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.
(blank? s)
True if s is nil, empty, or contains only whitespace.
(capitalize s)
Converts first character of the string to upper-case, all other
characters to lower-case.
(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.
(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.
(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"
(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"
(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.
(trim s)
Removes whitespace from both ends of string.
(trim-newline s)
Removes all trailing newline \n or return \r characters from
string. Similar to Perl's chomp.
(triml s)
Removes whitespace from the left side of string.
(trimr s)
Removes whitespace from the right side of string.