You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
281 lines
11 KiB
281 lines
11 KiB
if
|
|
--
|
|
|
|
Conditionally execute a group of commands.
|
|
|
|
Synopsis
|
|
^^^^^^^^
|
|
|
|
.. code-block:: cmake
|
|
|
|
if(<condition>)
|
|
<commands>
|
|
elseif(<condition>) # optional block, can be repeated
|
|
<commands>
|
|
else() # optional block
|
|
<commands>
|
|
endif()
|
|
|
|
Evaluates the ``condition`` argument of the ``if`` clause according to the
|
|
`Condition syntax`_ described below. If the result is true, then the
|
|
``commands`` in the ``if`` block are executed.
|
|
Otherwise, optional ``elseif`` blocks are processed in the same way.
|
|
Finally, if no ``condition`` is true, ``commands`` in the optional ``else``
|
|
block are executed.
|
|
|
|
Per legacy, the :command:`else` and :command:`endif` commands admit
|
|
an optional ``<condition>`` argument.
|
|
If used, it must be a verbatim
|
|
repeat of the argument of the opening
|
|
``if`` command.
|
|
|
|
.. _`Condition Syntax`:
|
|
|
|
Condition Syntax
|
|
^^^^^^^^^^^^^^^^
|
|
|
|
The following syntax applies to the ``condition`` argument of
|
|
the ``if``, ``elseif`` and :command:`while` clauses.
|
|
|
|
Compound conditions are evaluated in the following order of precedence:
|
|
Innermost parentheses are evaluated first. Next come unary tests such
|
|
as ``EXISTS``, ``COMMAND``, and ``DEFINED``. Then binary tests such as
|
|
``EQUAL``, ``LESS``, ``LESS_EQUAL``, ``GREATER``, ``GREATER_EQUAL``,
|
|
``STREQUAL``, ``STRLESS``, ``STRLESS_EQUAL``, ``STRGREATER``,
|
|
``STRGREATER_EQUAL``, ``VERSION_EQUAL``, ``VERSION_LESS``,
|
|
``VERSION_LESS_EQUAL``, ``VERSION_GREATER``, ``VERSION_GREATER_EQUAL``,
|
|
and ``MATCHES``. Then the boolean operators in the order ``NOT``, ``AND``,
|
|
and finally ``OR``.
|
|
|
|
Possible conditions are:
|
|
|
|
``if(<constant>)``
|
|
True if the constant is ``1``, ``ON``, ``YES``, ``TRUE``, ``Y``,
|
|
or a non-zero number. False if the constant is ``0``, ``OFF``,
|
|
``NO``, ``FALSE``, ``N``, ``IGNORE``, ``NOTFOUND``, the empty string,
|
|
or ends in the suffix ``-NOTFOUND``. Named boolean constants are
|
|
case-insensitive. If the argument is not one of these specific
|
|
constants, it is treated as a variable or string and the following
|
|
signature is used.
|
|
|
|
``if(<variable|string>)``
|
|
True if given a variable that is defined to a value that is not a false
|
|
constant. False otherwise. (Note macro arguments are not variables.)
|
|
|
|
``if(NOT <condition>)``
|
|
True if the condition is not true.
|
|
|
|
``if(<cond1> AND <cond2>)``
|
|
True if both conditions would be considered true individually.
|
|
|
|
``if(<cond1> OR <cond2>)``
|
|
True if either condition would be considered true individually.
|
|
|
|
``if(COMMAND command-name)``
|
|
True if the given name is a command, macro or function that can be
|
|
invoked.
|
|
|
|
``if(POLICY policy-id)``
|
|
True if the given name is an existing policy (of the form ``CMP<NNNN>``).
|
|
|
|
``if(TARGET target-name)``
|
|
True if the given name is an existing logical target name created
|
|
by a call to the :command:`add_executable`, :command:`add_library`,
|
|
or :command:`add_custom_target` command that has already been invoked
|
|
(in any directory).
|
|
|
|
``if(TEST test-name)``
|
|
True if the given name is an existing test name created by the
|
|
:command:`add_test` command.
|
|
|
|
``if(EXISTS path-to-file-or-directory)``
|
|
True if the named file or directory exists. Behavior is well-defined
|
|
only for full paths. Resolves symbolic links, i.e. if the named file or
|
|
directory is a symbolic link, returns true if the target of the
|
|
symbolic link exists.
|
|
|
|
``if(file1 IS_NEWER_THAN file2)``
|
|
True if ``file1`` is newer than ``file2`` or if one of the two files doesn't
|
|
exist. Behavior is well-defined only for full paths. If the file
|
|
time stamps are exactly the same, an ``IS_NEWER_THAN`` comparison returns
|
|
true, so that any dependent build operations will occur in the event
|
|
of a tie. This includes the case of passing the same file name for
|
|
both file1 and file2.
|
|
|
|
``if(IS_DIRECTORY path-to-directory)``
|
|
True if the given name is a directory. Behavior is well-defined only
|
|
for full paths.
|
|
|
|
``if(IS_SYMLINK file-name)``
|
|
True if the given name is a symbolic link. Behavior is well-defined
|
|
only for full paths.
|
|
|
|
``if(IS_ABSOLUTE path)``
|
|
True if the given path is an absolute path.
|
|
|
|
``if(<variable|string> MATCHES regex)``
|
|
True if the given string or variable's value matches the given regular
|
|
condition. See :ref:`Regex Specification` for regex format.
|
|
``()`` groups are captured in :variable:`CMAKE_MATCH_<n>` variables.
|
|
|
|
``if(<variable|string> LESS <variable|string>)``
|
|
True if the given string or variable's value is a valid number and less
|
|
than that on the right.
|
|
|
|
``if(<variable|string> GREATER <variable|string>)``
|
|
True if the given string or variable's value is a valid number and greater
|
|
than that on the right.
|
|
|
|
``if(<variable|string> EQUAL <variable|string>)``
|
|
True if the given string or variable's value is a valid number and equal
|
|
to that on the right.
|
|
|
|
``if(<variable|string> LESS_EQUAL <variable|string>)``
|
|
True if the given string or variable's value is a valid number and less
|
|
than or equal to that on the right.
|
|
|
|
``if(<variable|string> GREATER_EQUAL <variable|string>)``
|
|
True if the given string or variable's value is a valid number and greater
|
|
than or equal to that on the right.
|
|
|
|
``if(<variable|string> STRLESS <variable|string>)``
|
|
True if the given string or variable's value is lexicographically less
|
|
than the string or variable on the right.
|
|
|
|
``if(<variable|string> STRGREATER <variable|string>)``
|
|
True if the given string or variable's value is lexicographically greater
|
|
than the string or variable on the right.
|
|
|
|
``if(<variable|string> STREQUAL <variable|string>)``
|
|
True if the given string or variable's value is lexicographically equal
|
|
to the string or variable on the right.
|
|
|
|
``if(<variable|string> STRLESS_EQUAL <variable|string>)``
|
|
True if the given string or variable's value is lexicographically less
|
|
than or equal to the string or variable on the right.
|
|
|
|
``if(<variable|string> STRGREATER_EQUAL <variable|string>)``
|
|
True if the given string or variable's value is lexicographically greater
|
|
than or equal to the string or variable on the right.
|
|
|
|
``if(<variable|string> VERSION_LESS <variable|string>)``
|
|
Component-wise integer version number comparison (version format is
|
|
``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
|
|
Any non-integer version component or non-integer trailing part of a version
|
|
component effectively truncates the string at that point.
|
|
|
|
``if(<variable|string> VERSION_GREATER <variable|string>)``
|
|
Component-wise integer version number comparison (version format is
|
|
``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
|
|
Any non-integer version component or non-integer trailing part of a version
|
|
component effectively truncates the string at that point.
|
|
|
|
``if(<variable|string> VERSION_EQUAL <variable|string>)``
|
|
Component-wise integer version number comparison (version format is
|
|
``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
|
|
Any non-integer version component or non-integer trailing part of a version
|
|
component effectively truncates the string at that point.
|
|
|
|
``if(<variable|string> VERSION_LESS_EQUAL <variable|string>)``
|
|
Component-wise integer version number comparison (version format is
|
|
``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
|
|
Any non-integer version component or non-integer trailing part of a version
|
|
component effectively truncates the string at that point.
|
|
|
|
``if(<variable|string> VERSION_GREATER_EQUAL <variable|string>)``
|
|
Component-wise integer version number comparison (version format is
|
|
``major[.minor[.patch[.tweak]]]``, omitted components are treated as zero).
|
|
Any non-integer version component or non-integer trailing part of a version
|
|
component effectively truncates the string at that point.
|
|
|
|
``if(<variable|string> IN_LIST <variable>)``
|
|
True if the given element is contained in the named list variable.
|
|
|
|
``if(DEFINED <name>|CACHE{<name>}|ENV{<name>})``
|
|
True if a variable, cache variable or environment variable
|
|
with given ``<name>`` is defined. The value of the variable
|
|
does not matter. Note that macro arguments are not variables.
|
|
|
|
``if((condition) AND (condition OR (condition)))``
|
|
The conditions inside the parenthesis are evaluated first and then
|
|
the remaining condition is evaluated as in the previous examples.
|
|
Where there are nested parenthesis the innermost are evaluated as part
|
|
of evaluating the condition that contains them.
|
|
|
|
Variable Expansion
|
|
^^^^^^^^^^^^^^^^^^
|
|
|
|
The if command was written very early in CMake's history, predating
|
|
the ``${}`` variable evaluation syntax, and for convenience evaluates
|
|
variables named by its arguments as shown in the above signatures.
|
|
Note that normal variable evaluation with ``${}`` applies before the if
|
|
command even receives the arguments. Therefore code like
|
|
|
|
.. code-block:: cmake
|
|
|
|
set(var1 OFF)
|
|
set(var2 "var1")
|
|
if(${var2})
|
|
|
|
appears to the if command as
|
|
|
|
.. code-block:: cmake
|
|
|
|
if(var1)
|
|
|
|
and is evaluated according to the ``if(<variable>)`` case documented
|
|
above. The result is ``OFF`` which is false. However, if we remove the
|
|
``${}`` from the example then the command sees
|
|
|
|
.. code-block:: cmake
|
|
|
|
if(var2)
|
|
|
|
which is true because ``var2`` is defined to ``var1`` which is not a false
|
|
constant.
|
|
|
|
Automatic evaluation applies in the other cases whenever the
|
|
above-documented condition syntax accepts ``<variable|string>``:
|
|
|
|
* The left hand argument to ``MATCHES`` is first checked to see if it is
|
|
a defined variable, if so the variable's value is used, otherwise the
|
|
original value is used.
|
|
|
|
* If the left hand argument to ``MATCHES`` is missing it returns false
|
|
without error
|
|
|
|
* Both left and right hand arguments to ``LESS``, ``GREATER``, ``EQUAL``,
|
|
``LESS_EQUAL``, and ``GREATER_EQUAL``, are independently tested to see if
|
|
they are defined variables, if so their defined values are used otherwise
|
|
the original value is used.
|
|
|
|
* Both left and right hand arguments to ``STRLESS``, ``STRGREATER``,
|
|
``STREQUAL``, ``STRLESS_EQUAL``, and ``STRGREATER_EQUAL`` are independently
|
|
tested to see if they are defined variables, if so their defined values are
|
|
used otherwise the original value is used.
|
|
|
|
* Both left and right hand arguments to ``VERSION_LESS``,
|
|
``VERSION_GREATER``, ``VERSION_EQUAL``, ``VERSION_LESS_EQUAL``, and
|
|
``VERSION_GREATER_EQUAL`` are independently tested to see if they are defined
|
|
variables, if so their defined values are used otherwise the original value
|
|
is used.
|
|
|
|
* The right hand argument to ``NOT`` is tested to see if it is a boolean
|
|
constant, if so the value is used, otherwise it is assumed to be a
|
|
variable and it is dereferenced.
|
|
|
|
* The left and right hand arguments to ``AND`` and ``OR`` are independently
|
|
tested to see if they are boolean constants, if so they are used as
|
|
such, otherwise they are assumed to be variables and are dereferenced.
|
|
|
|
To prevent ambiguity, potential variable or keyword names can be
|
|
specified in a :ref:`Quoted Argument` or a :ref:`Bracket Argument`.
|
|
A quoted or bracketed variable or keyword will be interpreted as a
|
|
string and not dereferenced or interpreted.
|
|
See policy :policy:`CMP0054`.
|
|
|
|
There is no automatic evaluation for environment or cache
|
|
:ref:`Variable References`. Their values must be referenced as
|
|
``$ENV{<name>}`` or ``$CACHE{<name>}`` wherever the above-documented
|
|
condition syntax accepts ``<variable|string>``.
|