tags: parse tag names and options

tags.go

@@ -0,0 +1,39 @@
+package structure
+
+import "strings"
+
+// tagOptions contains a slice of tag options
+type tagOptions []string
+
+// Has returns true if the given opt is available inside the slice.
+func (t tagOptions) Has(opt string) bool {
+	for _, tagOpt := range t {
+		if tagOpt == opt {
+			return true
+		}
+	}
+
+	return false
+}
+
+// parseTag splits a struct field's tag into its name and a list of options
+// which comes after a name
+func parseTag(tag string) (string, tagOptions) {
+	res := strings.Split(tag, ",")
+
+	// tag = ""
+	if len(res) == 0 {
+		return tag, res
+	}
+
+	// tag = "name"
+	if len(res) == 1 {
+		return tag, res[1:]
+	}
+
+	// tag is one of followings:
+	// "name,opt"
+	// "name,opt,opt2"
+	// ",opt"
+	return res[0], res[1:]
+}

tags_test.go

@@ -0,0 +1,45 @@
+package structure
+
+import "testing"
+
+func TestParseTag_Name(t *testing.T) {
+	tags := []struct {
+		tag string
+		has bool
+	}{
+		{"name", true},
+		{"name,opt", true},
+		{"name , opt, opt2", false}, // has a single whitespace
+		{", opt, opt2", false},
+	}
+
+	for _, tag := range tags {
+		name, _ := parseTag(tag.tag)
+
+		if (name != "name") && tag.has {
+			t.Errorf("Parse tag should return name: %#v", tag)
+		}
+	}
+}
+
+func TestParseTag_Opts(t *testing.T) {
+	tags := []struct {
+		opts string
+		has  bool
+	}{
+		{"name", false},
+		{"name,opt", true},
+		{"name , opt, opt2", false}, // has a single whitespace
+		{",opt, opt2", true},
+		{", opt3, opt4", false},
+	}
+
+	// search for "opt"
+	for _, tag := range tags {
+		_, opts := parseTag(tag.opts)
+
+		if opts.Has("opt") != tag.has {
+			t.Errorf("Tag opts should have opt: %#v", tag)
+		}
+	}
+}