1 files changed, 53 insertions, 0 deletions
diff --git a/vendor/fst/src/raw/registry_minimal.rs b/vendor/fst/src/raw/registry_minimal.rs
new file mode 100644
index 000000000..663b0123a
--- /dev/null
+++ b/vendor/fst/src/raw/registry_minimal.rs
@@ -0,0 +1,53 @@
+// This module is a drop-in but inefficient replacement of the LRU registry.
+// In particular, this registry will never forget a node. In other words, if
+// this registry is used during construction, then you're guaranteed a minimal
+// FST.
+//
+// This is really only meant to be used for debugging and experiments. It is
+// a memory/CPU hog.
+//
+// One "easy" improvement here is to use an FNV hash instead of the super
+// expensive SipHasher.
+
+#![allow(dead_code)]
+
+use std::collections::hash_map::{Entry, HashMap};
+
+use crate::raw::build::BuilderNode;
+use crate::raw::CompiledAddr;
+
+#[derive(Debug)]
+pub struct Registry {
+    table: HashMap<BuilderNode, RegistryCell>,
+}
+
+#[derive(Debug)]
+pub enum RegistryEntry<'a> {
+    Found(CompiledAddr),
+    NotFound(&'a mut RegistryCell),
+    Rejected,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct RegistryCell(CompiledAddr);
+
+impl Registry {
+    pub fn new(table_size: usize, _lru_size: usize) -> Registry {
+        Registry { table: HashMap::with_capacity(table_size) }
+    }
+
+    pub fn entry<'a>(&'a mut self, bnode: &BuilderNode) -> RegistryEntry<'a> {
+        match self.table.entry(bnode.clone()) {
+            Entry::Occupied(v) => RegistryEntry::Found(v.get().0),
+            Entry::Vacant(v) => {
+                RegistryEntry::NotFound(v.insert(RegistryCell(0)))
+            }
+        }
+    }
+}
+
+impl RegistryCell {
+    pub fn insert(&mut self, addr: CompiledAddr) {
+        self.0 = addr;
+    }
+}