move contents of taskchampion repo to tc/

rust/lib/src/util.rs

@@ -0,0 +1,23 @@
+use crate::string::RustString;
+
+pub(crate) fn err_to_ruststring(e: impl std::string::ToString) -> RustString<'static> {
+    RustString::from(e.to_string())
+}
+
+/// An implementation of Vec::into_raw_parts, which is still unstable.  Returns ptr, len, cap.
+pub(crate) fn vec_into_raw_parts<T>(vec: Vec<T>) -> (*mut T, usize, usize) {
+    // emulate Vec::into_raw_parts():
+    // - disable dropping the Vec with ManuallyDrop
+    // - extract ptr, len, and capacity using those methods
+    let mut vec = std::mem::ManuallyDrop::new(vec);
+    (vec.as_mut_ptr(), vec.len(), vec.capacity())
+}
+
+/// An implementation of String::into_raw_parts, which is still unstable.  Returns ptr, len, cap.
+pub(crate) fn string_into_raw_parts(string: String) -> (*mut u8, usize, usize) {
+    // emulate String::into_raw_parts():
+    // - disable dropping the String with ManuallyDrop
+    // - extract ptr, len, and capacity using those methods
+    let mut string = std::mem::ManuallyDrop::new(string);
+    (string.as_mut_ptr(), string.len(), string.capacity())
+}