short-name aliasing

Add support for short-name aliasing.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/juju/ansiterm/attribute.go

@@ -0,0 +1,50 @@
+// Copyright 2016 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package ansiterm
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+type attribute int
+
+const (
+	unknownAttribute attribute = -1
+	reset            attribute = 0
+)
+
+// sgr returns the escape sequence for the Select Graphic Rendition
+// for the attribute.
+func (a attribute) sgr() string {
+	if a < 0 {
+		return ""
+	}
+	return fmt.Sprintf("\x1b[%dm", a)
+}
+
+type attributes []attribute
+
+func (a attributes) Len() int           { return len(a) }
+func (a attributes) Less(i, j int) bool { return a[i] < a[j] }
+func (a attributes) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// sgr returns the combined escape sequence for the Select Graphic Rendition
+// for the sequence of attributes.
+func (a attributes) sgr() string {
+	switch len(a) {
+	case 0:
+		return ""
+	case 1:
+		return a[0].sgr()
+	default:
+		sort.Sort(a)
+		var values []string
+		for _, attr := range a {
+			values = append(values, fmt.Sprint(attr))
+		}
+		return fmt.Sprintf("\x1b[%sm", strings.Join(values, ";"))
+	}
+}