labels: add string constructor, expose matcher

labels/labels.go

@@ -87,3 +87,17 @@ func FromMap(m map[string]string) Labels {
 	}
 	return New(l...)
 }
+
+// FromStrings creates new labels from pairs of strings.
+func FromStrings(ss ...string) Labels {
+	if len(ss)%2 != 0 {
+		panic("invalid number of strings")
+	}
+	var res Labels
+	for i := 0; i < len(ss); i += 2 {
+		res = append(res, Label{Name: ss[i], Value: ss[i+1]})
+	}
+
+	sort.Sort(res)
+	return res
+}

labels/selector.go

@@ -23,16 +23,16 @@ type Matcher interface {
 	Matches(v string) bool
 }
 
-type equalMatcher struct {
-	name, value string
+type EqualMatcher struct {
+	LabelName, Value string
 }
 
-func (m *equalMatcher) Name() string          { return m.name }
-func (m *equalMatcher) Matches(v string) bool { return v == m.value }
+func (m *EqualMatcher) Name() string          { return m.LabelName }
+func (m *EqualMatcher) Matches(v string) bool { return v == m.Value }
 
 // NewEqualMatcher returns a new matcher matching an exact label value.
 func NewEqualMatcher(name, value string) Matcher {
-	return &equalMatcher{name: name, value: value}
+	return &EqualMatcher{LabelName: name, Value: value}
 }
 
 type regexpMatcher struct {