snapshot of https://github.com/nats-io/nats-server.git (main, 2026-09-15; blobs > 131072B omitted)

server/stree/util.go

@@ -0,0 +1,47 @@
+// Copyright 2023-2026 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stree
+
+// For subject matching.
+const (
+	pwc  = '*'
+	fwc  = '>'
+	tsep = '.'
+)
+
+// Determine index of common prefix. No match at all is 0, etc.
+func commonPrefixLen(s1, s2 []byte) int {
+	limit := min(len(s1), len(s2))
+	var i int
+	for ; i < limit; i++ {
+		if s1[i] != s2[i] {
+			break
+		}
+	}
+	return i
+}
+
+type position interface{ int | uint16 }
+
+// No pivot available.
+const noPivot = byte(127)
+
+// Can return 127 (DEL) if we have all the subject as prefixes.
+// We used to use 0, but when that was in the subject would cause infinite recursion in some situations.
+func pivot[N position](subject []byte, pos N) byte {
+	if int(pos) >= len(subject) {
+		return noPivot
+	}
+	return subject[pos]
+}