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-- Copyright 2006-2019 Mitchell mitchell.att.foicica.com. See License.txt.
-- Markdown LPeg lexer.
local lexer = require('lexer')
local token, word_match = lexer.token, lexer.word_match
local P, R, S = lpeg.P, lpeg.R, lpeg.S
local lex = lexer.new('markdown')
-- Block elements.
lex:add_rule('header',
token('h6', lexer.starts_line('######') * lexer.nonnewline^0) +
token('h5', lexer.starts_line('#####') * lexer.nonnewline^0) +
token('h4', lexer.starts_line('####') * lexer.nonnewline^0) +
token('h3', lexer.starts_line('###') * lexer.nonnewline^0) +
token('h2', lexer.starts_line('##') * lexer.nonnewline^0) +
token('h1', lexer.starts_line('#') * lexer.nonnewline^0))
local font_size = lexer.property_int['fontsize'] > 0 and
lexer.property_int['fontsize'] or 10
local hstyle = 'fore:$(color.red)'
lex:add_style('h6', hstyle)
lex:add_style('h5', hstyle..',size:'..(font_size + 1))
lex:add_style('h4', hstyle..',size:'..(font_size + 2))
lex:add_style('h3', hstyle..',size:'..(font_size + 3))
lex:add_style('h2', hstyle..',size:'..(font_size + 4))
lex:add_style('h1', hstyle..',size:'..(font_size + 5))
lex:add_rule('blockquote',
token(lexer.STRING,
lpeg.Cmt(lexer.starts_line(S(' \t')^0 * '>'),
function(input, index)
local _, e = input:find('\n[ \t]*\r?\n', index)
return (e or #input) + 1
end)))
lex:add_rule('list', token('list', lexer.starts_line(S(' \t')^0 * (S('*+-') +
R('09')^1 * '.')) *
S(' \t')))
lex:add_style('list', lexer.STYLE_CONSTANT)
lex:add_rule('block_code',
token('code', lexer.starts_line(P(' ')^4 + P('\t')) * -P('<') *
lexer.nonnewline^0 * lexer.newline^-1) +
token('code', lexer.starts_line(P('```')) * (lexer.any - '```')^0 *
P('```')^-1))
lex:add_rule('inline_code',
token('code', P('``') * (lexer.any - '``')^0 * P('``')^-1 +
lexer.delimited_range('`', false, true)))
lex:add_style('code', lexer.STYLE_EMBEDDED..',eolfilled')
lex:add_rule('hr',
token('hr',
lpeg.Cmt(lexer.starts_line(S(' \t')^0 * lpeg.C(S('*-_'))),
function(input, index, c)
local line = input:match('[^\r\n]*', index)
line = line:gsub('[ \t]', '')
if line:find('[^'..c..']') or #line < 2 then
return nil
end
return (select(2, input:find('\r?\n', index)) or
#input) + 1
end)))
lex:add_style('hr', 'back:$(color.black),eolfilled')
-- Whitespace.
local ws = token(lexer.WHITESPACE, S(' \t')^1 + S('\v\r\n')^1)
lex:add_rule('whitespace', ws)
-- Span elements.
lex:add_rule('escape', token(lexer.DEFAULT, P('\\') * 1))
lex:add_rule('link_label',
token('link_label', lexer.delimited_range('[]') * ':') * ws *
token('link_url', (lexer.any - lexer.space)^1) *
(ws * token(lexer.STRING, lexer.delimited_range('"', false, true) +
lexer.delimited_range("'", false, true) +
lexer.delimited_range('()')))^-1)
lex:add_style('link_label', lexer.STYLE_LABEL)
lex:add_style('link_url', 'underlined')
lex:add_rule('link',
token('link', P('!')^-1 * lexer.delimited_range('[]') *
(P('(') * (lexer.any - S(') \t'))^0 *
(S(' \t')^1 *
lexer.delimited_range('"', false, true))^-1 * ')' +
S(' \t')^0 * lexer.delimited_range('[]')) +
'http' * P('s')^-1 * '://' *
(lexer.any - lexer.space)^1))
lex:add_style('link', 'underlined')
local punct_space = lexer.punct + lexer.space
-- Handles flanking delimiters as described in
-- https://github.github.com/gfm/#emphasis-and-strong-emphasis in the cases
-- where simple delimited ranges are not sufficient.
local function flanked_range(s, not_inword)
local fl_char = lexer.any - s - lexer.space
local left_fl = lpeg.B(punct_space - s) * s * #fl_char +
s * #(fl_char - lexer.punct)
local right_fl = lpeg.B(lexer.punct) * s * #(punct_space - s) +
lpeg.B(fl_char) * s
return left_fl * (lexer.any - (not_inword and s * #punct_space or s))^0 *
right_fl
end
lex:add_rule('strong',
token('strong', flanked_range('**') +
(lpeg.B(punct_space) + #lexer.starts_line('_')) *
flanked_range('__', true) * #(punct_space + -1)))
lex:add_style('strong', 'bold')
lex:add_rule('em',
token('em', flanked_range('*') +
(lpeg.B(punct_space) + #lexer.starts_line('_')) *
flanked_range('_', true) * #(punct_space + -1)))
lex:add_style('em', 'italics')
-- Embedded HTML.
local html = lexer.load('html')
local start_rule = lexer.starts_line(S(' \t')^0) * #P('<') *
html:get_rule('element')
local end_rule = token(lexer.DEFAULT, P('\n')) -- TODO: lexer.WHITESPACE errors
lex:embed(html, start_rule, end_rule)
return lex
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