(* reStructuredText EBNF Grammar *)

document = { block } ;

block = section
      | transition
      | paragraph
      | literal_block
      | line_block
      | block_quote
      | doctest_block
      | table
      | bullet_list
      | enumerated_list
      | definition_list
      | field_list
      | option_list
      | directive
      | comment
      | substitution_definition
      | target
      | blank_line ;

(* Sections *)
section = section_title section_underline [ section_overline ] ;

section_title = inline_text newline ;

section_underline = section_adornment newline ;

section_overline = section_adornment newline ;

section_adornment = adornment_char { adornment_char } ;

adornment_char = "!" | '"' | "#" | "$" | "%" | "&" | "'" | "(" | ")" | "*" | "+" | "," | "-" | "." | "/" | ":" | ";" | "<" | "=" | ">" | "?" | "@" | "[" | "\\" | "]" | "^" | "_" | "`" | "{" | "|" | "}" | "~" ;

(* Transitions *)
transition = transition_marker newline ;

transition_marker = transition_char { transition_char } ;

transition_char = adornment_char ;

(* Paragraphs *)
paragraph = inline_text { newline inline_text } newline ;

(* Literal Blocks *)
literal_block = literal_block_marker newline { indented_line } ;

literal_block_marker = "::" | paragraph "::" ;

indented_line = indent line_content newline ;

indent = "    " | "\t" ;

line_content = { character - newline } ;

(* Line Blocks *)
line_block = { line_block_line } ;

line_block_line = "|" [ " " ] inline_text newline ;

(* Block Quotes *)
block_quote = { indented_paragraph } [ attribution ] ;

indented_paragraph = indent inline_text { newline indent inline_text } newline ;

attribution = indent "-- " inline_text newline ;

(* Doctest Blocks *)
doctest_block = { doctest_line } ;

doctest_line = ">>>" " " line_content newline
             | "..." " " line_content newline ;

(* Tables *)
table = simple_table | grid_table ;

simple_table = simple_table_row { simple_table_row } simple_table_separator { simple_table_row } ;

simple_table_row = { table_cell } newline ;

simple_table_separator = "=" { ( "=" | " " ) } newline ;

grid_table = grid_table_border { grid_table_row grid_table_border } ;

grid_table_border = "+" { ( "-" | "+" ) } newline ;

grid_table_row = "|" { table_cell "|" } newline ;

table_cell = { character - ( "|" | newline ) } ;

(* Lists *)
bullet_list = { bullet_list_item } ;

bullet_list_item = bullet_marker " " list_item_content ;

bullet_marker = "*" | "+" | "-" | "•" | "‣" | "⁃" ;

enumerated_list = { enumerated_list_item } ;

enumerated_list_item = enumeration_marker " " list_item_content ;

enumeration_marker = ( digit { digit } "." )
                   | ( digit { digit } ")" )
                   | ( "(" digit { digit } ")" )
                   | ( letter "." )
                   | ( letter ")" )
                   | ( "(" letter ")" )
                   | ( roman "." )
                   | ( roman ")" )
                   | ( "(" roman ")" )
                   | "#." | "#)" | "(#)" ;

list_item_content = inline_text { newline [ indent ] inline_text } newline ;

definition_list = { definition_list_item } ;

definition_list_item = term newline indent definition newline ;

term = inline_text ;

definition = inline_text { newline indent inline_text } ;

(* Field Lists *)
field_list = { field_list_item } ;

field_list_item = ":" field_name ":" " " field_body newline ;

field_name = { letter | digit | " " | "-" | "_" } ;

field_body = inline_text { newline indent inline_text } ;

(* Option Lists *)
option_list = { option_list_item } ;

option_list_item = option_group "  " option_description newline ;

option_group = option { ", " option } ;

option = short_option | long_option ;

short_option = "-" letter [ " " option_argument ] ;

long_option = "--" { letter | digit | "-" } [ "=" option_argument ] ;

option_argument = { letter | digit | "-" | "_" } ;

option_description = inline_text { newline indent inline_text } ;

(* Directives *)
directive = ".." " " directive_name "::" [ " " directive_arguments ] newline
            [ directive_options ]
            [ blank_line ]
            [ directive_content ] ;

directive_name = { letter | digit | "-" | "_" } ;

directive_arguments = { character - newline } ;

directive_options = { directive_option } ;

directive_option = indent ":" option_name ":" [ " " option_value ] newline ;

option_name = { letter | digit | "-" | "_" } ;

option_value = { character - newline } ;

directive_content = { indented_line } ;

(* Comments *)
comment = ".." [ " " comment_text ] newline { indented_line } ;

comment_text = { character - newline } ;

(* Substitution Definitions *)
substitution_definition = ".." " " "|" substitution_name "|" " " directive_name "::" [ " " directive_arguments ] newline
                         [ directive_options ]
                         [ directive_content ] ;

substitution_name = { character - ( "|" | newline ) } ;

(* Targets *)
target = internal_target | external_target ;

internal_target = ".." " " "_" target_name ":" newline ;

external_target = ".." " " "_" target_name ":" " " target_url newline ;

target_name = { character - ( ":" | newline ) } ;

target_url = { character - newline } ;

(* Inline Elements *)
inline_text = { inline_element } ;

inline_element = emphasis
               | strong
               | literal
               | interpreted_text
               | phrase_reference
               | substitution_reference
               | inline_internal_target
               | hyperlink_reference
               | footnote_reference
               | citation_reference
               | inline_literal
               | plain_text ;

emphasis = "*" emphasis_text "*" ;

strong = "**" strong_text "**" ;

literal = "``" literal_text "``" ;

interpreted_text = "`" interpreted_text_content "`" [ role_suffix ]
                 | role_prefix "`" interpreted_text_content "`" ;

role_prefix = ":" role_name ":" ;

role_suffix = ":" role_name ":" ;

role_name = { letter | digit | "-" | "_" | "." } ;

interpreted_text_content = { character - "`" } ;

phrase_reference = "`" phrase_reference_text "`_" [ "_" ] ;

phrase_reference_text = { character - ( "`" | "<" ) } [ " " "<" target_url ">" ] ;

substitution_reference = "|" substitution_name "|" [ "_" [ "_" ] ] ;

inline_internal_target = "_`" target_text "`" ;

target_text = { character - "`" } ;

hyperlink_reference = reference_name "_" [ "_" ] ;

reference_name = { letter | digit | "-" | "_" | "." } ;

footnote_reference = "[" footnote_label "]_" ;

footnote_label = digit { digit } | "#" [ footnote_name ] | "*" ;

footnote_name = { letter | digit | "-" | "_" } ;

citation_reference = "[" citation_label "]_" ;

citation_label = { letter | digit | "-" | "_" | "." } ;

inline_literal = "`" "`" literal_content "`" "`" ;

literal_content = { character - "`" } ;

(* Text Content *)
plain_text = { character - markup_char } ;

emphasis_text = { character - ( "*" | newline ) } ;

strong_text = { character - ( "*" | newline ) } ;

literal_text = { character - ( "`" | newline ) } ;

markup_char = "*" | "`" | "_" | "|" | "[" | "]" | ":" | "." | ">" | "<" ;

(* Utilities *)
blank_line = newline ;

roman = "i" | "ii" | "iii" | "iv" | "v" | "vi" | "vii" | "viii" | "ix" | "x"
      | "I" | "II" | "III" | "IV" | "V" | "VI" | "VII" | "VIII" | "IX" | "X" ;

newline = "\n" | "\r\n" ;

character = letter | digit | symbol | " " ;

letter = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m"
       | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"
       | "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M"
       | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z" ;

digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;

symbol = "!" | "@" | "#" | "$" | "%" | "^" | "&" | "*" | "(" | ")" | "-" | "_" | "="
       | "+" | "[" | "]" | "{" | "}" | "\\" | "|" | ";" | ":" | "'" | '"' | "," | "."
       | "<" | ">" | "/" | "?" | "~" | "`" ;