Only build supported terminals

CHANGELOG.md

@@ -11,6 +11,7 @@ This project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html
 ### Changed
 - Refactor internal terminal representation, replacing the terminal enum with a
   new `Terminal` trait and dynamic dispatch.
+- Only include terminal backends supported on the platform.
 
 [GH-34]: https://github.com/lunaryorn/mdcat/pull/34
 

Cargo.toml

@@ -10,13 +10,14 @@ version = "0.8.1-pre"
 categories = ["command-line-utilities", "text-processing"]
 license = "Apache-2.0"
 authors = ["Sebastian Wiesner <sebastian@swsnr.de>"]
+build = "build.rs"
 
 [badges]
 travis-ci = { repository = "lunaryorn/mdcat" }
 maintenance = { status = "actively-developed" }
 
 [features]
-default = ["iterm2", "terminology"]
+default = []
 
 iterm2 = ["mime", "base64"]
 terminology = ["immeta"]

build.rs

@@ -0,0 +1,28 @@
+// Copyright 2018 Sebastian Wiesner <sebastian@swsnr.de>
+
+// 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.
+
+fn enable_feature(feature: &str) {
+    println!("rustc-cfg={}", feature);
+}
+
+fn main() {
+    #[cfg(target_os = "macos")]
+    {
+        enable_feature("iterm2");
+    }
+    #[cfg(all(unix, not(target_os = "macos")))]
+    {
+        enable_feature("terminology");
+    }
+}