feat(ast): ast_create_if, ast_create_cmd and header doc

src/utils/ast/ast.h

@@ -1,6 +1,8 @@
 #ifndef AST_H
 #define AST_H
 
+#include <stdbool.h>
+
 #include "../lists/lists.h"
 
 enum ast_type
@@ -35,4 +37,37 @@ struct ast
     void *data;
 };
 
+/**
+ * Checks if the given AST node is an if statement.
+ */
+bool ast_is_if(struct ast *node);
+
+/**
+ * Checks if the given AST node is a command.
+ */
+bool ast_is_cmd(struct ast *node);
+
+/**
+ * Retrieves the if statement data from the given AST node.
+ * Assumes that the node is of type AST_IF.
+ */
+struct ast_if *ast_get_if(struct ast *node);
+
+/**
+ * Retrieves the command data from the given AST node.
+ * Assumes that the node is of type AST_CMD.
+ */
+struct ast_cmd *ast_get_cmd(struct ast *node);
+
+/**
+ * Creates a new AST node representing an if statement.
+ */
+struct ast *ast_create_if(struct ast *condition, struct ast *then_clause,
+                          struct ast *else_clause);
+
+/**
+ * Creates a new AST node representing a command.
+ */
+struct ast *ast_create_cmd(struct list *cmd);
+
 #endif /* ! AST_H */