1//
  2// Blackfriday Markdown Processor
  3// Available at http://github.com/russross/blackfriday
  4//
  5// Copyright © 2011 Russ Ross <russ@russross.com>.
  6// Distributed under the Simplified BSD License.
  7// See README.md for details.
  8//
  9
 10//
 11//
 12// LaTeX rendering backend
 13//
 14//
 15
 16package blackfriday
 17
 18import (
 19	"bytes"
 20	"io"
 21)
 22
 23// Latex is a type that implements the Renderer interface for LaTeX output.
 24//
 25// Do not create this directly, instead use the NewLatexRenderer function.
 26type Latex struct {
 27	w bytes.Buffer
 28}
 29
 30// NewLatexRenderer creates and configures a Latex object, which
 31// satisfies the Renderer interface.
 32//
 33// flags is a set of LATEX_* options ORed together (currently no such options
 34// are defined).
 35func NewLatexRenderer(flags int) *Latex {
 36	var writer bytes.Buffer
 37	return &Latex{
 38		w: writer,
 39	}
 40}
 41
 42// render code chunks using verbatim, or listings if we have a language
 43func (r *Latex) BlockCode(text []byte, lang string) {
 44	if lang == "" {
 45		r.w.WriteString("\n\\begin{verbatim}\n")
 46	} else {
 47		r.w.WriteString("\n\\begin{lstlisting}[language=")
 48		r.w.WriteString(lang)
 49		r.w.WriteString("]\n")
 50	}
 51	r.w.Write(text)
 52	if lang == "" {
 53		r.w.WriteString("\n\\end{verbatim}\n")
 54	} else {
 55		r.w.WriteString("\n\\end{lstlisting}\n")
 56	}
 57}
 58
 59func (r *Latex) TitleBlock(text []byte) {
 60
 61}
 62
 63func (r *Latex) BlockQuote(text []byte) {
 64	r.w.WriteString("\n\\begin{quotation}\n")
 65	r.w.Write(text)
 66	r.w.WriteString("\n\\end{quotation}\n")
 67}
 68
 69func (r *Latex) BlockHtml(text []byte) {
 70	// a pretty lame thing to do...
 71	r.w.WriteString("\n\\begin{verbatim}\n")
 72	r.w.Write(text)
 73	r.w.WriteString("\n\\end{verbatim}\n")
 74}
 75
 76func (r *Latex) BeginHeader(level int, id string) {
 77	switch level {
 78	case 1:
 79		r.w.WriteString("\n\\section{")
 80	case 2:
 81		r.w.WriteString("\n\\subsection{")
 82	case 3:
 83		r.w.WriteString("\n\\subsubsection{")
 84	case 4:
 85		r.w.WriteString("\n\\paragraph{")
 86	case 5:
 87		r.w.WriteString("\n\\subparagraph{")
 88	case 6:
 89		r.w.WriteString("\n\\textbf{")
 90	}
 91}
 92
 93func (r *Latex) EndHeader(level int, id string, header []byte) {
 94	r.w.WriteString("}\n")
 95}
 96
 97func (r *Latex) HRule() {
 98	r.w.WriteString("\n\\HRule\n")
 99}
100
101func (r *Latex) BeginList(flags ListType) {
102	if flags&ListTypeOrdered != 0 {
103		r.w.WriteString("\n\\begin{enumerate}\n")
104	} else {
105		r.w.WriteString("\n\\begin{itemize}\n")
106	}
107}
108
109func (r *Latex) EndList(flags ListType) {
110	if flags&ListTypeOrdered != 0 {
111		r.w.WriteString("\n\\end{enumerate}\n")
112	} else {
113		r.w.WriteString("\n\\end{itemize}\n")
114	}
115}
116
117func (r *Latex) ListItem(text []byte, flags ListType) {
118	r.w.WriteString("\n\\item ")
119	r.w.Write(text)
120}
121
122func (r *Latex) BeginParagraph() {
123	r.w.WriteString("\n")
124}
125
126func (r *Latex) EndParagraph() {
127	r.w.WriteString("\n")
128}
129
130func (r *Latex) Table(header []byte, body []byte, columnData []CellAlignFlags) {
131	r.w.WriteString("\n\\begin{tabular}{")
132	for _, elt := range columnData {
133		switch elt {
134		case TableAlignmentLeft:
135			r.w.WriteByte('l')
136		case TableAlignmentRight:
137			r.w.WriteByte('r')
138		default:
139			r.w.WriteByte('c')
140		}
141	}
142	r.w.WriteString("}\n")
143	r.w.Write(header)
144	r.w.WriteString(" \\\\\n\\hline\n")
145	r.w.Write(body)
146	r.w.WriteString("\n\\end{tabular}\n")
147}
148
149func (r *Latex) TableRow(text []byte) {
150	r.w.WriteString(" \\\\\n")
151	r.w.Write(text)
152}
153
154func (r *Latex) TableHeaderCell(out *bytes.Buffer, text []byte, align CellAlignFlags) {
155	if out.Len() > 0 {
156		out.WriteString(" & ")
157	}
158	out.Write(text)
159}
160
161func (r *Latex) TableCell(out *bytes.Buffer, text []byte, align CellAlignFlags) {
162	if out.Len() > 0 {
163		out.WriteString(" & ")
164	}
165	out.Write(text)
166}
167
168// TODO: this
169func (r *Latex) BeginFootnotes() {
170}
171
172// TODO: this
173func (r *Latex) EndFootnotes() {
174}
175
176func (r *Latex) FootnoteItem(name, text []byte, flags ListType) {
177
178}
179
180func (r *Latex) AutoLink(link []byte, kind LinkType) {
181	r.w.WriteString("\\href{")
182	if kind == LinkTypeEmail {
183		r.w.WriteString("mailto:")
184	}
185	r.w.Write(link)
186	r.w.WriteString("}{")
187	r.w.Write(link)
188	r.w.WriteString("}")
189}
190
191func (r *Latex) CodeSpan(text []byte) {
192	r.w.WriteString("\\texttt{")
193	r.escapeSpecialChars(text)
194	r.w.WriteString("}")
195}
196
197func (r *Latex) DoubleEmphasis(text []byte) {
198	r.w.WriteString("\\textbf{")
199	r.w.Write(text)
200	r.w.WriteString("}")
201}
202
203func (r *Latex) Emphasis(text []byte) {
204	r.w.WriteString("\\textit{")
205	r.w.Write(text)
206	r.w.WriteString("}")
207}
208
209func (r *Latex) Image(link []byte, title []byte, alt []byte) {
210	if bytes.HasPrefix(link, []byte("http://")) || bytes.HasPrefix(link, []byte("https://")) {
211		// treat it like a link
212		r.w.WriteString("\\href{")
213		r.w.Write(link)
214		r.w.WriteString("}{")
215		r.w.Write(alt)
216		r.w.WriteString("}")
217	} else {
218		r.w.WriteString("\\includegraphics{")
219		r.w.Write(link)
220		r.w.WriteString("}")
221	}
222}
223
224func (r *Latex) LineBreak() {
225	r.w.WriteString(" \\\\\n")
226}
227
228func (r *Latex) Link(link []byte, title []byte, content []byte) {
229	r.w.WriteString("\\href{")
230	r.w.Write(link)
231	r.w.WriteString("}{")
232	r.w.Write(content)
233	r.w.WriteString("}")
234}
235
236func (r *Latex) RawHtmlTag(tag []byte) {
237}
238
239func (r *Latex) TripleEmphasis(text []byte) {
240	r.w.WriteString("\\textbf{\\textit{")
241	r.w.Write(text)
242	r.w.WriteString("}}")
243}
244
245func (r *Latex) StrikeThrough(text []byte) {
246	r.w.WriteString("\\sout{")
247	r.w.Write(text)
248	r.w.WriteString("}")
249}
250
251// TODO: this
252func (r *Latex) FootnoteRef(ref []byte, id int) {
253}
254
255func needsBackslash(c byte) bool {
256	for _, r := range []byte("_{}%$&\\~#") {
257		if c == r {
258			return true
259		}
260	}
261	return false
262}
263
264func (r *Latex) escapeSpecialChars(text []byte) {
265	for i := 0; i < len(text); i++ {
266		// directly copy normal characters
267		org := i
268
269		for i < len(text) && !needsBackslash(text[i]) {
270			i++
271		}
272		if i > org {
273			r.w.Write(text[org:i])
274		}
275
276		// escape a character
277		if i >= len(text) {
278			break
279		}
280		r.w.WriteByte('\\')
281		r.w.WriteByte(text[i])
282	}
283}
284
285func (r *Latex) Entity(entity []byte) {
286	// TODO: convert this into a unicode character or something
287	r.w.Write(entity)
288}
289
290func (r *Latex) NormalText(text []byte) {
291	r.escapeSpecialChars(text)
292}
293
294// header and footer
295func (r *Latex) DocumentHeader() {
296	r.w.WriteString("\\documentclass{article}\n")
297	r.w.WriteString("\n")
298	r.w.WriteString("\\usepackage{graphicx}\n")
299	r.w.WriteString("\\usepackage{listings}\n")
300	r.w.WriteString("\\usepackage[margin=1in]{geometry}\n")
301	r.w.WriteString("\\usepackage[utf8]{inputenc}\n")
302	r.w.WriteString("\\usepackage{verbatim}\n")
303	r.w.WriteString("\\usepackage[normalem]{ulem}\n")
304	r.w.WriteString("\\usepackage{hyperref}\n")
305	r.w.WriteString("\n")
306	r.w.WriteString("\\hypersetup{colorlinks,%\n")
307	r.w.WriteString("  citecolor=black,%\n")
308	r.w.WriteString("  filecolor=black,%\n")
309	r.w.WriteString("  linkcolor=black,%\n")
310	r.w.WriteString("  urlcolor=black,%\n")
311	r.w.WriteString("  pdfstartview=FitH,%\n")
312	r.w.WriteString("  breaklinks=true,%\n")
313	r.w.WriteString("  pdfauthor={Blackfriday Markdown Processor v")
314	r.w.WriteString(Version)
315	r.w.WriteString("}}\n")
316	r.w.WriteString("\n")
317	r.w.WriteString("\\newcommand{\\HRule}{\\rule{\\linewidth}{0.5mm}}\n")
318	r.w.WriteString("\\addtolength{\\parskip}{0.5\\baselineskip}\n")
319	r.w.WriteString("\\parindent=0pt\n")
320	r.w.WriteString("\n")
321	r.w.WriteString("\\begin{document}\n")
322}
323
324func (r *Latex) DocumentFooter() {
325	r.w.WriteString("\n\\end{document}\n")
326}
327
328func (r *Latex) Render(ast *Node) []byte {
329	// TODO
330	return nil
331}
332
333func (r *Latex) RenderNode(w io.Writer, node *Node, entering bool) WalkStatus {
334	// TODO
335	return GoToNext
336}