Rewrite fzf in Go

1 files changed, 215 insertions, 0 deletions

diff --git a/src/matcher.go b/src/matcher.go
new file mode 100644
index 00000000..363b07fd
--- /dev/null
+++ b/src/matcher.go
@@ -0,0 +1,215 @@
+package fzf
+
+import (
+	"fmt"
+	"runtime"
+	"sort"
+	"time"
+)
+
+type MatchRequest struct {
+	chunks  []*Chunk
+	pattern *Pattern
+}
+
+type Matcher struct {
+	patternBuilder func([]rune) *Pattern
+	sort           bool
+	eventBox       *EventBox
+	reqBox         *EventBox
+	partitions     int
+	queryCache     QueryCache
+}
+
+const (
+	REQ_RETRY EventType = iota
+	REQ_RESET
+)
+
+const (
+	STAT_CANCELLED int = iota
+	STAT_QCH
+	STAT_CHUNKS
+)
+
+const (
+	PROGRESS_MIN_DURATION = 200 * time.Millisecond
+)
+
+func NewMatcher(patternBuilder func([]rune) *Pattern,
+	sort bool, eventBox *EventBox) *Matcher {
+	return &Matcher{
+		patternBuilder: patternBuilder,
+		sort:           sort,
+		eventBox:       eventBox,
+		reqBox:         NewEventBox(),
+		partitions:     runtime.NumCPU(),
+		queryCache:     make(QueryCache)}
+}
+
+func (m *Matcher) Loop() {
+	prevCount := 0
+
+	for {
+		var request MatchRequest
+
+		m.reqBox.Wait(func(events *Events) {
+			for _, val := range *events {
+				switch val := val.(type) {
+				case MatchRequest:
+					request = val
+				default:
+					panic(fmt.Sprintf("Unexpected type: %T", val))
+				}
+			}
+			events.Clear()
+		})
+
+		// Restart search
+		patternString := request.pattern.AsString()
+		allMatches := []*Item{}
+		cancelled := false
+		count := CountItems(request.chunks)
+
+		foundCache := false
+		if count == prevCount {
+			// Look up queryCache
+			if cached, found := m.queryCache[patternString]; found {
+				foundCache = true
+				allMatches = cached
+			}
+		} else {
+			// Invalidate queryCache
+			prevCount = count
+			m.queryCache = make(QueryCache)
+		}
+
+		if !foundCache {
+			allMatches, cancelled = m.scan(request, 0)
+		}
+
+		if !cancelled {
+			m.queryCache[patternString] = allMatches
+			m.eventBox.Set(EVT_SEARCH_FIN, allMatches)
+		}
+	}
+}
+
+func (m *Matcher) sliceChunks(chunks []*Chunk) [][]*Chunk {
+	perSlice := len(chunks) / m.partitions
+
+	// No need to parallelize
+	if perSlice == 0 {
+		return [][]*Chunk{chunks}
+	}
+
+	slices := make([][]*Chunk, m.partitions)
+	for i := 0; i < m.partitions; i++ {
+		start := i * perSlice
+		end := start + perSlice
+		if i == m.partitions-1 {
+			end = len(chunks)
+		}
+		slices[i] = chunks[start:end]
+	}
+	return slices
+}
+
+type partialResult struct {
+	index   int
+	matches []*Item
+}
+
+func (m *Matcher) scan(request MatchRequest, limit int) ([]*Item, bool) {
+	startedAt := time.Now()
+
+	numChunks := len(request.chunks)
+	if numChunks == 0 {
+		return []*Item{}, false
+	}
+	pattern := request.pattern
+	empty := pattern.IsEmpty()
+	cancelled := NewAtomicBool(false)
+
+	slices := m.sliceChunks(request.chunks)
+	numSlices := len(slices)
+	resultChan := make(chan partialResult, numSlices)
+	countChan := make(chan int, numSlices)
+
+	for idx, chunks := range slices {
+		go func(idx int, chunks []*Chunk) {
+			sliceMatches := []*Item{}
+			for _, chunk := range chunks {
+				var matches []*Item
+				if empty {
+					matches = *chunk
+				} else {
+					matches = request.pattern.Match(chunk)
+				}
+				sliceMatches = append(sliceMatches, matches...)
+				if cancelled.Get() {
+					return
+				}
+				countChan <- len(sliceMatches)
+			}
+			if !empty && m.sort {
+				sort.Sort(ByRelevance(sliceMatches))
+			}
+			resultChan <- partialResult{idx, sliceMatches}
+		}(idx, chunks)
+	}
+
+	count := 0
+	matchCount := 0
+	for matchesInChunk := range countChan {
+		count += 1
+		matchCount += matchesInChunk
+
+		if limit > 0 && matchCount > limit {
+			return nil, true // For --select-1 and --exit-0
+		}
+
+		if count == numChunks {
+			break
+		}
+
+		if !empty && m.reqBox.Peak(REQ_RESET) {
+			cancelled.Set(true)
+			return nil, true
+		}
+
+		if time.Now().Sub(startedAt) > PROGRESS_MIN_DURATION {
+			m.eventBox.Set(EVT_SEARCH_PROGRESS, float32(count)/float32(numChunks))
+		}
+	}
+
+	partialResults := make([][]*Item, numSlices)
+	for range slices {
+		partialResult := <-resultChan
+		partialResults[partialResult.index] = partialResult.matches
+	}
+
+	var allMatches []*Item
+	if empty || !m.sort {
+		allMatches = []*Item{}
+		for _, matches := range partialResults {
+			allMatches = append(allMatches, matches...)
+		}
+	} else {
+		allMatches = SortMerge(partialResults)
+	}
+
+	return allMatches, false
+}
+
+func (m *Matcher) Reset(chunks []*Chunk, patternRunes []rune, cancel bool) {
+	pattern := m.patternBuilder(patternRunes)
+
+	var event EventType
+	if cancel {
+		event = REQ_RESET
+	} else {
+		event = REQ_RETRY
+	}
+	m.reqBox.Set(event, MatchRequest{chunks, pattern})
+}