add some UUID support

lib/Cargo.toml

@@ -11,6 +11,7 @@ crate-type = ["cdylib"]
 [dependencies]
 libc = "0.2.113"
 taskchampion = { path = "../taskchampion" }
+uuid = { version = "^0.8.2", features = ["serde", "v4"] }
 anyhow = "1.0"
 
 [build-dependencies]

lib/build.rs

@@ -10,6 +10,16 @@ fn main() {
         .with_language(Language::C)
         .with_config(Config {
             cpp_compat: true,
+            export: ExportConfig {
+                item_types: vec![
+                    ItemType::Structs,
+                    ItemType::Globals,
+                    ItemType::Functions,
+                    ItemType::Constants,
+                    ItemType::OpaqueItems,
+                ],
+                ..Default::default()
+            },
             ..Default::default()
         })
         .generate()

lib/src/lib.rs

@@ -1 +1,2 @@
 pub mod replica;
+pub mod uuid;

lib/src/uuid.rs

@@ -0,0 +1,63 @@
+use libc;
+use taskchampion::Uuid as TcUuid;
+
+/// Uuid is used as a task identifier.  Uuids do not contain any pointers and need not be freed.
+#[repr(C)]
+pub struct Uuid([u8; 16]);
+
+impl From<TcUuid> for Uuid {
+    fn from(uuid: TcUuid) -> Uuid {
+        // TODO: can we avoid clone here?
+        Uuid(uuid.as_bytes().clone())
+    }
+}
+
+impl From<Uuid> for TcUuid {
+    fn from(uuid: Uuid) -> TcUuid {
+        TcUuid::from_bytes(uuid.0)
+    }
+}
+
+/// Create a new, randomly-generated UUID.
+#[no_mangle]
+pub extern "C" fn tc_uuid_new_v4() -> Uuid {
+    TcUuid::new_v4().into()
+}
+
+/// Create a new UUID with the nil value.
+#[no_mangle]
+pub extern "C" fn tc_uuid_nil() -> Uuid {
+    TcUuid::nil().into()
+}
+
+/// Length, in bytes, of a C string containing a Uuid.
+#[no_mangle]
+pub static TC_UUID_STRING_BYTES: usize = ::uuid::adapter::Hyphenated::LENGTH;
+
+/// Write the string representation of a Uuid into the given buffer, which must be
+/// at least TC_UUID_STRING_BYTES long.  No NUL terminator is added.
+#[no_mangle]
+pub extern "C" fn tc_uuid_to_str<'a>(uuid: Uuid, out: *mut libc::c_char) {
+    debug_assert!(!out.is_null());
+    let buf: &'a mut [u8] = unsafe {
+        std::slice::from_raw_parts_mut(out as *mut u8, ::uuid::adapter::Hyphenated::LENGTH)
+    };
+    let uuid: TcUuid = uuid.into();
+    uuid.to_hyphenated().encode_lower(buf);
+}
+
+/// Parse the given value as a UUID.  The value must be exactly TC_UUID_STRING_BYTES long.  Returns
+/// false on failure.
+#[no_mangle]
+pub extern "C" fn tc_uuid_from_str<'a>(val: *const libc::c_char, out: *mut Uuid) -> bool {
+    debug_assert!(!val.is_null());
+    debug_assert!(!out.is_null());
+    let slice = unsafe { std::slice::from_raw_parts(val as *const u8, TC_UUID_STRING_BYTES) };
+    if let Ok(s) = std::str::from_utf8(slice) {
+        if let Ok(u) = TcUuid::parse_str(s) {
+            unsafe { *out = u.into() };
+            return true;
+        }
+    }
+    false
+}

lib/taskchampion.h

@@ -8,8 +8,15 @@
 /// for querying and modifying that data.
 struct Replica;
 
+/// Uuid is used as a task identifier.  Uuids do not contain any pointers and need not be freed.
+struct Uuid {
+  uint8_t _0[16];
+};
+
 extern "C" {
 
+extern const uintptr_t TC_UUID_STRING_BYTES;
+
 /// Create a new Replica.
 ///
 /// If path is NULL, then an in-memory replica is created.  Otherwise, path is the path to the
@@ -34,4 +41,18 @@ const char *tc_replica_error(Replica *rep);
 /// Free a Replica.
 void tc_replica_free(Replica *rep);
 
+/// Create a new, randomly-generated UUID.
+Uuid tc_uuid_new_v4();
+
+/// Create a new UUID with the nil value.
+Uuid tc_uuid_nil();
+
+/// Write the string representation of a Uuid into the given buffer, which must be
+/// at least TC_UUID_STRING_BYTES long.  No NUL terminator is added.
+void tc_uuid_to_str(Uuid uuid, char *out);
+
+/// Parse the given value as a UUID.  The value must be exactly TC_UUID_STRING_BYTES long.  Returns
+/// false on failure.
+bool tc_uuid_from_str(const char *val, Uuid *out);
+
 } // extern "C"