feat(readerx): basic functionality

.gitignore

@@ -0,0 +1 @@
+/.idea/

readerx.go

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+package readerx
+
+import "io"
+
+type Reader struct {
+	reader io.Reader
+	fun    func([]byte) (int, error)
+}
+
+func NewReader(reader io.Reader) Reader {
+	return Reader{
+		reader: reader,
+	}
+}
+
+func (r Reader) Read(b []byte) (l []byte, n int, err error) {
+	n, err = r.reader.Read(b)
+	if n > 0 {
+		l = b[:n]
+	}
+	return
+}
+
+func (r Reader) ReadX(b []byte) (l []byte, err error) {
+	l, _, err = r.Read(b)
+	return
+}
+
+func (r Reader) readFunc(b []byte) (l []byte, n int, err error) {
+	n, err = r.fun(b)
+	if n > 0 {
+		l = b[:n]
+	}
+	return
+}
+
+func ReadFrom(reader io.Reader, b []byte) (l []byte, n int, err error) {
+	l, n, err = NewReader(reader).Read(b)
+	return
+}
+
+func ReadFromX(reader io.Reader, b []byte) (l []byte, err error) {
+	l, err = NewReader(reader).ReadX(b)
+	return
+}
+
+func ReadFunc(f func([]byte) (int, error), b []byte) (l []byte, n int, err error) {
+	r := Reader{
+		fun: f,
+	}
+	l, n, err = r.readFunc(b)
+	return
+}
+
+func ReadFuncX(f func([]byte) (int, error), b []byte) (l []byte, err error) {
+	l, _, err = ReadFunc(f, b)
+	return
+}