defmodule Textile.MarkupLexer do import NimbleParsec import Textile.Helpers # Markup tags def markup_ending_in(ending_sequence) do double_newline = string("\n\n") |> unwrap_and_tag(:double_newline) newline = string("\n") |> unwrap_and_tag(:newline) preceding_whitespace = choice([ double_newline, newline, special_characters() ]) # The literal tag is special, because # 1. It needs to capture everything inside it as a distinct token. # 2. It can be surrounded by markup on all sides. # 3. If it successfully tokenizes, it will always be in the output. literal_open_stops = choice([ space(), ending_sequence, string("=") ]) literal_close_stops = lookahead_not( choice([ ending_sequence, string("\n\n"), string("="), space() |> concat(string("=")) ]) ) |> utf8_char([]) literal = ignore(string("==")) |> lookahead_not(literal_open_stops) |> repeat(literal_close_stops) |> ignore(string("==")) |> reduce({List, :to_string, []}) |> unwrap_and_tag(:literal) b_open = markup_open_tag("**", "*", :b) i_open = markup_open_tag("__", "*", :i) strong_open = markup_open_tag("*", :strong) em_open = markup_open_tag("_", :em) code_open = markup_open_tag("@", :code) ins_open = markup_open_tag("+", :ins) sup_open = markup_open_tag("^", :sup) del_open = markup_open_tag("-", :del) sub_open = markup_open_tag("~", :sub) b_b_open = markup_open_tag("[**", "*", :b_b) b_i_open = markup_open_tag("[__", "_", :b_i) b_strong_open = markup_open_tag("[*", "*", :b_strong) b_em_open = markup_open_tag("[_", "_", :b_em) b_code_open = markup_open_tag("[@", "@", :b_code) b_ins_open = markup_open_tag("[+", "+", :b_ins) b_sup_open = markup_open_tag("[^", "^", :b_sup) b_del_open = markup_open_tag("[-", "-", :b_del) b_sub_open = markup_open_tag("[~", "~", :b_sub) b_b_close = string("**]") |> unwrap_and_tag(:b_b_close) b_i_close = string("__]") |> unwrap_and_tag(:b_i_close) b_strong_close = string("*]") |> unwrap_and_tag(:b_strong_close) b_em_close = string("_]") |> unwrap_and_tag(:b_em_close) b_code_close = string("@]") |> unwrap_and_tag(:b_code_close) b_ins_close = string("+]") |> unwrap_and_tag(:b_ins_close) b_sup_close = string("^]") |> unwrap_and_tag(:b_sup_close) b_del_close = string("-]") |> unwrap_and_tag(:b_del_close) b_sub_close = string("~]") |> unwrap_and_tag(:b_sub_close) b_close = string("**") |> unwrap_and_tag(:b_close) i_close = string("__") |> unwrap_and_tag(:i_close) strong_close = string("*") |> unwrap_and_tag(:strong_close) em_close = string("_") |> unwrap_and_tag(:em_close) code_close = string("@") |> unwrap_and_tag(:code_close) ins_close = string("+") |> unwrap_and_tag(:ins_close) sup_close = string("^") |> unwrap_and_tag(:sup_close) del_close = string("-") |> unwrap_and_tag(:del_close) sub_close = string("~") |> unwrap_and_tag(:sub_close) bracketed_markup_opening_tags = choice([ b_b_open, b_i_open, b_strong_open, b_em_open, b_code_open, b_ins_open, b_sup_open, b_del_open, b_sub_open ]) markup_opening_tags = choice([ b_open, i_open, strong_open, em_open, code_open, ins_open, sup_open, del_open, sub_open ]) bracketed_markup_closing_tags = choice([ b_b_close, b_i_close, b_strong_close, b_em_close, b_code_close, b_ins_close, b_sup_close, b_del_close, b_sub_close, ]) markup_closing_tags = choice([ b_close, i_close, strong_close, em_close, code_close, ins_close, sup_close, del_close, sub_close ]) markup_at_start = choice([ times(markup_opening_tags, min: 1), bracketed_markup_opening_tags ]) markup_element = lookahead_not(ending_sequence) |> choice([ literal, bracketed_markup_closing_tags, bracketed_markup_opening_tags |> lookahead_not(space()), preceding_whitespace |> times(markup_opening_tags, min: 1), times(markup_closing_tags, min: 1) |> lookahead(choice([special_characters(), ending_sequence])), double_newline, newline, utf8_char([]) ]) {markup_at_start, markup_element} end end