code review 2098044: godoc: moved package directory support code into separa...

src/cmd/godoc/dirtrees.go

Index: src/cmd/godoc/dirtrees.go
===================================================================
new file mode 100644
--- /dev/null
+++ b/src/cmd/godoc/dirtrees.go
@@ -0,0 +1,301 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the code dealing with package directory trees.
+
+package main
+
+import (
+	"go/doc"
+	"go/parser"
+	"io/ioutil"
+	"os"
+	pathutil "path"
+	"strings"
+	"unicode"
+)
+
+
+type Directory struct {
+	Depth int
+	Path  string // includes Name
+	Name  string
+	Text  string       // package documentation, if any
+	Dirs  []*Directory // subdirectories
+}
+
+
+func isGoFile(f *os.FileInfo) bool {
+	return f.IsRegular() &&
+		!strings.HasPrefix(f.Name, ".") && // ignore .files
+		pathutil.Ext(f.Name) == ".go"
+}
+
+
+func isPkgFile(f *os.FileInfo) bool {
+	return isGoFile(f) &&
+		!strings.HasSuffix(f.Name, "_test.go") // ignore test files
+}
+
+
+func isPkgDir(f *os.FileInfo) bool {
+	return f.IsDirectory() && len(f.Name) > 0 && f.Name[0] != '_'
+}
+
+
+func firstSentence(s string) string {
+	i := -1 // index+1 of first terminator (punctuation ending a sentence)
+	j := -1 // index+1 of first terminator followed by white space
+	prev := 'A'
+	for k, ch := range s {
+		k1 := k + 1
+		if ch == '.' || ch == '!' || ch == '?' {
+			if i < 0 {
+				i = k1 // first terminator
+			}
+			if k1 < len(s) && s[k1] <= ' ' {
+				if j < 0 {
+					j = k1 // first terminator followed by white space
+				}
+				if !unicode.IsUpper(prev) {
+					j = k1
+					break
+				}
+			}
+		}
+		prev = ch
+	}
+
+	if j < 0 {
+		// use the next best terminator
+		j = i
+		if j < 0 {
+			// no terminator at all, use the entire string
+			j = len(s)
+		}
+	}
+
+	return s[0:j]
+}
+
+
+func newDirTree(path, name string, depth, maxDepth int) *Directory {
+	if depth >= maxDepth {
+		// return a dummy directory so that the parent directory
+		// doesn't get discarded just because we reached the max
+		// directory depth
+		return &Directory{depth, path, name, "", nil}
+	}
+
+	list, _ := ioutil.ReadDir(path) // ignore errors
+
+	// determine number of subdirectories and package files
+	ndirs := 0
+	nfiles := 0
+	var synopses [4]string // prioritized package documentation (0 == highest priority)
+	for _, d := range list {
+		switch {
+		case isPkgDir(d):
+			ndirs++
+		case isPkgFile(d):
+			nfiles++
+			if synopses[0] == "" {
+				// no "optimal" package synopsis yet; continue to collect synopses
+				file, err := parser.ParseFile(pathutil.Join(path, d.Name), nil,
+					parser.ParseComments|parser.PackageClauseOnly)
+				if err == nil && file.Doc != nil {
+					// prioritize documentation
+					i := -1
+					switch file.Name.Name {
+					case name:
+						i = 0 // normal case: directory name matches package name
+					case fakePkgName:
+						i = 1 // synopses for commands
+					case "main":
+						i = 2 // directory contains a main package
+					default:
+						i = 3 // none of the above
+					}
+					if 0 <= i && i < len(synopses) && synopses[i] == "" {
+						synopses[i] = firstSentence(doc.CommentText(file.Doc))
+					}
+				}
+			}
+		}
+	}
+
+	// create subdirectory tree
+	var dirs []*Directory
+	if ndirs > 0 {
+		dirs = make([]*Directory, ndirs)
+		i := 0
+		for _, d := range list {
+			if isPkgDir(d) {
+				dd := newDirTree(pathutil.Join(path, d.Name), d.Name, depth+1, maxDepth)
+				if dd != nil {
+					dirs[i] = dd
+					i++
+				}
+			}
+		}
+		dirs = dirs[0:i]
+	}
+
+	// if there are no package files and no subdirectories
+	// (with package files), ignore the directory
+	if nfiles == 0 && len(dirs) == 0 {
+		return nil
+	}
+
+	// select the highest-priority synopsis for the directory entry, if any
+	synopsis := ""
+	for _, synopsis = range synopses {
+		if synopsis != "" {
+			break
+		}
+	}
+
+	return &Directory{depth, path, name, synopsis, dirs}
+}
+
+
+// newDirectory creates a new package directory tree with at most maxDepth
+// levels, anchored at root. The result tree is pruned such that it only
+// contains directories that contain package files or that contain
+// subdirectories containing package files (transitively). If maxDepth is
+// too shallow, the leaf nodes are assumed to contain package files even if
+// their contents are not known (i.e., in this case the tree may contain
+// directories w/o any package files).
+//
+func newDirectory(root string, maxDepth int) *Directory {
+	d, err := os.Lstat(root)
+	if err != nil || !isPkgDir(d) {
+		return nil
+	}
+	return newDirTree(root, d.Name, 0, maxDepth)
+}
+
+
+func (dir *Directory) walk(c chan<- *Directory, skipRoot bool) {
+	if dir != nil {
+		if !skipRoot {
+			c <- dir
+		}
+		for _, d := range dir.Dirs {
+			d.walk(c, false)
+		}
+	}
+}
+
+
+func (dir *Directory) iter(skipRoot bool) <-chan *Directory {
+	c := make(chan *Directory)
+	go func() {
+		dir.walk(c, skipRoot)
+		close(c)
+	}()
+	return c
+}
+
+
+func (dir *Directory) lookupLocal(name string) *Directory {
+	for _, d := range dir.Dirs {
+		if d.Name == name {
+			return d
+		}
+	}
+	return nil
+}
+
+
+// lookup looks for the *Directory for a given path, relative to dir.
+func (dir *Directory) lookup(path string) *Directory {
+	d := strings.Split(dir.Path, "/", -1)
+	p := strings.Split(path, "/", -1)
+	i := 0
+	for i < len(d) {
+		if i >= len(p) || d[i] != p[i] {
+			return nil
+		}
+		i++
+	}
+	for dir != nil && i < len(p) {
+		dir = dir.lookupLocal(p[i])
+		i++
+	}
+	return dir
+}
+
+
+// DirEntry describes a directory entry. The Depth and Height values
+// are useful for presenting an entry in an indented fashion.
+//
+type DirEntry struct {
+	Depth    int    // >= 0
+	Height   int    // = DirList.MaxHeight - Depth, > 0
+	Path     string // includes Name, relative to DirList root
+	Name     string
+	Synopsis string
+}
+
+
+type DirList struct {
+	MaxHeight int // directory tree height, > 0
+	List      []DirEntry
+}
+
+
+// listing creates a (linear) directory listing from a directory tree.
+// If skipRoot is set, the root directory itself is excluded from the list.
+//
+func (root *Directory) listing(skipRoot bool) *DirList {
+	if root == nil {
+		return nil
+	}
+
+	// determine number of entries n and maximum height
+	n := 0
+	minDepth := 1 << 30 // infinity
+	maxDepth := 0
+	for d := range root.iter(skipRoot) {
+		n++
+		if minDepth > d.Depth {
+			minDepth = d.Depth
+		}
+		if maxDepth < d.Depth {
+			maxDepth = d.Depth
+		}
+	}
+	maxHeight := maxDepth - minDepth + 1
+
+	if n == 0 {
+		return nil
+	}
+
+	// create list
+	list := make([]DirEntry, n)
+	i := 0
+	for d := range root.iter(skipRoot) {
+		p := &list[i]
+		p.Depth = d.Depth - minDepth
+		p.Height = maxHeight - p.Depth
+		// the path is relative to root.Path - remove the root.Path
+		// prefix (the prefix should always be present but avoid
+		// crashes and check)
+		path := d.Path
+		if strings.HasPrefix(d.Path, root.Path) {
+			path = d.Path[len(root.Path):]
+		}
+		// remove trailing '/' if any - path must be relative
+		if len(path) > 0 && path[0] == '/' {
+			path = path[1:]
+		}
+		p.Path = path
+		p.Name = d.Name
+		p.Synopsis = d.Text
+		i++
+	}
+
+	return &DirList{maxHeight, list}
+}