feat: add offset and update sort

go.mod

@@ -2,4 +2,9 @@ module github.com/radulucut/search
 
 go 1.22.1
 
-require github.com/google/go-cmp v0.6.0
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.9.0
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -1,2 +1,10 @@
-github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
-github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

search.go

@@ -1,7 +1,8 @@
 package search
 
 import (
-	"sort"
+	"math"
+	"slices"
 	"sync"
 )
 
@@ -55,24 +56,30 @@ type itemScore struct {
 	score int
 }
 
+type SearchOptions struct {
+	Query  string
+	Limit  int
+	Offset int
+	Ignore []int64
+}
+
 // Search finds the most similar items to the given query.
 // limit is the maximum number of items to return.
 // ignore is a list of item ids to ignore.
-func (e *Engine) Search(query string, limit int, ignore []int64) []int64 {
+func (e *Engine) Search(opts SearchOptions) []int64 {
 	var ignoreMap map[int64]struct{}
 	hasIgnore := false
-	if len(ignore) != 0 {
+	if len(opts.Ignore) != 0 {
 		hasIgnore = true
 		ignoreMap = make(map[int64]struct{})
-		for i := range ignore {
-			ignoreMap[ignore[i]] = struct{}{}
+		for i := range opts.Ignore {
+			ignoreMap[opts.Ignore[i]] = struct{}{}
 		}
 	}
-
-	q := e.tokenize(query)
+	q := e.tokenize(opts.Query)
 	e.RLock()
 	defer e.RUnlock()
-	scores := make([]itemScore, 0)
+	scores := make([]*itemScore, 0)
 	for id := range e.items {
 		if hasIgnore {
 			if _, ok := ignoreMap[id]; ok {
@@ -83,18 +90,26 @@ func (e *Engine) Search(query string, limit int, ignore []int64) []int64 {
 		if score == -1 {
 			continue
 		}
-		scores = append(scores, itemScore{id: id, score: score})
+		scores = append(scores, &itemScore{id: id, score: score})
 	}
-	sort.Slice(scores, func(i, j int) bool {
-		if scores[i].score == scores[j].score {
-			return scores[i].id > scores[j].id
-		} else {
-			return scores[i].score < scores[j].score
+	slices.SortFunc(scores, func(a, b *itemScore) int {
+		if a.score < b.score {
+			return -1
+		}
+		if a.score > b.score {
+			return 1
+		}
+		if a.id > b.id {
+			return -1
+		}
+		if a.id < b.id {
+			return 1
 		}
+		return 0
 	})
-	limit = min(limit, len(scores))
+	limit := min(opts.Offset+opts.Limit, len(scores))
 	res := make([]int64, 0, limit)
-	for i := 0; i < limit; i++ {
+	for i := opts.Offset; i < limit; i++ {
 		res = append(res, scores[i].id)
 	}
 	return res
@@ -104,7 +119,7 @@ func (e *Engine) score(q, b [][]rune) int {
 	var score int
 	skip := true
 	for i := range q {
-		best := (1<<63 - 1)
+		best := math.MaxInt
 		for j := range b {
 			best = min(best, LevenshteinDistance(q[i], b[j]))
 		}

search_test.go

@@ -3,7 +3,7 @@ package search
 import (
 	"testing"
 
-	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/assert"
 )
 
 type Book struct {
@@ -45,41 +45,51 @@ func Test_Engine(t *testing.T) {
 		{"spânzuraţilor", []int64{2}},
 		{"amintiri din copilărie", []int64{8, 11, 10, 5, 15}},
 		{"xyz zyx", []int64{}},
+		{"din", []int64{11, 8, 15, 14, 13}},
 	}
 
 	for _, test := range tests {
 		t.Run(test.query, func(t *testing.T) {
-			actual := engine.Search(test.query, 5, nil)
-			if diff := cmp.Diff(test.expected, actual); diff != "" {
-				t.Errorf("mismatch (-want +got):\n%s", diff)
-			}
+			actual := engine.Search(SearchOptions{Query: test.query, Limit: 5})
+			assert.Equal(t, test.expected, actual)
 		})
 	}
 
+	t.Run("offset", func(t *testing.T) {
+		actual := engine.Search(SearchOptions{
+			Query:  "de",
+			Limit:  5,
+			Offset: 5,
+			Ignore: []int64{15},
+		})
+		assert.Equal(t, []int64{9, 8, 7, 6, 5}, actual)
+	})
+
 	t.Run("Ignore ids", func(t *testing.T) {
-		actual := engine.Search("maitreyi", 5, []int64{4})
-		expected := []int64{}
-		if diff := cmp.Diff(expected, actual); diff != "" {
-			t.Errorf("mismatch (-want +got):\n%s", diff)
-		}
+		actual := engine.Search(SearchOptions{
+			Query:  "maitreyi",
+			Limit:  5,
+			Ignore: []int64{4},
+		})
+		assert.ElementsMatch(t, []int64{}, actual)
 	})
 
 	engine.SetItem(16, "Ciocoii vechi și noi de Nicolae Filimon")
 	t.Run("SetItem", func(t *testing.T) {
-		actual := engine.Search("Ciocoii vechi", 5, nil)
-		expected := []int64{16}
-		if diff := cmp.Diff(expected, actual); diff != "" {
-			t.Errorf("mismatch (-want +got):\n%s", diff)
-		}
+		actual := engine.Search(SearchOptions{
+			Query: "Ciocoii vechi",
+			Limit: 5,
+		})
+		assert.ElementsMatch(t, []int64{16}, actual)
 	})
 
 	engine.DeleteItem(7)
 	t.Run("DeleteItem", func(t *testing.T) {
-		actual := engine.Search("Moara", 5, nil)
-		expected := []int64{}
-		if diff := cmp.Diff(expected, actual); diff != "" {
-			t.Errorf("mismatch (-want +got):\n%s", diff)
-		}
+		actual := engine.Search(SearchOptions{
+			Query: "Moara",
+			Limit: 5,
+		})
+		assert.ElementsMatch(t, []int64{}, actual)
 	})
 }
 
@@ -94,9 +104,7 @@ func Test_Tokenize(t *testing.T) {
 		{'4'},
 		{'a', 'a', 'a', 'a', 'i', 'i', 's', 's', 's', 's', 't', 't', 't', 't'},
 	}
-	if diff := cmp.Diff(expected, tokens); diff != "" {
-		t.Errorf("mismatch (-want +got):\n%s", diff)
-	}
+	assert.Equal(t, expected, tokens)
 }
 
 func Test_LevenshteinDistance(t *testing.T) {
@@ -121,9 +129,7 @@ func Test_LevenshteinDistance(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run("LevenshteinDistance", func(t *testing.T) {
-			if diff := cmp.Diff(test.expected, LevenshteinDistance(test.a, test.b)); diff != "" {
-				t.Errorf("mismatch (-want +got):\n%s", diff)
-			}
+			assert.Equal(t, test.expected, LevenshteinDistance(test.a, test.b))
 		})
 	}
 }