Added optional Lua lexer support.

This support is disabled by default and must be enabled via compile-time option.

1 files changed, 102 insertions, 0 deletions

diff --git a/lexlua/markdown.lua b/lexlua/markdown.lua
new file mode 100644
index 000000000..2622a11d7
--- /dev/null
+++ b/lexlua/markdown.lua
@@ -0,0 +1,102 @@
+-- Copyright 2006-2018 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:$(color.red)'
+lex:add_style('h6', hstyle)
+lex:add_style('h5', hstyle..',size:'..(font_size + 1))
+lex:add_style('h4', hstyle..',size:'..(font_size + 2))
+lex:add_style('h3', hstyle..',size:'..(font_size + 3))
+lex:add_style('h2', hstyle..',size:'..(font_size + 4))
+lex:add_style('h1', hstyle..',size:'..(font_size + 5))
+
+lex:add_rule('blockquote',
+             token(lexer.STRING,
+                   lpeg.Cmt(lexer.starts_line(S(' \t')^0 * '>'),
+                            function(input, index)
+                              local _, e = input:find('\n[ \t]*\r?\n', index)
+                              return (e or #input) + 1
+                            end)))
+
+lex:add_rule('blockcode',
+             token('code', lexer.starts_line(P(' ')^4 + P('\t')) * -P('<') *
+                           lexer.nonnewline^0 * lexer.newline^-1))
+lex:add_style('code', lexer.STYLE_EMBEDDED..',eolfilled')
+
+lex:add_rule('hr',
+             token('hr',
+                   lpeg.Cmt(lexer.starts_line(S(' \t')^0 * lpeg.C(S('*-_'))),
+                            function(input, index, c)
+                              local line = input:match('[^\n]*', index)
+                              line = line:gsub('[ \t]', '')
+                              if line:find('[^'..c..']') or #line < 2 then
+                                return nil
+                              end
+                              return (input:find('\n', index) or #input) + 1
+                            end)))
+lex:add_style('hr', 'back:$(color.black),eolfilled')
+
+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)
+
+-- 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('[]')) +
+                           P('http://') * (lexer.any - lexer.space)^1))
+lex:add_style('link', 'underlined')
+
+lex:add_rule('strong', token('strong', P('**') * (lexer.any - '**')^0 *
+                                       P('**')^-1 +
+                                       P('__') * (lexer.any - '__')^0 *
+                                       P('__')^-1))
+lex:add_style('strong', 'bold')
+lex:add_rule('em', token('em', lexer.delimited_range('*', true) +
+                               lexer.delimited_range('_', true)))
+lex:add_style('em', 'italics')
+lex:add_rule('code', token('code', P('``') * (lexer.any - '``')^0 * P('``')^-1 +
+                                   lexer.delimited_range('`', true, true)))
+
+-- 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