add SliceExt

nixide/src/stdext/mod.rs

@@ -1,3 +1,5 @@
 mod cchar_ptr;
+mod slice;
 
 pub(crate) use cchar_ptr::{AsCPtr, CCharPtrExt};
+pub(crate) use slice::SliceExt;

nixide/src/stdext/slice.rs

@@ -0,0 +1,43 @@
+use std::iter;
+use std::ptr::null_mut;
+
+use crate::util::wrappers::AsInnerPtr;
+
+pub trait SliceExt<T, S> {
+    #[allow(unused)]
+    fn as_c_array(&self) -> *mut *mut S;
+
+    #[allow(unused)]
+    fn into_c_array(self) -> *mut *mut S;
+}
+
+impl<T, S> SliceExt<T, S> for &[&T]
+where
+    T: AsInnerPtr<S>,
+{
+    fn as_c_array(&self) -> *mut *mut S {
+        let mut ptrs: Vec<*mut S> = self
+            .into_iter()
+            .map(|x| unsafe { x.as_ptr() })
+            .chain(iter::once(null_mut()))
+            .collect();
+
+        let ptr = ptrs.as_mut_ptr();
+        std::mem::forget(ptrs);
+
+        ptr
+    }
+
+    fn into_c_array(self) -> *mut *mut S {
+        let mut ptrs: Vec<*mut S> = self
+            .into_iter()
+            .map(|x| unsafe { x.as_ptr() })
+            .chain(iter::once(null_mut()))
+            .collect();
+
+        let ptr = ptrs.as_mut_ptr();
+        std::mem::forget(ptrs);
+
+        ptr
+    }
+}