bshell: re-organise build into three separate components

bshell: the front-end binary
bshell.runtime: contains the parser, compiler, and classes needed to run bshell scripts
bshell.core: contains the builtin commandlets and aliases

bshell.runtime/ast/op.c

@@ -0,0 +1,38 @@
+#include <bshell/ast.h>
+#include <bshell/parse/token.h>
+#include <bshell/runtime/operator.h>
+
+static enum bshell_status collect_children(
+	struct bshell_ast_node *node,
+	struct bshell_ast_iterator *it)
+{
+	struct bshell_op_ast_node *op = (struct bshell_op_ast_node *)node;
+
+	if (op->n_left) {
+		bshell_ast_iterator_enqueue(it, op->n_left);
+	}
+
+	if (op->n_right) {
+		bshell_ast_iterator_enqueue(it, op->n_right);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+static void to_string(const struct bshell_ast_node *node, fx_bstr *out)
+{
+	const struct bshell_op_ast_node *op = (const struct bshell_op_ast_node
+	                                               *)node;
+	fx_bstr_write_fmt(
+		out,
+		NULL,
+		"%s",
+		bshell_operator_id_to_string(op->n_op->op_id));
+}
+
+struct bshell_ast_node_definition op_bshell_ast_node = {
+	.def_id = BSHELL_AST_OP,
+	.def_node_size = sizeof(struct bshell_op_ast_node),
+	.def_collect_children = collect_children,
+	.def_to_string = to_string,
+};