Rewrite fzf in Go

src/item.go

@@ -0,0 +1,135 @@
+package fzf
+
+import (
+	"fmt"
+	"sort"
+)
+
+type Offset [2]int
+
+type Item struct {
+	text        *string
+	origText    *string
+	offsets     []Offset
+	index       int
+	rank        Rank
+	transformed *Transformed
+}
+
+type Rank [3]int
+
+var NilRank = Rank{-1, 0, 0}
+
+func (i *Item) Rank() Rank {
+	if i.rank[0] > 0 {
+		return i.rank
+	}
+	sort.Sort(ByOrder(i.offsets))
+	matchlen := 0
+	prevEnd := 0
+	for _, offset := range i.offsets {
+		begin := offset[0]
+		end := offset[1]
+		if prevEnd > begin {
+			begin = prevEnd
+		}
+		if end > prevEnd {
+			prevEnd = end
+		}
+		if end > begin {
+			matchlen += end - begin
+		}
+	}
+	i.rank = Rank{matchlen, len(*i.text), i.index}
+	return i.rank
+}
+
+func (i *Item) Print() {
+	if i.origText != nil {
+		fmt.Println(*i.origText)
+	} else {
+		fmt.Println(*i.text)
+	}
+}
+
+type ByOrder []Offset
+
+func (a ByOrder) Len() int {
+	return len(a)
+}
+
+func (a ByOrder) Swap(i, j int) {
+	a[i], a[j] = a[j], a[i]
+}
+
+func (a ByOrder) Less(i, j int) bool {
+	ioff := a[i]
+	joff := a[j]
+	return (ioff[0] < joff[0]) || (ioff[0] == joff[0]) && (ioff[1] <= joff[1])
+}
+
+type ByRelevance []*Item
+
+func (a ByRelevance) Len() int {
+	return len(a)
+}
+
+func (a ByRelevance) Swap(i, j int) {
+	a[i], a[j] = a[j], a[i]
+}
+
+func (a ByRelevance) Less(i, j int) bool {
+	irank := a[i].Rank()
+	jrank := a[j].Rank()
+
+	return compareRanks(irank, jrank)
+}
+
+func compareRanks(irank Rank, jrank Rank) bool {
+	for idx := range irank {
+		if irank[idx] < jrank[idx] {
+			return true
+		} else if irank[idx] > jrank[idx] {
+			return false
+		}
+	}
+	return true
+}
+
+func SortMerge(partialResults [][]*Item) []*Item {
+	if len(partialResults) == 1 {
+		return partialResults[0]
+	}
+
+	merged := []*Item{}
+
+	for len(partialResults) > 0 {
+		minRank := Rank{0, 0, 0}
+		minIdx := -1
+
+		for idx, partialResult := range partialResults {
+			if len(partialResult) > 0 {
+				rank := partialResult[0].Rank()
+				if minIdx < 0 || compareRanks(rank, minRank) {
+					minRank = rank
+					minIdx = idx
+				}
+			}
+		}
+
+		if minIdx >= 0 {
+			merged = append(merged, partialResults[minIdx][0])
+			partialResults[minIdx] = partialResults[minIdx][1:]
+		}
+
+		nonEmptyPartialResults := make([][]*Item, 0, len(partialResults))
+		for _, partialResult := range partialResults {
+			if len(partialResult) > 0 {
+				nonEmptyPartialResults = append(nonEmptyPartialResults, partialResult)
+			}
+		}
+		partialResults = nonEmptyPartialResults
+	}
+
+	return merged
+}