Add ZeroAsciiIgnoreCaseTrie::get_strict

utils/zerotrie/src/options.rs

@@ -73,6 +73,15 @@ pub(crate) enum CaseSensitivity {
     IgnoreCase,
 }
 
+/// How to handle lookup for strings with mixed ASCII case. Only used in ignore-case tries
+#[derive(Copy, Clone)]
+pub(crate) enum LookupStrictness {
+    /// Select strings that differ in case so long as their `to_ascii_lowercase` matches
+    Normal,
+    /// Select strings only if they match exactly
+    Strict,
+}
+
 impl CaseSensitivity {
     #[cfg(feature = "serde")]
     const fn to_u8_flag(self) -> u8 {
@@ -89,6 +98,7 @@ pub(crate) struct ZeroTrieBuilderOptions {
     pub ascii_mode: AsciiMode,
     pub capacity_mode: CapacityMode,
     pub case_sensitivity: CaseSensitivity,
+    pub lookup_strictness: LookupStrictness,
 }
 
 impl ZeroTrieBuilderOptions {
@@ -113,6 +123,7 @@ impl<S: ?Sized> ZeroTrieWithOptions for crate::ZeroTrieSimpleAscii<S> {
         ascii_mode: AsciiMode::AsciiOnly,
         capacity_mode: CapacityMode::Normal,
         case_sensitivity: CaseSensitivity::Sensitive,
+        lookup_strictness: LookupStrictness::Normal,
     };
 }
 
@@ -129,6 +140,7 @@ impl<S: ?Sized> ZeroTrieWithOptions for crate::ZeroAsciiIgnoreCaseTrie<S> {
         ascii_mode: AsciiMode::AsciiOnly,
         capacity_mode: CapacityMode::Normal,
         case_sensitivity: CaseSensitivity::IgnoreCase,
+        lookup_strictness: LookupStrictness::Normal,
     };
 }
 
@@ -137,13 +149,24 @@ impl<S: ?Sized> crate::ZeroAsciiIgnoreCaseTrie<S> {
     pub(crate) const FLAGS: u8 = Self::OPTIONS.to_u8_flags();
 }
 
+/// Internal struct to power `get_strict`
+pub(crate) struct ZeroAsciiIgnoreCaseStrictTrie;
+
+impl ZeroTrieWithOptions for ZeroAsciiIgnoreCaseStrictTrie {
+    const OPTIONS: ZeroTrieBuilderOptions = ZeroTrieBuilderOptions {
+        lookup_strictness: LookupStrictness::Strict,
+        ..ZeroAsciiIgnoreCaseTrie::OPTIONS
+    };
+}
+
 /// Branch nodes could be either binary search or PHF.
 impl<S: ?Sized> ZeroTrieWithOptions for crate::ZeroTriePerfectHash<S> {
     const OPTIONS: ZeroTrieBuilderOptions = ZeroTrieBuilderOptions {
         phf_mode: PhfMode::UsePhf,
         ascii_mode: AsciiMode::BinarySpans,
         capacity_mode: CapacityMode::Normal,
         case_sensitivity: CaseSensitivity::Sensitive,
+        lookup_strictness: LookupStrictness::Normal,
     };
 }
 
@@ -159,6 +182,7 @@ impl<S: ?Sized> ZeroTrieWithOptions for crate::ZeroTrieExtendedCapacity<S> {
         ascii_mode: AsciiMode::BinarySpans,
         capacity_mode: CapacityMode::Extended,
         case_sensitivity: CaseSensitivity::Sensitive,
+        lookup_strictness: LookupStrictness::Normal,
     };
 }
 

utils/zerotrie/src/reader.rs

@@ -322,6 +322,7 @@ pub(crate) fn get_parameterized<T: ZeroTrieWithOptions + ?Sized>(
         if let Some((c, temp)) = ascii.split_first() {
             if matches!(byte_type, NodeType::Ascii) {
                 let is_match = if matches!(T::OPTIONS.case_sensitivity, CaseSensitivity::IgnoreCase)
+                    && matches!(T::OPTIONS.lookup_strictness, LookupStrictness::Normal)
                 {
                     b.to_ascii_lowercase() == c.to_ascii_lowercase()
                 } else {
@@ -367,12 +368,28 @@ pub(crate) fn get_parameterized<T: ZeroTrieWithOptions + ?Sized>(
             if matches!(T::OPTIONS.phf_mode, PhfMode::BinaryOnly) || x < 16 {
                 // binary search
                 (search, trie) = trie.debug_split_at(x);
+                // TODO(#5584): Consider making all of these have the same order of elements
                 let bsearch_result =
                     if matches!(T::OPTIONS.case_sensitivity, CaseSensitivity::IgnoreCase) {
-                        search.binary_search_by_key(&c.to_ascii_lowercase(), |x| {
-                            x.to_ascii_lowercase()
-                        })
+                        if matches!(T::OPTIONS.lookup_strictness, LookupStrictness::Normal) {
+                            // Ordering: (A=a), (B=b), (C=c), ..., (Z=z)
+                            search.binary_search_by_key(&c.to_ascii_lowercase(), |x| {
+                                x.to_ascii_lowercase()
+                            })
+                        } else {
+                            // Ordering: A, a, B, b, C, c, ..., Z, z
+                            let c_lowercase = c.to_ascii_lowercase();
+                            search.binary_search_by(move |p| {
+                                let p_lowercase = p.to_ascii_lowercase();
+                                if c_lowercase == p_lowercase {
+                                    p.cmp(c)
+                                } else {
+                                    p_lowercase.cmp(&c_lowercase)
+                                }
+                            })
+                        }
                     } else {
+                        // Ordering: A, B, C, ..., Z, a, b, c, ..., z
                         search.binary_search(c)
                     };
                 i = bsearch_result.ok()?;

utils/zerotrie/src/zerotrie.rs

@@ -665,6 +665,45 @@ impl_zerotrie_subtype!(
     Vec::into_boxed_slice
 );
 
+impl<Store> ZeroAsciiIgnoreCaseTrie<Store>
+where
+    Store: AsRef<[u8]> + ?Sized,
+{
+    /// Queries the trie for a string, requiring that it matches case.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use litemap::LiteMap;
+    /// use zerotrie::ZeroAsciiIgnoreCaseTrie;
+    ///
+    /// let mut map = LiteMap::new_vec();
+    /// map.insert(&b"foo"[..], 1);
+    /// map.insert(b"Bar", 2);
+    /// map.insert(b"Bingo", 3);
+    ///
+    /// let trie = ZeroAsciiIgnoreCaseTrie::try_from(&map)?;
+    ///
+    /// assert_eq!(trie.get(b"foo"), Some(1));
+    /// assert_eq!(trie.get(b"bar"), Some(2));
+    /// assert_eq!(trie.get(b"BaR"), Some(2));
+    /// assert_eq!(trie.get_strict(b"bar"), None);
+    /// assert_eq!(trie.get_strict(b"BaR"), None);
+    /// assert_eq!(trie.get_strict(b"Bar"), Some(2));
+    ///
+    /// # Ok::<_, zerotrie::ZeroTrieBuildError>(())
+    /// ```
+    pub fn get_strict<K>(&self, key: K) -> Option<usize>
+    where
+        K: AsRef<[u8]>,
+    {
+        reader::get_parameterized::<crate::options::ZeroAsciiIgnoreCaseStrictTrie>(
+            self.store.as_ref(),
+            key.as_ref(),
+        )
+    }
+}
+
 macro_rules! impl_dispatch {
     ($self:ident, $inner_fn:ident()) => {
         match $self.0 {