Add a new Match method to the reference package

The Match method allows to see if a reference matches a specified
patterns.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

reference/reference.go

@@ -24,6 +24,7 @@ package reference
 import (
 	"errors"
 	"fmt"
+	"path"
 	"strings"
 
 	"github.com/docker/distribution/digest"
@@ -236,6 +237,16 @@ func WithDigest(name Named, digest digest.Digest) (Canonical, error) {
 	}, nil
 }
 
+// Match reports whether ref matches the specified pattern.
+// See https://godoc.org/path#Match for supported patterns.
+func Match(pattern string, ref Reference) (bool, error) {
+	matched, err := path.Match(pattern, ref.String())
+	if namedRef, isNamed := ref.(Named); isNamed && !matched {
+		matched, _ = path.Match(pattern, namedRef.Name())
+	}
+	return matched, err
+}
+
 func getBestReferenceType(ref reference) Reference {
 	if ref.name == "" {
 		// Allow digest only references

reference/reference_test.go

@@ -552,3 +552,81 @@ func TestWithDigest(t *testing.T) {
 		}
 	}
 }
+
+func TestMatchError(t *testing.T) {
+	named, err := Parse("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = Match("[-x]", named)
+	if err == nil {
+		t.Fatalf("expected an error, got nothing")
+	}
+}
+
+func TestMatch(t *testing.T) {
+	matchCases := []struct {
+		reference string
+		pattern   string
+		expected  bool
+	}{
+		{
+			reference: "foo",
+			pattern:   "foo/**/ba[rz]",
+			expected:  false,
+		},
+		{
+			reference: "foo/any/bat",
+			pattern:   "foo/**/ba[rz]",
+			expected:  false,
+		},
+		{
+			reference: "foo/a/bar",
+			pattern:   "foo/**/ba[rz]",
+			expected:  true,
+		},
+		{
+			reference: "foo/b/baz",
+			pattern:   "foo/**/ba[rz]",
+			expected:  true,
+		},
+		{
+			reference: "foo/c/baz:tag",
+			pattern:   "foo/**/ba[rz]",
+			expected:  true,
+		},
+		{
+			reference: "foo/c/baz:tag",
+			pattern:   "foo/*/baz:tag",
+			expected:  true,
+		},
+		{
+			reference: "foo/c/baz:tag",
+			pattern:   "foo/c/baz:tag",
+			expected:  true,
+		},
+		{
+			reference: "example.com/foo/c/baz:tag",
+			pattern:   "*/foo/c/baz",
+			expected:  true,
+		},
+		{
+			reference: "example.com/foo/c/baz:tag",
+			pattern:   "example.com/foo/c/baz",
+			expected:  true,
+		},
+	}
+	for _, c := range matchCases {
+		named, err := Parse(c.reference)
+		if err != nil {
+			t.Fatal(err)
+		}
+		actual, err := Match(c.pattern, named)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if actual != c.expected {
+			t.Fatalf("expected %s match %s to be %v, was %v", c.reference, c.pattern, c.expected, actual)
+		}
+	}
+}