mirror of
https://github.com/go-gitea/gitea
synced 2024-11-17 23:54:25 +00:00
112 lines
3.3 KiB
Go
112 lines
3.3 KiB
Go
// Copyright (c) 2017 Couchbase, Inc.
|
|
//
|
|
// 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 vellum is a library for building, serializing and executing an FST (finite
|
|
state transducer).
|
|
|
|
There are two distinct phases, building an FST and using it.
|
|
|
|
When building an FST, you insert keys ([]byte) and their associated value
|
|
(uint64). Insert operations MUST be done in lexicographic order. While
|
|
building the FST, data is streamed to an underlying Writer. At the conclusion
|
|
of building, you MUST call Close() on the builder.
|
|
|
|
After completion of the build phase, you can either Open() the FST if you
|
|
serialized it to disk. Alternatively, if you already have the bytes in
|
|
memory, you can use Load(). By default, Open() will use mmap to avoid loading
|
|
the entire file into memory.
|
|
|
|
Once the FST is ready, you can use the Contains() method to see if a keys is
|
|
in the FST. You can use the Get() method to see if a key is in the FST and
|
|
retrieve it's associated value. And, you can use the Iterator method to
|
|
enumerate key/value pairs within a specified range.
|
|
|
|
*/
|
|
package vellum
|
|
|
|
import (
|
|
"errors"
|
|
"io"
|
|
)
|
|
|
|
// ErrOutOfOrder is returned when values are not inserted in
|
|
// lexicographic order.
|
|
var ErrOutOfOrder = errors.New("values not inserted in lexicographic order")
|
|
|
|
// ErrIteratorDone is returned by Iterator/Next/Seek methods when the
|
|
// Current() value pointed to by the iterator is greater than the last
|
|
// key in this FST, or outside the configured startKeyInclusive/endKeyExclusive
|
|
// range of the Iterator.
|
|
var ErrIteratorDone = errors.New("iterator-done")
|
|
|
|
// BuilderOpts is a structure to let advanced users customize the behavior
|
|
// of the builder and some aspects of the generated FST.
|
|
type BuilderOpts struct {
|
|
Encoder int
|
|
RegistryTableSize int
|
|
RegistryMRUSize int
|
|
}
|
|
|
|
// New returns a new Builder which will stream out the
|
|
// underlying representation to the provided Writer as the set is built.
|
|
func New(w io.Writer, opts *BuilderOpts) (*Builder, error) {
|
|
return newBuilder(w, opts)
|
|
}
|
|
|
|
// Open loads the FST stored in the provided path
|
|
func Open(path string) (*FST, error) {
|
|
return open(path)
|
|
}
|
|
|
|
// Load will return the FST represented by the provided byte slice.
|
|
func Load(data []byte) (*FST, error) {
|
|
return new(data, nil)
|
|
}
|
|
|
|
// Merge will iterate through the provided Iterators, merge duplicate keys
|
|
// with the provided MergeFunc, and build a new FST to the provided Writer.
|
|
func Merge(w io.Writer, opts *BuilderOpts, itrs []Iterator, f MergeFunc) error {
|
|
builder, err := New(w, opts)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
itr, err := NewMergeIterator(itrs, f)
|
|
for err == nil {
|
|
k, v := itr.Current()
|
|
err = builder.Insert(k, v)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
err = itr.Next()
|
|
}
|
|
|
|
if err != nil && err != ErrIteratorDone {
|
|
return err
|
|
}
|
|
|
|
err = itr.Close()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
err = builder.Close()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|