add PeekUintXX

ring_buffer.go

@@ -1,6 +1,7 @@
 package ringbuffer
 
 import (
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"unsafe"
@@ -174,6 +175,58 @@ func (r *RingBuffer) PeekAll() (first []byte, end []byte) {
 	return
 }
 
+func (r *RingBuffer) PeekUint8() uint8 {
+	if r.Length() < 1 {
+		return 0
+	}
+
+	f, e := r.Peek(1)
+	if len(e) > 0 {
+		return e[0]
+	} else {
+		return f[0]
+	}
+}
+
+func (r *RingBuffer) PeekUint16() uint16 {
+	if r.Length() < 2 {
+		return 0
+	}
+
+	f, e := r.Peek(2)
+	if len(e) > 0 {
+		return binary.BigEndian.Uint16(copyByte(f, e))
+	} else {
+		return binary.BigEndian.Uint16(f)
+	}
+}
+
+func (r *RingBuffer) PeekUint32() uint32 {
+	if r.Length() < 4 {
+		return 0
+	}
+
+	f, e := r.Peek(4)
+	if len(e) > 0 {
+		return binary.BigEndian.Uint32(copyByte(f, e))
+	} else {
+		return binary.BigEndian.Uint32(f)
+	}
+}
+
+func (r *RingBuffer) PeekUint64() uint64 {
+	if r.Length() < 8 {
+		return 0
+	}
+
+	f, e := r.Peek(8)
+	if len(e) > 0 {
+		return binary.BigEndian.Uint64(copyByte(f, e))
+	} else {
+		return binary.BigEndian.Uint64(f)
+	}
+}
+
 func (r *RingBuffer) Read(p []byte) (n int, err error) {
 	if len(p) == 0 {
 		return 0, nil
@@ -374,3 +427,10 @@ func (r *RingBuffer) free() int {
 
 	return r.size - r.w + r.r
 }
+
+func copyByte(f, e []byte) []byte {
+	buf := make([]byte, len(f)+len(e))
+	_ = copy(buf, f)
+	_ = copy(buf, e)
+	return buf
+}

ring_buffer_test.go

@@ -2,6 +2,7 @@ package ringbuffer
 
 import (
 	"bytes"
+	"encoding/binary"
 	"io"
 	"strings"
 	"testing"
@@ -582,3 +583,48 @@ func TestRingBuffer_VirtualXXX(t *testing.T) {
 	}
 
 }
+
+func TestRingBuffer_PeekUintXX(t *testing.T) {
+	rb := New(1024)
+	_ = rb.WriteByte(0x01)
+
+	toWrite := make([]byte, 2)
+	binary.BigEndian.PutUint16(toWrite, 100)
+	_, _ = rb.Write(toWrite)
+
+	toWrite = make([]byte, 4)
+	binary.BigEndian.PutUint32(toWrite, 200)
+	_, _ = rb.Write(toWrite)
+
+	toWrite = make([]byte, 8)
+	binary.BigEndian.PutUint64(toWrite, 300)
+	_, _ = rb.Write(toWrite)
+
+	if rb.Length() != 15 {
+		t.Fatal()
+	}
+
+	v := rb.PeekUint8()
+	if v != 0x01 {
+		t.Fatal()
+	}
+	rb.Retrieve(1)
+
+	v1 := rb.PeekUint16()
+	if v1 != 100 {
+		t.Fatal()
+	}
+	rb.Retrieve(2)
+
+	v2 := rb.PeekUint32()
+	if v2 != 200 {
+		t.Fatal()
+	}
+	rb.Retrieve(4)
+
+	v3 := rb.PeekUint64()
+	if v3 != 300 {
+		t.Fatal(v3)
+	}
+	rb.Retrieve(8)
+}