ExternalData: Format module documentation

Manually revise the .rst format of the documentation.  Use inline
literal quotes appropriately in paragraph text.  Move the :: literal
block openers to the end of the preceding paragraphs.  Convert the
command signature documentation and examples to cmake code-block
directives.

Modules/ExternalData.cmake

@@ -7,22 +7,22 @@
 # Use this module to unambiguously reference data files stored outside
 # the source tree and fetch them at build time from arbitrary local and
 # remote content-addressed locations.  Functions provided by this module
-# recognize arguments with the syntax "DATA{<name>}" as references to
+# recognize arguments with the syntax ``DATA{<name>}`` as references to
 # external data, replace them with full paths to local copies of those
 # data, and create build rules to fetch and update the local copies.
 #
-# The DATA{} syntax is literal and the <name> is a full or relative path
+# The ``DATA{}`` syntax is literal and the ``<name>`` is a full or relative path
 # within the source tree.  The source tree must contain either a real
-# data file at <name> or a "content link" at <name><ext> containing a
-# hash of the real file using a hash algorithm corresponding to <ext>.
-# For example, the argument "DATA{img.png}" may be satisfied by either a
-# real "img.png" file in the current source directory or a "img.png.md5"
+# data file at ``<name>`` or a "content link" at ``<name><ext>`` containing a
+# hash of the real file using a hash algorithm corresponding to ``<ext>``.
+# For example, the argument ``DATA{img.png}`` may be satisfied by either a
+# real ``img.png`` file in the current source directory or a ``img.png.md5``
 # file containing its MD5 sum.
 #
-# The 'ExternalData_Expand_Arguments' function evaluates DATA{}
+# The ``ExternalData_Expand_Arguments`` function evaluates ``DATA{}``
 # references in its arguments and constructs a new list of arguments:
 #
-# ::
+# .. code-block:: cmake
 #
 #  ExternalData_Expand_Arguments(
 #    <target>   # Name of data management target
@@ -30,42 +30,41 @@
 #    [args...]  # Input arguments, DATA{} allowed
 #    )
 #
-# It replaces each DATA{} reference in an argument with the full path of
-# a real data file on disk that will exist after the <target> builds.
+# It replaces each ``DATA{}`` reference in an argument with the full path of
+# a real data file on disk that will exist after the ``<target>`` builds.
 #
-# The 'ExternalData_Add_Test' function wraps around the CMake add_test()
-# command but supports DATA{} references in its arguments:
+# The ``ExternalData_Add_Test`` function wraps around the CMake
+# :command:`add_test` command but supports ``DATA{}`` references in
+# its arguments:
 #
-# ::
+# .. code-block:: cmake
 #
 #  ExternalData_Add_Test(
 #    <target>   # Name of data management target
 #    ...        # Arguments of add_test(), DATA{} allowed
 #    )
 #
-# It passes its arguments through ExternalData_Expand_Arguments and then
-# invokes add_test() using the results.
+# It passes its arguments through ``ExternalData_Expand_Arguments`` and then
+# invokes the :command:`add_test` command using the results.
 #
-# The 'ExternalData_Add_Target' function creates a custom target to
+# The ``ExternalData_Add_Target`` function creates a custom target to
 # manage local instances of data files stored externally:
 #
-# ::
+# .. code-block:: cmake
 #
 #  ExternalData_Add_Target(
 #    <target>   # Name of data management target
 #    )
 #
 # It creates custom commands in the target as necessary to make data
-# files available for each DATA{} reference previously evaluated by
+# files available for each ``DATA{}`` reference previously evaluated by
 # other functions provided by this module.  A list of URL templates must
-# be provided in the variable ExternalData_URL_TEMPLATES using the
-# placeholders "%(algo)" and "%(hash)" in each template.  Data fetch
+# be provided in the variable ``ExternalData_URL_TEMPLATES`` using the
+# placeholders ``%(algo)`` and ``%(hash)`` in each template.  Data fetch
 # rules try each URL template in order by substituting the hash
-# algorithm name for "%(algo)" and the hash value for "%(hash)".
+# algorithm name for ``%(algo)`` and the hash value for ``%(hash)``.
 #
-# The following hash algorithms are supported:
-#
-# ::
+# The following hash algorithms are supported::
 #
 #  %(algo)     <ext>     Description
 #  -------     -----     -----------
@@ -81,7 +80,7 @@
 #
 # Example usage:
 #
-# ::
+# .. code-block:: cmake
 #
 #  include(ExternalData)
 #  set(ExternalData_URL_TEMPLATES "file:///local/%(algo)/%(hash)"
@@ -92,30 +91,26 @@
 #    )
 #  ExternalData_Add_Target(MyData)
 #
-# When test "MyTest" runs the "DATA{MyInput.png}" argument will be
+# When test ``MyTest`` runs the ``DATA{MyInput.png}`` argument will be
 # replaced by the full path to a real instance of the data file
-# "MyInput.png" on disk.  If the source tree contains a content link
-# such as "MyInput.png.md5" then the "MyData" target creates a real
-# "MyInput.png" in the build tree.
+# ``MyInput.png`` on disk.  If the source tree contains a content link
+# such as ``MyInput.png.md5`` then the ``MyData`` target creates a real
+# ``MyInput.png`` in the build tree.
 #
-# The DATA{} syntax can be told to fetch a file series using the form
-# "DATA{<name>,:}", where the ":" is literal.  If the source tree
+# The ``DATA{}`` syntax can be told to fetch a file series using the form
+# ``DATA{<name>,:}``, where the ``:`` is literal.  If the source tree
 # contains a group of files or content links named like a series then a
 # reference to one member adds rules to fetch all of them.  Although all
 # members of a series are fetched, only the file originally named by the
-# DATA{} argument is substituted for it.  The default configuration
-# recognizes file series names ending with "#.ext", "_#.ext", ".#.ext",
-# or "-#.ext" where "#" is a sequence of decimal digits and ".ext" is
-# any single extension.  Configure it with a regex that parses <number>
-# and <suffix> parts from the end of <name>:
-#
-# ::
+# ``DATA{}`` argument is substituted for it.  The default configuration
+# recognizes file series names ending with ``#.ext``, ``_#.ext``, ``.#.ext``,
+# or ``-#.ext`` where ``#`` is a sequence of decimal digits and ``.ext`` is
+# any single extension.  Configure it with a regex that parses ``<number>``
+# and ``<suffix>`` parts from the end of ``<name>``::
 #
 #  ExternalData_SERIES_PARSE = regex of the form (<number>)(<suffix>)$
 #
-# For more complicated cases set:
-#
-# ::
+# For more complicated cases set::
 #
 #  ExternalData_SERIES_PARSE = regex with at least two () groups
 #  ExternalData_SERIES_PARSE_PREFIX = <prefix> regex group number, if any
@@ -123,70 +118,66 @@
 #  ExternalData_SERIES_PARSE_SUFFIX = <suffix> regex group number
 #
 # Configure series number matching with a regex that matches the
-# <number> part of series members named <prefix><number><suffix>:
-#
-# ::
+# ``<number>`` part of series members named ``<prefix><number><suffix>``::
 #
 #  ExternalData_SERIES_MATCH = regex matching <number> in all series members
 #
-# Note that the <suffix> of a series does not include a hash-algorithm
+# Note that the ``<suffix>`` of a series does not include a hash-algorithm
 # extension.
 #
-# The DATA{} syntax can alternatively match files associated with the
+# The ``DATA{}`` syntax can alternatively match files associated with the
 # named file and contained in the same directory.  Associated files may
 # be specified by options using the syntax
-# DATA{<name>,<opt1>,<opt2>,...}.  Each option may specify one file by
+# ``DATA{<name>,<opt1>,<opt2>,...}``.  Each option may specify one file by
 # name or specify a regular expression to match file names using the
-# syntax REGEX:<regex>.  For example, the arguments
-#
-# ::
+# syntax ``REGEX:<regex>``.  For example, the arguments::
 #
 #  DATA{MyData/MyInput.mhd,MyInput.img}                   # File pair
 #  DATA{MyData/MyFrames00.png,REGEX:MyFrames[0-9]+\\.png} # Series
 #
-# will pass MyInput.mha and MyFrames00.png on the command line but
+# will pass ``MyInput.mha`` and ``MyFrames00.png`` on the command line but
 # ensure that the associated files are present next to them.
 #
-# The DATA{} syntax may reference a directory using a trailing slash and
-# a list of associated files.  The form DATA{<name>/,<opt1>,<opt2>,...}
+# The ``DATA{}`` syntax may reference a directory using a trailing slash and
+# a list of associated files.  The form ``DATA{<name>/,<opt1>,<opt2>,...}``
 # adds rules to fetch any files in the directory that match one of the
 # associated file options.  For example, the argument
-# DATA{MyDataDir/,REGEX:.*} will pass the full path to a MyDataDir
+# ``DATA{MyDataDir/,REGEX:.*}`` will pass the full path to a ``MyDataDir``
 # directory on the command line and ensure that the directory contains
-# files corresponding to every file or content link in the MyDataDir
+# files corresponding to every file or content link in the ``MyDataDir``
 # source directory.
 #
-# The variable ExternalData_LINK_CONTENT may be set to the name of a
+# The variable ``ExternalData_LINK_CONTENT`` may be set to the name of a
 # supported hash algorithm to enable automatic conversion of real data
-# files referenced by the DATA{} syntax into content links.  For each
-# such <file> a content link named "<file><ext>" is created.  The
-# original file is renamed to the form ".ExternalData_<algo>_<hash>" to
+# files referenced by the ``DATA{}`` syntax into content links.  For each
+# such ``<file>`` a content link named ``<file><ext>`` is created.  The
+# original file is renamed to the form ``.ExternalData_<algo>_<hash>`` to
 # stage it for future transmission to one of the locations in the list
 # of URL templates (by means outside the scope of this module).  The
 # data fetch rule created for the content link will use the staged
 # object if it cannot be found using any URL template.
 #
-# The variable ExternalData_OBJECT_STORES may be set to a list of local
-# directories that store objects using the layout <dir>/%(algo)/%(hash).
+# The variable ``ExternalData_OBJECT_STORES`` may be set to a list of local
+# directories that store objects using the layout ``<dir>/%(algo)/%(hash)``.
 # These directories will be searched first for a needed object.  If the
 # object is not available in any store then it will be fetched remotely
 # using the URL templates and added to the first local store listed.  If
 # no stores are specified the default is a location inside the build
 # tree.
 #
-# The variable ExternalData_SOURCE_ROOT may be set to the highest source
-# directory containing any path named by a DATA{} reference.  The
-# default is CMAKE_SOURCE_DIR.  ExternalData_SOURCE_ROOT and
-# CMAKE_SOURCE_DIR must refer to directories within a single source
+# The variable ``ExternalData_SOURCE_ROOT`` may be set to the highest source
+# directory containing any path named by a ``DATA{}`` reference.  The
+# default is ``CMAKE_SOURCE_DIR``.  ``ExternalData_SOURCE_ROOT`` and
+# ``CMAKE_SOURCE_DIR`` must refer to directories within a single source
 # distribution (e.g.  they come together in one tarball).
 #
-# The variable ExternalData_BINARY_ROOT may be set to the directory to
-# hold the real data files named by expanded DATA{} references.  The
-# default is CMAKE_BINARY_DIR.  The directory layout will mirror that of
-# content links under ExternalData_SOURCE_ROOT.
+# The variable ``ExternalData_BINARY_ROOT`` may be set to the directory to
+# hold the real data files named by expanded ``DATA{}`` references.  The
+# default is ``CMAKE_BINARY_DIR``.  The directory layout will mirror that of
+# content links under ``ExternalData_SOURCE_ROOT``.
 #
-# Variables ExternalData_TIMEOUT_INACTIVITY and
-# ExternalData_TIMEOUT_ABSOLUTE set the download inactivity and absolute
+# Variables ``ExternalData_TIMEOUT_INACTIVITY`` and
+# ``ExternalData_TIMEOUT_ABSOLUTE`` set the download inactivity and absolute
 # timeouts, in seconds.  The defaults are 60 seconds and 300 seconds,
 # respectively.  Set either timeout to 0 seconds to disable enforcement.