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mdcat.go
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mdcat.go
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//
// mdcat
// Available at http://github.com/ec1oud/mdcat
// based on example code from http://github.com/russross/blackfriday-tool
//
// Copyright © 2017 Shawn Rutledge <s@ecloud.org>.
// Distributed under the Simplified BSD License.
// See README.md for details.
//
package main
import (
"flag"
"fmt"
"github.com/ec1oud/blackfriday"
//~ "github.com/russross/blackfriday"
"io/ioutil"
"os"
"strings"
)
const DEFAULT_TITLE = ""
func main() {
// parse command-line options
var ansi, html, page, toc, toconly, xhtml, latex, smartypants, latexdashes, fractions bool
var css string
flag.BoolVar(&ansi, "ansi", true,
"Generate ANSI terminal escape codes")
flag.BoolVar(&page, "page", false,
"Generate a standalone HTML page (implies -latex=false)")
flag.BoolVar(&toc, "toc", false,
"Generate a table of contents (implies -latex=false)")
flag.BoolVar(&toconly, "toconly", false,
"Generate a table of contents only (implies -toc)")
flag.BoolVar(&xhtml, "xhtml", true,
"Use XHTML-style tags in HTML output")
flag.BoolVar(&latex, "latex", false,
"Generate LaTeX output instead of HTML")
flag.BoolVar(&smartypants, "smartypants", true,
"Apply smartypants-style substitutions")
flag.BoolVar(&latexdashes, "latexdashes", true,
"Use LaTeX-style dash rules for smartypants")
flag.BoolVar(&fractions, "fractions", true,
"Use improved fraction rules for smartypants")
flag.StringVar(&css, "css", "",
"Link to a CSS stylesheet (implies -page)")
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "mdcat Markdown Renderer using Blackfriday v"+blackfriday.VERSION+
"\nAvailable at http://github.com/ec1oud/mdcat\n\n"+
"Usage:\n"+
" %s [options] [inputfile [outputfile]]\n\n"+
"Options:\n",
os.Args[0])
flag.PrintDefaults()
}
flag.Parse()
// enforce implied options
if css != "" {
page = true
html = true
ansi = false
}
if page {
latex = false
html = true
ansi = false
}
if toconly {
toc = true
}
if toc {
latex = false
html = true
ansi = false
}
// read the input
var input []byte
var err error
args := flag.Args()
switch len(args) {
case 0:
if input, err = ioutil.ReadAll(os.Stdin); err != nil {
fmt.Fprintln(os.Stderr, "Error reading from Stdin:", err)
os.Exit(-1)
}
case 1, 2:
if input, err = ioutil.ReadFile(args[0]); err != nil {
fmt.Fprintln(os.Stderr, "Error reading from", args[0], ":", err)
os.Exit(-1)
}
default:
flag.Usage()
os.Exit(-1)
}
// set up options
extensions := 0
extensions |= blackfriday.EXTENSION_NO_INTRA_EMPHASIS
extensions |= blackfriday.EXTENSION_TABLES
extensions |= blackfriday.EXTENSION_FENCED_CODE
extensions |= blackfriday.EXTENSION_AUTOLINK
extensions |= blackfriday.EXTENSION_STRIKETHROUGH
extensions |= blackfriday.EXTENSION_SPACE_HEADERS
var renderer blackfriday.Renderer
if latex {
// render the data into LaTeX
renderer = blackfriday.LatexRenderer(0)
} else if html {
// render the data into HTML
htmlFlags := 0
if xhtml {
htmlFlags |= blackfriday.HTML_USE_XHTML
}
if smartypants {
htmlFlags |= blackfriday.HTML_USE_SMARTYPANTS
}
if fractions {
htmlFlags |= blackfriday.HTML_SMARTYPANTS_FRACTIONS
}
if latexdashes {
htmlFlags |= blackfriday.HTML_SMARTYPANTS_LATEX_DASHES
}
title := ""
if page {
htmlFlags |= blackfriday.HTML_COMPLETE_PAGE
title = getTitle(input)
}
if toconly {
htmlFlags |= blackfriday.HTML_OMIT_CONTENTS
}
if toc {
htmlFlags |= blackfriday.HTML_TOC
}
renderer = blackfriday.HtmlRenderer(htmlFlags, title, css)
} else {
ansiFlags := 0
if smartypants {
ansiFlags |= blackfriday.ANSI_USE_SMARTYPANTS
}
if fractions {
ansiFlags |= blackfriday.ANSI_SMARTYPANTS_FRACTIONS
}
if latexdashes {
ansiFlags |= blackfriday.ANSI_SMARTYPANTS_LATEX_DASHES
}
renderer = blackfriday.AnsiRenderer(80, ansiFlags) // TODO get terminal width
}
// parse and render
var output []byte = blackfriday.Markdown(input, renderer, extensions)
// output the result
var out *os.File
if len(args) == 2 {
if out, err = os.Create(args[1]); err != nil {
fmt.Fprintf(os.Stderr, "Error creating %s: %v", args[1], err)
os.Exit(-1)
}
defer out.Close()
} else {
out = os.Stdout
}
if _, err = out.Write(output); err != nil {
fmt.Fprintln(os.Stderr, "Error writing output:", err)
os.Exit(-1)
}
}
// try to guess the title from the input buffer
// just check if it starts with an <h1> element and use that
func getTitle(input []byte) string {
i := 0
// skip blank lines
for i < len(input) && (input[i] == '\n' || input[i] == '\r') {
i++
}
if i >= len(input) {
return DEFAULT_TITLE
}
if input[i] == '\r' && i+1 < len(input) && input[i+1] == '\n' {
i++
}
// find the first line
start := i
for i < len(input) && input[i] != '\n' && input[i] != '\r' {
i++
}
line1 := input[start:i]
if input[i] == '\r' && i+1 < len(input) && input[i+1] == '\n' {
i++
}
i++
// check for a prefix header
if len(line1) >= 3 && line1[0] == '#' && (line1[1] == ' ' || line1[1] == '\t') {
return strings.TrimSpace(string(line1[2:]))
}
// check for an underlined header
if i >= len(input) || input[i] != '=' {
return DEFAULT_TITLE
}
for i < len(input) && input[i] == '=' {
i++
}
for i < len(input) && (input[i] == ' ' || input[i] == '\t') {
i++
}
if i >= len(input) || (input[i] != '\n' && input[i] != '\r') {
return DEFAULT_TITLE
}
return strings.TrimSpace(string(line1))
}