Add BBCode writer (#11242)

`bbcode` is now supported as an output format, as well as variants
`bbcode_fluxbb` (FluxBB), `bbcode_phpbb` (phpBB), `bbcode_steam` (Hubzilla),
`bbcode_hubzilla` (Hubzilla), and `bbcode_xenforo` (xenForo).

[API change]
Adds a new module Text.Pandoc.Writers.BBCode, exporting a number of functions.
Also exports `writeBBCode`,  `writeBBCodeSteam`, `writeBBCodeFluxBB`,
`writeBBCodePhpBB`, `writeBBCodeHubzilla`, `writeBBCodeXenforo` from
Text.Pandoc.Writers.

1 files changed, 729 insertions, 0 deletions

diff --git a/test/writer.bbcode b/test/writer.bbcode
new file mode 100644
index 000000000..b81451659
--- /dev/null
+++ b/test/writer.bbcode
@@ -0,0 +1,729 @@
+This is a set of tests for pandoc. Most of them are adapted from John Gruber's markdown test suite.
+
+* * *
+
+[u][b]Headers[/b][/u]
+
+[b]Level 2 with an [url=/url]embedded link[/url][/b]
+
+[u]Level 3 with [i]emphasis[/i][/u]
+
+Level 4
+
+Level 5
+
+[u][b]Level 1[/b][/u]
+
+[b]Level 2 with [i]emphasis[/i][/b]
+
+[u]Level 3[/u]
+
+with no blank line
+
+[b]Level 2[/b]
+
+with no blank line
+
+* * *
+
+[u][b]Paragraphs[/b][/u]
+
+Here's a regular paragraph.
+
+In Markdown 1.0.0 and earlier. Version 8. This line turns into a list item. Because a hard-wrapped line in the middle of a paragraph looked like a list item.
+
+Here's one with a bullet. * criminey.
+
+There should be a hard line break
+here.
+
+* * *
+
+[u][b]Block Quotes[/b][/u]
+
+E-mail style:
+
+[quote]
+This is a block quote. It is pretty short.
+[/quote]
+
+[quote]
+Code in a block quote:
+
+[code]sub status {
+    print "working";
+}
+[/code]
+
+A list:
+
+[list=1]
+[*]item one
+[*]item two
+[/list]
+
+Nested block quotes:
+
+[quote]
+nested
+[/quote]
+
+[quote]
+nested
+[/quote]
+[/quote]
+
+This should not be a block quote: 2 > 1.
+
+And a following paragraph.
+
+* * *
+
+[u][b]Code Blocks[/b][/u]
+
+Code:
+
+[code]---- (should be four hyphens)
+
+sub status {
+    print "working";
+}
+
+this code block is indented by one tab
+[/code]
+
+And:
+
+[code]    this code block is indented by two tabs
+
+These should not be escaped:  \$ \\ \> \[ \{
+[/code]
+
+* * *
+
+[u][b]Lists[/b][/u]
+
+[b]Unordered[/b]
+
+Asterisks tight:
+
+[list]
+[*]asterisk 1
+[*]asterisk 2
+[*]asterisk 3
+[/list]
+
+Asterisks loose:
+
+[list]
+[*]asterisk 1
+[*]asterisk 2
+[*]asterisk 3
+[/list]
+
+Pluses tight:
+
+[list]
+[*]Plus 1
+[*]Plus 2
+[*]Plus 3
+[/list]
+
+Pluses loose:
+
+[list]
+[*]Plus 1
+[*]Plus 2
+[*]Plus 3
+[/list]
+
+Minuses tight:
+
+[list]
+[*]Minus 1
+[*]Minus 2
+[*]Minus 3
+[/list]
+
+Minuses loose:
+
+[list]
+[*]Minus 1
+[*]Minus 2
+[*]Minus 3
+[/list]
+
+[b]Ordered[/b]
+
+Tight:
+
+[list=1]
+[*]First
+[*]Second
+[*]Third
+[/list]
+
+and:
+
+[list=1]
+[*]One
+[*]Two
+[*]Three
+[/list]
+
+Loose using tabs:
+
+[list=1]
+[*]First
+[*]Second
+[*]Third
+[/list]
+
+and using spaces:
+
+[list=1]
+[*]One
+[*]Two
+[*]Three
+[/list]
+
+Multiple paragraphs:
+
+[list=1]
+[*]Item 1, graf one.
+
+Item 1. graf two. The quick brown fox jumped over the lazy dog's back.
+[*]Item 2.
+[*]Item 3.
+[/list]
+
+[b]Nested[/b]
+
+[list]
+[*]Tab
+
+[list]
+[*]Tab
+
+[list]
+[*]Tab
+[/list]
+[/list]
+[/list]
+
+Here's another:
+
+[list=1]
+[*]First
+[*]Second:
+
+[list]
+[*]Fee
+[*]Fie
+[*]Foe
+[/list]
+[*]Third
+[/list]
+
+Same thing but with paragraphs:
+
+[list=1]
+[*]First
+[*]Second:
+
+[list]
+[*]Fee
+[*]Fie
+[*]Foe
+[/list]
+[*]Third
+[/list]
+
+[b]Tabs and spaces[/b]
+
+[list]
+[*]this is a list item indented with tabs
+[*]this is a list item indented with spaces
+
+[list]
+[*]this is an example list item indented with tabs
+[*]this is an example list item indented with spaces
+[/list]
+[/list]
+
+[b]Fancy list markers[/b]
+
+[list=1]
+[*]begins with 2
+[*]and now 3
+
+with a continuation
+
+[list=i]
+[*]sublist with roman numerals, starting with 4
+[*]more items
+
+[list=A]
+[*]a subsublist
+[*]a subsublist
+[/list]
+[/list]
+[/list]
+
+Nesting:
+
+[list=A]
+[*]Upper Alpha
+
+[list=I]
+[*]Upper Roman.
+
+[list=1]
+[*]Decimal start with 6
+
+[list=a]
+[*]Lower alpha with paren
+[/list]
+[/list]
+[/list]
+[/list]
+
+Autonumbering:
+
+[list=1]
+[*]Autonumber.
+[*]More.
+
+[list=1]
+[*]Nested.
+[/list]
+[/list]
+
+Should not be a list item:
+
+M.A. 2007
+
+B. Williams
+
+* * *
+
+[u][b]Definition Lists[/b][/u]
+
+Tight using spaces:
+
+apple
+[list]
+[*]red fruit
+[/list]
+orange
+[list]
+[*]orange fruit
+[/list]
+banana
+[list]
+[*]yellow fruit
+[/list]
+
+Tight using tabs:
+
+apple
+[list]
+[*]red fruit
+[/list]
+orange
+[list]
+[*]orange fruit
+[/list]
+banana
+[list]
+[*]yellow fruit
+[/list]
+
+Loose:
+
+apple
+[list]
+[*]red fruit
+[/list]
+orange
+[list]
+[*]orange fruit
+[/list]
+banana
+[list]
+[*]yellow fruit
+[/list]
+
+Multiple blocks with italics:
+
+[i]apple[/i]
+[list]
+[*]red fruit
+
+contains seeds, crisp, pleasant to taste
+[/list]
+[i]orange[/i]
+[list]
+[*]orange fruit
+
+[code]{ orange code block }
+[/code]
+
+[quote]
+orange block quote
+[/quote]
+[/list]
+
+Multiple definitions, tight:
+
+apple
+[list]
+[*]red fruit
+[*]computer
+[/list]
+orange
+[list]
+[*]orange fruit
+[*]bank
+[/list]
+
+Multiple definitions, loose:
+
+apple
+[list]
+[*]red fruit
+[*]computer
+[/list]
+orange
+[list]
+[*]orange fruit
+[*]bank
+[/list]
+
+Blank line after term, indented marker, alternate markers:
+
+apple
+[list]
+[*]red fruit
+[*]computer
+[/list]
+orange
+[list]
+[*]orange fruit
+
+[list=1]
+[*]sublist
+[*]sublist
+[/list]
+[/list]
+
+[u][b]HTML Blocks[/b][/u]
+
+Simple block on one line:
+
+foo
+
+And nested without indentation:
+
+foo
+
+bar
+
+Interpreted markdown in a table:
+
+This is [i]emphasized[/i]
+
+And this is [b]strong[/b]
+
+Here's a simple block:
+
+foo
+
+This should be a code block, though:
+
+[code]<div>
+    foo
+</div>
+[/code]
+
+As should this:
+
+[code]<div>foo</div>
+[/code]
+
+Now, nested:
+
+foo
+
+This should just be an HTML comment:
+
+Multiline:
+
+Code block:
+
+[code]<!-- Comment -->
+[/code]
+
+Just plain comment, with trailing spaces on the line:
+
+Code:
+
+[code]<hr />
+[/code]
+
+Hr's:
+
+* * *
+
+[u][b]Inline Markup[/b][/u]
+
+This is [i]emphasized[/i], and so [i]is this[/i].
+
+This is [b]strong[/b], and so [b]is this[/b].
+
+An [i][url=/url]emphasized link[/url][/i].
+
+[b][i]This is strong and em.[/i][/b]
+
+So is [b][i]this[/i][/b] word.
+
+[b][i]This is strong and em.[/i][/b]
+
+So is [b][i]this[/i][/b] word.
+
+This is code: >, $, \, \$, <html>.
+
+[s]This is [i]strikeout[/i].[/s]
+
+Superscripts: abcd a[i]hello[/i] ahello there.
+
+Subscripts: H2O, H23O, Hmany of themO.
+
+These should not be superscripts or subscripts, because of the unescaped spaces: a^b c^d, a~b c~d.
+
+* * *
+
+[u][b]Smart quotes, ellipses, dashes[/b][/u]
+
+"Hello," said the spider. "'Shelob' is my name."
+
+'A', 'B', and 'C' are letters.
+
+'Oak,' 'elm,' and 'beech' are names of trees. So is 'pine.'
+
+'He said, "I want to go."' Were you alive in the 70's?
+
+Here is some quoted 'code' and a "[url=http://example.com/?foo=1&bar=2]quoted link[/url]".
+
+Some dashes: one---two --- three---four --- five.
+
+Dashes between numbers: 5--7, 255--66, 1987--1999.
+
+Ellipses...and...and....
+
+* * *
+
+[u][b]LaTeX[/b][/u]
+
+[list]
+[*]
+[*]$2+2=4$
+[*]$x \in y$
+[*]$\alpha \wedge \omega$
+[*]$223$
+[*]$p$-Tree
+[*]Here's some display math: [code=latex]$$\frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}$$
+[/code]
+[*]Here's one that has a line break in it: $\alpha + \omega \times x^2$.
+[/list]
+
+These shouldn't be math:
+
+[list]
+[*]To get the famous equation, write $e = mc^2$.
+[*]$22,000 is a [i]lot[/i] of money. So is $34,000. (It worked if "lot" is emphasized.)
+[*]Shoes ($20) and socks ($5).
+[*]Escaped $: $73 [i]this should be emphasized[/i] 23$.
+[/list]
+
+Here's a LaTeX table:
+
+* * *
+
+[u][b]Special Characters[/b][/u]
+
+Here is some unicode:
+
+[list]
+[*]I hat: Î
+[*]o umlaut: ö
+[*]section: §
+[*]set membership: ∈
+[*]copyright: ©
+[/list]
+
+AT&T has an ampersand in their name.
+
+AT&T is another way to write it.
+
+This & that.
+
+4 < 5.
+
+6 > 5.
+
+Backslash: \
+
+Backtick: `
+
+Asterisk: *
+
+Underscore: _
+
+Left brace: {
+
+Right brace: }
+
+Left bracket: [
+
+Right bracket: ]
+
+Left paren: (
+
+Right paren: )
+
+Greater-than: >
+
+Hash: #
+
+Period: .
+
+Bang: !
+
+Plus: +
+
+Minus: -
+
+* * *
+
+[u][b]Links[/b][/u]
+
+[b]Explicit[/b]
+
+Just a [url=/url/]URL[/url].
+
+[url=/url/]URL and title[/url].
+
+[url=/url/]URL and title[/url].
+
+[url=/url/]URL and title[/url].
+
+[url=/url/]URL and title[/url]
+
+[url=/url/]URL and title[/url]
+
+[url=/url/with_underscore]with_underscore[/url]
+
+[[email protected]]Email link[/email]
+
+[url]Empty[/url].
+
+[b]Reference[/b]
+
+Foo [url=/url/]bar[/url].
+
+With [url=/url/]embedded [brackets][/url].
+
+[url=/url/]b[/url] by itself should be a link.
+
+Indented [url=/url]once[/url].
+
+Indented [url=/url]twice[/url].
+
+Indented [url=/url]thrice[/url].
+
+This should [not][] be a link.
+
+[code][not]: /url
+[/code]
+
+Foo [url=/url/]bar[/url].
+
+Foo [url=/url/]biz[/url].
+
+[b]With ampersands[/b]
+
+Here's a [url=http://example.com/?foo=1&bar=2]link with an ampersand in the URL[/url].
+
+Here's a link with an amersand in the link text: [url=http://att.com/]AT&T[/url].
+
+Here's an [url=/script?foo=1&bar=2]inline link[/url].
+
+Here's an [url=/script?foo=1&bar=2]inline link in pointy braces[/url].
+
+[b]Autolinks[/b]
+
+With an ampersand: [url]http://example.com/?foo=1&bar=2[/url]
+
+[list]
+[*]In a list?
+[*][url]http://example.com/[/url]
+[*]It should.
+[/list]
+
+An e-mail address: [email][email protected][/email]
+
+[quote]
+Blockquoted: [url]http://example.com/[/url]
+[/quote]
+
+Auto-links should not occur here: <http://example.com/>
+
+[code]or here: <http://example.com/>
+[/code]
+
+* * *
+
+[u][b]Images[/b][/u]
+
+From "Voyage dans la Lune" by Georges Melies (1902):
+
+[img alt="lalune" title="Voyage dans la Lune"]lalune.jpg[/img]
+lalune
+
+Here is a movie [img alt="movie"]movie.jpg[/img] icon.
+
+* * *
+
+[u][b]Footnotes[/b][/u]
+
+Here is a footnote reference,(1) and another.(2) This should [i]not[/i] be a footnote reference, because it contains a space.[^my note] Here is an inline note.(3)
+
+[quote]
+Notes can go in quotes.(4)
+[/quote]
+
+[list=1]
+[*]And in list items.(5)
+[/list]
+
+This paragraph should not be part of the note, as it is not indented.
+
+* * *
+
+(1) Here is the footnote. It can go anywhere after the footnote reference. It need not be placed at the end of the document.
+
+(2) Here's the long note. This one contains multiple blocks.
+
+Subsequent blocks are indented to show that they belong to the footnote (as with list items).
+
+[code]  { <code> }
+[/code]
+
+If you want, you can indent every line, but you can also be lazy and just indent the first line of each block.
+
+(3) This is [i]easier[/i] to type. Inline notes may contain [url=http://google.com]links[/url] and ] verbatim characters, as well as [bracketed text].
+
+(4) In quote.
+
+(5) In list.