add zero copy reader (#44)

utils/codec/zero_copy_reader.go

@@ -0,0 +1,160 @@
+package codec
+
+import (
+	"io"
+
+	"github.com/laizy/web3"
+)
+
+type ZeroCopyReader struct {
+	Source *ZeroCopySource
+	err    error
+}
+
+func (self *ZeroCopyReader) Error() error {
+	return self.err
+}
+
+// Len returns the number of bytes of the unread portion of the
+// slice.
+func (self *ZeroCopyReader) Len() uint64 {
+	return self.Source.Len()
+}
+
+func (self *ZeroCopyReader) Pos() uint64 {
+	return self.Source.Pos()
+}
+
+// Size returns the original length of the underlying byte slice.
+// Size is the number of bytes available for reading via ReadAt.
+// The returned value is always the same and is not affected by calls
+// to any other method.
+func (self *ZeroCopyReader) Size() uint64 { return self.Source.Size() }
+
+// Read implements the io.ZeroCopyReader interface.
+func (self *ZeroCopyReader) ReadBytes(n uint64) (data []byte) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadBytes(n)
+	return
+}
+
+func (self *ZeroCopyReader) Skip(n uint64) {
+	if self.err != nil {
+		return
+	}
+	eof := self.Source.Skip(n)
+	if eof {
+		self.err = io.ErrUnexpectedEOF
+	}
+	return
+}
+
+func (self *ZeroCopyReader) ReadUint8() (data uint8) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadByte()
+	return
+}
+
+func (self *ZeroCopyReader) ReadBool() (data bool) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadBool()
+	return
+}
+
+// Backs up a number of bytes, so that the next call to NextXXX() returns data again
+// that was already returned by the last call to NextXXX().
+func (self *ZeroCopyReader) BackUp(n uint64) {
+	self.Source.BackUp(n)
+}
+
+func (self *ZeroCopyReader) ReadUint32() (data uint32) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadUint32BE()
+	return
+}
+
+func (self *ZeroCopyReader) ReadUint32BE() (data uint32) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadUint32BE()
+	return
+}
+
+func (self *ZeroCopyReader) ReadUint64() (data uint64) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadUint64()
+	return
+}
+
+func (self *ZeroCopyReader) ReadUint64BE() (data uint64) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadUint64BE()
+	return
+}
+
+func (self *ZeroCopyReader) ReadInt32() (data int32) {
+	return int32(self.ReadUint32())
+}
+
+func (self *ZeroCopyReader) ReadInt64() (data int64) {
+	return int64(self.ReadUint64())
+}
+
+func (self *ZeroCopyReader) ReadString() (data string) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadString()
+	return
+}
+
+func (self *ZeroCopyReader) ReadVarBytes() (data []byte) {
+	if self.err != nil {
+		return nil
+	}
+	data, self.err = self.Source.ReadVarBytes()
+	return data
+}
+
+func (self *ZeroCopyReader) ReadAddress() (addr web3.Address) {
+	if self.err != nil {
+		return
+	}
+	addr, self.err = self.Source.ReadAddress()
+	return
+}
+
+func (self *ZeroCopyReader) ReadHash() (hash web3.Hash) {
+	if self.err != nil {
+		return
+	}
+	hash, self.err = self.Source.ReadHash()
+	return
+}
+
+func (self *ZeroCopyReader) ReadVarUint() (data uint64) {
+	if self.err != nil {
+		return
+	}
+	data, self.err = self.Source.ReadVarUint()
+	return
+}
+
+func NewZeroCopyReader(b []byte) *ZeroCopyReader {
+	return &ZeroCopyReader{
+		Source: NewZeroCopySource(b),
+	}
+}

utils/codec/zero_copy_source.go

@@ -96,10 +96,23 @@ func (self *ZeroCopySource) NextByte() (data byte, eof bool) {
 	return b, false
 }
 
+func (self *ZeroCopySource) ReadByte() (data byte, err error) {
+	d, eof := self.NextByte()
+	if eof {
+		err = io.ErrUnexpectedEOF
+		return
+	}
+	return d, nil
+}
+
+func (self *ZeroCopySource) ReadUint8() (data uint8, err error) {
+	return self.ReadByte()
+}
+
 func (self *ZeroCopySource) NextUint8() (data uint8, eof bool) {
 	var val byte
 	val, eof = self.NextByte()
-	return uint8(val), eof
+	return val, eof
 }
 
 func (self *ZeroCopySource) NextBool() (data bool, irregular bool, eof bool) {
@@ -116,9 +129,24 @@ func (self *ZeroCopySource) NextBool() (data bool, irregular bool, eof bool) {
 	return
 }
 
+func (self *ZeroCopySource) ReadBool() (data bool, err error) {
+	d, irr, eof := self.NextBool()
+	if eof {
+		err = io.ErrUnexpectedEOF
+		return
+	} else if irr {
+		err = ErrIrregularData
+		return
+	}
+	return d, nil
+}
+
 // Backs up a number of bytes, so that the next call to NextXXX() returns data again
 // that was already returned by the last call to NextXXX().
 func (self *ZeroCopySource) BackUp(n uint64) {
+	if n > self.off {
+		panic("backup too large")
+	}
 	self.off -= n
 }
 
@@ -224,6 +252,16 @@ func (self *ZeroCopySource) ReadString() (string, error) {
 	return string(d), err
 }
 
+func (self *ZeroCopySource) ReadBytes(n uint64) (data []byte, err error) {
+	d, eof := self.NextBytes(n)
+	if eof {
+		err = io.ErrUnexpectedEOF
+		return
+	}
+
+	return d, nil
+}
+
 func (self *ZeroCopySource) ReadVarBytes() (data []byte, err error) {
 	data, _, irr, eof := self.NextVarBytes()
 	if irr {
@@ -283,6 +321,18 @@ func (self *ZeroCopySource) NextString() (data string, size uint64, irregular bo
 	return
 }
 
+func (self *ZeroCopySource) ReadVarUint() (data uint64, err error) {
+	d, _, irr, eof := self.NextVarUint()
+	if eof {
+		err = io.ErrUnexpectedEOF
+		return
+	} else if irr {
+		err = ErrIrregularData
+		return
+	}
+	return d, nil
+}
+
 func (self *ZeroCopySource) NextVarUint() (data uint64, size uint64, irregular bool, eof bool) {
 	var fb byte
 	fb, eof = self.NextByte()
@@ -345,3 +395,7 @@ func NewZeroCopySource(b []byte) *ZeroCopySource {
 		byteOrder: binary.LittleEndian,
 	}
 }
+
+func (self *ZeroCopySource) Reader() *ZeroCopyReader {
+	return &ZeroCopyReader{Source: self}
+}