peek_arith_expr(ctx)) {
+		unknown = false;
+		ok = parse_arith_expr(ctx, PRECEDENCE_MINIMUM, out);
 	}
 
 	if (!ok && peek_command(ctx)) {
+		unknown = false;
 		ok = parse_command(ctx, out);
 	}
 
+	if (!ok && unknown) {
+		report_error(
+			ctx,
+			"encountered unknown token while parsing statement");
+		return false;
+	}
+
 	return ok;
 }
+
+static struct ast_node *convert_single_statement(
+	struct stmt_list_ast_node *list)
+{
+	fx_queue_entry *first_entry = fx_queue_first(&list->n_statements);
+	if (!first_entry || fx_queue_next(first_entry)) {
+		return (struct ast_node *)list;
+	}
+
+	fx_queue_delete(&list->n_statements, first_entry);
+	struct ast_node *first
+		= fx_unbox(struct ast_node, first_entry, n_entry);
+	ast_node_destroy((struct ast_node *)list);
+
+	return first;
+}
+
+bool parse_statement_list(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct stmt_list_ast_node *stmt_list
+		= (struct stmt_list_ast_node *)ast_node_create(AST_STMT_LIST);
+
+	bool ok = true;
+	while (ok) {
+		parse_linefeed(ctx);
+
+		struct ast_node *stmt = NULL;
+		if (!parse_statement(ctx, &stmt)) {
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&stmt_list->n_statements, &stmt->n_entry);
+
+		if (!parse_symbol(ctx, SYM_SEMICOLON)) {
+			break;
+		}
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)stmt_list);
+		return false;
+	}
+
+	*out = convert_single_statement(stmt_list);
+	return true;
+}