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// 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 leveldb

import (
    "github.com/syndtr/goleveldb/leveldb/comparer"
)

type iComparer struct {
    ucmp comparer.Comparer
}

func (icmp *iComparer) uName() string {
    return icmp.ucmp.Name()
}

func (icmp *iComparer) uCompare(a, b []byte) int {
    return icmp.ucmp.Compare(a, b)
}

func (icmp *iComparer) uSeparator(dst, a, b []byte) []byte {
    return icmp.ucmp.Separator(dst, a, b)
}

func (icmp *iComparer) uSuccessor(dst, b []byte) []byte {
    return icmp.ucmp.Successor(dst, b)
}

func (icmp *iComparer) Name() string {
    return icmp.uName()
}

func (icmp *iComparer) Compare(a, b []byte) int {
    x := icmp.uCompare(internalKey(a).ukey(), internalKey(b).ukey())
    if x == 0 {
        if m, n := internalKey(a).num(), internalKey(b).num(); m > n {
            return -1
        } else if m < n {
            return 1
        }
    }
    return x
}

func (icmp *iComparer) Separator(dst, a, b []byte) []byte {
    ua, ub := internalKey(a).ukey(), internalKey(b).ukey()
    dst = icmp.uSeparator(dst, ua, ub)
    if dst != nil && len(dst) < len(ua) && icmp.uCompare(ua, dst) < 0 {
        // Append earliest possible number.
        return append(dst, keyMaxNumBytes...)
    }
    return nil
}

func (icmp *iComparer) Successor(dst, b []byte) []byte {
    ub := internalKey(b).ukey()
    dst = icmp.uSuccessor(dst, ub)
    if dst != nil && len(dst) < len(ub) && icmp.uCompare(ub, dst) < 0 {
        // Append earliest possible number.
        return append(dst, keyMaxNumBytes...)
    }
    return nil
}