Implement wikilink util function and test it

util/url.go

@@ -0,0 +1,44 @@
+/* This file implements things defined by Wikilink RFC. See :main/help/wikilink
+ */
+package util
+
+import (
+	"path"
+	"regexp"
+	"strings"
+)
+
+// `name` must be non-empty.
+func sections(name string) (mycel, hyphaName string) {
+	mycelRe := regexp.MustCompile(`^:.*/`)
+	loc := mycelRe.FindIndex([]byte(name))
+	if loc != nil { // if has mycel
+		mycel = name[:loc[1]]
+		name = name[loc[1]:]
+	}
+	return mycel, name
+}
+
+// Wikilink processes `link` as defined by :main/help/wikilink assuming that `atHypha` is current hypha name.
+func Wikilink(link, atHypha string) string {
+	mycel, hyphaName := sections(atHypha)
+	urlProtocolRe := regexp.MustCompile(`^[a-zA-Z]+:`)
+	switch {
+	case strings.HasPrefix(link, "::"):
+		return "/" + mycel + link[2:]
+	case strings.HasPrefix(link, ":"):
+		return "/" + link
+	case strings.HasPrefix(link, "../") && strings.Count(hyphaName, "/") > 0:
+		return "/" + path.Dir(atHypha) + "/" + link[3:]
+	case strings.HasPrefix(link, "../"):
+		return "/" + mycel + link[3:]
+	case strings.HasPrefix(link, "/"):
+		return "/" + atHypha + link
+	case strings.HasPrefix(link, "./"):
+		return "/" + atHypha + link[1:]
+	case urlProtocolRe.MatchString(link):
+		return link
+	default:
+		return "/" + link
+	}
+}

util/util_test.go

@@ -0,0 +1,22 @@
+package util
+
+import (
+	"testing"
+)
+
+func TestWikilink(t *testing.T) {
+	atHypha := ":example/test"
+	results := map[string]string{
+		"foo":      "/foo",
+		"::foo":    "/:example/foo",
+		":bar/foo": "/:bar/foo",
+		"/baz":     "/:example/test/baz",
+		"./baz":    "/:example/test/baz",
+		"../qux":   "/:example/qux",
+	}
+	for link, expect := range results {
+		if res := Wikilink(link, atHypha); expect != res {
+			t.Errorf("%s → %s; expected %s", link, res, expect)
+		}
+	}
+}

wiki/main/doc/wikilink/1.markdown

@@ -40,7 +40,7 @@ wikilink    actual path
 foo      == /foo
 ::foo    == /:example/foo
 :bar/foo == /:bar/foo
-/baz     == /:example/baz
+/baz     == /:example/test/baz
-./baz    == /:example/baz
+./baz    == /:example/test/baz
 ../qux   == /:example/qux
 ```