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// Copyright 2009 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.
// Process plain text into HTML.
// - h2's are made from lines followed by a line "----\n"
// - tab-indented blocks become <pre> blocks
// - blank lines become <p> marks (except inside <pre> tags)
// - "quoted strings" become <code>quoted strings</code>
package main
import (
"bufio"
"bytes"
"log"
"os"
)
var (
lines = make([][]byte, 0, 2000) // probably big enough; grows if not
empty = []byte("")
newline = []byte("\n")
tab = []byte("\t")
quote = []byte(`"`)
indent = []byte{' ', ' ', ' ', ' '}
sectionMarker = []byte("----\n")
preStart = []byte("<pre>")
preEnd = []byte("</pre>\n")
pp = []byte("<p>\n")
)
func main() {
read()
headings()
coalesce(preStart, foldPre)
coalesce(tab, foldTabs)
paragraphs()
quotes()
write()
}
func read() {
b := bufio.NewReader(os.Stdin)
for {
line, err := b.ReadBytes('\n')
if err == os.EOF {
break
}
if err != nil {
log.Fatal(err)
}
lines = append(lines, line)
}
}
func write() {
b := bufio.NewWriter(os.Stdout)
for _, line := range lines {
b.Write(expandTabs(line))
}
b.Flush()
}
// each time prefix is found on a line, call fold and replace
// line with return value from fold.
func coalesce(prefix []byte, fold func(i int) (n int, line []byte)) {
j := 0 // output line number goes up by one each loop
for i := 0; i < len(lines); {
if bytes.HasPrefix(lines[i], prefix) {
nlines, block := fold(i)
lines[j] = block
i += nlines
} else {
lines[j] = lines[i]
i++
}
j++
}
lines = lines[0:j]
}
// return the <pre> block as a single slice
func foldPre(i int) (n int, line []byte) {
buf := new(bytes.Buffer)
for i < len(lines) {
buf.Write(lines[i])
n++
if bytes.Equal(lines[i], preEnd) {
break
}
i++
}
return n, buf.Bytes()
}
// return the tab-indented block as a single <pre>-bounded slice
func foldTabs(i int) (n int, line []byte) {
buf := new(bytes.Buffer)
buf.WriteString("<pre>\n")
for i < len(lines) {
if !bytes.HasPrefix(lines[i], tab) {
break
}
buf.Write(lines[i])
n++
i++
}
buf.WriteString("</pre>\n")
return n, buf.Bytes()
}
func headings() {
b := bufio.NewWriter(os.Stdout)
for i, l := range lines {
if i > 0 && bytes.Equal(l, sectionMarker) {
lines[i-1] = []byte("<h2>" + string(trim(lines[i-1])) + "</h2>\n")
lines[i] = empty
}
}
b.Flush()
}
func paragraphs() {
for i, l := range lines {
if bytes.Equal(l, newline) {
lines[i] = pp
}
}
}
func quotes() {
for i, l := range lines {
lines[i] = codeQuotes(l)
}
}
func codeQuotes(l []byte) []byte {
if bytes.HasPrefix(l, preStart) {
return l
}
n := bytes.Index(l, quote)
if n < 0 {
return l
}
buf := new(bytes.Buffer)
inQuote := false
for _, c := range l {
if c == '"' {
if inQuote {
buf.WriteString("</code>")
} else {
buf.WriteString("<code>")
}
inQuote = !inQuote
} else {
buf.WriteByte(c)
}
}
return buf.Bytes()
}
// drop trailing newline
func trim(l []byte) []byte {
n := len(l)
if n > 0 && l[n-1] == '\n' {
return l[0 : n-1]
}
return l
}
// expand tabs to spaces. don't worry about columns.
func expandTabs(l []byte) []byte {
return bytes.Replace(l, tab, indent, -1)
}
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