VictoriaMetrics/vendor/github.com/cpuguy83/go-md2man/v2/md2man/roff.go
Aliaksandr Valialkin 7f4fb34182 app/vmctl: move vmctl code from github.com/VictoriaMetrics/vmctl
It is better developing vmctl tool in VictoriaMetrics repository, so it could be released
together with the rest of vmutils tools such as vmalert, vmagent, vmbackup, vmrestore and vmauth.
2021-02-01 01:18:39 +02:00

346 lines
8.4 KiB
Go

package md2man
import (
"fmt"
"io"
"os"
"strings"
"github.com/russross/blackfriday/v2"
)
// roffRenderer implements the blackfriday.Renderer interface for creating
// roff format (manpages) from markdown text
type roffRenderer struct {
extensions blackfriday.Extensions
listCounters []int
firstHeader bool
defineTerm bool
listDepth int
}
const (
titleHeader = ".TH "
topLevelHeader = "\n\n.SH "
secondLevelHdr = "\n.SH "
otherHeader = "\n.SS "
crTag = "\n"
emphTag = "\\fI"
emphCloseTag = "\\fP"
strongTag = "\\fB"
strongCloseTag = "\\fP"
breakTag = "\n.br\n"
paraTag = "\n.PP\n"
hruleTag = "\n.ti 0\n\\l'\\n(.lu'\n"
linkTag = "\n\\[la]"
linkCloseTag = "\\[ra]"
codespanTag = "\\fB\\fC"
codespanCloseTag = "\\fR"
codeTag = "\n.PP\n.RS\n\n.nf\n"
codeCloseTag = "\n.fi\n.RE\n"
quoteTag = "\n.PP\n.RS\n"
quoteCloseTag = "\n.RE\n"
listTag = "\n.RS\n"
listCloseTag = "\n.RE\n"
arglistTag = "\n.TP\n"
tableStart = "\n.TS\nallbox;\n"
tableEnd = ".TE\n"
tableCellStart = "T{\n"
tableCellEnd = "\nT}\n"
)
// NewRoffRenderer creates a new blackfriday Renderer for generating roff documents
// from markdown
func NewRoffRenderer() *roffRenderer { // nolint: golint
var extensions blackfriday.Extensions
extensions |= blackfriday.NoIntraEmphasis
extensions |= blackfriday.Tables
extensions |= blackfriday.FencedCode
extensions |= blackfriday.SpaceHeadings
extensions |= blackfriday.Footnotes
extensions |= blackfriday.Titleblock
extensions |= blackfriday.DefinitionLists
return &roffRenderer{
extensions: extensions,
}
}
// GetExtensions returns the list of extensions used by this renderer implementation
func (r *roffRenderer) GetExtensions() blackfriday.Extensions {
return r.extensions
}
// RenderHeader handles outputting the header at document start
func (r *roffRenderer) RenderHeader(w io.Writer, ast *blackfriday.Node) {
// disable hyphenation
out(w, ".nh\n")
}
// RenderFooter handles outputting the footer at the document end; the roff
// renderer has no footer information
func (r *roffRenderer) RenderFooter(w io.Writer, ast *blackfriday.Node) {
}
// RenderNode is called for each node in a markdown document; based on the node
// type the equivalent roff output is sent to the writer
func (r *roffRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
var walkAction = blackfriday.GoToNext
switch node.Type {
case blackfriday.Text:
r.handleText(w, node, entering)
case blackfriday.Softbreak:
out(w, crTag)
case blackfriday.Hardbreak:
out(w, breakTag)
case blackfriday.Emph:
if entering {
out(w, emphTag)
} else {
out(w, emphCloseTag)
}
case blackfriday.Strong:
if entering {
out(w, strongTag)
} else {
out(w, strongCloseTag)
}
case blackfriday.Link:
if !entering {
out(w, linkTag+string(node.LinkData.Destination)+linkCloseTag)
}
case blackfriday.Image:
// ignore images
walkAction = blackfriday.SkipChildren
case blackfriday.Code:
out(w, codespanTag)
escapeSpecialChars(w, node.Literal)
out(w, codespanCloseTag)
case blackfriday.Document:
break
case blackfriday.Paragraph:
// roff .PP markers break lists
if r.listDepth > 0 {
return blackfriday.GoToNext
}
if entering {
out(w, paraTag)
} else {
out(w, crTag)
}
case blackfriday.BlockQuote:
if entering {
out(w, quoteTag)
} else {
out(w, quoteCloseTag)
}
case blackfriday.Heading:
r.handleHeading(w, node, entering)
case blackfriday.HorizontalRule:
out(w, hruleTag)
case blackfriday.List:
r.handleList(w, node, entering)
case blackfriday.Item:
r.handleItem(w, node, entering)
case blackfriday.CodeBlock:
out(w, codeTag)
escapeSpecialChars(w, node.Literal)
out(w, codeCloseTag)
case blackfriday.Table:
r.handleTable(w, node, entering)
case blackfriday.TableCell:
r.handleTableCell(w, node, entering)
case blackfriday.TableHead:
case blackfriday.TableBody:
case blackfriday.TableRow:
// no action as cell entries do all the nroff formatting
return blackfriday.GoToNext
default:
fmt.Fprintln(os.Stderr, "WARNING: go-md2man does not handle node type "+node.Type.String())
}
return walkAction
}
func (r *roffRenderer) handleText(w io.Writer, node *blackfriday.Node, entering bool) {
var (
start, end string
)
// handle special roff table cell text encapsulation
if node.Parent.Type == blackfriday.TableCell {
if len(node.Literal) > 30 {
start = tableCellStart
end = tableCellEnd
} else {
// end rows that aren't terminated by "tableCellEnd" with a cr if end of row
if node.Parent.Next == nil && !node.Parent.IsHeader {
end = crTag
}
}
}
out(w, start)
escapeSpecialChars(w, node.Literal)
out(w, end)
}
func (r *roffRenderer) handleHeading(w io.Writer, node *blackfriday.Node, entering bool) {
if entering {
switch node.Level {
case 1:
if !r.firstHeader {
out(w, titleHeader)
r.firstHeader = true
break
}
out(w, topLevelHeader)
case 2:
out(w, secondLevelHdr)
default:
out(w, otherHeader)
}
}
}
func (r *roffRenderer) handleList(w io.Writer, node *blackfriday.Node, entering bool) {
openTag := listTag
closeTag := listCloseTag
if node.ListFlags&blackfriday.ListTypeDefinition != 0 {
// tags for definition lists handled within Item node
openTag = ""
closeTag = ""
}
if entering {
r.listDepth++
if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
r.listCounters = append(r.listCounters, 1)
}
out(w, openTag)
} else {
if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
r.listCounters = r.listCounters[:len(r.listCounters)-1]
}
out(w, closeTag)
r.listDepth--
}
}
func (r *roffRenderer) handleItem(w io.Writer, node *blackfriday.Node, entering bool) {
if entering {
if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
out(w, fmt.Sprintf(".IP \"%3d.\" 5\n", r.listCounters[len(r.listCounters)-1]))
r.listCounters[len(r.listCounters)-1]++
} else if node.ListFlags&blackfriday.ListTypeDefinition != 0 {
// state machine for handling terms and following definitions
// since blackfriday does not distinguish them properly, nor
// does it seperate them into separate lists as it should
if !r.defineTerm {
out(w, arglistTag)
r.defineTerm = true
} else {
r.defineTerm = false
}
} else {
out(w, ".IP \\(bu 2\n")
}
} else {
out(w, "\n")
}
}
func (r *roffRenderer) handleTable(w io.Writer, node *blackfriday.Node, entering bool) {
if entering {
out(w, tableStart)
//call walker to count cells (and rows?) so format section can be produced
columns := countColumns(node)
out(w, strings.Repeat("l ", columns)+"\n")
out(w, strings.Repeat("l ", columns)+".\n")
} else {
out(w, tableEnd)
}
}
func (r *roffRenderer) handleTableCell(w io.Writer, node *blackfriday.Node, entering bool) {
var (
start, end string
)
if node.IsHeader {
start = codespanTag
end = codespanCloseTag
}
if entering {
if node.Prev != nil && node.Prev.Type == blackfriday.TableCell {
out(w, "\t"+start)
} else {
out(w, start)
}
} else {
// need to carriage return if we are at the end of the header row
if node.IsHeader && node.Next == nil {
end = end + crTag
}
out(w, end)
}
}
// because roff format requires knowing the column count before outputting any table
// data we need to walk a table tree and count the columns
func countColumns(node *blackfriday.Node) int {
var columns int
node.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
switch node.Type {
case blackfriday.TableRow:
if !entering {
return blackfriday.Terminate
}
case blackfriday.TableCell:
if entering {
columns++
}
default:
}
return blackfriday.GoToNext
})
return columns
}
func out(w io.Writer, output string) {
io.WriteString(w, output) // nolint: errcheck
}
func needsBackslash(c byte) bool {
for _, r := range []byte("-_&\\~") {
if c == r {
return true
}
}
return false
}
func escapeSpecialChars(w io.Writer, text []byte) {
for i := 0; i < len(text); i++ {
// escape initial apostrophe or period
if len(text) >= 1 && (text[0] == '\'' || text[0] == '.') {
out(w, "\\&")
}
// directly copy normal characters
org := i
for i < len(text) && !needsBackslash(text[i]) {
i++
}
if i > org {
w.Write(text[org:i]) // nolint: errcheck
}
// escape a character
if i >= len(text) {
break
}
w.Write([]byte{'\\', text[i]}) // nolint: errcheck
}
}