| 1 | // Copyright 2009 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package godoc |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "encoding/json" |
| 10 | "errors" |
| 11 | "log" |
| 12 | "os" |
| 13 | pathpkg "path" |
| 14 | "strings" |
| 15 | "time" |
| 16 | |
| 17 | "golang.org/x/tools/godoc/vfs" |
| 18 | ) |
| 19 | |
| 20 | var ( |
| 21 | doctype = []byte("<!DOCTYPE ") |
| 22 | jsonStart = []byte("<!--{") |
| 23 | jsonEnd = []byte("}-->") |
| 24 | ) |
| 25 | |
| 26 | // ---------------------------------------------------------------------------- |
| 27 | // Documentation Metadata |
| 28 | |
| 29 | type Metadata struct { |
| 30 | // These fields can be set in the JSON header at the top of a doc. |
| 31 | Title string |
| 32 | Subtitle string |
| 33 | Template bool // execute as template |
| 34 | Path string // canonical path for this page |
| 35 | AltPaths []string // redirect these other paths to this page |
| 36 | |
| 37 | // These are internal to the implementation. |
| 38 | filePath string // filesystem path relative to goroot |
| 39 | } |
| 40 | |
| 41 | func (m *Metadata) FilePath() string { return m.filePath } |
| 42 | |
| 43 | // extractMetadata extracts the Metadata from a byte slice. |
| 44 | // It returns the Metadata value and the remaining data. |
| 45 | // If no metadata is present the original byte slice is returned. |
| 46 | func extractMetadata(b []byte) (meta Metadata, tail []byte, err error) { |
| 47 | tail = b |
| 48 | if !bytes.HasPrefix(b, jsonStart) { |
| 49 | return |
| 50 | } |
| 51 | end := bytes.Index(b, jsonEnd) |
| 52 | if end < 0 { |
| 53 | return |
| 54 | } |
| 55 | b = b[len(jsonStart)-1 : end+1] // drop leading <!-- and include trailing } |
| 56 | if err = json.Unmarshal(b, &meta); err != nil { |
| 57 | return |
| 58 | } |
| 59 | tail = tail[end+len(jsonEnd):] |
| 60 | return |
| 61 | } |
| 62 | |
| 63 | // UpdateMetadata scans $GOROOT/doc for HTML and Markdown files, reads their metadata, |
| 64 | // and updates the DocMetadata map. |
| 65 | func (c *Corpus) updateMetadata() { |
| 66 | metadata := make(map[string]*Metadata) |
| 67 | var scan func(string) // scan is recursive |
| 68 | scan = func(dir string) { |
| 69 | fis, err := c.fs.ReadDir(dir) |
| 70 | if err != nil { |
| 71 | if dir == "/doc" && errors.Is(err, os.ErrNotExist) { |
| 72 | // Be quiet during tests that don't have a /doc tree. |
| 73 | return |
| 74 | } |
| 75 | log.Printf("updateMetadata %s: %v", dir, err) |
| 76 | return |
| 77 | } |
| 78 | for _, fi := range fis { |
| 79 | name := pathpkg.Join(dir, fi.Name()) |
| 80 | if fi.IsDir() { |
| 81 | scan(name) // recurse |
| 82 | continue |
| 83 | } |
| 84 | if !strings.HasSuffix(name, ".html") && !strings.HasSuffix(name, ".md") { |
| 85 | continue |
| 86 | } |
| 87 | // Extract metadata from the file. |
| 88 | b, err := vfs.ReadFile(c.fs, name) |
| 89 | if err != nil { |
| 90 | log.Printf("updateMetadata %s: %v", name, err) |
| 91 | continue |
| 92 | } |
| 93 | meta, _, err := extractMetadata(b) |
| 94 | if err != nil { |
| 95 | log.Printf("updateMetadata: %s: %v", name, err) |
| 96 | continue |
| 97 | } |
| 98 | // Present all .md as if they were .html, |
| 99 | // so that it doesn't matter which one a page is written in. |
| 100 | if strings.HasSuffix(name, ".md") { |
| 101 | name = strings.TrimSuffix(name, ".md") + ".html" |
| 102 | } |
| 103 | // Store relative filesystem path in Metadata. |
| 104 | meta.filePath = name |
| 105 | if meta.Path == "" { |
| 106 | // If no Path, canonical path is actual path with .html removed. |
| 107 | meta.Path = strings.TrimSuffix(name, ".html") |
| 108 | } |
| 109 | // Store under both paths. |
| 110 | metadata[meta.Path] = &meta |
| 111 | metadata[meta.filePath] = &meta |
| 112 | for _, path := range meta.AltPaths { |
| 113 | metadata[path] = &meta |
| 114 | } |
| 115 | } |
| 116 | } |
| 117 | scan("/doc") |
| 118 | c.docMetadata.Set(metadata) |
| 119 | } |
| 120 | |
| 121 | // MetadataFor returns the *Metadata for a given relative path or nil if none |
| 122 | // exists. |
| 123 | func (c *Corpus) MetadataFor(relpath string) *Metadata { |
| 124 | if m, _ := c.docMetadata.Get(); m != nil { |
| 125 | meta := m.(map[string]*Metadata) |
| 126 | // If metadata for this relpath exists, return it. |
| 127 | if p := meta[relpath]; p != nil { |
| 128 | return p |
| 129 | } |
| 130 | // Try with or without trailing slash. |
| 131 | if strings.HasSuffix(relpath, "/") { |
| 132 | relpath = relpath[:len(relpath)-1] |
| 133 | } else { |
| 134 | relpath = relpath + "/" |
| 135 | } |
| 136 | return meta[relpath] |
| 137 | } |
| 138 | return nil |
| 139 | } |
| 140 | |
| 141 | // refreshMetadata sends a signal to update DocMetadata. If a refresh is in |
| 142 | // progress the metadata will be refreshed again afterward. |
| 143 | func (c *Corpus) refreshMetadata() { |
| 144 | select { |
| 145 | case c.refreshMetadataSignal <- true: |
| 146 | default: |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | // RefreshMetadataLoop runs forever, updating DocMetadata when the underlying |
| 151 | // file system changes. It should be launched in a goroutine. |
| 152 | func (c *Corpus) refreshMetadataLoop() { |
| 153 | for { |
| 154 | <-c.refreshMetadataSignal |
| 155 | c.updateMetadata() |
| 156 | time.Sleep(10 * time.Second) // at most once every 10 seconds |
| 157 | } |
| 158 | } |
| 159 |
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