Rebrand to Galaxy, major improvements to Bedrock support, still needs some TLC though

crates/galaxyui/src/windowing/winit/fonts/str_index_map.rs

@@ -0,0 +1,57 @@
+//! Module containing the definition of [`StrIndexMap`], allowing for repeated, efficient conversion
+//! between a byte and/or char index from a backing `str`.
+
+use std::collections::HashMap;
+
+/// Map that provides efficient conversion from byte <-> char index from a backing `str`.
+/// See [`StrIndexMap::byte_index`] and [`StrIndexMap::char_index`] for conversion functions to
+/// convert from/to a byte index to a char index.   
+pub(super) struct StrIndexMap {
+    byte_to_char_index: HashMap<usize, usize>,
+    char_to_byte_index: Vec<usize>,
+}
+
+impl StrIndexMap {
+    /// Constructs a new [`StrIndexMap`] with byte <-> char indices based on the input `str`.
+    /// NOTE this runs in O(n) time as it requires walking through each char index in the `str`.
+    pub(super) fn new(str: impl AsRef<str>) -> Self {
+        let char_indices = str.as_ref().char_indices();
+        let (_, upper_bound) = char_indices.size_hint();
+
+        let (mut byte_to_char_index, mut char_to_byte_index) = match upper_bound {
+            None => (HashMap::new(), Vec::new()),
+            Some(size) => (HashMap::with_capacity(size), Vec::with_capacity(size)),
+        };
+
+        for (char_index, (byte_index, _)) in char_indices.enumerate() {
+            byte_to_char_index.insert(byte_index, char_index);
+            char_to_byte_index.push(byte_index);
+        }
+
+        Self {
+            byte_to_char_index,
+            char_to_byte_index,
+        }
+    }
+
+    /// Returns the _byte_ index of the string at the given `char_index`. If the `char_index` does
+    /// not exist in the string, `None` is returned.
+    pub(super) fn byte_index(&self, char_index: usize) -> Option<usize> {
+        self.char_to_byte_index.get(char_index).copied()
+    }
+
+    /// Returns the _char_ index of the string at the given byte index. If the `byte_index` does not
+    /// exist in the string or if it does not lie at a char boundary, `None` is returned.
+    pub(super) fn char_index(&self, byte_index: usize) -> Option<usize> {
+        self.byte_to_char_index.get(&byte_index).copied()
+    }
+
+    /// Returns the total number of characters in the string.
+    pub(super) fn num_chars(&self) -> usize {
+        self.char_to_byte_index.len()
+    }
+}
+
+#[cfg(test)]
+#[path = "str_index_map_tests.rs"]
+mod tests;