add parser feature grammar expansion WIP

Author: marcnnn

lib/ebnf.ex

@@ -149,10 +149,12 @@ defmodule EBNF do
 
         "*" ->
           # S' ::= S S' |
+          # from == 0 to--
           [alternate: [factor, {:identifier, [next_rule_name]}, "|", {:empty, []}]]
 
         "+" ->
           # S' ::= S S' | S
+          # from-- to--
           [alternate: [factor, {:identifier, [next_rule_name]}, "|", factor]]
       end
 

lib/ebnf/parser.ex

@@ -2,7 +2,20 @@ defmodule EBNF.Parser do
   @moduledoc false
 
   import NimbleParsec
-  import EBNF.Parser.Helpers
+
+  from_to =
+    ignore(string("{"))
+    |> integer(min: 1)
+    |> ignore(string(","))
+    |> integer(min: 1)
+    |> ignore(string("}"))
+    |> tag(:from_to)
+
+    times =
+      ignore(string("{"))
+      |> integer(min: 1)
+      |> ignore(string("}"))
+      |> tag(:times)
 
   whitespace = repeat(choice([string(" "), string("\n"), string("\t")]))
 
@@ -25,8 +38,16 @@ defmodule EBNF.Parser do
     choice([
       string(~S( )) |> replace(?\s),
       string(~S(\t)) |> replace(?\t),
+      string("\t") |> replace(?\t),
       string(~S(\n)) |> replace(?\n),
+      string("\n") |> replace(?\n),
+      string("\r") |> replace(?\r),
       string(~S(\\)) |> replace(?\\),
+      string("\\") |> replace(?\\),
+      string("\"") |> replace(?\"),
+      string("\d") |> replace(?\d),
+      string("\0") |> replace(?\0),
+      string("\x1F") |> replace(~s(\x1F)),
       ascii_char([?a..?z, ?A..?Z, ?0..?9, ?_, ?-, ?+, ?*, ?/])
     ])
     |> tag(:char)
@@ -37,11 +58,20 @@ defmodule EBNF.Parser do
     |> concat(char)
     |> tag(:range)
 
+
+
   range_or_char = choice([range, char])
 
+  negation =
+    ignore(string("^"))
+    |> concat(range_or_char)
+    |> tag(:negation)
+
+  negation_range_or_char = choice([negation, range, char])
+
   character_set =
     ignore(string("["))
-    |> times(range_or_char, min: 1)
+    |> times(negation_range_or_char, min: 1)
     |> ignore(string("]"))
     |> tag(:character_set)
 
@@ -50,7 +80,7 @@ defmodule EBNF.Parser do
     |> tag(:terminal)
 
   identifier =
-    ascii_string([?a..?z, ?A..?Z, ?0..?9, ?_], min: 1)
+    ascii_string([?a..?z, ?A..?Z, ?0..?9, ?_, ?-], min: 1)
     |> tag(:identifier)
 
   grouping =
@@ -63,10 +93,13 @@ defmodule EBNF.Parser do
 
   factor =
     choice([identifier, terminal, grouping])
-    |> repeatable()
+    |> then(&choice([
+      tag(concat(&1,choice([string("*"), string("+"), string("?"), from_to, times])),:repetition),
+      &1
+    ]))
     |> ignore(repeat(choice([string(" "), string("\t")])))
 
-  term = times(factor, min: 1)
+  term = times(factor, min: 0)
 
   choice_separator =
     ignore(repeat(string(" ")))