Clojure code to escape regExp characters from string

clojure string to pattern

(def regex-char-esc-smap
  (let [esc-chars "()&^%$#!?*."]
    (zipmap esc-chars
            (map #(str "\\" %) esc-chars))))

(defn str-to-pattern
  [string]
  (->> string
       (replace regex-char-esc-smap)
       (reduce str)
       re-pattern))

This doesn’t work if you already have a backslash in your string:

(re-matches (str-to-pattern "\\.") "\\.")
; => "\\."
(re-matches (str-to-pattern "\\.") "\\a")
; => "\\a"

(re-matches #"\\\." "\\.")
; => "\\."
(re-matches #"\\\." "\\a")
; => nil

@bfontaine simply include a backslash inside the esc-chars string (doubled-up obviously)