Merge pull request #201 from Bytom/v0.1

[bytom/vapor.git] / vendor / github.com / bytom / errors / writer.go

diff --git a/vendor/github.com/bytom/errors/writer.go b/vendor/github.com/bytom/errors/writer.go
new file mode 100644 (file)
index 0000000..fd59b65
--- /dev/null
+++ b/vendor/github.com/bytom/errors/writer.go
@@ -0,0 +1,46 @@
+package errors
+
+import "io"
+
+// NewWriter returns a new Writer that writes to w
+// until an error is returned.
+func NewWriter(w io.Writer) *Writer {
+       return &Writer{w: w}
+}
+
+// Writer is in an implementation of the
+// "sticky error writer" pattern as described
+// in https://blog.golang.org/errors-are-values.
+//
+// A Writer makes one call
+// on the underlying writer for each call to Write,
+// until an error is returned. From that point on,
+// it makes no calls on the underlying writer,
+// and returns the same error value every time.
+type Writer struct {
+       w   io.Writer
+       n   int64
+       err error
+}
+
+// Write makes one call on the underlying writer
+// if no error has previously occurred.
+func (w *Writer) Write(buf []byte) (n int, err error) {
+       if w.err != nil {
+               return 0, w.err
+       }
+       n, w.err = w.w.Write(buf)
+       w.n += int64(n)
+       return n, w.err
+}
+
+// Err returns the first error encountered by Write, if any.
+func (w *Writer) Err() error {
+       return w.err
+}
+
+// Written returns the number of bytes written
+// to the underlying writer.
+func (w *Writer) Written() int64 {
+       return w.n
+}