Extract useragent package

Fixes #30

useragent/useragent.go

@@ -0,0 +1,38 @@
+package useragent
+
+import (
+	"strings"
+)
+
+type UserAgent struct {
+	Product string
+	Version string
+	Comment string
+}
+
+func Parse(s string) UserAgent {
+	parts := strings.SplitN(s, "/", 2)
+	var version, comment string
+	if len(parts) > 1 {
+		// If first character is a number, treat it as version
+		if parts[1][0] >= 48 && parts[1][0] <= 57 {
+			rest := strings.SplitN(parts[1], " ", 2)
+			version = rest[0]
+			if len(rest) > 1 {
+				comment = rest[1]
+			}
+		} else {
+			comment = parts[1]
+		}
+	} else {
+		parts = strings.SplitN(s, " ", 2)
+		if len(parts) > 1 {
+			comment = parts[1]
+		}
+	}
+	return UserAgent{
+		Product: parts[0],
+		Version: version,
+		Comment: comment,
+	}
+}

useragent/useragent_test.go

@@ -0,0 +1,36 @@
+package useragent
+
+import (
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	var tests = []struct {
+		in  string
+		out UserAgent
+	}{
+		{"", UserAgent{}},
+		{"curl/7.26.0", UserAgent{Product: "curl", Version: "7.26.0"}},
+		{"Wget/1.13.4 (linux-gnu)", UserAgent{Product: "Wget", Version: "1.13.4", Comment: "(linux-gnu)"}},
+		{"Wget", UserAgent{Product: "Wget"}},
+		{"fetch libfetch/2.0", UserAgent{Product: "fetch libfetch", Version: "2.0"}},
+		{"Go 1.1 package http", UserAgent{Product: "Go", Comment: "1.1 package http"}},
+		{"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) " +
+			"AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.28 " +
+			"Safari/537.36", UserAgent{Product: "Mozilla", Version: "5.0", Comment: "(Macintosh; Intel Mac OS X 10_8_4) " +
+			"AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.28 " +
+			"Safari/537.36"}},
+	}
+	for _, tt := range tests {
+		ua := Parse(tt.in)
+		if got := ua.Product; got != tt.out.Product {
+			t.Errorf("got Product=%q for %q, want %q", got, tt.in, tt.out.Product)
+		}
+		if got := ua.Version; got != tt.out.Version {
+			t.Errorf("got Version=%q for %q, want %q", got, tt.in, tt.out.Version)
+		}
+		if got := ua.Comment; got != tt.out.Comment {
+			t.Errorf("got Comment=%q for %q, want %q", got, tt.in, tt.out.Comment)
+		}
+	}
+}