STWL {
  Program = &(Directive*) SourceElement*
  /*
    STWL - Strongly Typed Web Language is just a working title

    This grammar is based on the ES5 and ES6 grammars and extends/cuts it where
    necessary to clear STWL from many, in my opinion unnecessary, features
    while extending it with a clearer syntax
  */

  sourceCharacter = any

  // Override Ohm's built-in definition of space.
  space := whitespace | lineTerminator | comment

  whitespace = "\t"
             | "\x0B"    -- verticalTab
             | "\x0C"    -- formFeed
             | " "
             | "\u00A0"  -- noBreakSpace
             | "\uFEFF"  -- byteOrderMark
             | unicodeSpaceSeparator

  lineTerminator = "\n" | "\r" | "\u2028" | "\u2029"
  lineTerminatorSequence = "\n" | "\r" ~"\n" | "\u2028" | "\u2029" | "\r\n"

  comment = multiLineComment | singleLineComment

  multiLineComment = "/*" (~"*/" sourceCharacter)* "*/"
  singleLineComment = "//" (~lineTerminator sourceCharacter)*

  identifier (an identifier) = ~reservedWord identifierName
  identifierName = identifierStart identifierPart*

  identifierStart = letter | "$" | "_"
  identifierPart = identifierStart | unicodeDigit
  letter += unicodeCategoryNl
  unicodeCategoryNl
    = "\u2160".."\u2182" | "\u3007" | "\u3021".."\u3029"
  unicodeDigit (a digit)
    = "\u0030".."\u0039" | "\u0660".."\u0669" | "\u06F0".."\u06F9" | "\u0966".."\u096F" | "\u09E6".."\u09EF" | "\u0A66".."\u0A6F" | "\u0AE6".."\u0AEF" | "\u0B66".."\u0B6F" | "\u0BE7".."\u0BEF" | "\u0C66".."\u0C6F" | "\u0CE6".."\u0CEF" | "\u0D66".."\u0D6F" | "\u0E50".."\u0E59" | "\u0ED0".."\u0ED9" | "\u0F20".."\u0F29" | "\uFF10".."\uFF19"

  unicodeSpaceSeparator = "\u2000".."\u200B" | "\u3000"

  reservedWord = keyword | futureReservedWord | nullLiteral | booleanLiteral

  // Note: keywords that are the complete prefix of another keyword should
  // be prioritized (e.g. 'in' should come before 'instanceof')
  keyword =  for | while | do | break | continue | match
          | if | else | const | var | live | computed
          | catch | fn | return | void | this
          | has | enum | interface | extends | implements | struct
          | export | import | defer

  futureReservedWord = fallthrough

  literal = nullLiteral | booleanLiteral | numericLiteral
          | stringLiteral | regularExpressionLiteral

  // Optionals, which can be either Some<T> or None, are translated to T | null
  nullLiteral = "None" ~identifierPart
  booleanLiteral = ("true" | "false") ~identifierPart

  // For semantics on how decimal literals are constructed, see section 7.8.3

  // Note that the ordering of hexIntegerLiteral and decimalLiteral is reversed w.r.t. the spec
  // This is intentional: the order decimalLiteral | hexIntegerLiteral will parse
  // "0x..." as a decimal literal "0" followed by "x..."
  numericLiteral = octalIntegerLiteral | hexIntegerLiteral | decimalLiteral

  decimalLiteral = decimalIntegerLiteral "." decimalDigit* exponentPart -- bothParts
                 |                       "." decimalDigit+ exponentPart -- decimalsOnly
                 | decimalIntegerLiteral                   exponentPart -- integerOnly

  decimalIntegerLiteral = nonZeroDigit decimalDigit*  -- nonZero
                        | "0"                         -- zero
  decimalDigit = "0".."9"
  nonZeroDigit = "1".."9"

  exponentPart = exponentIndicator signedInteger -- present
               |                                 -- absent
  exponentIndicator = "e" | "E"
  signedInteger = "+" decimalDigit* -- positive
                | "-" decimalDigit* -- negative
                |     decimalDigit+ -- noSign

  hexIntegerLiteral = "0x" hexDigit+
                    | "0X" hexDigit+

  // hexDigit defined in Ohm's built-in rules (otherwise: hexDigit = "0".."9" | "a".."f" | "A".."F")

  octalIntegerLiteral = "0" octalDigit+

  octalDigit = "0".."7"
  zeroToThree = "0".."3"
  fourToSeven = "4".."7"

  // For semantics on how string literals are constructed, see section 7.8.4
  stringLiteral = "\"" doubleStringCharacter* "\""
                | "'" singleStringCharacter* "'"
  doubleStringCharacter = ~("\"" | "\\" | lineTerminator) sourceCharacter -- nonEscaped
                        | "\\" escapeSequence                             -- escaped
                        | lineContinuation                                -- lineContinuation
  singleStringCharacter = ~("'" | "\\" | lineTerminator) sourceCharacter -- nonEscaped
                        | "\\" escapeSequence                            -- escaped
                        | lineContinuation                               -- lineContinuation
  lineContinuation = "\\" lineTerminatorSequence
  escapeSequence = unicodeEscapeSequence
                 | hexEscapeSequence
                 | octalEscapeSequence
                 | characterEscapeSequence  // Must come last.
  characterEscapeSequence = singleEscapeCharacter
                          | nonEscapeCharacter
  singleEscapeCharacter = "'" | "\"" | "\\" | "b" | "f" | "n" | "r" | "t" | "v"
  nonEscapeCharacter = ~(escapeCharacter | lineTerminator) sourceCharacter
  escapeCharacter = singleEscapeCharacter | decimalDigit | "x" | "u"
  octalEscapeSequence = zeroToThree octalDigit octalDigit    -- whole
                      | fourToSeven octalDigit               -- eightTimesfourToSeven
                      | zeroToThree octalDigit ~decimalDigit -- eightTimesZeroToThree
                      | octalDigit ~decimalDigit             -- octal
  hexEscapeSequence = "x" hexDigit hexDigit
  unicodeEscapeSequence = "u" hexDigit hexDigit hexDigit hexDigit

  // §7.8.5 Regular Expression Literals -- https://es5.github.io/#x7.8.5

  regularExpressionLiteral = "/" regularExpressionBody "/" regularExpressionFlags
  regularExpressionBody = regularExpressionFirstChar regularExpressionChar*
  regularExpressionFirstChar = ~("*" | "\\" | "/" | "[") regularExpressionNonTerminator
                             | regularExpressionBackslashSequence
                             | regularExpressionClass
  regularExpressionChar = ~("\\" | "/" | "[") regularExpressionNonTerminator
                        | regularExpressionBackslashSequence
                        | regularExpressionClass
  regularExpressionBackslashSequence = "\\" regularExpressionNonTerminator
  regularExpressionNonTerminator = ~(lineTerminator) sourceCharacter
  regularExpressionClass = "[" regularExpressionClassChar* "]"
  regularExpressionClassChar = ~("]" | "\\") regularExpressionNonTerminator
                             | regularExpressionBackslashSequence
  regularExpressionFlags = identifierPart*

  // === Implementation-level rules (not part of the spec) ===

  multiLineCommentNoNL = "/*" (~("*/" | lineTerminator) sourceCharacter)* "*/"

  // does not accept lineTerminators, not even implicit ones in a multiLineComment (cf. section 7.4)
  spacesNoNL = (whitespace | singleLineComment | multiLineCommentNoNL)*

  // A semicolon is "automatically inserted" if a newline or the end of the input stream is
  // reached, or the offending token is "}".
  // See https://es5.github.io/#x7.9 for more information.
  // NOTE: Applications of this rule *must* appear in a lexical context -- either in the body of a
  // lexical rule, or inside `#()`.
  sc = space* (";" | end)
     | spacesNoNL (lineTerminator | ~multiLineCommentNoNL multiLineComment | &"}")

  // Convenience rules for parsing keyword tokens.
  for = "for" ~identifierPart
  while = "while" ~identifierPart
  do = "do" ~identifierPart // will we support do-while loops?
  break = "break" ~identifierPart
  continue = "continue" ~identifierPart
  if = "if" ~identifierPart
  else = "else" ~identifierPart
  const = "const" ~identifierPart
  var = "var" ~identifierPart
  live = "live" ~identifierPart
  track = "track" ~identifierPart
  computed = "computed" ~identifierPart
  catch = "catch" ~identifierPart
  fn = "fn" ~identifierPart
  return = "return" ~identifierPart
  void = "void" ~identifierPart
  this = "_" ~identifierPart
  in = "in" ~identifierPart   -- value in ArrayLike
  has = "has" ~identifierPart -- struct has Property
  enum = "enum" ~identifierPart
  interface = "interface" ~identifierPart
  extends = "extends" ~identifierPart
  implements = "implements" ~identifierPart
  export = "export" ~identifierPart
  import = "import" ~identifierPart
  struct = "struct" ~identifierPart
  defer = "defer" ~identifierPart
  match = "match" ~identifierPart
  fallthrough = "fallthrough" ~identifierPart
  
  // end of lexical rules

  noIn = ~in
  withIn =

  noHas = ~has
  withHas =

  noInHas = ~(in | has)
  withInHas =

  // §A.3 Expressions -- https://es5.github.io/#A.3

  PrimaryExpression = this
                    | identifier
                    | literal
                      // ( litToken.type === "regexp"
                      //   ? this.ast(_fromIdx, "RegExpExpr",{body:  litToken.value.body
                      //                            flags: litToken.value.flags}, [])
                      //   : this.ast(_fromIdx, "LiteralExpr",{type:  litToken.type
                      //                             value: litToken.value}, []) )
                    | ArrayLiteral
                    | ObjectLiteral
                    | "(" Expression<withIn> ")"  -- parenExpr

  ArrayLiteral = "[" ListOf<AssignmentExpressionOrElision, ","> "]"
  AssignmentExpressionOrElision = AssignmentExpression<withIn>
                                |                       -- elision

  ObjectLiteral = "{" ListOf<PropertyAssignment, ","> "}"              -- noTrailingComma
                | "{" NonemptyListOf<PropertyAssignment, ","> "," "}"  -- trailingComma

  PropertyAssignment = get PropertyName "(" ")" "{" FunctionBody "}"                  -- getter
                     | set PropertyName "(" FormalParameter ")" "{" FunctionBody "}"  -- setter
                     | PropertyName ":" AssignmentExpression<withIn>                  -- simple

  PropertyName = identifierName
               | stringLiteral
               | numericLiteral

  MemberExpression = MemberExpression "[" Expression<withIn> "]"  -- arrayRefExp
                   | MemberExpression "." identifierName  -- propRefExp
                   | new MemberExpression Arguments       -- newExp
                   | FunctionExpression
                   | PrimaryExpression

  NewExpression = MemberExpression
                | new NewExpression -- newExp

  CallExpression = CallExpression "[" Expression<withIn> "]"  -- arrayRefExp
                 | CallExpression "." identifierName  -- propRefExp
                 | CallExpression Arguments           -- callExpExp
                 | MemberExpression Arguments         -- memberExpExp

  Arguments = "(" ListOf<AssignmentExpression<withIn>, ","> ")"

  LeftHandSideExpression = CallExpression
                         | NewExpression

  PostfixExpression = LeftHandSideExpression #(spacesNoNL "++")  -- postIncrement
                    | LeftHandSideExpression #(spacesNoNL "--")  -- postDecrement
                    | LeftHandSideExpression

  UnaryExpression = void   UnaryExpression  -- voidExp
                  | "++"   UnaryExpression  -- preIncrement
                  | "--"   UnaryExpression  -- preDecrement
                  | "+"    UnaryExpression  -- unaryPlus
                  | "-"    UnaryExpression  -- unaryMinus
                  | "~"    UnaryExpression  -- bnot
                  | "!"    UnaryExpression  -- lnot
                  | PostfixExpression

  MultiplicativeExpression = MultiplicativeExpression "*" UnaryExpression -- mul
                           | MultiplicativeExpression "/" UnaryExpression -- div
                           | MultiplicativeExpression "%" UnaryExpression -- mod
                           | UnaryExpression

  AdditiveExpression = AdditiveExpression "+" MultiplicativeExpression -- add
                     | AdditiveExpression "-" MultiplicativeExpression -- sub
                     | MultiplicativeExpression

  ShiftExpression = ShiftExpression "<<" AdditiveExpression  -- lsl
                  | ShiftExpression ">>>" AdditiveExpression -- lsr
                  | ShiftExpression ">>" AdditiveExpression  -- asr
                  | AdditiveExpression

  RelationalExpression<guardIn>
    = RelationalExpression<guardIn> "<" ShiftExpression           -- lt
    | RelationalExpression<guardIn> ">" ShiftExpression           -- gt
    | RelationalExpression<guardIn> "<=" ShiftExpression          -- le
    | RelationalExpression<guardIn> ">=" ShiftExpression          -- ge
    | RelationalExpression<guardIn> guardIn "in" ShiftExpression  -- inExp
    | ShiftExpression

  EqualityExpression<guardIn>
    = EqualityExpression<guardIn> "==" RelationalExpression<guardIn>  -- equal
    | EqualityExpression<guardIn> "!=" RelationalExpression<guardIn>  -- notEqual
    | EqualityExpression<guardIn> "===" RelationalExpression<guardIn> -- eq
    | EqualityExpression<guardIn> "!==" RelationalExpression<guardIn> -- notEq
    | RelationalExpression<guardIn>

  BitwiseANDExpression<guardIn>
    = BitwiseANDExpression<guardIn> "&" EqualityExpression<guardIn> -- band
    | EqualityExpression<guardIn>

  BitwiseXORExpression<guardIn>
    = BitwiseXORExpression<guardIn> "^" BitwiseANDExpression<guardIn> -- bxor
    | BitwiseANDExpression<guardIn>

  BitwiseORExpression<guardIn>
    = BitwiseORExpression<guardIn> "|" BitwiseXORExpression<guardIn> -- bor
    | BitwiseXORExpression<guardIn>

  LogicalANDExpression<guardIn>
    = LogicalANDExpression<guardIn> "&&" BitwiseORExpression<guardIn> -- land
    | BitwiseORExpression<guardIn>

  LogicalORExpression<guardIn>
    = LogicalORExpression<guardIn> "||" LogicalANDExpression<guardIn> -- lor
    | LogicalANDExpression<guardIn>

  ConditionalExpression<guardIn>
    = LogicalORExpression<guardIn> "?" AssignmentExpression<withIn> ":" AssignmentExpression<guardIn> -- conditional
    | LogicalORExpression<guardIn>

  AssignmentExpression<guardIn>
    = LeftHandSideExpression assignmentOperator AssignmentExpression<guardIn> -- assignment
    | ConditionalExpression<guardIn>

  Expression<guardIn> (an expression)
    = Expression<guardIn> "," AssignmentExpression<guardIn> -- commaExp
    | AssignmentExpression<guardIn>

  assignmentOperator = "=" | ">>>=" | "<<=" | ">>="
                     | "*=" | "/=" | "%=" | "+=" | "-=" | "&=" | "^=" | "|="

  // Statements -- (extends https://es5.github.io/#A.4)

  Statement
    = Block
    | VariableStatement
    | EmptyStatement
    | ExpressionStatement
    | IfStatement
    | IterationStatement
    | ContinueStatement
    | BreakStatement
    | ReturnStatement

  Block = "{" StatementList "}"
  LambdaParameters = "|" ListOf<identifier, ","> "|"

  StatementList = Statement*

  ComputedStatement = computed identifier Block

  TrackStatement = track ListOf<identifier, ","> LambdaParameters? Block
  
  VariableStatement = VariableAssignment VariableDeclarationList<withIn> #sc

  VariableAssignment = var | const | live

  VariableDeclarationList<guardIn> = NonemptyListOf<VariableDeclaration<guardIn>, ",">

  VariableDeclaration<guardIn> = identifier Initialiser<guardIn>?

  Initialiser<guardIn> = "=" AssignmentExpression<guardIn>

  EmptyStatement = ";" // note: this semicolon eats newlines

  ExpressionStatement = ~("{" | function) Expression<withIn> #sc

  IfStatement = if "(" Expression<withIn> ")" Statement (else Statement)?

  IterationStatement = do Statement while "(" Expression<withIn> ")" #sc  -- doWhile
                     | while "(" Expression<withIn> ")" Statement           -- whileDo
                     | for "(" Expression<noIn>? ";"
                                 Expression<withIn>? ";"
                                 Expression<withIn>? ")" Statement          -- for3
                     | for "(" var VariableDeclarationList<noIn> ";"
                                 Expression<withIn>? ";"
                                 Expression<withIn>? ")" Statement          -- for3var
                     | for "(" LeftHandSideExpression in
                                 Expression<withIn> ")" Statement           -- forIn
                     | for "(" var VariableDeclaration<noIn> in
                                 Expression<withIn> ")" Statement           -- forInVar

  ContinueStatement = continue #((spacesNoNL identifier)? sc)

  BreakStatement = break #((spacesNoNL identifier)? sc)

  ReturnStatement = return (#(spacesNoNL ~space) Expression<withIn>)? #sc

  Catch = catch "(" FormalParameter ")" Block

  Defer = defer (when Expression<withIn>)? Block

  // Pattern Matching

  MatchExpr = match Expression<withIn> (if Pattern)? "{" MatchArm+ "}" (else Block)?
  MatchArm = Pattern "=>" (Expression<withIn> | Block)
  Pattern = identifier
          | literal
          | GuardPattern
  GuardPattern = Expression<withIn>  // Just an expression! No special syntax needed


  // §A.5 Functions and Programs -- https://es5.github.io/#A.5

  FunctionDeclaration
    = function identifier "(" FormalParameterList ")" "{" FunctionBody "}"

  FunctionExpression
    = function identifier "(" FormalParameterList ")" "{" FunctionBody "}"  -- named
    | function "(" FormalParameterList ")" "{" FunctionBody "}"             -- anonymous

  FormalParameterList = ListOf<FormalParameter, ",">

  FormalParameter = identifier

  /*
    Note: The Directive Prologue is the longest sequence of ExpressionStatement
    productions occurring as the initial SourceElement (see https://es5.github.io/#x14.1)
  */
  FunctionBody = &(Directive*) SourceElement*

  SourceElement = Declaration | Statement

  // Broken out so es6 can override to include ConstDecl and LetDecl
  Declaration = FunctionDeclaration

  Directive = stringLiteral #sc
}

ES5Lax <: ES5 {
  futureReservedWord := futureReservedWordLax
}