module WebIDL
  module Parser

    # http://dev.w3.org/2006/webapi/WebIDL/#idl-grammar
    grammar IDL

      rule Definitions
        ws metadef:(eal:ExtendedAttributeList ws d:Definition ws defs:Definitions)? ws <ParseTree::Definitions>
      end

      rule Definition
          Module
        / Interface
        / Exception
        / TypeDef
        / ImplementsStatement
      end

      rule Module
        "module" ws name:identifier ws "{" ws defs:Definitions ws "}" ws ";" <ParseTree::Module>
      end

      rule Interface
        "interface" ws name:identifier ws inherits:InterfaceInheritance ws "{" ws members:InterfaceMembers ws "}" ws ";" <ParseTree::Interface>
      end

      rule InterfaceInheritance
        (":" ws names:ScopedNameList <ParseTree::InterfaceInheritance>)?
      end

      # extract to a generic Members syntax node?
      rule InterfaceMembers
        (eal:ExtendedAttributeList ws member:InterfaceMember ws members:InterfaceMembers ws <ParseTree::InterfaceMembers>)?
      end

      rule InterfaceMember
        Const / AttributeOrOperation
      end

      rule Exception
        "exception" ws name:identifier ws "{" ws members:ExceptionMembers ws "}" ws ";" <ParseTree::Exception>
      end

      # extract to a generic Members syntax node?
      rule ExceptionMembers
        (eal:ExtendedAttributeList ws member:ExceptionMember ws members:ExceptionMembers ws <ParseTree::InterfaceMembers>)?
      end

      rule TypeDef
        "typedef" ws type:Type ws name:identifier ws ";" <ParseTree::TypeDef>
      end

      rule ImplementsStatement
        implementor:ScopedName ws "implements" ws implementee:ScopedName ws ";" <ParseTree::ImplementsStatement>
      end

      rule Const
        "const" ws type:Type ws name:identifier ws "=" ws const_expr:ConstExpr ws ";" <ParseTree::Const>
      end

      rule ConstExpr
        BooleanLiteral / integer / float
      end

      rule BooleanLiteral
        ("true" / "false") { def build() text_value == "true" end }
      end

      rule AttributeOrOperation
        StringifierAttributeOrOperation / Attribute / Operation
      end

      rule StringifierAttributeOrOperation
        "stringifier" ws a_or_op:(Attribute / OperationRest / ";") <ParseTree::StringifierAttributeOrOperation>
      end

      rule Attribute
        readonly:ReadOnly ws "attribute" ws type:Type ws name:identifier ws getraises:GetRaises ws setraises:SetRaises ws ";" <ParseTree::Attribute>
      end

      rule ReadOnly
        "readonly"?
      end

      rule GetRaises
        ("getraises" ws list:ExceptionList)?
      end

      rule SetRaises
        ("setraises" ws list:ExceptionList)?
      end

      rule Operation
        static:"static"? specials:(OmittableSpecials / Specials) ws op:OperationRest <ParseTree::Operation>
      end

      rule OmittableSpecials
        omit:"omittable" ws Specials <ParseTree::OmittableSpecials>
      end

      rule Specials
        (first:Special ws rest:Specials <ParseTree::Specials>)?
      end

      rule Special
          "getter"
        / "setter"
        / "creator"
        / "deleter"
        / "caller"
      end

      rule OperationRest
        type:ReturnType ws optional_id:OptionalIdentifier ws "(" ws args:ArgumentList ws ")" ws raises:Raises ws ";" <ParseTree::Operation>
      end

      rule OptionalIdentifier
        identifier?
      end

      rule Raises
        ("raises" ExceptionList)?
      end

      rule ExceptionList
        "(" ScopedNameList ")"
      end

      rule ArgumentList
        (arg:Argument ws args:Arguments <ParseTree::ArgumentList>)?
      end

      rule Arguments
        ("," ws arg:Argument ws args:Arguments <ParseTree::ArgumentList>)?
      end

      rule Argument
        eal:ExtendedAttributeList ws In ws optional:Optional ws type:Type ws variadic:Ellipsis ws id:identifier <ParseTree::Argument>
      end

      rule In
        "in"?
      end

      rule Optional
        "optional"?
      end

      rule Ellipsis
        "..."?
      end

      rule ExceptionMember
        Const / ExceptionField
      end

      rule ExceptionField
        type:Type ws id:identifier ws ";" <ParseTree::ExceptionField>
      end

      rule ExtendedAttributeList
        ("[" ws attribute:ExtendedAttribute ws attributes:ExtendedAttributes ws "]" <ParseTree::ExtendedAttributeList>)?
      end

      rule ExtendedAttributes
        ("," ws attribute:ExtendedAttribute ws attributes:ExtendedAttributes <ParseTree::ExtendedAttributeList>)?
      end


      #
      # avoid infinite recursion trouble with the actual spec by using the "more restricted" ones
      #

      rule ExtendedAttribute
          ExtendedAttributeNamedArgList
        / ExtendedAttributeIdent
        / ExtendedAttributeScopedName
        / ExtendedAttributeArgList
        / ExtendedAttributeNoArg
      end

      rule ExtendedAttributeNoArg
        identifier {
          def build(parent)
            Ast::ExtendedAttribute.new(text_value)
          end
        }
      end

      rule ExtendedAttributeArgList
        name:identifier "(" ws args:ArgumentList ws ")" <ParseTree::ExtendedAttributeArgList>
      end

      rule ExtendedAttributeScopedName
        key:identifier "=" scoped_name:ScopedName <ParseTree::ExtendedAttributeScopedName>
      end

      rule ExtendedAttributeIdent
        key:identifier "=" value:identifier !"::" <ParseTree::ExtendedAttributeIdent>
      end

      rule ExtendedAttributeNamedArgList
        key:identifier "=" value:(name:identifier "(" ws args:ArgumentList ws ")" <ParseTree::ExtendedAttributeArgList>) <ParseTree::ExtendedAttributeNamedArgList>
      end


    #  rule ExtendedAttribute
    #      "(" ws ExtendedAttributeInner ws ")" ws ExtendedAttributeRest
    #    / "[" ws ExtendedAttributeInner ws "]" ws ExtendedAttributeRest
    #    / "{" ws ExtendedAttributeInner ws "}" ws ExtendedAttributeRest
    #    / Other ws ExtendedAttributeRest
    #  end
    #
    #  rule ExtendedAttributeRest
    #    ExtendedAttribute?
    #  end
    #
    #  rule ExtendedAttributeInner
    #    ( "(" ws ExtendedAttributeInner ws ")" ws ExtendedAttributeInner
    #    / "[" ws ExtendedAttributeInner ws "]" ws ExtendedAttributeInner
    #    / "{" ws ExtendedAttributeInner ws "}" ws ExtendedAttributeInner
    #    / OtherOrComma ExtendedAttributeInner)?
    #  end
    #
      rule Other
          integer
        / float
        / identifier
        / string
        / other
        / "..."
        / ":"
        / "::"
        / ";"
        / "<"
        / "="
        / ">"
        / "?"
        / "false"
        / "object"
        / "true"
        / "any"
        / "attribute"
        / "boolean"
        / "caller"
        / "const"
        / "creator"
        / "deleter"
        / "double"
        / "exception"
        / "float"
        / "getraises"
        / "getter"
        / "implements"
        / "in"
        / "interface"
        / "long"
        / "module"
        / "octet"
        / "omittable"
        / "optional"
        / "raises"
        / "sequence"
        / "setraises"
        / "setter"
        / "short"
        / "DOMString"
        / "stringifier"
        / "typedef"
        / "unsigned"
        / "void"
      end

      rule OtherOrComma
        Other / ","
      end

      rule Type
        type:(  NullableType
          / ScopedName
          / "any"     # not sure why these two are here, since
          / "object"  # they will be caught by ScopedName anyway..
        ) array:Array <ParseTree::Type>
      end

      #
      # added: cannot be followed by a NonSpace character, since e.g. DOMStringMap would break parsing
      #

      rule NullableType
          type:UnsignedIntegerType              null:Nullable           <ParseTree::NullableType>
        / type:"boolean"                        null:Nullable !NonSpace <ParseTree::NullableType>
        / type:"octet"                          null:Nullable !NonSpace <ParseTree::NullableType>
        / type:"float"                          null:Nullable !NonSpace <ParseTree::NullableType>
        / type:"double"                         null:Nullable !NonSpace <ParseTree::NullableType>
        / type:"DOMString"                      null:Nullable !NonSpace <ParseTree::NullableType>
        / type:"sequence" ws "<" ws Type ws ">" null:Nullable !NonSpace <ParseTree::NullableType>
      end

      rule UnsignedIntegerType
        "unsigned" ws IntegerType / IntegerType
      end

      rule IntegerType
        ("short" / "long" ws OptionalLong)
      end

      rule OptionalLong
        "long"?
      end

      rule Nullable
        "?"?
      end

      rule Array
        ("[" ws "]")?
      end

      rule NonSpace
        (!' ' .)
      end

      rule ReturnType
        Type / "void" <ParseTree::VoidType>
      end

      rule ScopedNameList
        name:ScopedName ws names:ScopedNames  <ParseTree::ScopedNameList>
      end

      rule ScopedNames
        ("," ScopedName ws ScopedNames)?
      end

      rule ScopedName
        AbsoluteScopedName / RelativeScopedName
      end

      rule AbsoluteScopedName
        "::" name:identifier parts:ScopedNameParts <ParseTree::AbsoluteScopedName>
      end

      rule RelativeScopedName
        name:identifier parts:ScopedNameParts <ParseTree::RelativeScopedName>
      end

      rule ScopedNameParts
        ("::" ws name:identifier parts:ScopedNameParts)?
      end

      rule integer
        (hexint / octint / decint) { def build() Integer(text_value) end} # TODO: check edge cases
      end

      rule hexint
        "-"? "0" [Xx] [0-9A-Fa-f]+
      end

      rule octint
        "-"? "0" [0-7]+
      end

      rule decint
        "-"? [0-9]*
      end

      rule float
        ("-"? ([0-9]+ "." [0-9]* / [0-9]* "." [0-9]+) ([Ee] [+-]? [0-9]+)? / [0-9]+ [Ee] [+-]? [0-9]+) { def build() Float(text_value) end} # TODO: check edge cases
      end

      rule identifier
        [A-Z_a-z] [0-9A-Z_a-z]* { def build() text_value[/^_?(.+)/, 1] end }
      end

      rule string
        "\"" [^"]* "\""
      end

      rule ws
        ([\t\n\r ]* ((line_comment /  block_comment) [\t\n\r ]*)+ / [\t\n\r ]+)?
      end

      rule other
        [^\t\n\r 0-9A-Z_a-z]
      end

      rule line_comment
        "//" (![\n\r] . )*
      end

      rule block_comment
         '/*' (!'*/' . )* '*/'
      end

    end # IDL
  end # Parser
end # WebIDL