feat: array iterator

dec_arr_iter.go

@@ -0,0 +1,62 @@
+package jx
+
+import (
+	"github.com/go-faster/errors"
+)
+
+// ArrIter is decoding array iterator.
+type ArrIter struct {
+	d      *Decoder
+	err    error
+	closed bool
+	comma  bool
+}
+
+// ArrIter creates new array iterator.
+func (d *Decoder) ArrIter() (ArrIter, error) {
+	if err := d.consume('['); err != nil {
+		return ArrIter{}, errors.Wrap(err, "start")
+	}
+	if err := d.incDepth(); err != nil {
+		return ArrIter{}, errors.Wrap(err, "inc")
+	}
+	if _, err := d.more(); err != nil {
+		return ArrIter{}, err
+	}
+	d.unread()
+	return ArrIter{d: d}, nil
+}
+
+// Next consumes element and returns false, if there is no elements anymore.
+func (i *ArrIter) Next() bool {
+	if i.closed {
+		return false
+	}
+
+	dec := i.d
+	c, err := dec.more()
+	if err != nil {
+		i.err = err
+		return false
+	}
+	if c == ']' {
+		i.closed = true
+		i.err = dec.decDepth()
+		return false
+	}
+	if i.comma {
+		if c != ',' {
+			i.err = badToken(c)
+			return false
+		}
+	} else {
+		dec.unread()
+	}
+	i.comma = true
+	return true
+}
+
+// Err returns the error, if any, that was encountered during iteration.
+func (i *ArrIter) Err() error {
+	return i.err
+}

dec_arr_iter_test.go

@@ -0,0 +1,46 @@
+package jx
+
+import (
+	"encoding/json"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDecoder_ArrIter(t *testing.T) {
+	testIter := func(d *Decoder) error {
+		iter, err := d.ArrIter()
+		if err != nil {
+			return err
+		}
+		for iter.Next() {
+			if err := d.Skip(); err != nil {
+				return err
+			}
+		}
+		if iter.Next() {
+			panic("BUG")
+		}
+		return iter.Err()
+	}
+	for _, s := range testArrs {
+		checker := require.Error
+		if json.Valid([]byte(s)) {
+			checker = require.NoError
+		}
+
+		d := DecodeStr(s)
+		checker(t, testIter(d), s)
+	}
+	t.Run("Depth", func(t *testing.T) {
+		d := DecodeStr(`[`)
+		// Emulate depth
+		d.depth = maxDepth
+		require.ErrorIs(t, testIter(d), errMaxDepth)
+	})
+	t.Run("Empty", func(t *testing.T) {
+		d := DecodeStr(``)
+		require.ErrorIs(t, testIter(d), io.ErrUnexpectedEOF)
+	})
+}

dec_arr_test.go

@@ -1,6 +1,7 @@
 package jx
 
 import (
+	_ "embed"
 	"encoding/json"
 	"io"
 	"testing"
@@ -79,3 +80,61 @@ func TestDecoder_Elem(t *testing.T) {
 		require.False(t, ok)
 	})
 }
+
+//go:embed testdata/bools.json
+var boolsData []byte
+
+func BenchmarkDecodeBools(b *testing.B) {
+	b.Run("Callback", func(b *testing.B) {
+		d := DecodeBytes(boolsData)
+		r := make([]bool, 0, 100)
+
+		b.SetBytes(int64(len(boolsData)))
+		b.ReportAllocs()
+		b.ResetTimer()
+
+		for i := 0; i < b.N; i++ {
+			r = r[:0]
+			d.ResetBytes(boolsData)
+
+			if err := d.Arr(func(d *Decoder) error {
+				f, err := d.Bool()
+				if err != nil {
+					return err
+				}
+				r = append(r, f)
+				return nil
+			}); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+	b.Run("Iterator", func(b *testing.B) {
+		d := DecodeBytes(boolsData)
+		r := make([]bool, 0, 100)
+
+		b.SetBytes(int64(len(boolsData)))
+		b.ReportAllocs()
+		b.ResetTimer()
+
+		for i := 0; i < b.N; i++ {
+			r = r[:0]
+			d.ResetBytes(boolsData)
+
+			iter, err := d.ArrIter()
+			if err != nil {
+				b.Fatal(err)
+			}
+			for iter.Next() {
+				v, err := d.Bool()
+				if err != nil {
+					b.Fatal(err)
+				}
+				r = append(r, v)
+			}
+			if err := iter.Err(); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+}

dec_skip_cases_test.go

@@ -208,22 +208,29 @@ var testObjs = []string{
 }
 
 var testArrs = []string{
-	`[]`,             // valid
-	`[1]`,            // valid
-	`[  1, "hello"]`, // valid
-	`[abc]`,          // invalid
-	`[`,              // invalid
-	`[,`,             // invalid
-	`[[]`,            // invalid
-	"[true,f",        // invalid
-	"[true",          // invalid
-	"[true,",         // invalid
-	"[true]",         // invalid
-	"[true,]",        // invalid
-	"[true,false",    // invalid
-	"[true,false,",   // invalid
-	"[true,false,]",  // invalid
-	"[true,false}",   // invalid
+	`[]`,                          // valid
+	`[ ]`,                         // valid
+	"[1]",                         // valid
+	"[true]",                      // valid
+	"[null]",                      // valid
+	`[ 1]`,                        // valid
+	`[ true]`,                     // valid
+	`[ null]`,                     // valid
+	`[ "abc"   ` + "\n]",          // valid
+	`[ "abc",` + "\n" + `"text"]`, // valid
+	`[  1, "hello"]`,              // valid
+	`[abc]`,                       // invalid
+	`[`,                           // invalid
+	`[,`,                          // invalid
+	`[[]`,                         // invalid
+	"[true,f",                     // invalid
+	"[true",                       // invalid
+	"[true,",                      // invalid
+	"[true,]",                     // invalid
+	"[true,false",                 // invalid
+	"[true,false,",                // invalid
+	"[true,false,]",               // invalid
+	"[true,false}",                // invalid
 }
 
 func TestDecoder_Skip(t *testing.T) {