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internal/godoc: split text formatting into internal/texthtml 

Change-Id: Iaef43e66c32dbeb7c3fc3a4a769112d153c57ce1
Reviewed-on: https://go-review.googlesource.com/c/website/+/295409
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
This commit is contained in:
Russ Cox 2021-02-17 22:50:57 -05:00
Родитель 2d643c47ce
Коммит 4eb9b856a3
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374
internal/godoc/format.go
Просмотреть файл

@ -1,374 +0,0 @@
// Copyright 2011 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.
//go:build go1.16
// +build go1.16
// This file implements FormatSelections and FormatText.
// FormatText is used to HTML-format Go and non-Go source
// text with line numbers and highlighted sections. It is
// built on top of FormatSelections, a generic formatter
// for "selected" text.
package godoc
import (
"fmt"
"go/scanner"
"go/token"
"io"
"regexp"
"strconv"
"text/template"
)
// ----------------------------------------------------------------------------
// Implementation of FormatSelections
// A Segment describes a text segment [start, end).
// The zero value of a Segment is a ready-to-use empty segment.
//
type Segment struct {
start, end int
}
func (seg *Segment) isEmpty() bool { return seg.start >= seg.end }
// A Selection is an "iterator" function returning a text segment.
// Repeated calls to a selection return consecutive, non-overlapping,
// non-empty segments, followed by an infinite sequence of empty
// segments. The first empty segment marks the end of the selection.
//
type Selection func() Segment
// A LinkWriter writes some start or end "tag" to w for the text offset offs.
// It is called by FormatSelections at the start or end of each link segment.
//
type LinkWriter func(w io.Writer, offs int, start bool)
// A SegmentWriter formats a text according to selections and writes it to w.
// The selections parameter is a bit set indicating which selections provided
// to FormatSelections overlap with the text segment: If the n'th bit is set
// in selections, the n'th selection provided to FormatSelections is overlapping
// with the text.
//
type SegmentWriter func(w io.Writer, text []byte, selections int)
// FormatSelections takes a text and writes it to w using link and segment
// writers lw and sw as follows: lw is invoked for consecutive segment starts
// and ends as specified through the links selection, and sw is invoked for
// consecutive segments of text overlapped by the same selections as specified
// by selections. The link writer lw may be nil, in which case the links
// Selection is ignored.
//
func FormatSelections(w io.Writer, text []byte, lw LinkWriter, links Selection, sw SegmentWriter, selections ...Selection) {
// If we have a link writer, make the links
// selection the last entry in selections
if lw != nil {
selections = append(selections, links)
}
// compute the sequence of consecutive segment changes
changes := newMerger(selections)
// The i'th bit in bitset indicates that the text
// at the current offset is covered by selections[i].
bitset := 0
lastOffs := 0
// Text segments are written in a delayed fashion
// such that consecutive segments belonging to the
// same selection can be combined (peephole optimization).
// last describes the last segment which has not yet been written.
var last struct {
begin, end int // valid if begin < end
bitset int
}
// flush writes the last delayed text segment
flush := func() {
if last.begin < last.end {
sw(w, text[last.begin:last.end], last.bitset)
}
last.begin = last.end // invalidate last
}
// segment runs the segment [lastOffs, end) with the selection
// indicated by bitset through the segment peephole optimizer.
segment := func(end int) {
if lastOffs < end { // ignore empty segments
if last.end != lastOffs || last.bitset != bitset {
// the last segment is not adjacent to or
// differs from the new one
flush()
// start a new segment
last.begin = lastOffs
}
last.end = end
last.bitset = bitset
}
}
for {
// get the next segment change
index, offs, start := changes.next()
if index < 0 || offs > len(text) {
// no more segment changes or the next change
// is past the end of the text - we're done
break
}
// determine the kind of segment change
if lw != nil && index == len(selections)-1 {
// we have a link segment change (see start of this function):
// format the previous selection segment, write the
// link tag and start a new selection segment
segment(offs)
flush()
lastOffs = offs
lw(w, offs, start)
} else {
// we have a selection change:
// format the previous selection segment, determine
// the new selection bitset and start a new segment
segment(offs)
lastOffs = offs
mask := 1 << uint(index)
if start {
bitset |= mask
} else {
bitset &^= mask
}
}
}
segment(len(text))
flush()
}
// A merger merges a slice of Selections and produces a sequence of
// consecutive segment change events through repeated next() calls.
//
type merger struct {
selections []Selection
segments []Segment // segments[i] is the next segment of selections[i]
}
const infinity int = 2e9
func newMerger(selections []Selection) *merger {
segments := make([]Segment, len(selections))
for i, sel := range selections {
segments[i] = Segment{infinity, infinity}
if sel != nil {
if seg := sel(); !seg.isEmpty() {
segments[i] = seg
}
}
}
return &merger{selections, segments}
}
// next returns the next segment change: index specifies the Selection
// to which the segment belongs, offs is the segment start or end offset
// as determined by the start value. If there are no more segment changes,
// next returns an index value < 0.
//
func (m *merger) next() (index, offs int, start bool) {
// find the next smallest offset where a segment starts or ends
offs = infinity
index = -1
for i, seg := range m.segments {
switch {
case seg.start < offs:
offs = seg.start
index = i
start = true
case seg.end < offs:
offs = seg.end
index = i
start = false
}
}
if index < 0 {
// no offset found => all selections merged
return
}
// offset found - it's either the start or end offset but
// either way it is ok to consume the start offset: set it
// to infinity so it won't be considered in the following
// next call
m.segments[index].start = infinity
if start {
return
}
// end offset found - consume it
m.segments[index].end = infinity
// advance to the next segment for that selection
seg := m.selections[index]()
if !seg.isEmpty() {
m.segments[index] = seg
}
return
}
// ----------------------------------------------------------------------------
// Implementation of FormatText
// lineSelection returns the line segments for text as a Selection.
func lineSelection(text []byte) Selection {
i, j := 0, 0
return func() (seg Segment) {
// find next newline, if any
for j < len(text) {
j++
if text[j-1] == '\n' {
break
}
}
if i < j {
// text[i:j] constitutes a line
seg = Segment{i, j}
i = j
}
return
}
}
// tokenSelection returns, as a selection, the sequence of
// consecutive occurrences of token sel in the Go src text.
//
func tokenSelection(src []byte, sel token.Token) Selection {
var s scanner.Scanner
fset := token.NewFileSet()
file := fset.AddFile("", fset.Base(), len(src))
s.Init(file, src, nil, scanner.ScanComments)
return func() (seg Segment) {
for {
pos, tok, lit := s.Scan()
if tok == token.EOF {
break
}
offs := file.Offset(pos)
if tok == sel {
seg = Segment{offs, offs + len(lit)}
break
}
}
return
}
}
// makeSelection is a helper function to make a Selection from a slice of pairs.
// Pairs describing empty segments are ignored.
//
func makeSelection(matches [][]int) Selection {
i := 0
return func() Segment {
for i < len(matches) {
m := matches[i]
i++
if m[0] < m[1] {
// non-empty segment
return Segment{m[0], m[1]}
}
}
return Segment{}
}
}
// regexpSelection computes the Selection for the regular expression expr in text.
func regexpSelection(text []byte, expr string) Selection {
var matches [][]int
if rx, err := regexp.Compile(expr); err == nil {
matches = rx.FindAllIndex(text, -1)
}
return makeSelection(matches)
}
var selRx = regexp.MustCompile(`^([0-9]+):([0-9]+)`)
// RangeSelection computes the Selection for a text range described
// by the argument str; the range description must match the selRx
// regular expression.
func RangeSelection(str string) Selection {
m := selRx.FindStringSubmatch(str)
if len(m) >= 2 {
from, _ := strconv.Atoi(m[1])
to, _ := strconv.Atoi(m[2])
if from < to {
return makeSelection([][]int{{from, to}})
}
}
return nil
}
// Span tags for all the possible selection combinations that may
// be generated by FormatText. Selections are indicated by a bitset,
// and the value of the bitset specifies the tag to be used.
//
// bit 0: comments
// bit 1: highlights
// bit 2: selections
//
var startTags = [][]byte{
/* 000 */ []byte(``),
/* 001 */ []byte(`<span class="comment">`),
/* 010 */ []byte(`<span class="highlight">`),
/* 011 */ []byte(`<span class="highlight-comment">`),
/* 100 */ []byte(`<span class="selection">`),
/* 101 */ []byte(`<span class="selection-comment">`),
/* 110 */ []byte(`<span class="selection-highlight">`),
/* 111 */ []byte(`<span class="selection-highlight-comment">`),
}
var endTag = []byte(`</span>`)
func selectionTag(w io.Writer, text []byte, selections int) {
if selections < len(startTags) {
if tag := startTags[selections]; len(tag) > 0 {
w.Write(tag)
template.HTMLEscape(w, text)
w.Write(endTag)
return
}
}
template.HTMLEscape(w, text)
}
// FormatText HTML-escapes text and writes it to w.
// Consecutive text segments are wrapped in HTML spans (with tags as
// defined by startTags and endTag) as follows:
//
// - if line >= 0, line number (ln) spans are inserted before each line,
// starting with the value of line
// - if the text is Go source, comments get the "comment" span class
// - each occurrence of the regular expression pattern gets the "highlight"
// span class
// - text segments covered by selection get the "selection" span class
//
// Comments, highlights, and selections may overlap arbitrarily; the respective
// HTML span classes are specified in the startTags variable.
//
func FormatText(w io.Writer, text []byte, line int, goSource bool, pattern string, selection Selection) {
var comments, highlights Selection
if goSource {
comments = tokenSelection(text, token.COMMENT)
}
if pattern != "" {
highlights = regexpSelection(text, pattern)
}
if line >= 0 || comments != nil || highlights != nil || selection != nil {
var lineTag LinkWriter
if line >= 0 {
lineTag = func(w io.Writer, _ int, start bool) {
if start {
fmt.Fprintf(w, "<span id=\"L%d\" class=\"ln\">%6d</span>", line, line)
line++
}
}
}
FormatSelections(w, text, lineTag, lineSelection(text), selectionTag, comments, highlights, selection)
} else {
template.HTMLEscape(w, text)
}
}

149
internal/godoc/godoc.go
Просмотреть файл

@ -31,6 +31,8 @@ import (
"time"
"unicode"
"unicode/utf8"
"golang.org/x/website/internal/texthtml"
)
// Fake relative package path for built-ins. Documentation for all globals
@ -127,150 +129,17 @@ func (p *Presentation) node_htmlFunc(info *PageInfo, node interface{}, linkify b
p.writeNode(&buf1, info, info.FSet, node)
var buf2 bytes.Buffer
if n, _ := node.(ast.Node); n != nil && linkify && p.DeclLinks {
LinkifyText(&buf2, buf1.Bytes(), n)
if st, name := isStructTypeDecl(n); st != nil {
addStructFieldIDAttributes(&buf2, name, st)
var n ast.Node
if linkify && p.DeclLinks {
n, _ = node.(ast.Node)
}
} else {
FormatText(&buf2, buf1.Bytes(), -1, true, "", nil)
}
buf2.Write(texthtml.Format(buf1.Bytes(), texthtml.Config{
AST: n,
GoComments: true,
}))
return buf2.String()
}
// isStructTypeDecl checks whether n is a struct declaration.
// It either returns a non-nil StructType and its name, or zero values.
func isStructTypeDecl(n ast.Node) (st *ast.StructType, name string) {
gd, ok := n.(*ast.GenDecl)
if !ok || gd.Tok != token.TYPE {
return nil, ""
}
if gd.Lparen > 0 {
// Parenthesized type. Who does that, anyway?
// TODO: Reportedly gri does. Fix this to handle that too.
return nil, ""
}
if len(gd.Specs) != 1 {
return nil, ""
}
ts, ok := gd.Specs[0].(*ast.TypeSpec)
if !ok {
return nil, ""
}
st, ok = ts.Type.(*ast.StructType)
if !ok {
return nil, ""
}
return st, ts.Name.Name
}
// addStructFieldIDAttributes modifies the contents of buf such that
// all struct fields of the named struct have <span id='name.Field'>
// in them, so people can link to /#Struct.Field.
func addStructFieldIDAttributes(buf *bytes.Buffer, name string, st *ast.StructType) {
if st.Fields == nil {
return
}
// needsLink is a set of identifiers that still need to be
// linked, where value == key, to avoid an allocation in func
// linkedField.
needsLink := make(map[string]string)
for _, f := range st.Fields.List {
if len(f.Names) == 0 {
continue
}
fieldName := f.Names[0].Name
needsLink[fieldName] = fieldName
}
var newBuf bytes.Buffer
foreachLine(buf.Bytes(), func(line []byte) {
if fieldName := linkedField(line, needsLink); fieldName != "" {
fmt.Fprintf(&newBuf, `<span id="%s.%s"></span>`, name, fieldName)
delete(needsLink, fieldName)
}
newBuf.Write(line)
})
buf.Reset()
buf.Write(newBuf.Bytes())
}
// foreachLine calls fn for each line of in, where a line includes
// the trailing "\n", except on the last line, if it doesn't exist.
func foreachLine(in []byte, fn func(line []byte)) {
for len(in) > 0 {
nl := bytes.IndexByte(in, '\n')
if nl == -1 {
fn(in)
return
}
fn(in[:nl+1])
in = in[nl+1:]
}
}
// commentPrefix is the line prefix for comments after they've been HTMLified.
var commentPrefix = []byte(`<span class="comment">// `)
// linkedField determines whether the given line starts with an
// identifier in the provided ids map (mapping from identifier to the
// same identifier). The line can start with either an identifier or
// an identifier in a comment. If one matches, it returns the
// identifier that matched. Otherwise it returns the empty string.
func linkedField(line []byte, ids map[string]string) string {
line = bytes.TrimSpace(line)
// For fields with a doc string of the
// conventional form, we put the new span into
// the comment instead of the field.
// The "conventional" form is a complete sentence
// per https://golang.org/s/style#comment-sentences like:
//
// // Foo is an optional Fooer to foo the foos.
// Foo Fooer
//
// In this case, we want the #StructName.Foo
// link to make the browser go to the comment
// line "Foo is an optional Fooer" instead of
// the "Foo Fooer" line, which could otherwise
// obscure the docs above the browser's "fold".
//
// TODO: do this better, so it works for all
// comments, including unconventional ones.
line = bytes.TrimPrefix(line, commentPrefix)
id := scanIdentifier(line)
if len(id) == 0 {
// No leading identifier. Avoid map lookup for
// somewhat common case.
return ""
}
return ids[string(id)]
}
// scanIdentifier scans a valid Go identifier off the front of v and
// either returns a subslice of v if there's a valid identifier, or
// returns a zero-length slice.
func scanIdentifier(v []byte) []byte {
var n int // number of leading bytes of v belonging to an identifier
for {
r, width := utf8.DecodeRune(v[n:])
if !(isLetter(r) || n > 0 && isDigit(r)) {
break
}
n += width
}
return v[:n]
}
func isLetter(ch rune) bool {
return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
}
func isDigit(ch rune) bool {
return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
}
func comment_htmlFunc(comment string) string {
var buf bytes.Buffer
// TODO(gri) Provide list of words (e.g. function parameters)

19
internal/godoc/godoc_test.go
Просмотреть файл

@ -250,25 +250,6 @@ func linkifySource(t *testing.T, src []byte) string {
return buf.String()
}
func TestScanIdentifier(t *testing.T) {
tests := []struct {
in, want string
}{
{"foo bar", "foo"},
{"foo/bar", "foo"},
{" foo", ""},
{"фоо", "фоо"},
{"f123", "f123"},
{"123f", ""},
}
for _, tt := range tests {
got := scanIdentifier([]byte(tt.in))
if string(got) != tt.want {
t.Errorf("scanIdentifier(%q) = %q; want %q", tt.in, got, tt.want)
}
}
}
func TestReplaceLeadingIndentation(t *testing.T) {
oldIndent := strings.Repeat(" ", 2)
newIndent := strings.Repeat(" ", 4)

198
internal/godoc/linkify.go
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@ -1,198 +0,0 @@
// Copyright 2013 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.
//go:build go1.16
// +build go1.16
// This file implements LinkifyText which introduces
// links for identifiers pointing to their declarations.
// The approach does not cover all cases because godoc
// doesn't have complete type information, but it's
// reasonably good for browsing.
package godoc
import (
"fmt"
"go/ast"
"go/doc"
"go/token"
"io"
"strconv"
)
// LinkifyText HTML-escapes source text and writes it to w.
// Identifiers that are in a "use" position (i.e., that are
// not being declared), are wrapped with HTML links pointing
// to the respective declaration, if possible. Comments are
// formatted the same way as with FormatText.
//
func LinkifyText(w io.Writer, text []byte, n ast.Node) {
links := linksFor(n)
i := 0 // links index
prev := "" // prev HTML tag
linkWriter := func(w io.Writer, _ int, start bool) {
// end tag
if !start {
if prev != "" {
fmt.Fprintf(w, `</%s>`, prev)
prev = ""
}
return
}
// start tag
prev = ""
if i < len(links) {
switch info := links[i]; {
case info.path != "" && info.name == "":
// package path
fmt.Fprintf(w, `<a href="/pkg/%s/">`, info.path)
prev = "a"
case info.path != "" && info.name != "":
// qualified identifier
fmt.Fprintf(w, `<a href="/pkg/%s/#%s">`, info.path, info.name)
prev = "a"
case info.path == "" && info.name != "":
// local identifier
if info.isVal {
fmt.Fprintf(w, `<span id="%s">`, info.name)
prev = "span"
} else if ast.IsExported(info.name) {
fmt.Fprintf(w, `<a href="#%s">`, info.name)
prev = "a"
}
}
i++
}
}
idents := tokenSelection(text, token.IDENT)
comments := tokenSelection(text, token.COMMENT)
FormatSelections(w, text, linkWriter, idents, selectionTag, comments)
}
// A link describes the (HTML) link information for an identifier.
// The zero value of a link represents "no link".
//
type link struct {
path, name string // package path, identifier name
isVal bool // identifier is defined in a const or var declaration
}
// linksFor returns the list of links for the identifiers used
// by node in the same order as they appear in the source.
//
func linksFor(node ast.Node) (links []link) {
// linkMap tracks link information for each ast.Ident node. Entries may
// be created out of source order (for example, when we visit a parent
// definition node). These links are appended to the returned slice when
// their ast.Ident nodes are visited.
linkMap := make(map[*ast.Ident]link)
ast.Inspect(node, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.Field:
for _, n := range n.Names {
linkMap[n] = link{}
}
case *ast.ImportSpec:
if name := n.Name; name != nil {
linkMap[name] = link{}
}
case *ast.ValueSpec:
for _, n := range n.Names {
linkMap[n] = link{name: n.Name, isVal: true}
}
case *ast.FuncDecl:
linkMap[n.Name] = link{}
case *ast.TypeSpec:
linkMap[n.Name] = link{}
case *ast.AssignStmt:
// Short variable declarations only show up if we apply
// this code to all source code (as opposed to exported
// declarations only).
if n.Tok == token.DEFINE {
// Some of the lhs variables may be re-declared,
// so technically they are not defs. We don't
// care for now.
for _, x := range n.Lhs {
// Each lhs expression should be an
// ident, but we are conservative and check.
if n, _ := x.(*ast.Ident); n != nil {
linkMap[n] = link{isVal: true}
}
}
}
case *ast.SelectorExpr:
// Detect qualified identifiers of the form pkg.ident.
// If anything fails we return true and collect individual
// identifiers instead.
if x, _ := n.X.(*ast.Ident); x != nil {
// Create links only if x is a qualified identifier.
if obj := x.Obj; obj != nil && obj.Kind == ast.Pkg {
if spec, _ := obj.Decl.(*ast.ImportSpec); spec != nil {
// spec.Path.Value is the import path
if path, err := strconv.Unquote(spec.Path.Value); err == nil {
// Register two links, one for the package
// and one for the qualified identifier.
linkMap[x] = link{path: path}
linkMap[n.Sel] = link{path: path, name: n.Sel.Name}
}
}
}
}
case *ast.CompositeLit:
// Detect field names within composite literals. These links should
// be prefixed by the type name.
fieldPath := ""
prefix := ""
switch typ := n.Type.(type) {
case *ast.Ident:
prefix = typ.Name + "."
case *ast.SelectorExpr:
if x, _ := typ.X.(*ast.Ident); x != nil {
// Create links only if x is a qualified identifier.
if obj := x.Obj; obj != nil && obj.Kind == ast.Pkg {
if spec, _ := obj.Decl.(*ast.ImportSpec); spec != nil {
// spec.Path.Value is the import path
if path, err := strconv.Unquote(spec.Path.Value); err == nil {
// Register two links, one for the package
// and one for the qualified identifier.
linkMap[x] = link{path: path}
linkMap[typ.Sel] = link{path: path, name: typ.Sel.Name}
fieldPath = path
prefix = typ.Sel.Name + "."
}
}
}
}
}
for _, e := range n.Elts {
if kv, ok := e.(*ast.KeyValueExpr); ok {
if k, ok := kv.Key.(*ast.Ident); ok {
// Note: there is some syntactic ambiguity here. We cannot determine
// if this is a struct literal or a map literal without type
// information. We assume struct literal.
name := prefix + k.Name
linkMap[k] = link{path: fieldPath, name: name}
}
}
}
case *ast.Ident:
if l, ok := linkMap[n]; ok {
links = append(links, l)
} else {
l := link{name: n.Name}
if n.Obj == nil && doc.IsPredeclared(n.Name) {
l.path = builtinPkgPath
}
links = append(links, l)
}
}
return true
})
return
}

81
internal/godoc/server.go
Просмотреть файл

@ -25,10 +25,14 @@ import (
"os"
pathpkg "path"
"path/filepath"
"regexp"
"sort"
"strconv"
"strings"
"text/template"
"time"
"golang.org/x/website/internal/texthtml"
)
// handlerServer is a migration from an old godoc http Handler type.
@ -555,6 +559,23 @@ func redirectFile(w http.ResponseWriter, r *http.Request) (redirected bool) {
return
}
var selRx = regexp.MustCompile(`^([0-9]+):([0-9]+)`)
// rangeSelection computes the Selection for a text range described
// by the argument str, of the form Start:End, where Start and End
// are decimal byte offsets.
func rangeSelection(str string) texthtml.Selection {
m := selRx.FindStringSubmatch(str)
if len(m) >= 2 {
from, _ := strconv.Atoi(m[1])
to, _ := strconv.Atoi(m[2])
if from < to {
return texthtml.Spans(texthtml.Span{Start: from, End: to})
}
}
return nil
}
func (p *Presentation) serveTextFile(w http.ResponseWriter, r *http.Request, abspath, relpath, title string) {
src, err := fs.ReadFile(p.Corpus.fs, toFS(abspath))
if err != nil {
@ -568,19 +589,18 @@ func (p *Presentation) serveTextFile(w http.ResponseWriter, r *http.Request, abs
return
}
h := r.FormValue("h")
s := RangeSelection(r.FormValue("s"))
cfg := texthtml.Config{
GoComments: pathpkg.Ext(abspath) == ".go",
Highlight: r.FormValue("h"),
Selection: rangeSelection(r.FormValue("s")),
Line: 1,
}
var buf bytes.Buffer
if pathpkg.Ext(abspath) == ".go" {
buf.WriteString("<pre>")
formatGoSource(&buf, src, h, s)
buf.Write(texthtml.Format(src, cfg))
buf.WriteString("</pre>")
} else {
buf.WriteString("<pre>")
FormatText(&buf, src, 1, false, h, s)
buf.WriteString("</pre>")
}
fmt.Fprintf(&buf, `<p><a href="/%s?m=text">View as plain text</a></p>`, htmlpkg.EscapeString(relpath))
p.ServePage(w, Page{
@ -592,49 +612,6 @@ func (p *Presentation) serveTextFile(w http.ResponseWriter, r *http.Request, abs
})
}
// formatGoSource HTML-escapes Go source text and writes it to w.
func formatGoSource(buf *bytes.Buffer, text []byte, pattern string, selection Selection) {
// Emit to a temp buffer so that we can add line anchors at the end.
saved, buf := buf, new(bytes.Buffer)
comments := tokenSelection(text, token.COMMENT)
var highlights Selection
if pattern != "" {
highlights = regexpSelection(text, pattern)
}
FormatSelections(buf, text, nil, nil, selectionTag, comments, highlights, selection)
// Now copy buf to saved, adding line anchors.
// The lineSelection mechanism can't be composed with our
// linkWriter, so we have to add line spans as another pass.
n := 1
for _, line := range bytes.Split(buf.Bytes(), []byte("\n")) {
// The line numbers are inserted into the document via a CSS ::before
// pseudo-element. This prevents them from being copied when users
// highlight and copy text.
// ::before is supported in 98% of browsers: https://caniuse.com/#feat=css-gencontent
// This is also the trick Github uses to hide line numbers.
//
// The first tab for the code snippet needs to start in column 9, so
// it indents a full 8 spaces, hence the two nbsp's. Otherwise the tab
// character only indents a short amount.
//
// Due to rounding and font width Firefox might not treat 8 rendered
// characters as 8 characters wide, and subsequently may treat the tab
// character in the 9th position as moving the width from (7.5 or so) up
// to 8. See
// https://github.com/webcompat/web-bugs/issues/17530#issuecomment-402675091
// for a fuller explanation. The solution is to add a CSS class to
// explicitly declare the width to be 8 characters.
fmt.Fprintf(saved, `<span id="L%d" class="ln">%6d&nbsp;&nbsp;</span>`, n, n)
n++
saved.Write(line)
saved.WriteByte('\n')
}
}
func (p *Presentation) serveDirectory(w http.ResponseWriter, r *http.Request, abspath, relpath string) {
if redirect(w, r) {
return

4
internal/godoc/template.go
Просмотреть файл

@ -41,6 +41,8 @@ import (
"log"
"regexp"
"strings"
"golang.org/x/website/internal/texthtml"
)
// Functions in this file panic on error, but the panic is recovered
@ -100,7 +102,7 @@ func (p *Presentation) code(file string, arg ...interface{}) (s string, err erro
text = strings.Replace(text, "\t", " ", -1)
var buf bytes.Buffer
// HTML-escape text and syntax-color comments like elsewhere.
FormatText(&buf, []byte(text), -1, true, "", nil)
buf.Write(texthtml.Format([]byte(text), texthtml.Config{GoComments: true}))
// Include the command as a comment.
text = fmt.Sprintf("<pre><!--{{%s}}\n-->%s</pre>", command, buf.Bytes())
return text, nil

298
internal/texthtml/ast.go Normal file
Просмотреть файл

@ -0,0 +1,298 @@
// Copyright 2011 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.
package texthtml
import (
"bytes"
"fmt"
"go/ast"
"go/doc"
"go/token"
"strconv"
"unicode"
"unicode/utf8"
)
// A goLink describes the (HTML) link information for a Go identifier.
// The zero value of a link represents "no link".
type goLink struct {
path, name string // package path, identifier name
isVal bool // identifier is defined in a const or var declaration
}
func (l *goLink) tags() (start, end string) {
switch {
case l.path != "" && l.name == "":
// package path
return `<a href="/pkg/` + l.path + `/">`, `</a>`
case l.path != "" && l.name != "":
// qualified identifier
return `<a href="/pkg/` + l.path + `/#` + l.name + `">`, `</a>`
case l.path == "" && l.name != "":
// local identifier
if l.isVal {
return `<span id="` + l.name + `">`, `</span>`
}
if ast.IsExported(l.name) {
return `<a href="#` + l.name + `">`, `</a>`
}
}
return "", ""
}
// goLinksFor returns the list of links for the identifiers used
// by node in the same order as they appear in the source.
func goLinksFor(node ast.Node) (links []goLink) {
// linkMap tracks link information for each ast.Ident node. Entries may
// be created out of source order (for example, when we visit a parent
// definition node). These links are appended to the returned slice when
// their ast.Ident nodes are visited.
linkMap := make(map[*ast.Ident]goLink)
ast.Inspect(node, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.Field:
for _, n := range n.Names {
linkMap[n] = goLink{}
}
case *ast.ImportSpec:
if name := n.Name; name != nil {
linkMap[name] = goLink{}
}
case *ast.ValueSpec:
for _, n := range n.Names {
linkMap[n] = goLink{name: n.Name, isVal: true}
}
case *ast.FuncDecl:
linkMap[n.Name] = goLink{}
case *ast.TypeSpec:
linkMap[n.Name] = goLink{}
case *ast.AssignStmt:
// Short variable declarations only show up if we apply
// this code to all source code (as opposed to exported
// declarations only).
if n.Tok == token.DEFINE {
// Some of the lhs variables may be re-declared,
// so technically they are not defs. We don't
// care for now.
for _, x := range n.Lhs {
// Each lhs expression should be an
// ident, but we are conservative and check.
if n, _ := x.(*ast.Ident); n != nil {
linkMap[n] = goLink{isVal: true}
}
}
}
case *ast.SelectorExpr:
// Detect qualified identifiers of the form pkg.ident.
// If anything fails we return true and collect individual
// identifiers instead.
if x, _ := n.X.(*ast.Ident); x != nil {
// Create links only if x is a qualified identifier.
if obj := x.Obj; obj != nil && obj.Kind == ast.Pkg {
if spec, _ := obj.Decl.(*ast.ImportSpec); spec != nil {
// spec.Path.Value is the import path
if path, err := strconv.Unquote(spec.Path.Value); err == nil {
// Register two links, one for the package
// and one for the qualified identifier.
linkMap[x] = goLink{path: path}
linkMap[n.Sel] = goLink{path: path, name: n.Sel.Name}
}
}
}
}
case *ast.CompositeLit:
// Detect field names within composite literals. These links should
// be prefixed by the type name.
fieldPath := ""
prefix := ""
switch typ := n.Type.(type) {
case *ast.Ident:
prefix = typ.Name + "."
case *ast.SelectorExpr:
if x, _ := typ.X.(*ast.Ident); x != nil {
// Create links only if x is a qualified identifier.
if obj := x.Obj; obj != nil && obj.Kind == ast.Pkg {
if spec, _ := obj.Decl.(*ast.ImportSpec); spec != nil {
// spec.Path.Value is the import path
if path, err := strconv.Unquote(spec.Path.Value); err == nil {
// Register two links, one for the package
// and one for the qualified identifier.
linkMap[x] = goLink{path: path}
linkMap[typ.Sel] = goLink{path: path, name: typ.Sel.Name}
fieldPath = path
prefix = typ.Sel.Name + "."
}
}
}
}
}
for _, e := range n.Elts {
if kv, ok := e.(*ast.KeyValueExpr); ok {
if k, ok := kv.Key.(*ast.Ident); ok {
// Note: there is some syntactic ambiguity here. We cannot determine
// if this is a struct literal or a map literal without type
// information. We assume struct literal.
name := prefix + k.Name
linkMap[k] = goLink{path: fieldPath, name: name}
}
}
}
case *ast.Ident:
if l, ok := linkMap[n]; ok {
links = append(links, l)
} else {
l := goLink{name: n.Name}
if n.Obj == nil && doc.IsPredeclared(n.Name) {
l.path = "builtin"
}
links = append(links, l)
}
}
return true
})
return
}
// postFormatAST makes any appropriate changes to the formatting of node in buf.
// Specifically, it adds span links to each struct field, so they can be linked properly.
// TODO(rsc): Why not do this as part of the linking above?
func postFormatAST(buf *bytes.Buffer, node ast.Node) {
if st, name := isStructTypeDecl(node); st != nil {
addStructFieldIDAttributes(buf, name, st)
}
}
// isStructTypeDecl checks whether n is a struct declaration.
// It either returns a non-nil StructType and its name, or zero values.
func isStructTypeDecl(n ast.Node) (st *ast.StructType, name string) {
gd, ok := n.(*ast.GenDecl)
if !ok || gd.Tok != token.TYPE {
return nil, ""
}
if gd.Lparen > 0 {
// Parenthesized type. Who does that, anyway?
// TODO: Reportedly gri does. Fix this to handle that too.
return nil, ""
}
if len(gd.Specs) != 1 {
return nil, ""
}
ts, ok := gd.Specs[0].(*ast.TypeSpec)
if !ok {
return nil, ""
}
st, ok = ts.Type.(*ast.StructType)
if !ok {
return nil, ""
}
return st, ts.Name.Name
}
// addStructFieldIDAttributes modifies the contents of buf such that
// all struct fields of the named struct have <span id='name.Field'>
// in them, so people can link to /#Struct.Field.
func addStructFieldIDAttributes(buf *bytes.Buffer, name string, st *ast.StructType) {
if st.Fields == nil {
return
}
// needsLink is a set of identifiers that still need to be
// linked, where value == key, to avoid an allocation in func
// linkedField.
needsLink := make(map[string]string)
for _, f := range st.Fields.List {
if len(f.Names) == 0 {
continue
}
fieldName := f.Names[0].Name
needsLink[fieldName] = fieldName
}
var newBuf bytes.Buffer
foreachLine(buf.Bytes(), func(line []byte) {
if fieldName := linkedField(line, needsLink); fieldName != "" {
fmt.Fprintf(&newBuf, `<span id="%s.%s"></span>`, name, fieldName)
delete(needsLink, fieldName)
}
newBuf.Write(line)
})
buf.Reset()
buf.Write(newBuf.Bytes())
}
// foreachLine calls fn for each line of in, where a line includes
// the trailing "\n", except on the last line, if it doesn't exist.
func foreachLine(in []byte, fn func(line []byte)) {
for len(in) > 0 {
nl := bytes.IndexByte(in, '\n')
if nl == -1 {
fn(in)
return
}
fn(in[:nl+1])
in = in[nl+1:]
}
}
// commentPrefix is the line prefix for comments after they've been HTMLified.
var commentPrefix = []byte(`<span class="comment">// `)
// linkedField determines whether the given line starts with an
// identifier in the provided ids map (mapping from identifier to the
// same identifier). The line can start with either an identifier or
// an identifier in a comment. If one matches, it returns the
// identifier that matched. Otherwise it returns the empty string.
func linkedField(line []byte, ids map[string]string) string {
line = bytes.TrimSpace(line)
// For fields with a doc string of the
// conventional form, we put the new span into
// the comment instead of the field.
// The "conventional" form is a complete sentence
// per https://golang.org/s/style#comment-sentences like:
//
// // Foo is an optional Fooer to foo the foos.
// Foo Fooer
//
// In this case, we want the #StructName.Foo
// link to make the browser go to the comment
// line "Foo is an optional Fooer" instead of
// the "Foo Fooer" line, which could otherwise
// obscure the docs above the browser's "fold".
//
// TODO: do this better, so it works for all
// comments, including unconventional ones.
line = bytes.TrimPrefix(line, commentPrefix)
id := scanIdentifier(line)
if len(id) == 0 {
// No leading identifier. Avoid map lookup for
// somewhat common case.
return ""
}
return ids[string(id)]
}
// scanIdentifier scans a valid Go identifier off the front of v and
// either returns a subslice of v if there's a valid identifier, or
// returns a zero-length slice.
func scanIdentifier(v []byte) []byte {
var n int // number of leading bytes of v belonging to an identifier
for {
r, width := utf8.DecodeRune(v[n:])
if !(isLetter(r) || n > 0 && isDigit(r)) {
break
}
n += width
}
return v[:n]
}
func isLetter(ch rune) bool {
return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
}
func isDigit(ch rune) bool {
return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
}

355
internal/texthtml/texthtml.go Normal file
Просмотреть файл

@ -0,0 +1,355 @@
// Copyright 2011 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.
// Package texthtml formats text files to HTML.
package texthtml
import (
"bytes"
"fmt"
"go/ast"
"go/scanner"
"go/token"
"io"
"regexp"
"text/template"
)
// A Span describes a text span [start, end).
// The zero value of a Span is an empty span.
type Span struct {
Start, End int
}
func (s *Span) isEmpty() bool { return s.Start >= s.End }
// A Selection is an "iterator" function returning a text span.
// Repeated calls to a selection return consecutive, non-overlapping,
// non-empty spans, followed by an infinite sequence of empty
// spans. The first empty span marks the end of the selection.
type Selection func() Span
// A Config configures how to format text as HTML.
type Config struct {
Line int // if >= 1, number lines beginning with number Line, with <span class="ln">
GoComments bool // mark comments in Go text with <span class="comment">
Highlight string // highlight matches for this regexp with <span class="highlight">
Selection Selection // mark selected spans with <span class="selection">
AST ast.Node // link uses to declarations, assuming text is formatting of AST
}
// Format formats text to HTML according to the configuration cfg.
func Format(text []byte, cfg Config) (html []byte) {
var comments, highlights Selection
if cfg.GoComments {
comments = tokenSelection(text, token.COMMENT)
}
if cfg.Highlight != "" {
highlights = regexpSelection(text, cfg.Highlight)
}
var buf bytes.Buffer
var idents Selection = Spans()
var goLinks []goLink
if cfg.AST != nil {
idents = tokenSelection(text, token.IDENT)
goLinks = goLinksFor(cfg.AST)
}
formatSelections(&buf, text, goLinks, comments, highlights, cfg.Selection, idents)
if cfg.AST != nil {
postFormatAST(&buf, cfg.AST)
}
if cfg.Line > 0 {
// Add line numbers in a separate pass.
old := buf.Bytes()
buf = bytes.Buffer{}
n := cfg.Line
for _, line := range bytes.Split(old, []byte("\n")) {
// The line numbers are inserted into the document via a CSS ::before
// pseudo-element. This prevents them from being copied when users
// highlight and copy text.
// ::before is supported in 98% of browsers: https://caniuse.com/#feat=css-gencontent
// This is also the trick Github uses to hide line numbers.
//
// The first tab for the code snippet needs to start in column 9, so
// it indents a full 8 spaces, hence the two nbsp's. Otherwise the tab
// character only indents a short amount.
//
// Due to rounding and font width Firefox might not treat 8 rendered
// characters as 8 characters wide, and subsequently may treat the tab
// character in the 9th position as moving the width from (7.5 or so) up
// to 8. See
// https://github.com/webcompat/web-bugs/issues/17530#issuecomment-402675091
// for a fuller explanation. The solution is to add a CSS class to
// explicitly declare the width to be 8 characters.
fmt.Fprintf(&buf, `<span id="L%d" class="ln">%6d&nbsp;&nbsp;</span>`, n, n)
n++
buf.Write(line)
buf.WriteByte('\n')
}
}
return buf.Bytes()
}
// formatSelections takes a text and writes it to w using link and span
// writers lw and sw as follows: lw is invoked for consecutive span starts
// and ends as specified through the links selection, and sw is invoked for
// consecutive spans of text overlapped by the same selections as specified
// by selections.
func formatSelections(w io.Writer, text []byte, goLinks []goLink, selections ...Selection) {
// compute the sequence of consecutive span changes
changes := newMerger(selections)
// The i'th bit in bitset indicates that the text
// at the current offset is covered by selections[i].
bitset := 0
lastOffs := 0
// Text spans are written in a delayed fashion
// such that consecutive spans belonging to the
// same selection can be combined (peephole optimization).
// last describes the last span which has not yet been written.
var last struct {
begin, end int // valid if begin < end
bitset int
}
// flush writes the last delayed text span
flush := func() {
if last.begin < last.end {
selectionTag(w, text[last.begin:last.end], last.bitset)
}
last.begin = last.end // invalidate last
}
// span runs the span [lastOffs, end) with the selection
// indicated by bitset through the span peephole optimizer.
span := func(end int) {
if lastOffs < end { // ignore empty spans
if last.end != lastOffs || last.bitset != bitset {
// the last span is not adjacent to or
// differs from the new one
flush()
// start a new span
last.begin = lastOffs
}
last.end = end
last.bitset = bitset
}
}
linkEnd := ""
for {
// get the next span change
index, offs, start := changes.next()
if index < 0 || offs > len(text) {
// no more span changes or the next change
// is past the end of the text - we're done
break
}
// format the previous selection span, determine
// the new selection bitset and start a new span
span(offs)
if index == 3 { // Go link
flush()
if start {
if len(goLinks) > 0 {
start, end := goLinks[0].tags()
io.WriteString(w, start)
linkEnd = end
goLinks = goLinks[1:]
}
} else {
if linkEnd != "" {
io.WriteString(w, linkEnd)
linkEnd = ""
}
}
} else {
mask := 1 << uint(index)
if start {
bitset |= mask
} else {
bitset &^= mask
}
}
lastOffs = offs
}
span(len(text))
flush()
}
// A merger merges a slice of Selections and produces a sequence of
// consecutive span change events through repeated next() calls.
type merger struct {
selections []Selection
spans []Span // spans[i] is the next span of selections[i]
}
const infinity int = 2e9
func newMerger(selections []Selection) *merger {
spans := make([]Span, len(selections))
for i, sel := range selections {
spans[i] = Span{infinity, infinity}
if sel != nil {
if seg := sel(); !seg.isEmpty() {
spans[i] = seg
}
}
}
return &merger{selections, spans}
}
// next returns the next span change: index specifies the Selection
// to which the span belongs, offs is the span start or end offset
// as determined by the start value. If there are no more span changes,
// next returns an index value < 0.
func (m *merger) next() (index, offs int, start bool) {
// find the next smallest offset where a span starts or ends
offs = infinity
index = -1
for i, seg := range m.spans {
switch {
case seg.Start < offs:
offs = seg.Start
index = i
start = true
case seg.End < offs:
offs = seg.End
index = i
start = false
}
}
if index < 0 {
// no offset found => all selections merged
return
}
// offset found - it's either the start or end offset but
// either way it is ok to consume the start offset: set it
// to infinity so it won't be considered in the following
// next call
m.spans[index].Start = infinity
if start {
return
}
// end offset found - consume it
m.spans[index].End = infinity
// advance to the next span for that selection
seg := m.selections[index]()
if !seg.isEmpty() {
m.spans[index] = seg
}
return
}
// lineSelection returns the line spans for text as a Selection.
func lineSelection(text []byte) Selection {
i, j := 0, 0
return func() (seg Span) {
// find next newline, if any
for j < len(text) {
j++
if text[j-1] == '\n' {
break
}
}
if i < j {
// text[i:j] constitutes a line
seg = Span{i, j}
i = j
}
return
}
}
// tokenSelection returns, as a selection, the sequence of
// consecutive occurrences of token sel in the Go src text.
func tokenSelection(src []byte, sel token.Token) Selection {
var s scanner.Scanner
fset := token.NewFileSet()
file := fset.AddFile("", fset.Base(), len(src))
s.Init(file, src, nil, scanner.ScanComments)
return func() (seg Span) {
for {
pos, tok, lit := s.Scan()
if tok == token.EOF {
break
}
offs := file.Offset(pos)
if tok == sel {
seg = Span{offs, offs + len(lit)}
break
}
}
return
}
}
// Spans is a helper function to make a Selection from a slice of spans.
// Empty spans are discarded.
func Spans(spans ...Span) Selection {
i := 0
return func() Span {
for i < len(spans) {
s := spans[i]
i++
if s.Start < s.End {
// non-empty
return s
}
}
return Span{}
}
}
// regexpSelection computes the Selection for the regular expression expr in text.
func regexpSelection(text []byte, expr string) Selection {
var matches [][]int
if rx, err := regexp.Compile(expr); err == nil {
matches = rx.FindAllIndex(text, -1)
}
var spans []Span
for _, m := range matches {
spans = append(spans, Span{m[0], m[1]})
}
return Spans(spans...)
}
// Span tags for all the possible selection combinations that may
// be generated by FormatText. Selections are indicated by a bitset,
// and the value of the bitset specifies the tag to be used.
//
// bit 0: comments
// bit 1: highlights
// bit 2: selections
//
var startTags = [][]byte{
/* 000 */ []byte(``),
/* 001 */ []byte(`<span class="comment">`),
/* 010 */ []byte(`<span class="highlight">`),
/* 011 */ []byte(`<span class="highlight-comment">`),
/* 100 */ []byte(`<span class="selection">`),
/* 101 */ []byte(`<span class="selection-comment">`),
/* 110 */ []byte(`<span class="selection-highlight">`),
/* 111 */ []byte(`<span class="selection-highlight-comment">`),
}
var endTag = []byte(`</span>`)
func selectionTag(w io.Writer, text []byte, selections int) {
if selections < len(startTags) {
if tag := startTags[selections]; len(tag) > 0 {
w.Write(tag)
template.HTMLEscape(w, text)
w.Write(endTag)
return
}
}
template.HTMLEscape(w, text)
}