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diff --git a/Help/command/string.rst b/Help/command/string.rst new file mode 100644 index 000000000..4f0c45c29 --- /dev/null +++ b/Help/command/string.rst @@ -0,0 +1,367 @@ +string +------ + +.. only:: html + + .. contents:: + +String operations. + +Search and Replace +^^^^^^^^^^^^^^^^^^ + +FIND +"""" + +:: + + string(FIND <string> <substring> <output variable> [REVERSE]) + +Return the position where the given substring was found in +the supplied string. If the ``REVERSE`` flag was used, the command will +search for the position of the last occurrence of the specified +substring. If the substring is not found, a position of -1 is returned. + +REPLACE +""""""" + +:: + + string(REPLACE <match_string> + <replace_string> <output variable> + <input> [<input>...]) + +Replace all occurrences of ``match_string`` in the input +with ``replace_string`` and store the result in the output. + +Regular Expressions +^^^^^^^^^^^^^^^^^^^ + +REGEX MATCH +""""""""""" + +:: + + string(REGEX MATCH <regular_expression> + <output variable> <input> [<input>...]) + +Match the regular expression once and store the match in the output variable. +All ``<input>`` arguments are concatenated before matching. + +REGEX MATCHALL +"""""""""""""" + +:: + + string(REGEX MATCHALL <regular_expression> + <output variable> <input> [<input>...]) + +Match the regular expression as many times as possible and store the matches +in the output variable as a list. +All ``<input>`` arguments are concatenated before matching. + +REGEX REPLACE +""""""""""""" + +:: + + string(REGEX REPLACE <regular_expression> + <replace_expression> <output variable> + <input> [<input>...]) + +Match the regular expression as many times as possible and substitute the +replacement expression for the match in the output. +All ``<input>`` arguments are concatenated before matching. + +The replace expression may refer to paren-delimited subexpressions of the +match using ``\1``, ``\2``, ..., ``\9``. Note that two backslashes (``\\1``) +are required in CMake code to get a backslash through argument parsing. + +.. _`Regex Specification`: + +Regex Specification +""""""""""""""""""" + +The following characters have special meaning in regular expressions: + +``^`` + Matches at beginning of input +``$`` + Matches at end of input +``.`` + Matches any single character +``[ ]`` + Matches any character(s) inside the brackets +``[^ ]`` + Matches any character(s) not inside the brackets +``-`` + Inside brackets, specifies an inclusive range between + characters on either side e.g. ``[a-f]`` is ``[abcdef]`` + To match a literal ``-`` using brackets, make it the first + or the last character e.g. ``[+*/-]`` matches basic + mathematical operators. +``*`` + Matches preceding pattern zero or more times +``+`` + Matches preceding pattern one or more times +``?`` + Matches preceding pattern zero or once only +``|`` + Matches a pattern on either side of the ``|`` +``()`` + Saves a matched subexpression, which can be referenced + in the ``REGEX REPLACE`` operation. Additionally it is saved + by all regular expression-related commands, including + e.g. :command:`if(MATCHES)`, in the variables + :variable:`CMAKE_MATCH_<n>` for ``<n>`` 0..9. + +``*``, ``+`` and ``?`` have higher precedence than concatenation. ``|`` +has lower precedence than concatenation. This means that the regular +expression ``^ab+d$`` matches ``abbd`` but not ``ababd``, and the regular +expression ``^(ab|cd)$`` matches ``ab`` but not ``abd``. + +Manipulation +^^^^^^^^^^^^ + +APPEND +"""""" + +:: + + string(APPEND <string variable> [<input>...]) + +Append all the input arguments to the string. + +CONCAT +"""""" + +:: + + string(CONCAT <output variable> [<input>...]) + +Concatenate all the input arguments together and store +the result in the named output variable. + +TOLOWER +""""""" + +:: + + string(TOLOWER <string1> <output variable>) + +Convert string to lower characters. + +TOUPPER +""""""" + +:: + + string(TOUPPER <string1> <output variable>) + +Convert string to upper characters. + +LENGTH +"""""" + +:: + + string(LENGTH <string> <output variable>) + +Store in an output variable a given string's length. + +SUBSTRING +""""""""" + +:: + + string(SUBSTRING <string> <begin> <length> <output variable>) + +Store in an output variable a substring of a given string. If length is +``-1`` the remainder of the string starting at begin will be returned. +If string is shorter than length then end of string is used instead. + +.. note:: + CMake 3.1 and below reported an error if length pointed past + the end of string. + +STRIP +""""" + +:: + + string(STRIP <string> <output variable>) + +Store in an output variable a substring of a given string with leading and +trailing spaces removed. + +GENEX_STRIP +""""""""""" + +:: + + string(GENEX_STRIP <input string> <output variable>) + +Strip any :manual:`generator expressions <cmake-generator-expressions(7)>` +from the ``input string`` and store the result in the ``output variable``. + +Comparison +^^^^^^^^^^ + +:: + + string(COMPARE LESS <string1> <string2> <output variable>) + string(COMPARE GREATER <string1> <string2> <output variable>) + string(COMPARE EQUAL <string1> <string2> <output variable>) + string(COMPARE NOTEQUAL <string1> <string2> <output variable>) + string(COMPARE LESS_EQUAL <string1> <string2> <output variable>) + string(COMPARE GREATER_EQUAL <string1> <string2> <output variable>) + +Compare the strings and store true or false in the output variable. + +.. _`Supported Hash Algorithms`: + +Hashing +^^^^^^^ + +:: + + string(<HASH> <output variable> <input>) + +Compute a cryptographic hash of the input string. +The supported ``<HASH>`` algorithm names are: + +``MD5`` + Message-Digest Algorithm 5, RFC 1321. +``SHA1`` + US Secure Hash Algorithm 1, RFC 3174. +``SHA224`` + US Secure Hash Algorithms, RFC 4634. +``SHA256`` + US Secure Hash Algorithms, RFC 4634. +``SHA384`` + US Secure Hash Algorithms, RFC 4634. +``SHA512`` + US Secure Hash Algorithms, RFC 4634. +``SHA3_224`` + Keccak SHA-3. +``SHA3_256`` + Keccak SHA-3. +``SHA3_384`` + Keccak SHA-3. +``SHA3_512`` + Keccak SHA-3. + +Generation +^^^^^^^^^^ + +ASCII +""""" + +:: + + string(ASCII <number> [<number> ...] <output variable>) + +Convert all numbers into corresponding ASCII characters. + +CONFIGURE +""""""""" + +:: + + string(CONFIGURE <string1> <output variable> + [@ONLY] [ESCAPE_QUOTES]) + +Transform a string like :command:`configure_file` transforms a file. + +RANDOM +"""""" + +:: + + string(RANDOM [LENGTH <length>] [ALPHABET <alphabet>] + [RANDOM_SEED <seed>] <output variable>) + +Return a random string of given length consisting of +characters from the given alphabet. Default length is 5 characters +and default alphabet is all numbers and upper and lower case letters. +If an integer ``RANDOM_SEED`` is given, its value will be used to seed the +random number generator. + +TIMESTAMP +""""""""" + +:: + + string(TIMESTAMP <output variable> [<format string>] [UTC]) + +Write a string representation of the current date +and/or time to the output variable. + +Should the command be unable to obtain a timestamp the output variable +will be set to the empty string "". + +The optional ``UTC`` flag requests the current date/time representation to +be in Coordinated Universal Time (UTC) rather than local time. + +The optional ``<format string>`` may contain the following format +specifiers: + +:: + + %% A literal percent sign (%). + %d The day of the current month (01-31). + %H The hour on a 24-hour clock (00-23). + %I The hour on a 12-hour clock (01-12). + %j The day of the current year (001-366). + %m The month of the current year (01-12). + %b Abbreviated month name (e.g. Oct). + %M The minute of the current hour (00-59). + %s Seconds since midnight (UTC) 1-Jan-1970 (UNIX time). + %S The second of the current minute. + 60 represents a leap second. (00-60) + %U The week number of the current year (00-53). + %w The day of the current week. 0 is Sunday. (0-6) + %a Abbreviated weekday name (e.g. Fri). + %y The last two digits of the current year (00-99) + %Y The current year. + +Unknown format specifiers will be ignored and copied to the output +as-is. + +If no explicit ``<format string>`` is given it will default to: + +:: + + %Y-%m-%dT%H:%M:%S for local time. + %Y-%m-%dT%H:%M:%SZ for UTC. + + +:: + + string(MAKE_C_IDENTIFIER <input string> <output variable>) + +Write a string which can be used as an identifier in C. + +.. note:: + + If the ``SOURCE_DATE_EPOCH`` environment variable is set, + its value will be used instead of the current time. + See https://reproducible-builds.org/specs/source-date-epoch/ for details. + +UUID +"""" + +:: + + string(UUID <output variable> NAMESPACE <namespace> NAME <name> + TYPE <MD5|SHA1> [UPPER]) + +Create a univerally unique identifier (aka GUID) as per RFC4122 +based on the hash of the combined values of ``<namespace>`` +(which itself has to be a valid UUID) and ``<name>``. +The hash algorithm can be either ``MD5`` (Version 3 UUID) or +``SHA1`` (Version 5 UUID). +A UUID has the format ``xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`` +where each `x` represents a lower case hexadecimal character. +Where required an uppercase representation can be requested +with the optional ``UPPER`` flag. |