Add functions to get a `CGEventFlags` from a slice of `autopilot::Flag`

These two functions are copied from `autopilot-rs/src/key.rs` at
ab7ebc9fd8bc210717c0210aa20335ea9ceed200. I wanted to use the library
directly, but they're private functions.

I need this code in order to be able to convert the 'autopilot' `Flag`
type into `CGEventFlags`. I need a `CGEventFlags` because my media key
simulator, `dkess_press_key()` (an FFI function), requires a
`CGEventFlags`-typed value.

Needed to change the `from` function to a top-level function due to this
error:

    error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
       --> src/autopilot_internal.rs:213:1
        |
    213 | impl From<Flag> for CGEventFlags {
        | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl doesn't use types inside crate
        |
        = note: the impl does not reference any types defined in this crate
        = note: define and implement a trait or new type instead

Bringing the code into the project seemed to be the easiest way to
leverage the existing 'autopilot' work.

2 files changed, 233 insertions, 0 deletions

diff --git a/src/autopilot_internal.rs b/src/autopilot_internal.rs
new file mode 100644
index 0000000..519305e
--- /dev/null
+++ b/src/autopilot_internal.rs
@@ -0,0 +1,232 @@
+// autopilot-rs/src/key.rs
+// ab7ebc9fd8bc210717c0210aa20335ea9ceed200
+
+//                              Apache License
+//                        Version 2.0, January 2004
+//                     http://www.apache.org/licenses/
+//
+// TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+//
+// 1. Definitions.
+//
+//   "License" shall mean the terms and conditions for use, reproduction,
+//   and distribution as defined by Sections 1 through 9 of this document.
+//
+//   "Licensor" shall mean the copyright owner or entity authorized by
+//   the copyright owner that is granting the License.
+//
+//   "Legal Entity" shall mean the union of the acting entity and all
+//   other entities that control, are controlled by, or are under common
+//   control with that entity. For the purposes of this definition,
+//   "control" means (i) the power, direct or indirect, to cause the
+//   direction or management of such entity, whether by contract or
+//   otherwise, or (ii) ownership of fifty percent (50%) or more of the
+//   outstanding shares, or (iii) beneficial ownership of such entity.
+//
+//   "You" (or "Your") shall mean an individual or Legal Entity
+//   exercising permissions granted by this License.
+//
+//   "Source" form shall mean the preferred form for making modifications,
+//   including but not limited to software source code, documentation
+//   source, and configuration files.
+//
+//   "Object" form shall mean any form resulting from mechanical
+//   transformation or translation of a Source form, including but
+//   not limited to compiled object code, generated documentation,
+//   and conversions to other media types.
+//
+//   "Work" shall mean the work of authorship, whether in Source or
+//   Object form, made available under the License, as indicated by a
+//   copyright notice that is included in or attached to the work
+//   (an example is provided in the Appendix below).
+//
+//   "Derivative Works" shall mean any work, whether in Source or Object
+//   form, that is based on (or derived from) the Work and for which the
+//   editorial revisions, annotations, elaborations, or other modifications
+//   represent, as a whole, an original work of authorship. For the purposes
+//   of this License, Derivative Works shall not include works that remain
+//   separable from, or merely link (or bind by name) to the interfaces of,
+//   the Work and Derivative Works thereof.
+//
+//   "Contribution" shall mean any work of authorship, including
+//   the original version of the Work and any modifications or additions
+//   to that Work or Derivative Works thereof, that is intentionally
+//   submitted to Licensor for inclusion in the Work by the copyright owner
+//   or by an individual or Legal Entity authorized to submit on behalf of
+//   the copyright owner. For the purposes of this definition, "submitted"
+//   means any form of electronic, verbal, or written communication sent
+//   to the Licensor or its representatives, including but not limited to
+//   communication on electronic mailing lists, source code control systems,
+//   and issue tracking systems that are managed by, or on behalf of, the
+//   Licensor for the purpose of discussing and improving the Work, but
+//   excluding communication that is conspicuously marked or otherwise
+//   designated in writing by the copyright owner as "Not a Contribution."
+//
+//   "Contributor" shall mean Licensor and any individual or Legal Entity
+//   on behalf of whom a Contribution has been received by Licensor and
+//   subsequently incorporated within the Work.
+//
+// 2. Grant of Copyright License. Subject to the terms and conditions of
+//   this License, each Contributor hereby grants to You a perpetual,
+//   worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+//   copyright license to reproduce, prepare Derivative Works of,
+//   publicly display, publicly perform, sublicense, and distribute the
+//   Work and such Derivative Works in Source or Object form.
+//
+// 3. Grant of Patent License. Subject to the terms and conditions of
+//   this License, each Contributor hereby grants to You a perpetual,
+//   worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+//   (except as stated in this section) patent license to make, have made,
+//   use, offer to sell, sell, import, and otherwise transfer the Work,
+//   where such license applies only to those patent claims licensable
+//   by such Contributor that are necessarily infringed by their
+//   Contribution(s) alone or by combination of their Contribution(s)
+//   with the Work to which such Contribution(s) was submitted. If You
+//   institute patent litigation against any entity (including a
+//   cross-claim or counterclaim in a lawsuit) alleging that the Work
+//   or a Contribution incorporated within the Work constitutes direct
+//   or contributory patent infringement, then any patent licenses
+//   granted to You under this License for that Work shall terminate
+//   as of the date such litigation is filed.
+//
+// 4. Redistribution. You may reproduce and distribute copies of the
+//   Work or Derivative Works thereof in any medium, with or without
+//   modifications, and in Source or Object form, provided that You
+//   meet the following conditions:
+//
+//   (a) You must give any other recipients of the Work or
+//       Derivative Works a copy of this License; and
+//
+//   (b) You must cause any modified files to carry prominent notices
+//       stating that You changed the files; and
+//
+//   (c) You must retain, in the Source form of any Derivative Works
+//       that You distribute, all copyright, patent, trademark, and
+//       attribution notices from the Source form of the Work,
+//       excluding those notices that do not pertain to any part of
+//       the Derivative Works; and
+//
+//   (d) If the Work includes a "NOTICE" text file as part of its
+//       distribution, then any Derivative Works that You distribute must
+//       include a readable copy of the attribution notices contained
+//       within such NOTICE file, excluding those notices that do not
+//       pertain to any part of the Derivative Works, in at least one
+//       of the following places: within a NOTICE text file distributed
+//       as part of the Derivative Works; within the Source form or
+//       documentation, if provided along with the Derivative Works; or,
+//       within a display generated by the Derivative Works, if and
+//       wherever such third-party notices normally appear. The contents
+//       of the NOTICE file are for informational purposes only and
+//       do not modify the License. You may add Your own attribution
+//       notices within Derivative Works that You distribute, alongside
+//       or as an addendum to the NOTICE text from the Work, provided
+//       that such additional attribution notices cannot be construed
+//       as modifying the License.
+//
+//   You may add Your own copyright statement to Your modifications and
+//   may provide additional or different license terms and conditions
+//   for use, reproduction, or distribution of Your modifications, or
+//   for any such Derivative Works as a whole, provided Your use,
+//   reproduction, and distribution of the Work otherwise complies with
+//   the conditions stated in this License.
+//
+// 5. Submission of Contributions. Unless You explicitly state otherwise,
+//   any Contribution intentionally submitted for inclusion in the Work
+//   by You to the Licensor shall be under the terms and conditions of
+//   this License, without any additional terms or conditions.
+//   Notwithstanding the above, nothing herein shall supersede or modify
+//   the terms of any separate license agreement you may have executed
+//   with Licensor regarding such Contributions.
+//
+// 6. Trademarks. This License does not grant permission to use the trade
+//   names, trademarks, service marks, or product names of the Licensor,
+//   except as required for reasonable and customary use in describing the
+//   origin of the Work and reproducing the content of the NOTICE file.
+//
+// 7. Disclaimer of Warranty. Unless required by applicable law or
+//   agreed to in writing, Licensor provides the Work (and each
+//   Contributor provides its Contributions) on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+//   implied, including, without limitation, any warranties or conditions
+//   of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+//   PARTICULAR PURPOSE. You are solely responsible for determining the
+//   appropriateness of using or redistributing the Work and assume any
+//   risks associated with Your exercise of permissions under this License.
+//
+// 8. Limitation of Liability. In no event and under no legal theory,
+//   whether in tort (including negligence), contract, or otherwise,
+//   unless required by applicable law (such as deliberate and grossly
+//   negligent acts) or agreed to in writing, shall any Contributor be
+//   liable to You for damages, including any direct, indirect, special,
+//   incidental, or consequential damages of any character arising as a
+//   result of this License or out of the use or inability to use the
+//   Work (including but not limited to damages for loss of goodwill,
+//   work stoppage, computer failure or malfunction, or any and all
+//   other commercial damages or losses), even if such Contributor
+//   has been advised of the possibility of such damages.
+//
+// 9. Accepting Warranty or Additional Liability. While redistributing
+//   the Work or Derivative Works thereof, You may choose to offer,
+//   and charge a fee for, acceptance of support, warranty, indemnity,
+//   or other liability obligations and/or rights consistent with this
+//   License. However, in accepting such obligations, You may act only
+//   on Your own behalf and on Your sole responsibility, not on behalf
+//   of any other Contributor, and only if You agree to indemnify,
+//   defend, and hold each Contributor harmless for any liability
+//   incurred by, or claims asserted against, such Contributor by reason
+//   of your accepting any such warranty or additional liability.
+//
+// END OF TERMS AND CONDITIONS
+//
+// APPENDIX: How to apply the Apache License to your work.
+//
+//   To apply the Apache License to your work, attach the following
+//   boilerplate notice, with the fields enclosed by brackets "{}"
+//   replaced with your own identifying information. (Don't include
+//   the brackets!)  The text should be enclosed in the appropriate
+//   comment syntax for the file format. We also recommend that a
+//   file or class name and description of purpose be included on the
+//   same "printed page" as the copyright notice for easier
+//   identification within third-party archives.
+//
+// Copyright 2018 Michael Sanders.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Modifications:
+// * Remove the `event::` prefix
+// * Change `CGEventFlags::from<Flag>` to `cg_event_flags_from_flag`
+
+use autopilot::key::Flag;
+use core_graphics::event::CGEventFlags;
+
+#[cfg(target_os = "macos")]
+fn cg_event_flags_from_flag(flag: Flag) -> CGEventFlags {
+    match flag {
+        Flag::Shift => CGEventFlags::CGEventFlagShift,
+        Flag::Control => CGEventFlags::CGEventFlagControl,
+        Flag::Alt => CGEventFlags::CGEventFlagAlternate,
+        Flag::Meta => CGEventFlags::CGEventFlagCommand,
+        Flag::Help => CGEventFlags::CGEventFlagHelp,
+    }
+}
+
+#[cfg(target_os = "macos")]
+fn cg_event_mask_for_flags(flags: &[Flag]) -> CGEventFlags {
+    flags
+        .iter()
+        .map(|&x| cg_event_flags_from_flag(x))
+        .fold(CGEventFlags::CGEventFlagNull, |x, y| {
+            x | y as CGEventFlags
+        })
+}
diff --git a/src/lib.rs b/src/lib.rs
index 39e6a31..ed9e9c3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,6 +18,7 @@ extern crate objc;
 extern crate stderrlog;
 extern crate xdg;
 
+mod autopilot_internal;
 mod cocoa_bridge;
 mod config;
 mod key_code;