Carp/core/String.carp

(system-include "carp_string.h")

(defmodule String

  (register =          (Fn [&String &String] Bool))
  (register append     (Fn [&String &String] String))
  (register delete     (Fn [String] ()))
  (register copy       (Fn [&String] String))
  (register length     (Fn [&String] Int))
  (register cstr       (Fn [&String] (Ptr Char)))
  (register str        (Fn [&String] String))
  (register prn        (Fn [&String] String))
  (register index-of   (Fn [&String Char] Int))
  (register index-of-from (Fn [&String Char Int] Int))
  (register char-at    (Fn [&String Int] Char))
  (register chars      (Fn [&String] (Array Char)))
  (register from-chars (Fn [&(Array Char)] String))
  (register tail (λ [(Ref String)] String))
  (register format (Fn [&String &String] String))
  (register string-set! (Fn [&String Int Char] ()))
  (register string-set-at! (Fn [&String Int &String] ()))
  (register allocate (Fn [Int Char] String))

  (defn /= [a b]
    (not (= (the (Ref String) a) b)))

  (doc head "Returns the character at start of string.")
  (defn head [s]
    (char-at s 0))

  (doc repeat "Returns a new string which is `inpt` repeated `n` times.")
  (defn repeat [n inpt]
    (let [str @""]
      (do
        (for [i 0 n]
          (set! str (append &str inpt)))
        str)))

  (doc pad-left "Pads the left of a string with len bytes using the padding pad.")
  (defn pad-left [len pad s]
    (let [x (Int.max 0 (- len (length s)))]
      (append &(from-chars &(Array.replicate x &pad)) s)))

  (doc pad-right "Pads the right of a string with len bytes using the padding pad.")
  (defn pad-right [len pad s]
    (let [x (Int.max 0 (- len (length s)))]
      (append s &(from-chars &(Array.replicate x &pad)))))

  (doc count-char "Returns the number of occurrences of `c` in the string `s`.")
  (defn count-char [s c]
    (let-do [n 0]
      (for [i 0 (length s)]
        (when (= c (char-at s i))
          (set! n (Int.inc n))))
      n))

  (doc reverse "Produce a new string which is `s` reversed.")
  (defn reverse [s]
    (from-chars &(Array.reverse (chars s))))

  (doc empty? "Check if the string is the empty string.")
  (defn empty? [s]
    (Int.= (length s) 0))

  (defn substring [s a b]
    (from-chars &(Array.subarray &(chars s) a b)))

  (doc prefix-string "Return the first `a` characters of the string `s`.")
  (defn prefix-string [s a]
    (from-chars &(Array.prefix-array &(chars s) a)))

  (doc suffix-string "Return the last `b` characters of the string `s`.")
  (defn suffix-string [s b]
    (from-chars &(Array.suffix-array &(chars s) b)))

  (doc starts-with? "Check if the string `s` begins with the string `sub`.")
  (defn starts-with? [s sub]
    (= sub &(prefix-string s (length sub))))

  (doc ends-with? "Check if the string `s` ends with the string `sub`.")
  (defn ends-with? [s sub]
    (= sub &(suffix-string s (- (length s) (length sub)))))

  (doc zero "The empty string.")
  (defn zero [] @"")

  (doc sum-length "Returns the sum of lengths from an array of Strings.")
  (defn sum-length [strings]
    (let-do [sum 0
             lstrings (Array.length strings)]
      (for [i 0 lstrings]
        (set! sum (+ sum (String.length (Array.nth strings i)))))
      sum))

  (doc concat "Returns a new string which is the concatenation of the provided `strings`.")
  (defn concat [strings]
    ;; This is using a StringBuilder pattern to only perform one allocation and
    ;; to only copy each of the incoming strings once.
    ;; This currently performs wasted String.length calls, as we call it for each
    ;; string once here and once in sum-length.
    (let-do [j 0
             lstrings (Array.length strings)
             result (String.allocate (sum-length strings) \ )]
      (for [i 0 lstrings]
        (let-do [str (Array.nth strings i)
                 len (String.length str)]
          (string-set-at! &result j str)
          (set! j (+ j len))))
      result))

  (doc join "Returns a new string which is the concatenation of the provided `strings` separated by string `sep`.")
  (defn join [sep strings]
    (let-do [j 0
             lstrings (Array.length strings)
             num-seps (- lstrings 1)
             sep-length (String.length &sep)
             seps-size (* num-seps sep-length)
             result (String.allocate (+ seps-size (sum-length strings)) \ )]
      (for [i 0 lstrings]
        (let-do [str (Array.nth strings i)
                 len (String.length str)]
          (when (> i 0)
            (do
              (string-set-at! &result j &sep)
              (set! j (+ j sep-length))))
          (string-set-at! &result j str)
          (set! j (+ j len))))
      result))

  (doc join-with-char "Returns a new string which is the concatenation of the provided `strings` separated by char `sep`.")
  (defn join-with-char [sep strings]
    ;; (= (join-with-char \  ["Hello" "world"]) (join " " ["Hello" "world"]))
    (let-do [j 0
             lstrings (Array.length strings)
             sep-length (- lstrings 1)
             result (String.allocate (+ sep-length (sum-length strings)) \ )]
      (for [i 0 lstrings]
        (let-do [str (Array.nth strings i)
                 len (String.length str)]
          (when (> i 0)
            (do
              (string-set! &result j sep)
              (set! j (+ j 1))))
          (string-set-at! &result j str)
          (set! j (+ j len))))
      result))
)

(defmodule StringCopy
  (register append     (Fn [String String] String))

  (defn str [s] (the String s))

  (defn = [a b]
    (String.= &a &b))

  (defn /= [a b]
    (String./= &a &b))
)

(defmodule Bool
  (register str (Fn [Bool] String))
  (register format (Fn [&String Bool] String))
)

(defmodule Int
  (register str (Fn [Int] String))
  (register format (Fn [&String Int] String))
  (register from-string (λ [&String] Int))
)

(defmodule Float
  (register str (Fn [Float] String))
  (register format (Fn [&String Float] String))
)

(defmodule Long
  (register str (Fn [Long] String))
  (register format (Fn [&String Long] String))
  (register from-string (λ [&String] Long))
)

(defmodule Double
  (register str (Fn [Double] String))
  (register format (Fn [&String Double] String))
)

(defmodule Char
  (register str (Fn [Char] String))
  (register prn (Fn [Char] String))
  (register format (Fn [&String Char] String))
)

(defmodule Int (defn prn [x] (Int.str x)))
(defmodule Long (defn prn [x] (Long.str x)))
(defmodule Float (defn prn [x] (Float.str x)))
(defmodule Double (defn prn [x] (Double.str x)))
(defmodule Bool (defn prn [x] (Bool.str x)))
(defmodule Array (defn prn [x] (Array.str x)))