internal/source: add support for dmitri.shuralyov.com/... packages

Add support for a set of packages that defer to another website to
display their source code. To be able to produce expected URLs, we
need to add two more URL template variables:

• {importPath} - Package import path ("example.com/myrepo/mypkg").
• {base}       - Base name of file containing the identifier,
                 including file extension ("file.go").

Also add a new optional Repo URL template for overriding the home
page of the repository, which is something that was possible with
the original go-source meta tag.

Document the existing URL template variables, so that it's easier
to understand how to use them.

For golang/go#40477.

Change-Id: I70b857155f69c5c3ed41e78daccb90153a927290
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/246239
Run-TryBot: Dmitri Shuralyov <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Jonathan Amsterdam <[email protected]>

Author: dmitshur

internal/source/source.go

@@ -49,11 +49,18 @@ type Info struct {
 	templates urlTemplates // for building URLs
 }
 
+// RepoURL returns a URL for the home page of the repository.
 func (i *Info) RepoURL() string {
 	if i == nil {
 		return ""
 	}
-	return i.repoURL
+	if i.templates.Repo == "" {
+		// The default repo template is just "{repo}".
+		return i.repoURL
+	}
+	return expand(i.templates.Repo, map[string]string{
+		"repo": i.repoURL,
+	})
 }
 
 // ModuleURL returns a URL for the home page of the module.
@@ -67,9 +74,10 @@ func (i *Info) DirectoryURL(dir string) string {
 		return ""
 	}
 	return strings.TrimSuffix(expand(i.templates.Directory, map[string]string{
-		"repo":   i.repoURL,
-		"commit": i.commit,
-		"dir":    path.Join(i.moduleDir, dir),
+		"repo":       i.repoURL,
+		"importPath": path.Join(strings.TrimPrefix(i.repoURL, "https://"), dir),
+		"commit":     i.commit,
+		"dir":        path.Join(i.moduleDir, dir),
 	}), "/")
 }
 
@@ -78,10 +86,13 @@ func (i *Info) FileURL(pathname string) string {
 	if i == nil {
 		return ""
 	}
+	dir, base := path.Split(pathname)
 	return expand(i.templates.File, map[string]string{
-		"repo":   i.repoURL,
-		"commit": i.commit,
-		"file":   path.Join(i.moduleDir, pathname),
+		"repo":       i.repoURL,
+		"importPath": path.Join(strings.TrimPrefix(i.repoURL, "https://"), dir),
+		"commit":     i.commit,
+		"file":       path.Join(i.moduleDir, pathname),
+		"base":       base,
 	})
 }
 
@@ -90,11 +101,14 @@ func (i *Info) LineURL(pathname string, line int) string {
 	if i == nil {
 		return ""
 	}
+	dir, base := path.Split(pathname)
 	return expand(i.templates.Line, map[string]string{
-		"repo":   i.repoURL,
-		"commit": i.commit,
-		"file":   path.Join(i.moduleDir, pathname),
-		"line":   strconv.Itoa(line),
+		"repo":       i.repoURL,
+		"importPath": path.Join(strings.TrimPrefix(i.repoURL, "https://"), dir),
+		"commit":     i.commit,
+		"file":       path.Join(i.moduleDir, pathname),
+		"base":       base,
+		"line":       strconv.Itoa(line),
 	})
 }
 
@@ -521,6 +535,17 @@ var patterns = []struct {
 		// URLs anyway. See gogs/gogs#6242.
 		templates: giteaURLTemplates,
 	},
+
+	{
+		pattern: `^(?P<repo>dmitri\.shuralyov\.com\/.+)$`,
+		templates: urlTemplates{
+			Repo:      "{repo}/...",
+			Directory: "https://gotools.org/{importPath}?rev={commit}",
+			File:      "https://gotools.org/{importPath}?rev={commit}#{base}",
+			Line:      "https://gotools.org/{importPath}?rev={commit}#{base}-L{line}",
+		},
+	},
+
 	// Patterns that match the general go command pattern, where they must have
 	// a ".git" repo suffix in an import path. If matching a repo URL from a meta tag,
 	// there is no ".git".
@@ -577,11 +602,23 @@ func giteaTransformCommit(commit string, isHash bool) string {
 
 // urlTemplates describes how to build URLs from bits of source information.
 // The fields are exported for JSON encoding.
+//
+// The template variables are:
+//
+// 	• {repo}       - Repository URL with "https://" prefix ("https://example.com/myrepo").
+// 	• {importPath} - Package import path ("example.com/myrepo/mypkg").
+// 	• {commit}     - Tag name or commit hash corresponding to version ("v0.1.0" or "1234567890ab").
+// 	• {dir}        - Path to directory of the package, relative to repo root ("mypkg").
+// 	• {file}       - Path to file containing the identifier, relative to repo root ("mypkg/file.go").
+// 	• {base}       - Base name of file containing the identifier, including file extension ("file.go").
+// 	• {line}       - Line number for the identifier ("41").
+//
 type urlTemplates struct {
-	Directory string // URL template for a directory, with {repo}, {commit} and {dir}
-	File      string // URL template for a file, with {repo}, {commit} and {file}
-	Line      string // URL template for a line, with {repo}, {commit}, {file} and {line}
-	Raw       string // URL template for the raw contents of a file, with {repo}, {repoPath}, {commit} and {file}
+	Repo      string `json:",omitempty"` // Optional URL template for the repository home page, with {repo}. If left empty, a default template "{repo}" is used.
+	Directory string // URL template for a directory, with {repo}, {importPath}, {commit}, {dir}.
+	File      string // URL template for a file, with {repo}, {importPath}, {commit}, {file}, {base}.
+	Line      string // URL template for a line, with {repo}, {importPath}, {commit}, {file}, {base}, {line}.
+	Raw       string // Optional URL template for the raw contents of a file, with {repo}, {commit}, {file}.
 }
 
 var (

internal/source/source_test.go

@@ -333,14 +333,34 @@ func TestModuleInfo(t *testing.T) {
 			"https://github.com/gonum/gonum/blob/v0.6.1/doc.go#L1",
 			"https://github.com/gonum/gonum/raw/v0.6.1/doc.go",
 		},
+		{
+			"custom with gotools at repo root",
+			"dmitri.shuralyov.com/gpu/mtl", "v0.0.0-20191203043605-d42048ed14fd", "mtl.go",
+
+			"https://dmitri.shuralyov.com/gpu/mtl/...",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl?rev=d42048ed14fd",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl?rev=d42048ed14fd#mtl.go",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl?rev=d42048ed14fd#mtl.go-L1",
+			"",
+		},
+		{
+			"custom with gotools in subdir",
+			"dmitri.shuralyov.com/gpu/mtl", "v0.0.0-20191203043605-d42048ed14fd", "example/movingtriangle/internal/coreanim/coreanim.go",
+
+			"https://dmitri.shuralyov.com/gpu/mtl/...",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl?rev=d42048ed14fd",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl/example/movingtriangle/internal/coreanim?rev=d42048ed14fd#coreanim.go",
+			"https://gotools.org/dmitri.shuralyov.com/gpu/mtl/example/movingtriangle/internal/coreanim?rev=d42048ed14fd#coreanim.go-L1",
+			"",
+		},
 	} {
 		t.Run(test.desc, func(t *testing.T) {
 			info, err := ModuleInfo(context.Background(), &Client{client}, test.modulePath, test.version)
 			if err != nil {
 				t.Fatal(err)
 			}
 
-			check(t, "repo", info.repoURL, test.wantRepo)
+			check(t, "repo", info.RepoURL(), test.wantRepo)
 			check(t, "module", info.ModuleURL(), test.wantModule)
 			check(t, "file", info.FileURL(test.file), test.wantFile)
 			check(t, "line", info.LineURL(test.file, 1), test.wantLine)
@@ -837,6 +857,10 @@ func TestJSON(t *testing.T) {
 			&Info{repoURL: "r", moduleDir: "m", commit: "c", templates: urlTemplates{File: "f"}},
 			`{"RepoURL":"r","ModuleDir":"m","Commit":"c","Templates":{"Directory":"","File":"f","Line":"","Raw":""}}`,
 		},
+		{
+			&Info{repoURL: "r", moduleDir: "m", commit: "c", templates: urlTemplates{Repo: "r", File: "f"}},
+			`{"RepoURL":"r","ModuleDir":"m","Commit":"c","Templates":{"Repo":"r","Directory":"","File":"f","Line":"","Raw":""}}`,
+		},
 	} {
 		bytes, err := json.Marshal(&test.in)
 		if err != nil {
@@ -877,9 +901,9 @@ func TestURLTemplates(t *testing.T) {
 			}
 		}
 
-		check(p.templates.Directory, "commit", "dir")
-		check(p.templates.File, "commit", "file")
-		check(p.templates.Line, "commit", "file", "line")
+		check(p.templates.Directory, "commit")
+		check(p.templates.File, "commit")
+		check(p.templates.Line, "commit", "line")
 		check(p.templates.Raw, "commit", "file")
 	}
 }