Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/topdown/sink.go

@@ -0,0 +1,73 @@
+package topdown
+
+import (
+	"bytes"
+	"io"
+)
+
+var _ io.Writer = (*sinkW)(nil)
+
+type sinkWriter interface {
+	io.Writer
+	String() string
+	Grow(int)
+	WriteByte(byte) error
+	WriteString(string) (int, error)
+}
+
+type sinkW struct {
+	buf    *bytes.Buffer
+	cancel Cancel
+	err    error
+}
+
+func newSink(name string, hint int, c Cancel) sinkWriter {
+	b := &bytes.Buffer{}
+	if hint > 0 {
+		b.Grow(hint)
+	}
+
+	if c == nil {
+		return b
+	}
+
+	return &sinkW{
+		cancel: c,
+		buf:    b,
+		err: Halt{
+			Err: &Error{
+				Code:    CancelErr,
+				Message: name + ": timed out before finishing",
+			},
+		},
+	}
+}
+
+func (sw *sinkW) Grow(n int) {
+	sw.buf.Grow(n)
+}
+
+func (sw *sinkW) Write(bs []byte) (int, error) {
+	if sw.cancel.Cancelled() {
+		return 0, sw.err
+	}
+	return sw.buf.Write(bs)
+}
+
+func (sw *sinkW) WriteByte(b byte) error {
+	if sw.cancel.Cancelled() {
+		return sw.err
+	}
+	return sw.buf.WriteByte(b)
+}
+
+func (sw *sinkW) WriteString(s string) (int, error) {
+	if sw.cancel.Cancelled() {
+		return 0, sw.err
+	}
+	return sw.buf.WriteString(s)
+}
+
+func (sw *sinkW) String() string {
+	return sw.buf.String()
+}