Add doc comments

Author: iainireland

utils/codepointtrie/src/codepointtrie.rs

@@ -32,6 +32,7 @@ pub enum TrieType {
 /// A trait representing the values stored in the data array of a [`CodePointTrie`].
 /// This trait is used as a type parameter in constructing a `CodePointTrie`.
 pub trait TrieValue: Copy + zerovec::ule::AsULE + 'static {
+    /// The value to return if we cannot read data from the trie.
     const DATA_GET_ERROR_VALUE: Self;
 }
 

utils/codepointtrie/src/provider.rs

@@ -2,14 +2,22 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+//! Data provider struct definitions for this ICU4X component.
+//!
+//! Read more about data providers: [`icu_provider`]
+
 use crate::codepointtrie::{CodePointTrie, TrieValue};
 use icu_provider::yoke::{self, Yokeable, ZeroCopyFrom};
 
+/// A map efficiently storing data about individual characters.
 #[derive(Yokeable, ZeroCopyFrom)]
 pub struct UnicodePropertyMapV1<'data, T: TrieValue> {
+    /// A codepoint trie storing the data
     pub codepoint_trie: CodePointTrie<'data, T>,
 }
 
+/// Marker type for UnicodePropertyMapV1.
+/// This is generated by hand because icu_provider::data_struct doesn't support generics yet.
 pub struct UnicodePropertyMapV1Marker<T: TrieValue> {
     _phantom: core::marker::PhantomData<T>,
 }