clojure.string — org.clojure/clojure 1.5.0-alpha3

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? clj

(blank? s)

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

capitalize clj

(capitalize s)

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

ends-with? clj

(ends-with? s substr)

True if s ends with substr.

escape clj

(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.

includes? clj

(includes? s substr)

True if s includes substr.

index-of clj

(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. Return nil if value not found.

join clj

(join coll)

(join separator coll)

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

last-index-of clj

(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. Return nil if value not found.

lower-case clj

(lower-case s)

Converts string to all lower-case.

re-quote-replacement clj

(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 clj

(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 clj

(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"

reverse clj

(reverse s)

Returns s with its characters reversed.

split clj

(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.

split-lines clj

(split-lines s)

Splits s on \n or \r\n.

starts-with? clj

(starts-with? s substr)

True if s starts with substr.

trim clj

(trim s)

Removes whitespace from both ends of string.

trim-newline clj

(trim-newline s)

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

triml clj

(triml s)

Removes whitespace from the left side of string.

trimr clj

(trimr s)

Removes whitespace from the right side of string.

upper-case clj

(upper-case s)

Converts string to all upper-case.