From 3e29e3785deef6fac912164e07bb3af34d60ea94 Mon Sep 17 00:00:00 2001
From: "byte[]" <byteslice@airmail.cc>
Date: Sat, 2 Nov 2019 21:47:54 -0400
Subject: [PATCH] initial, bad attempt at lexing

---
 lib/textile/lexer.ex  | 192 ++++++++++++++++++++++++++++++++++++++++++
 lib/textile/parser.ex |   3 +
 2 files changed, 195 insertions(+)
 create mode 100644 lib/textile/lexer.ex
 create mode 100644 lib/textile/parser.ex

diff --git a/lib/textile/lexer.ex b/lib/textile/lexer.ex
new file mode 100644
index 00000000..d22b5edc
--- /dev/null
+++ b/lib/textile/lexer.ex
@@ -0,0 +1,192 @@
+defmodule Textile.Lexer do
+  import NimbleParsec
+
+  defp unwrap([{_name, value}]),
+    do: value
+
+  # Lots of extra unicode space characters
+  space =
+    choice([
+      utf8_char('\n\r\f \t\u00a0\u1680\u180e\u202f\u205f\u3000'),
+      utf8_char([0x2000..0x200a])
+    ])
+
+  bracketed_literal =
+    ignore(string("[=="))
+    |> repeat(lookahead_not(string("==]")) |> utf8_char([]))
+    |> ignore(string("==]"))
+    |> reduce({List, :to_string, []})
+    |> unwrap_and_tag(:bracketed_literal)
+
+  link_text_with_title =
+    ignore(string("\""))
+    |> times(utf8_char(not: ?(), min: 1)
+    |> reduce({List, :to_string, []})
+    |> unwrap_and_tag(:link_text)
+    |> ignore(string("("))
+    |> concat(
+      times(utf8_char(not: ?), not: ?"), min: 1)
+      |> reduce({List, :to_string, []})
+      |> unwrap_and_tag(:link_title)
+      |> ignore(string(")\":"))
+    )
+
+  link_text_without_title =
+    ignore(string("\""))
+    |> times(utf8_char(not: ?"), min: 1)
+    |> ignore(string("\":"))
+    |> reduce({List, :to_string, []})
+    |> unwrap_and_tag(:link_text)
+
+  link_text =
+    choice([
+      link_text_with_title,
+      link_text_without_title
+    ])
+
+  link_protocol =
+    choice([
+      string("/"), string("https://"), string("http://"), string("data:image/")
+    ])
+
+  uri_ending_at_space =
+    link_protocol
+    |> times(lookahead_not(space) |> utf8_char([]), min: 1)
+    |> reduce({List, :to_string, []})
+
+  uri_ending_at_bracket =
+    link_protocol
+    |> times(lookahead_not(string("]")) |> utf8_char([]), min: 1)
+    |> reduce({List, :to_string, []})
+
+  uri_ending_at_lparen =
+    link_protocol
+    |> times(lookahead_not(string("(")) |> utf8_char([]), min: 1)
+    |> reduce({List, :to_string, []})
+
+  uri_ending_at_bang =
+    link_protocol
+    |> times(lookahead_not(string("!")) |> utf8_char([]), min: 1)
+    |> reduce({List, :to_string, []})
+
+  unbracketed_link =
+    link_text
+    |> concat(uri_ending_at_space |> unwrap_and_tag(:link_url))
+
+  bracketed_link =
+    ignore(string("["))
+    |> concat(link_text)
+    |> concat(uri_ending_at_bracket |> unwrap_and_tag(:link_url))
+    |> ignore(string("]"))
+
+  link =
+    choice([
+      bracketed_link,
+      unbracketed_link
+    ])
+
+  image_url_with_title =
+    ignore(string("!"))
+    |> concat(uri_ending_at_lparen |> unwrap_and_tag(:image_url))
+    |> ignore(string("("))
+    |> concat(
+      times(utf8_char(not: ?), not: ?!), min: 1)
+      |> reduce({List, :to_string, []})
+      |> unwrap_and_tag(:image_title)
+      |> ignore(string(")!"))
+    )
+
+  image_url_without_title =
+    ignore(string("!"))
+    |> concat(uri_ending_at_bang |> unwrap_and_tag(:image_url))
+    |> ignore(string("!"))
+
+  image_url =
+    choice([
+      image_url_with_title,
+      image_url_without_title
+    ])
+
+  unbracketed_image =
+    image_url
+    |> optional(
+      ignore(string(":"))
+      |> concat(uri_ending_at_space)
+      |> unwrap_and_tag(:image_link_url)
+    )
+
+  bracketed_image =
+    ignore(string("["))
+    |> concat(image_url)
+    |> optional(
+      ignore(string(":"))
+      |> concat(uri_ending_at_bracket)
+      |> unwrap_and_tag(:image_link_url)
+    )
+    |> ignore(string("]"))
+
+  image =
+    choice([
+      bracketed_image,
+      unbracketed_image
+    ])
+
+  literal =
+    ignore(string("=="))
+    |> repeat(lookahead_not(string("==")) |> utf8_char([]))
+    |> reduce({List, :to_string, []})
+    |> unwrap_and_tag(:literal)
+    |> ignore(string("=="))
+
+  blockquote_author =
+    repeat(
+      lookahead_not(string("\"]"))
+      |> choice([
+        bracketed_literal,
+        literal,
+        utf8_char([])
+      ])
+    )
+    |> reduce(:unwrap)
+
+  l_bq_author =
+    ignore(string("[bq=\""))
+    |> concat(blockquote_author)
+    |> ignore(string("\"]"))
+    |> reduce({List, :to_string, []})
+    |> unwrap_and_tag(:l_bq_author)
+
+  l_bq = string("[bq]") |> unwrap_and_tag(:l_bq)
+  r_bq = string("[/bq]") |> unwrap_and_tag(:r_bq)
+
+  l_spoiler = string("[spoiler]") |> unwrap_and_tag(:l_spoiler)
+  r_spoiler = string("[/spoiler]") |> unwrap_and_tag(:r_spoiler)
+
+  stop_words =
+    choice([
+      bracketed_literal,
+      bracketed_link,
+      bracketed_image,
+      link,
+      image,
+      l_bq_author,
+      l_bq,
+      r_bq,
+      l_spoiler,
+      r_spoiler,
+    ])
+
+  defcombinatorp :top_level,
+    choice([
+      stop_words,
+      times(lookahead_not(stop_words) |> utf8_char([]), min: 1)
+      |> reduce({List, :to_string, []})
+      |> unwrap_and_tag(:text)
+    ])
+
+  textile =
+    repeat(parsec(:top_level))
+    |> eos()
+
+  defparsec :lex, textile
+end
\ No newline at end of file
diff --git a/lib/textile/parser.ex b/lib/textile/parser.ex
new file mode 100644
index 00000000..a157b2bd
--- /dev/null
+++ b/lib/textile/parser.ex
@@ -0,0 +1,3 @@
+defmodule Textile.Parser do
+  alias Textile.Lexer
+end
\ No newline at end of file