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Diffstat (limited to 'vendor/github.com/syndtr/goleveldb/leveldb/comparer/comparer.go')
| -rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/comparer/comparer.go | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/comparer/comparer.go b/vendor/github.com/syndtr/goleveldb/leveldb/comparer/comparer.go new file mode 100644 index 0000000..14a28f1 --- /dev/null +++ b/vendor/github.com/syndtr/goleveldb/leveldb/comparer/comparer.go @@ -0,0 +1,57 @@ +// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com> +// All rights reserved. +// +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +// Package comparer provides interface and implementation for ordering +// sets of data. +package comparer + +// BasicComparer is the interface that wraps the basic Compare method. +type BasicComparer interface { + // Compare returns -1, 0, or +1 depending on whether a is 'less than', + // 'equal to' or 'greater than' b. The two arguments can only be 'equal' + // if their contents are exactly equal. Furthermore, the empty slice + // must be 'less than' any non-empty slice. + Compare(a, b []byte) int +} + +// Comparer defines a total ordering over the space of []byte keys: a 'less +// than' relationship. +type Comparer interface { + BasicComparer + + // Name returns name of the comparer. + // + // The Level-DB on-disk format stores the comparer name, and opening a + // database with a different comparer from the one it was created with + // will result in an error. + // + // An implementation to a new name whenever the comparer implementation + // changes in a way that will cause the relative ordering of any two keys + // to change. + // + // Names starting with "leveldb." are reserved and should not be used + // by any users of this package. + Name() string + + // Bellow are advanced functions used used to reduce the space requirements + // for internal data structures such as index blocks. + + // Separator appends a sequence of bytes x to dst such that a <= x && x < b, + // where 'less than' is consistent with Compare. An implementation should + // return nil if x equal to a. + // + // Either contents of a or b should not by any means modified. Doing so + // may cause corruption on the internal state. + Separator(dst, a, b []byte) []byte + + // Successor appends a sequence of bytes x to dst such that x >= b, where + // 'less than' is consistent with Compare. An implementation should return + // nil if x equal to b. + // + // Contents of b should not by any means modified. Doing so may cause + // corruption on the internal state. + Successor(dst, b []byte) []byte +} |