Add Support for MSVC Makefiles

If we are building with the MSVC toolchain then use the existing NMAKE files instead of Cmake.

This is initial work on #35

onig_sys/build.rs

@@ -1,12 +1,22 @@
 extern crate pkg_config;
+
+#[cfg(not(target_env="msvc"))]
 extern crate cmake;
 
 use std::env;
 
-fn compile_with_cmake() {
-    use cmake::Config;
+fn rustc_link_type(static_link: bool) -> &'static str {
+    if static_link {
+        "static"
+    } else {
+        "dylib"
+    }
+}
 
-    let static_link = env::var("CARGO_FEATURE_STATIC_ONIG").is_ok();
+
+#[cfg(not(target_env="msvc"))]
+fn compile(static_link: bool) {
+    use cmake::Config;
 
     // Builds the project in the directory located in `oniguruma`, installing it
     // into $OUT_DIR
@@ -19,21 +29,44 @@ fn compile_with_cmake() {
               }
               .build();
 
-    let link_type = if static_link {
-        "static"
-    } else {
-        "dylib"
-    };
-
     println!("cargo:rustc-link-search=native={}",
              dst.join("build").display());
-    println!("cargo:rustc-link-lib={}=onig", link_type);
+    println!("cargo:rustc-link-lib={}=onig", rustc_link_type(static_link));
+}
+
+#[cfg(target_env="msvc")]
+pub fn compile(static_link: bool) {
+    use std::process::Command;
+
+    // TODO: does this need to be dynamically looked up?
+    let onig_dir = env::current_dir().unwrap().join("oniguruma");
+    let build_dir = onig_dir.join("src");
+    let lib_name = if static_link { "onig_s" } else { "onig" };
+
+    let bitness = if cfg!(target_pointer_width="64") { "64" } else { "32" };
+
+    let r = Command::new("cmd")
+        .args(&["/c", &format!("make_win{}.bat", bitness)])
+        .current_dir(&onig_dir)
+        .output()
+        .expect("error running build");
+
+    if !r.status.success() {
+        let err = String::from_utf8_lossy(&r.stderr);
+        let out = String::from_utf8_lossy(&r.stdout);
+        panic!("Build error:\nSTDERR:{}\nSTDOUT:{}", err, out);
+    }
+
+    println!("cargo:rustc-link-search=native={}", build_dir.display());
+    println!("cargo:rustc-link-lib={}={}", rustc_link_type(static_link), lib_name);
 }
 
 pub fn main() {
     if let Ok(_) = pkg_config::find_library("oniguruma") {
         return;
     }
+
+    let static_link = env::var("CARGO_FEATURE_STATIC_ONIG").is_ok();
 
-    compile_with_cmake();
+    compile(static_link);
 }