Utilities/Sphinx: Add 'cref' role

Add a role that can be used to create local links (a la '`LINK`_'), but
that also applies literal style. This is particularly useful for
referring to subcommands within the command's documentation in a style
that is consistent with ':command:`BAR <foo(BAR)>`' but is much less
verbose.

Although this is intended for subcommands, it works with any local
reference.

Co-authored-by: Brad King <brad.king@kitware.com>

5 files changed, 35 insertions, 3 deletions

diff --git a/Help/dev/documentation.rst b/Help/dev/documentation.rst
index b7a77c9..c6fb7a6 100644
--- a/Help/dev/documentation.rst
+++ b/Help/dev/documentation.rst
@@ -395,6 +395,10 @@ object names like ``OUTPUT_NAME_<CONFIG>``.  The form ``a <b>``,
 with a space preceding ``<``, is still interpreted as a link text
 with an explicit target.
 
+Additionally, the ``cref`` role may be used to create references
+to local targets that have literal styling.  This is especially
+useful for referencing a subcommand in the command's documentation.
+
 .. _`list()`: https://cmake.org/cmake/help/latest/command/list.html
 .. _`list(APPEND)`: https://cmake.org/cmake/help/latest/command/list.html
 .. _`list(APPEND) sub-command`: https://cmake.org/cmake/help/latest/command/list.html
diff --git a/Source/cmRST.cxx b/Source/cmRST.cxx
index 5ff7009..f48330d 100644
--- a/Source/cmRST.cxx
+++ b/Source/cmRST.cxx
@@ -33,6 +33,7 @@ cmRST::cmRST(std::ostream& os, std::string docroot)
   , VersionDirective("^.. version(added|changed)::[ \t]*(.*)$")
   , ModuleRST(R"(^#\[(=*)\[\.rst:$)")
   , CMakeRole("(:cmake)?:("
+              "cref|"
               "command|cpack_gen|generator|genex|"
               "variable|envvar|module|policy|"
               "prop_cache|prop_dir|prop_gbl|prop_inst|prop_sf|"
diff --git a/Tests/CMakeLib/testRST.expect b/Tests/CMakeLib/testRST.expect
index 483e220..424b7d4 100644
--- a/Tests/CMakeLib/testRST.expect
+++ b/Tests/CMakeLib/testRST.expect
@@ -26,10 +26,15 @@ Generator expression ``$<SOME_GENEX:...>`` with brackets and parameter.
 Generator expression ``some genex`` with space and target.
 Generator expression ``$<SOME_GENEX>`` with brackets, space, and target.
 Generator expression ``$<SOME_GENEX:...>`` with brackets, parameter, space, and target.
-Inline literal ``~!@#$%^&*( )_+-=\\[]{}'":;,<>.?/``.
+Inline cref ``Link Dest``.
+Inline cref ``Link_Dest_<Placeholder>``.
+Inline cref ``Link Text``.
+Inline cref ``Link_Text_<Placeholder>``.
+Inline link Link Dest.
 Inline link Link Text.
 Inline link Link Text <With \-escaped Brackets>.
 Inline literal ``__`` followed by inline link Link Text.
+Inline literal ``~!@#$%^&*( )_+-=\\[]{}'":;,<>.?/``.
 
 First TOC entry.
 
diff --git a/Tests/CMakeLib/testRST.rst b/Tests/CMakeLib/testRST.rst
index c23b69a..3a38407 100644
--- a/Tests/CMakeLib/testRST.rst
+++ b/Tests/CMakeLib/testRST.rst
@@ -33,10 +33,15 @@ Generator expression :genex:`$<SOME_GENEX:...>` with brackets and parameter.
 Generator expression :genex:`some genex <SOME_GENEX>` with space and target.
 Generator expression :genex:`$<SOME_GENEX> <SOME_GENEX>` with brackets, space, and target.
 Generator expression :genex:`$<SOME_GENEX:...> <SOME_GENEX>` with brackets, parameter, space, and target.
-Inline literal ``~!@#$%^&*( )_+-=\\[]{}'":;,<>.?/``.
+Inline cref :cref:`Link Dest`.
+Inline cref :cref:`Link_Dest_<Placeholder>`.
+Inline cref :cref:`Link Text <ExternalDest>`.
+Inline cref :cref:`Link_Text_<Placeholder> <ExternalDest>`.
+Inline link `Link Dest`_.
 Inline link `Link Text <ExternalDest>`_.
 Inline link `Link Text \<With \\-escaped Brackets\> <ExternalDest>`_.
 Inline literal ``__`` followed by inline link `Link Text <InternalDest_>`_.
+Inline literal ``~!@#$%^&*( )_+-=\\[]{}'":;,<>.?/``.
 
 .. |not replaced| replace:: not replaced through toctree
 .. |not replaced in literal| replace:: replaced in parsed literal
diff --git a/Utilities/Sphinx/cmake.py b/Utilities/Sphinx/cmake.py
index 111ea04..5990f8a 100644
--- a/Utilities/Sphinx/cmake.py
+++ b/Utilities/Sphinx/cmake.py
@@ -5,7 +5,7 @@ import os
 import re
 
 from dataclasses import dataclass
-from typing import Any, List, Tuple, cast
+from typing import Any, List, Tuple, Type, cast
 
 # Override much of pygments' CMakeLexer.
 # We need to parse CMake syntax definitions, not CMake code.
@@ -72,6 +72,7 @@ from docutils import io, nodes
 from sphinx.directives import ObjectDescription, nl_escape_re
 from sphinx.domains import Domain, ObjType
 from sphinx.roles import XRefRole
+from sphinx.util.docutils import ReferenceRole
 from sphinx.util.nodes import make_refnode
 from sphinx.util import logging, ws_re
 from sphinx import addnodes
@@ -508,6 +509,21 @@ class CMakeReferenceRole:
                 return super().__call__(name, rawtext, text, *args, **kwargs)
         return Class
 
+class CMakeCRefRole(CMakeReferenceRole[ReferenceRole]):
+    nodeclass: Type[Element] = nodes.reference
+    innernodeclass: Type[TextElement] = nodes.literal
+    classes: List[str] = ['cmake', 'literal']
+
+    def run(self) -> Tuple[List[Node], List[system_message]]:
+        refnode = self.nodeclass(self.rawtext)
+        self.set_source_info(refnode)
+
+        refnode['refid'] = nodes.make_id(self.target)
+        refnode += self.innernodeclass(self.rawtext, self.title,
+                                       classes=self.classes)
+
+        return [refnode], []
+
 class CMakeXRefRole(CMakeReferenceRole[XRefRole]):
 
     _re_sub = re.compile(r'^([^()\s]+)\s*\(([^()]*)\)$', re.DOTALL)
@@ -617,6 +633,7 @@ class CMakeDomain(Domain):
         # Other `object_types` cannot be created except by the `CMakeTransform`
     }
     roles = {
+        'cref':       CMakeCRefRole(),
         'command':    CMakeXRefRole(fix_parens = True, lowercase = True),
         'cpack_gen':  CMakeXRefRole(),
         'envvar':     CMakeXRefRole(),