Merge branch 'doc-regex-backslash' into release-3.13
Merge-request: !2460
diff --git a/Help/command/string.rst b/Help/command/string.rst
index 29a153a..cc18069 100644
--- a/Help/command/string.rst
+++ b/Help/command/string.rst
@@ -121,6 +121,11 @@
Matches at end of input
``.``
Matches any single character
+``\<char>``
+ Matches the single character specified by ``<char>``. Use this to
+ match special regex characters, e.g. ``\.`` for a literal ``.``
+ or ``\\`` for a literal backslash ``\``. Escaping a non-special
+ character is unnecessary but allowed, e.g. ``\a`` matches ``a``.
``[ ]``
Matches any character(s) inside the brackets
``[^ ]``
@@ -151,12 +156,9 @@
expression ``^ab+d$`` matches ``abbd`` but not ``ababd``, and the regular
expression ``^(ab|cd)$`` matches ``ab`` but not ``abd``.
-Backslash (``\``) characters in regular expressions are interpreted
-literally and do not escape anything or represent placeholders.
-However, CMake language :ref:`Escape Sequences` such as ``\t``,
-``\r``, ``\n``, and ``\\`` may be used to construct literal tabs,
-carriage returns, newlines, and backslashes (respectively) to pass
-in a regex. For example:
+CMake language :ref:`Escape Sequences` such as ``\t``, ``\r``, ``\n``,
+and ``\\`` may be used to construct literal tabs, carriage returns,
+newlines, and backslashes (respectively) to pass in a regex. For example:
* The quoted argument ``"[ \t\r\n]"`` specifies a regex that matches
any single whitespace character.
@@ -164,6 +166,11 @@
a single forward slash ``/`` or backslash ``\``.
* The quoted argument ``"[A-Za-z0-9_]"`` specifies a regex that matches
any single "word" character in the C locale.
+* The quoted argument ``"\\(\\a\\+b\\)"`` specifies a regex that matches
+ the exact string ``(a+b)``. Each ``\\`` is parsed in a quoted argument
+ as just ``\``, so the regex itself is actually ``\(\a\+\b\)``. This
+ can alternatively be specified in a :ref:`bracket argument` without
+ having to escape the backslashes, e.g. ``[[\(\a\+\b\)]]``.
Manipulation
^^^^^^^^^^^^
