#
# Context free grammar for the Emerald language.
# Emerald: a preprocessor for html5.
#
grammar Emerald
  include Tokens
  include Scopes
  include Variables

  rule main
    (scope / pair_list / value_list / nested / line / comment)+ <Root>
  end

  rule nested
    tag_statement newline lbrace newline main rbrace newline <Nested>
  end

  rule scope
    fn:scope_fn lbrace newline body:main rbrace newline <Scope>
  end

  rule line
    (tag_statement / comment) newline <Line>
  end

  rule value_list
    keyword:special_keyword newline lbrace newline
    list_items:(literal:inline_literal_string newline)+
    rbrace newline <ValueList>
  end

  rule pair_list
    keyword:base_keyword newline lbrace newline
    list_items:(pairs:(attr:attr space+ literal:inline_literal_string space*)+ newline)+
    rbrace newline <PairList>
  end

  rule comment
    space* '*' space* text_content <Comment>
  end

  rule text_content
    multiline_literal / multiline_templateless_literal / inline_literal
  end

  rule multiline_literal
    "->" space* newline
    body:(variable / escaped / !'$' .)*
    "$" <TextLiteral>
  end

  rule multiline_templateless_literal
    ("=>" / "~>") space* newline
    body:(escaped / !'$' .)*
    "$" <TextLiteral>
  end

  rule inline_literal
    body:( variable / escaped / !lparen !newline . )* <TextLiteral>
  end

  rule inline_literal_string
    '"' body:( variable / escaped / !'"' . )* '"' <TextLiteral>
  end

  rule escaped
    "\\" .
  end

  rule tag_statement
    tag identifier:id_name? classes:class_name* space* body:text_content? attributes:attr_list? <TagStatement>
  end

  rule id_name
    '#' name:([a-zA-Z_\-]+)
  end

  rule class_name
    '.' name:([a-zA-Z_\-]+)
  end

  rule attr_list
    lparen newline lbrace newline attributes rbrace newline rparen <AttributeList>
  end

  rule attributes
    attribute* <Attributes>
  end

  rule attribute
    attr space* inline_literal_string newline
  end
end