/
relation.go
98 lines (89 loc) · 2.72 KB
/
relation.go
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// The MIT License (MIT)
//
// Copyright (c) 2018 Fabian Wenzelmann
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package goel
import "log"
type Relation struct {
Mapping map[uint]map[uint]struct{}
ReverseMapping map[uint]map[uint]struct{}
}
func NewRelation(initialCapacity uint) *Relation {
return &Relation{
Mapping: make(map[uint]map[uint]struct{}, initialCapacity),
ReverseMapping: make(map[uint]map[uint]struct{}, initialCapacity),
}
}
func addToRelation(m map[uint]map[uint]struct{}, first, second uint) bool {
inner, has := m[first]
if !has {
inner = make(map[uint]struct{})
m[first] = inner
}
// TODO correct? should be...
oldLen := len(inner)
inner[second] = struct{}{}
return len(inner) != oldLen
}
func (r *Relation) Add(c, d uint) bool {
// TODO simplify when tested.
first := addToRelation(r.Mapping, c, d)
second := addToRelation(r.ReverseMapping, d, c)
if first != second {
log.Printf("Unexpected Relation behaviour while adding %d --> %d: Mappings not consistent",
c, d)
return false
}
return first
}
func (r *Relation) Contains(c, d uint) bool {
inner, hasInner := r.Mapping[c]
if !hasInner {
return false
}
_, has := inner[d]
return has
}
func (r *Relation) Equals(other *Relation) bool {
if len(r.Mapping) != len(other.Mapping) {
return false
}
// same length => check if each element is contained in other
for c, inner := range r.Mapping {
for d, _ := range inner {
if !other.Contains(c, d) {
return false
}
}
}
return true
}
func CompareRMapping(first, second []*Relation) bool {
if len(first) != len(second) {
return false
}
n := len(first)
for i := 0; i < n; i++ {
if !first[i].Equals(second[i]) {
return false
}
}
return true
}