[CommandLine] Add callbacks to Options
Summary:
Add a new cl::callback attribute to Option.
This attribute specifies a callback function that is called when
an option is seen, and can be used to set other options, as in
option A implies option B. If the option is a `cl::list`, and
`cl::CommaSeparated` is also specified, the callback will fire
once for each value. This could be used to validate combinations
or selectively set other options.
Reviewers: beanz, thomasfinch, MaskRay, thopre, serge-sans-paille
Reviewed By: beanz
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70620
diff --git a/llvm/docs/CommandLine.rst b/llvm/docs/CommandLine.rst
index a7db630..ab2826d 100644
--- a/llvm/docs/CommandLine.rst
+++ b/llvm/docs/CommandLine.rst
@@ -996,6 +996,31 @@
* The **cl::cat** attribute specifies the option category that the option
belongs to. The category should be a `cl::OptionCategory`_ object.
+.. _cl::callback:
+
+* The **cl::callback** attribute specifies a callback function that is
+ called when an option is seen, and can be used to set other options,
+ as in option B implies option A. If the option is a `cl::list`_,
+ and `cl::CommaSeparated`_ is also specified, the callback will fire
+ once for each value. This could be used to validate combinations or
+ selectively set other options.
+
+ .. code-block:: c++
+
+ cl::opt<bool> OptA("a", cl::desc("option a"));
+ cl::opt<bool> OptB(
+ "b", cl::desc("option b -- This option turns on option a"),
+ cl::callback([&](const bool &) { OptA = true; }));
+ cl::list<std::string, cl::list<std::string>> List(
+ "list",
+ cl::desc("option list -- This option turns on options a when "
+ "'foo' is included in list"),
+ cl::CommaSeparated,
+ cl::callback([&](const std::string &Str) {
+ if (Str == "foo")
+ OptA = true;
+ }));
+
Option Modifiers
----------------