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// Copyright 2023-2025 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
}
// Helper to copy bytes.
func copyBytes(src []byte) []byte {
if len(src) == 0 {
return nil
}
dst := make([]byte, len(src))
copy(dst, src)
return dst
}
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]
}
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