1 files changed, 200 insertions, 0 deletions
diff --git a/bar_option.go b/bar_option.go
new file mode 100644
index 0000000..d3cb3e2
--- /dev/null
+++ b/bar_option.go
@@ -0,0 +1,200 @@
+package mpb
+
+import (
+	"bytes"
+	"io"
+
+	"github.com/vbauerster/mpb/v8/decor"
+)
+
+// BarOption is a func option to alter default behavior of a bar.
+type BarOption func(*bState)
+
+func inspect(decorators []decor.Decorator) (dest []decor.Decorator) {
+	for _, decorator := range decorators {
+		if decorator == nil {
+			continue
+		}
+		dest = append(dest, decorator)
+	}
+	return
+}
+
+// AppendDecorators let you inject decorators to the bar's right side.
+func AppendDecorators(decorators ...decor.Decorator) BarOption {
+	decorators = inspect(decorators)
+	return func(s *bState) {
+		s.aDecorators = decorators
+	}
+}
+
+// PrependDecorators let you inject decorators to the bar's left side.
+func PrependDecorators(decorators ...decor.Decorator) BarOption {
+	decorators = inspect(decorators)
+	return func(s *bState) {
+		s.pDecorators = decorators
+	}
+}
+
+// BarID sets bar id.
+func BarID(id int) BarOption {
+	return func(s *bState) {
+		s.id = id
+	}
+}
+
+// BarWidth sets bar width independent of the container.
+func BarWidth(width int) BarOption {
+	return func(s *bState) {
+		s.reqWidth = width
+	}
+}
+
+// BarQueueAfter puts this (being constructed) bar into the queue.
+// BarPriority will be inherited from the argument bar.
+// When argument bar completes or aborts queued bar replaces its place.
+func BarQueueAfter(bar *Bar) BarOption {
+	return func(s *bState) {
+		s.waitBar = bar
+	}
+}
+
+// BarRemoveOnComplete removes both bar's filler and its decorators
+// on complete event.
+func BarRemoveOnComplete() BarOption {
+	return func(s *bState) {
+		s.rmOnComplete = true
+	}
+}
+
+// BarFillerClearOnComplete clears bar's filler on complete event.
+// It's shortcut for BarFillerOnComplete("").
+func BarFillerClearOnComplete() BarOption {
+	return BarFillerOnComplete("")
+}
+
+// BarFillerOnComplete replaces bar's filler with message, on complete event.
+func BarFillerOnComplete(message string) BarOption {
+	return BarFillerMiddleware(func(base BarFiller) BarFiller {
+		return BarFillerFunc(func(w io.Writer, st decor.Statistics) error {
+			if st.Completed {
+				_, err := io.WriteString(w, message)
+				return err
+			}
+			return base.Fill(w, st)
+		})
+	})
+}
+
+// BarFillerMiddleware provides a way to augment the underlying BarFiller.
+func BarFillerMiddleware(middle func(BarFiller) BarFiller) BarOption {
+	if middle == nil {
+		return nil
+	}
+	return func(s *bState) {
+		s.filler = middle(s.filler)
+	}
+}
+
+// BarPriority sets bar's priority. Zero is highest priority, i.e. bar
+// will be on top. This option isn't effective with `BarQueueAfter` option.
+func BarPriority(priority int) BarOption {
+	return func(s *bState) {
+		s.priority = priority
+	}
+}
+
+// BarExtender extends bar with arbitrary lines. Provided BarFiller will be
+// called at each render/flush cycle. Any lines written to the underlying
+// io.Writer will extend the bar either in above (rev = true) or below
+// (rev = false) direction.
+func BarExtender(filler BarFiller, rev bool) BarOption {
+	if filler == nil {
+		return nil
+	}
+	fn := makeExtenderFunc(filler, rev)
+	return func(s *bState) {
+		s.extender = fn
+	}
+}
+
+func makeExtenderFunc(filler BarFiller, rev bool) extenderFunc {
+	buf := new(bytes.Buffer)
+	base := func(rows []io.Reader, stat decor.Statistics) ([]io.Reader, error) {
+		err := filler.Fill(buf, stat)
+		if err != nil {
+			buf.Reset()
+			return rows, err
+		}
+		for {
+			b, err := buf.ReadBytes('\n')
+			if err != nil {
+				break
+			}
+			rows = append(rows, bytes.NewReader(b))
+		}
+		buf.Reset()
+		return rows, err
+	}
+
+	if !rev {
+		return base
+	}
+	return func(rows []io.Reader, stat decor.Statistics) ([]io.Reader, error) {
+		rows, err := base(rows, stat)
+		if err != nil {
+			return rows, err
+		}
+		for left, right := 0, len(rows)-1; left < right; left, right = left+1, right-1 {
+			rows[left], rows[right] = rows[right], rows[left]
+		}
+		return rows, err
+	}
+}
+
+// BarFillerTrim removes leading and trailing space around the underlying BarFiller.
+func BarFillerTrim() BarOption {
+	return func(s *bState) {
+		s.trimSpace = true
+	}
+}
+
+// BarNoPop disables bar pop out of container. Effective when
+// PopCompletedMode of container is enabled.
+func BarNoPop() BarOption {
+	return func(s *bState) {
+		s.noPop = true
+	}
+}
+
+// BarOptional will return provided option only when cond is true.
+func BarOptional(option BarOption, cond bool) BarOption {
+	if cond {
+		return option
+	}
+	return nil
+}
+
+// BarOptOn will return provided option only when predicate evaluates to true.
+func BarOptOn(option BarOption, predicate func() bool) BarOption {
+	if predicate() {
+		return option
+	}
+	return nil
+}
+
+// BarFuncOptional will call option and return its value only when cond is true.
+func BarFuncOptional(option func() BarOption, cond bool) BarOption {
+	if cond {
+		return option()
+	}
+	return nil
+}
+
+// BarFuncOptOn will call option and return its value only when predicate evaluates to true.
+func BarFuncOptOn(option func() BarOption, predicate func() bool) BarOption {
+	if predicate() {
+		return option()
+	}
+	return nil
+}