Completeness theorem for parse-ichar.
Theorem:
(defthm parse-ichar-when-tree-match (implies (and (tree-match-element-p tree element *grammar*) (element-case element :char-val) (char-val-case (element-char-val->get element) :insensitive) (equal (char-val-insensitive->get (element-char-val->get element)) (implode (list char)))) (equal (parse-ichar char (append (tree->string tree) rest-input)) (mv nil (tree-fix tree) (nat-list-fix rest-input)))))