clojure.string

Clojure String utilities

It is poor form to (:use clojure.string). Instead, use require
with :as to specify a prefix, e.g.

(ns your.namespace.here
  (:require [clojure.string :as str]))

Design notes for clojure.string:

1. Strings are objects (as opposed to sequences). As such, the
   string being manipulated is the first argument to a function;
   passing nil will result in a NullPointerException unless
   documented otherwise. If you want sequence-y behavior instead,
   use a sequence.

2. Functions are generally not lazy, and call straight to host
   methods where those are available and efficient.

3. Functions take advantage of String implementation details to
   write high-performing loop/recurs instead of using higher-order
   functions. (This is not idiomatic in general-purpose application
   code.)

4. When a function is documented to accept a string argument, it
   will take any implementation of the correct *interface* on the
   host platform. In Java, this is CharSequence, which is more
   general than String. In ordinary usage you will almost always
   pass concrete strings. If you are doing something unusual,
   e.g. passing a mutable implementation of CharSequence, then
   thread-safety is your responsibility.

Usage: (blank? s)

True if s is nil, empty, or contains only whitespace.

Usage: (capitalize s)

Converts first character of the string to upper-case, all other
characters to lower-case.

Usage: (ends-with? s substr)

True if s ends with substr.

Usage: (escape s cmap)

Return a new string, using cmap to escape each character ch
from s as follows:

If (cmap ch) is nil, append ch to the new string.
If (cmap ch) is non-nil, append (str (cmap ch)) instead.

Usage: (includes? s substr)

True if s includes substr.

Usage: (index-of s value)
       (index-of s value from-index)

Return index of value (string or char) in s, optionally searching
forward from from-index or nil if not found.

Usage: (join coll)
       (join separator coll)

Returns a string of all elements in coll, as returned by (seq coll),
separated by an optional separator.

Usage: (last-index-of s value)
       (last-index-of s value from-index)

Return last index of value (string or char) in s, optionally
searching backward from from-index or nil if not found.

Usage: (lower-case s)

Converts string to all lower-case.

Usage: (re-quote-replacement replacement)

Given a replacement string that you wish to be a literal
replacement for a pattern match in replace or replace-first, do the
necessary escaping of special characters in the replacement.

Usage: (replace s match replacement)

Replaces all instance of match with replacement in s.

match/replacement can be:

string / string
char / char
pattern / (string or function of match).

See also replace-first.

The replacement is literal (i.e. none of its characters are treated
specially) for all cases above except pattern / string.

For pattern / string, $1, $2, etc. in the replacement string are
substituted with the string that matched the corresponding
parenthesized group in the pattern.  If you wish your replacement
string r to be used literally, use (re-quote-replacement r) as the
replacement argument.  See also documentation for
java.util.regex.Matcher's appendReplacement method.

Example:
(clojure.string/replace "Almost Pig Latin" #"\b(\w)(\w+)\b" "$2$1ay")
-> "lmostAay igPay atinLay"

Usage: (replace-first s match replacement)

Replaces the first instance of match with replacement in s.

match/replacement can be:

char / char
string / string
pattern / (string or function of match).

See also replace.

The replacement is literal (i.e. none of its characters are treated
specially) for all cases above except pattern / string.

For pattern / string, $1, $2, etc. in the replacement string are
substituted with the string that matched the corresponding
parenthesized group in the pattern.  If you wish your replacement
string r to be used literally, use (re-quote-replacement r) as the
replacement argument.  See also documentation for
java.util.regex.Matcher's appendReplacement method.

Example:
(clojure.string/replace-first "swap first two words"
                              #"(\w+)(\s+)(\w+)" "$3$2$1")
-> "first swap two words"

Usage: (reverse s)

Returns s with its characters reversed.

Usage: (split s re)
       (split s re limit)

Splits string on a regular expression.  Optional argument limit is
the maximum number of splits. Not lazy. Returns vector of the splits.

Usage: (split-lines s)

Splits s on \n or \r\n.

Usage: (starts-with? s substr)

True if s starts with substr.

Usage: (trim s)

Removes whitespace from both ends of string.

Usage: (trim-newline s)

Removes all trailing newline \n or return \r characters from
string.  Similar to Perl's chomp.

Usage: (triml s)

Removes whitespace from the left side of string.

Usage: (trimr s)

Removes whitespace from the right side of string.

Usage: (upper-case s)

Converts string to all upper-case.

 © Rich Hickey