add build.rs file

bindings/c/.gitignore

@@ -0,0 +1 @@
+build

bindings/c/build.rs

@@ -0,0 +1,31 @@
+use std::env;
+use std::path::PathBuf;
+
+/// The directory where the generated header file will be written.
+const DIR_FOR_HEADER: &str = "build";
+
+fn main() {
+    // linker flags
+    // Link libm on Unix-like systems (needed due to use of num_cpus crate)
+    #[cfg(not(target_os = "windows"))]
+    println!("cargo:rustc-link-lib=m");
+
+    println!("cargo:rerun-if-changed=src/");
+    let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
+    let package_name = env::var("CARGO_PKG_NAME").unwrap();
+
+    let path_to_crate_dir = PathBuf::from(&crate_dir);
+
+    let output_file = PathBuf::from(&path_to_crate_dir)
+        .join(DIR_FOR_HEADER)
+        .join(format!("{}.h", package_name))
+        .display()
+        .to_string();
+
+    cbindgen::Builder::new()
+        .with_crate(crate_dir)
+        .with_language(cbindgen::Language::C)
+        .generate()
+        .unwrap()
+        .write_to_file(output_file);
+}