grammar.coffee

# The CoffeeScript parser is generated by [Jison](https://github.com/zaach/jison)
# from this grammar file. Jison is a bottom-up parser generator, similar in
# style to [Bison](http://www.gnu.org/software/bison), implemented in JavaScript.
# It can recognize [LALR(1), LR(0), SLR(1), and LR(1)](https://en.wikipedia.org/wiki/LR_grammar)
# type grammars. To create the Jison parser, we list the pattern to match
# on the left-hand side, and the action to take (usually the creation of syntax
# tree nodes) on the right. As the parser runs, it
# shifts tokens from our token stream, from left to right, and
# [attempts to match](https://en.wikipedia.org/wiki/Bottom-up_parsing)
# the token sequence against the rules below. When a match can be made, it
# reduces into the [nonterminal](https://en.wikipedia.org/wiki/Terminal_and_nonterminal_symbols)
# (the enclosing name at the top), and we proceed from there.
#
# If you run the `cake build:parser` command, Jison constructs a parse table
# from our rules and saves it into `lib/parser.js`.

# The only dependency is on the **Jison.Parser**.
{Parser} = require 'jison'

# Jison DSL
# ---------

# Since we're going to be wrapped in a function by Jison in any case, if our
# action immediately returns a value, we can optimize by removing the function
# wrapper and just returning the value directly.
unwrap = /^function\s*\(\)\s*\{\s*return\s*([\s\S]*);\s*\}/

# Our handy DSL for Jison grammar generation, thanks to
# [Tim Caswell](https://github.com/creationix). For every rule in the grammar,
# we pass the pattern-defining string, the action to run, and extra options,
# optionally. If no action is specified, we simply pass the value of the
# previous nonterminal.
o = (patternString, action, options) ->
  patternString = patternString.replace /\s{2,}/g, ' '
  patternCount = patternString.split(' ').length
  if action
    # This code block does string replacements in the generated `parser.js`
    # file, replacing the calls to the `LOC` function and other strings as
    # listed below.
    action = if match = unwrap.exec action then match[1] else "(#{action}())"

    # All runtime functions we need are defined on `yy`
    action = action.replace /\bnew /g, '$&yy.'
    action = action.replace /\b(?:Block\.wrap|extend)\b/g, 'yy.$&'

    # Returns strings of functions to add to `parser.js` which add extra data
    # that nodes may have, such as comments or location data. Location data
    # is added to the first parameter passed in, and the parameter is returned.
    # If the parameter is not a node, it will just be passed through unaffected.
    getAddDataToNodeFunctionString = (first, last, forceUpdateLocation = yes) ->
      "yy.addDataToNode(yy, @#{first}, #{if first[0] is '$' then '$$' else '$'}#{first}, #{if last then "@#{last}, #{if last[0] is '$' then '$$' else '$'}#{last}" else 'null, null'}, #{if forceUpdateLocation then 'true' else 'false'})"

    # This code replaces the calls to `LOC` with the `yy.addDataToNode` string
    # defined above. The `LOC` function, when used below in the grammar rules,
    # is used to make sure that newly created node class objects get correct
    # location data assigned to them. By default, the grammar will assign the
    # location data spanned by *all* of the tokens on the left (e.g. a string
    # such as `'Body TERMINATOR Line'`) to the “top-level” node returned by
    # the grammar rule (the function on the right). But for “inner” node class
    # objects created by grammar rules, they won’t get correct location data
    # assigned to them without adding `LOC`.

    # For example, consider the grammar rule `'NEW_TARGET . Property'`, which
    # is handled by a function that returns
    # `new MetaProperty LOC(1)(new IdentifierLiteral $1), LOC(3)(new Access $3)`.
    # The `1` in `LOC(1)` refers to the first token (`NEW_TARGET`) and the `3`
    # in `LOC(3)` refers to the third token (`Property`). In order for the
    # `new IdentifierLiteral` to get assigned the location data corresponding
    # to `new` in the source code, we use
    # `LOC(1)(new IdentifierLiteral ...)` to mean “assign the location data of
    # the *first* token of this grammar rule (`NEW_TARGET`) to this
    # `new IdentifierLiteral`”. The `LOC(3)` means “assign the location data of
    # the *third* token of this grammar rule (`Property`) to this
    # `new Access`”.
    returnsLoc = /^LOC/.test action
    action = action.replace /LOC\(([0-9]*)\)/g, getAddDataToNodeFunctionString('$1')
    # A call to `LOC` with two arguments, e.g. `LOC(2,4)`, sets the location
    # data for the generated node on both of the referenced tokens  (the second
    # and fourth in this example).
    action = action.replace /LOC\(([0-9]*),\s*([0-9]*)\)/g, getAddDataToNodeFunctionString('$1', '$2')
    performActionFunctionString = "$$ = #{getAddDataToNodeFunctionString(1, patternCount, not returnsLoc)}(#{action});"
  else
    performActionFunctionString = '$$ = $1;'

  [patternString, performActionFunctionString, options]

# Grammatical Rules
# -----------------

# In all of the rules that follow, you'll see the name of the nonterminal as
# the key to a list of alternative matches. With each match's action, the
# dollar-sign variables are provided by Jison as references to the value of
# their numeric position, so in this rule:
#
#     'Expression UNLESS Expression'
#
# `$1` would be the value of the first `Expression`, `$2` would be the token
# for the `UNLESS` terminal, and `$3` would be the value of the second
# `Expression`.
grammar =

  # The **Root** is the top-level node in the syntax tree. Since we parse bottom-up,
  # all parsing must end here.
  Root: [
    o '',                                       -> new Root new Block
    o 'Body',                                   -> new Root $1
  ]

  # Any list of statements and expressions, separated by line breaks or semicolons.
  Body: [
    o 'Line',                                   -> Block.wrap [$1]
    o 'Body TERMINATOR Line',                   -> $1.push $3
    o 'Body TERMINATOR'
  ]

  # Block and statements, which make up a line in a body. FuncDirective is a
  # statement, but not included in Statement because that results in an ambiguous
  # grammar.
  Line: [
    o 'Expression'
    o 'ExpressionLine'
    o 'Statement'
    o 'FuncDirective'
  ]

  FuncDirective: [
    o 'YieldReturn'
    o 'AwaitReturn'
  ]

  # Pure statements which cannot be expressions.
  Statement: [
    o 'Return'
    o 'STATEMENT',                              -> new StatementLiteral $1
    o 'Import'
    o 'Export'
  ]

  # All the different types of expressions in our language. The basic unit of
  # CoffeeScript is the **Expression** -- everything that can be an expression
  # is one. Blocks serve as the building blocks of many other rules, making
  # them somewhat circular.
  Expression: [
    o 'Value'
    o 'Code'
    o 'Operation'
    o 'Assign'
    o 'If'
    o 'Try'
    o 'While'
    o 'For'
    o 'Switch'
    o 'Class'
    o 'Throw'
    o 'Yield'
  ]

  # Expressions which are written in single line and would otherwise require being
  # wrapped in braces: E.g `a = b if do -> f a is 1`, `if f (a) -> a*2 then ...`,
  # `for x in do (obj) -> f obj when x > 8 then f x`
  ExpressionLine: [
    o 'CodeLine'
    o 'IfLine'
    o 'OperationLine'
  ]

  Yield: [
    o 'YIELD',                                  -> new Op $1, new Value new Literal ''
    o 'YIELD Expression',                       -> new Op $1, $2
    o 'YIELD INDENT Object OUTDENT',            -> new Op $1, $3
    o 'YIELD FROM Expression',                  -> new Op $1.concat($2), $3
  ]

  # An indented block of expressions. Note that the [Rewriter](rewriter.html)
  # will convert some postfix forms into blocks for us, by adjusting the
  # token stream.
  Block: [
    o 'INDENT OUTDENT',                         -> new Block
    o 'INDENT Body OUTDENT',                    -> $2
  ]

  Identifier: [
    o 'IDENTIFIER',                             -> new IdentifierLiteral $1
    o 'JSX_TAG',                                -> new JSXTag $1.toString(),
                                                     tagNameLocationData:                  $1.tagNameToken[2]
                                                     closingTagOpeningBracketLocationData: $1.closingTagOpeningBracketToken?[2]
                                                     closingTagSlashLocationData:          $1.closingTagSlashToken?[2]
                                                     closingTagNameLocationData:           $1.closingTagNameToken?[2]
                                                     closingTagClosingBracketLocationData: $1.closingTagClosingBracketToken?[2]
  ]

  Property: [
    o 'PROPERTY',                               -> new PropertyName $1.toString()
  ]

  # Alphanumerics are separated from the other **Literal** matchers because
  # they can also serve as keys in object literals.
  AlphaNumeric: [
    o 'NUMBER',                                 -> new NumberLiteral $1.toString(), parsedValue: $1.parsedValue
    o 'String'
  ]

  String: [
    o 'STRING', ->
      new StringLiteral(
        $1.slice 1, -1 # strip artificial quotes and unwrap to primitive string
        quote:        $1.quote
        initialChunk: $1.initialChunk
        finalChunk:   $1.finalChunk
        indent:       $1.indent
        double:       $1.double
        heregex:      $1.heregex
      )
    o 'STRING_START Interpolations STRING_END', -> new StringWithInterpolations Block.wrap($2), quote: $1.quote, startQuote: LOC(1)(new Literal $1.toString())
  ]

  Interpolations: [
    o 'InterpolationChunk',                     -> [$1]
    o 'Interpolations InterpolationChunk',      -> $1.concat $2
  ]

  InterpolationChunk: [
    o 'INTERPOLATION_START Body INTERPOLATION_END',                -> new Interpolation $2
    o 'INTERPOLATION_START INDENT Body OUTDENT INTERPOLATION_END', -> new Interpolation $3
    o 'INTERPOLATION_START INTERPOLATION_END',                     -> new Interpolation
    o 'String',                                                    -> $1
  ]

  # The .toString() calls here and elsewhere are to convert `String` objects
  # back to primitive strings now that we've retrieved stowaway extra properties
  Regex: [
    o 'REGEX',                                  -> new RegexLiteral $1.toString(), delimiter: $1.delimiter, heregexCommentTokens: $1.heregexCommentTokens
    o 'REGEX_START Invocation REGEX_END',       -> new RegexWithInterpolations $2, heregexCommentTokens: $3.heregexCommentTokens
  ]

  # All of our immediate values. Generally these can be passed straight
  # through and printed to JavaScript.
  Literal: [
    o 'AlphaNumeric'
    o 'JS',                                     -> new PassthroughLiteral $1.toString(), here: $1.here, generated: $1.generated
    o 'Regex'
    o 'UNDEFINED',                              -> new UndefinedLiteral $1
    o 'NULL',                                   -> new NullLiteral $1
    o 'BOOL',                                   -> new BooleanLiteral $1.toString(), originalValue: $1.original
    o 'INFINITY',                               -> new InfinityLiteral $1.toString(), originalValue: $1.original
    o 'NAN',                                    -> new NaNLiteral $1
  ]

  # Assignment of a variable, property, or index to a value.
  Assign: [
    o 'Assignable = Expression',                -> new Assign $1, $3
    o 'Assignable = TERMINATOR Expression',     -> new Assign $1, $4
    o 'Assignable = INDENT Expression OUTDENT', -> new Assign $1, $4
  ]

  # Assignment when it happens within an object literal. The difference from
  # the ordinary **Assign** is that these allow numbers and strings as keys.
  AssignObj: [
    o 'ObjAssignable',                          -> new Value $1
    o 'ObjRestValue'
    o 'ObjAssignable : Expression',             -> new Assign LOC(1)(new Value $1), $3, 'object',
                                                              operatorToken: LOC(2)(new Literal $2)
    o 'ObjAssignable :
       INDENT Expression OUTDENT',              -> new Assign LOC(1)(new Value $1), $4, 'object',
                                                              operatorToken: LOC(2)(new Literal $2)
    o 'SimpleObjAssignable = Expression',       -> new Assign LOC(1)(new Value $1), $3, null,
                                                              operatorToken: LOC(2)(new Literal $2)
    o 'SimpleObjAssignable =
       INDENT Expression OUTDENT',              -> new Assign LOC(1)(new Value $1), $4, null,
                                                              operatorToken: LOC(2)(new Literal $2)
  ]

  SimpleObjAssignable: [
    o 'Identifier'
    o 'Property'
    o 'ThisProperty'
  ]

  ObjAssignable: [
    o 'SimpleObjAssignable'
    o '[ Expression ]',          -> new Value new ComputedPropertyName $2
    o '@ [ Expression ]',        -> new Value LOC(1)(new ThisLiteral $1), [LOC(3)(new ComputedPropertyName($3))], 'this'
    o 'AlphaNumeric'
  ]

  # Object literal spread properties.
  ObjRestValue: [
    o 'SimpleObjAssignable ...', -> new Splat new Value $1
    o '... SimpleObjAssignable', -> new Splat new Value($2), postfix: no
    o 'ObjSpreadExpr ...',       -> new Splat $1
    o '... ObjSpreadExpr',       -> new Splat $2, postfix: no
  ]

  ObjSpreadExpr: [
    o 'ObjSpreadIdentifier'
    o 'Object'
    o 'Parenthetical'
    o 'Super'
    o 'This'
    o 'SUPER OptFuncExist Arguments',               -> new SuperCall LOC(1)(new Super), $3, $2.soak, $1
    o 'DYNAMIC_IMPORT Arguments',                   -> new DynamicImportCall LOC(1)(new DynamicImport), $2
    o 'SimpleObjAssignable OptFuncExist Arguments', -> new Call (new Value $1), $3, $2.soak
    o 'ObjSpreadExpr OptFuncExist Arguments',       -> new Call $1, $3, $2.soak
  ]

  ObjSpreadIdentifier: [
    o 'SimpleObjAssignable Accessor', -> (new Value $1).add $2
    o 'ObjSpreadExpr Accessor',       -> (new Value $1).add $2
  ]

  # A return statement from a function body.
  Return: [
    o 'RETURN Expression',                      -> new Return $2
    o 'RETURN INDENT Object OUTDENT',           -> new Return new Value $3
    o 'RETURN',                                 -> new Return
  ]

  YieldReturn: [
    o 'YIELD RETURN Expression',                -> new YieldReturn $3,   returnKeyword: LOC(2)(new Literal $2)
    o 'YIELD RETURN',                           -> new YieldReturn null, returnKeyword: LOC(2)(new Literal $2)
  ]

  AwaitReturn: [
    o 'AWAIT RETURN Expression',                -> new AwaitReturn $3,   returnKeyword: LOC(2)(new Literal $2)
    o 'AWAIT RETURN',                           -> new AwaitReturn null, returnKeyword: LOC(2)(new Literal $2)
  ]

  # The **Code** node is the function literal. It’s defined by an indented block
  # of **Block** preceded by a function arrow, with an optional parameter list.
  Code: [
    o 'PARAM_START ParamList PARAM_END FuncGlyph Block', -> new Code $2, $5, $4, LOC(1)(new Literal $1)
    o 'FuncGlyph Block',                                 -> new Code [], $2, $1
  ]

  # The Codeline is the **Code** node with **Line** instead of indented **Block**.
  CodeLine: [
    o 'PARAM_START ParamList PARAM_END FuncGlyph Line', -> new Code $2, LOC(5)(Block.wrap [$5]), $4,
                                                              LOC(1)(new Literal $1)
    o 'FuncGlyph Line',                                 -> new Code [], LOC(2)(Block.wrap [$2]), $1
  ]

  # CoffeeScript has two different symbols for functions. `->` is for ordinary
  # functions, and `=>` is for functions bound to the current value of *this*.
  FuncGlyph: [
    o '->',                                     -> new FuncGlyph $1
    o '=>',                                     -> new FuncGlyph $1
  ]

  # An optional, trailing comma.
  OptComma: [
    o ''
    o ','
  ]

  # The list of parameters that a function accepts can be of any length.
  ParamList: [
    o '',                                       -> []
    o 'Param',                                  -> [$1]
    o 'ParamList , Param',                      -> $1.concat $3
    o 'ParamList OptComma TERMINATOR Param',    -> $1.concat $4
    o 'ParamList OptComma INDENT ParamList OptComma OUTDENT', -> $1.concat $4
  ]

  # A single parameter in a function definition can be ordinary, or a splat
  # that hoovers up the remaining arguments.
  Param: [
    o 'ParamVar',                               -> new Param $1
    o 'ParamVar ...',                           -> new Param $1, null, on
    o '... ParamVar',                           -> new Param $2, null, postfix: no
    o 'ParamVar = Expression',                  -> new Param $1, $3
    o '...',                                    -> new Expansion
  ]

  # Function Parameters
  ParamVar: [
    o 'Identifier'
    o 'ThisProperty'
    o 'Array'
    o 'Object'
  ]

  # A splat that occurs outside of a parameter list.
  Splat: [
    o 'Expression ...',                         -> new Splat $1
    o '... Expression',                         -> new Splat $2, {postfix: no}
  ]

  # Variables and properties that can be assigned to.
  SimpleAssignable: [
    o 'Identifier',                             -> new Value $1
    o 'Value Accessor',                         -> $1.add $2
    o 'Code Accessor',                          -> new Value($1).add $2
    o 'ThisProperty'
  ]

  # Everything that can be assigned to.
  Assignable: [
    o 'SimpleAssignable'
    o 'Array',                                  -> new Value $1
    o 'Object',                                 -> new Value $1
  ]

  # The types of things that can be treated as values -- assigned to, invoked
  # as functions, indexed into, named as a class, etc.
  Value: [
    o 'Assignable'
    o 'Literal',                                -> new Value $1
    o 'Parenthetical',                          -> new Value $1
    o 'Range',                                  -> new Value $1
    o 'Invocation',                             -> new Value $1
    o 'DoIife',                                 -> new Value $1
    o 'This'
    o 'Super',                                  -> new Value $1
    o 'MetaProperty',                           -> new Value $1
  ]

  # A `super`-based expression that can be used as a value.
  Super: [
    o 'SUPER . Property',                                      -> new Super LOC(3)(new Access $3), LOC(1)(new Literal $1)
    o 'SUPER INDEX_START Expression INDEX_END',                -> new Super LOC(3)(new Index $3),  LOC(1)(new Literal $1)
    o 'SUPER INDEX_START INDENT Expression OUTDENT INDEX_END', -> new Super LOC(4)(new Index $4),  LOC(1)(new Literal $1)
  ]

  # A “meta-property” access e.g. `new.target` or `import.meta`, where
  # something that looks like a property is referenced on a keyword.
  MetaProperty: [
    o 'NEW_TARGET . Property',                  -> new MetaProperty LOC(1)(new IdentifierLiteral $1), LOC(3)(new Access $3)
    o 'IMPORT_META . Property',                 -> new MetaProperty LOC(1)(new IdentifierLiteral $1), LOC(3)(new Access $3)
  ]

  # The general group of accessors into an object, by property, by prototype
  # or by array index or slice.
  Accessor: [
    o '.  Property',                            -> new Access $2
    o '?. Property',                            -> new Access $2, soak: yes
    o ':: Property',                            -> [LOC(1)(new Access new PropertyName('prototype'), shorthand: yes), LOC(2)(new Access $2)]
    o '?:: Property',                           -> [LOC(1)(new Access new PropertyName('prototype'), shorthand: yes, soak: yes), LOC(2)(new Access $2)]
    o '::',                                     -> new Access new PropertyName('prototype'), shorthand: yes
    o '?::',                                    -> new Access new PropertyName('prototype'), shorthand: yes, soak: yes
    o 'Index'
  ]

  # Indexing into an object or array using bracket notation.
  Index: [
    o 'INDEX_START IndexValue INDEX_END',                -> $2
    o 'INDEX_START INDENT IndexValue OUTDENT INDEX_END', -> $3
    o 'INDEX_SOAK  Index',                               -> extend $2, soak: yes
  ]

  IndexValue: [
    o 'Expression',                             -> new Index $1
    o 'Slice',                                  -> new Slice $1
  ]

  # In CoffeeScript, an object literal is simply a list of assignments.
  Object: [
    o '{ AssignList OptComma }',                -> new Obj $2, $1.generated
  ]

  # Assignment of properties within an object literal can be separated by
  # comma, as in JavaScript, or simply by newline.
  AssignList: [
    o '',                                                       -> []
    o 'AssignObj',                                              -> [$1]
    o 'AssignList , AssignObj',                                 -> $1.concat $3
    o 'AssignList OptComma TERMINATOR AssignObj',               -> $1.concat $4
    o 'AssignList OptComma INDENT AssignList OptComma OUTDENT', -> $1.concat $4
  ]

  # Class definitions have optional bodies of prototype property assignments,
  # and optional references to the superclass.
  Class: [
    o 'CLASS',                                           -> new Class
    o 'CLASS Block',                                     -> new Class null, null, $2
    o 'CLASS EXTENDS Expression',                        -> new Class null, $3
    o 'CLASS EXTENDS Expression Block',                  -> new Class null, $3, $4
    o 'CLASS SimpleAssignable',                          -> new Class $2
    o 'CLASS SimpleAssignable Block',                    -> new Class $2, null, $3
    o 'CLASS SimpleAssignable EXTENDS Expression',       -> new Class $2, $4
    o 'CLASS SimpleAssignable EXTENDS Expression Block', -> new Class $2, $4, $5
  ]

  Import: [
    o 'IMPORT String',                                                                              -> new ImportDeclaration null, $2
    o 'IMPORT String ASSERT Object',                                                                -> new ImportDeclaration null, $2, $4
    o 'IMPORT ImportDefaultSpecifier FROM String',                                                  -> new ImportDeclaration new ImportClause($2, null), $4
    o 'IMPORT ImportDefaultSpecifier FROM String ASSERT Object',                                    -> new ImportDeclaration new ImportClause($2, null), $4, $6
    o 'IMPORT ImportNamespaceSpecifier FROM String',                                                -> new ImportDeclaration new ImportClause(null, $2), $4
    o 'IMPORT ImportNamespaceSpecifier FROM String ASSERT Object',                                  -> new ImportDeclaration new ImportClause(null, $2), $4, $6
    o 'IMPORT { } FROM String',                                                                     -> new ImportDeclaration new ImportClause(null, new ImportSpecifierList []), $5
    o 'IMPORT { } FROM String ASSERT Object',                                                       -> new ImportDeclaration new ImportClause(null, new ImportSpecifierList []), $5, $7
    o 'IMPORT { ImportSpecifierList OptComma } FROM String',                                        -> new ImportDeclaration new ImportClause(null, new ImportSpecifierList $3), $7
    o 'IMPORT { ImportSpecifierList OptComma } FROM String ASSERT Object',                          -> new ImportDeclaration new ImportClause(null, new ImportSpecifierList $3), $7, $9
    o 'IMPORT ImportDefaultSpecifier , ImportNamespaceSpecifier FROM String',                       -> new ImportDeclaration new ImportClause($2, $4), $6
    o 'IMPORT ImportDefaultSpecifier , ImportNamespaceSpecifier FROM String ASSERT Object',         -> new ImportDeclaration new ImportClause($2, $4), $6, $8
    o 'IMPORT ImportDefaultSpecifier , { ImportSpecifierList OptComma } FROM String',               -> new ImportDeclaration new ImportClause($2, new ImportSpecifierList $5), $9
    o 'IMPORT ImportDefaultSpecifier , { ImportSpecifierList OptComma } FROM String ASSERT Object', -> new ImportDeclaration new ImportClause($2, new ImportSpecifierList $5), $9, $11
  ]

  ImportSpecifierList: [
    o 'ImportSpecifier',                                                          -> [$1]
    o 'ImportSpecifierList , ImportSpecifier',                                    -> $1.concat $3
    o 'ImportSpecifierList OptComma TERMINATOR ImportSpecifier',                  -> $1.concat $4
    o 'INDENT ImportSpecifierList OptComma OUTDENT',                              -> $2
    o 'ImportSpecifierList OptComma INDENT ImportSpecifierList OptComma OUTDENT', -> $1.concat $4
  ]

  ImportSpecifier: [
    o 'Identifier',                             -> new ImportSpecifier $1
    o 'Identifier AS Identifier',               -> new ImportSpecifier $1, $3
    o 'DEFAULT',                                -> new ImportSpecifier LOC(1)(new DefaultLiteral $1)
    o 'DEFAULT AS Identifier',                  -> new ImportSpecifier LOC(1)(new DefaultLiteral($1)), $3
  ]

  ImportDefaultSpecifier: [
    o 'Identifier',                             -> new ImportDefaultSpecifier $1
  ]

  ImportNamespaceSpecifier: [
    o 'IMPORT_ALL AS Identifier',               -> new ImportNamespaceSpecifier new Literal($1), $3
  ]

  Export: [
    o 'EXPORT { }',                                                        -> new ExportNamedDeclaration new ExportSpecifierList []
    o 'EXPORT { ExportSpecifierList OptComma }',                           -> new ExportNamedDeclaration new ExportSpecifierList $3
    o 'EXPORT Class',                                                      -> new ExportNamedDeclaration $2
    o 'EXPORT Identifier = Expression',                                    -> new ExportNamedDeclaration LOC(2,4)(new Assign $2, $4, null,
                                                                                                      moduleDeclaration: 'export')
    o 'EXPORT Identifier = TERMINATOR Expression',                         -> new ExportNamedDeclaration LOC(2,5)(new Assign $2, $5, null,
                                                                                                      moduleDeclaration: 'export')
    o 'EXPORT Identifier = INDENT Expression OUTDENT',                     -> new ExportNamedDeclaration LOC(2,6)(new Assign $2, $5, null,
                                                                                                      moduleDeclaration: 'export')
    o 'EXPORT DEFAULT Expression',                                         -> new ExportDefaultDeclaration $3
    o 'EXPORT DEFAULT INDENT Object OUTDENT',                              -> new ExportDefaultDeclaration new Value $4
    o 'EXPORT EXPORT_ALL FROM String',                                     -> new ExportAllDeclaration new Literal($2), $4
    o 'EXPORT EXPORT_ALL FROM String ASSERT Object',                       -> new ExportAllDeclaration new Literal($2), $4, $6
    o 'EXPORT { } FROM String',                                            -> new ExportNamedDeclaration new ExportSpecifierList([]), $5
    o 'EXPORT { } FROM String ASSERT Object',                              -> new ExportNamedDeclaration new ExportSpecifierList([]), $5, $7
    o 'EXPORT { ExportSpecifierList OptComma } FROM String',               -> new ExportNamedDeclaration new ExportSpecifierList($3), $7
    o 'EXPORT { ExportSpecifierList OptComma } FROM String ASSERT Object', -> new ExportNamedDeclaration new ExportSpecifierList($3), $7, $9
  ]

  ExportSpecifierList: [
    o 'ExportSpecifier',                                                          -> [$1]
    o 'ExportSpecifierList , ExportSpecifier',                                    -> $1.concat $3
    o 'ExportSpecifierList OptComma TERMINATOR ExportSpecifier',                  -> $1.concat $4
    o 'INDENT ExportSpecifierList OptComma OUTDENT',                              -> $2
    o 'ExportSpecifierList OptComma INDENT ExportSpecifierList OptComma OUTDENT', -> $1.concat $4
  ]

  ExportSpecifier: [
    o 'Identifier',                             -> new ExportSpecifier $1
    o 'Identifier AS Identifier',               -> new ExportSpecifier $1, $3
    o 'Identifier AS DEFAULT',                  -> new ExportSpecifier $1, LOC(3)(new DefaultLiteral $3)
    o 'DEFAULT',                                -> new ExportSpecifier LOC(1)(new DefaultLiteral $1)
    o 'DEFAULT AS Identifier',                  -> new ExportSpecifier LOC(1)(new DefaultLiteral($1)), $3
  ]

  # Ordinary function invocation, or a chained series of calls.
  Invocation: [
    o 'Value OptFuncExist String',              -> new TaggedTemplateCall $1, $3, $2.soak
    o 'Value OptFuncExist Arguments',           -> new Call $1, $3, $2.soak
    o 'SUPER OptFuncExist Arguments',           -> new SuperCall LOC(1)(new Super), $3, $2.soak, $1
    o 'DYNAMIC_IMPORT Arguments',               -> new DynamicImportCall LOC(1)(new DynamicImport), $2
  ]

  # An optional existence check on a function.
  OptFuncExist: [
    o '',                                       -> soak: no
    o 'FUNC_EXIST',                             -> soak: yes
  ]

  # The list of arguments to a function call.
  Arguments: [
    o 'CALL_START CALL_END',                    -> []
    o 'CALL_START ArgList OptComma CALL_END',   -> $2.implicit = $1.generated; $2
  ]

  # A reference to the *this* current object.
  This: [
    o 'THIS',                                   -> new Value new ThisLiteral $1
    o '@',                                      -> new Value new ThisLiteral $1
  ]

  # A reference to a property on *this*.
  ThisProperty: [
    o '@ Property',                             -> new Value LOC(1)(new ThisLiteral $1), [LOC(2)(new Access($2))], 'this'
  ]

  # The array literal.
  Array: [
    o '[ ]',                                    -> new Arr []
    o '[ Elisions ]',                           -> new Arr $2
    o '[ ArgElisionList OptElisions ]',         -> new Arr [].concat $2, $3
  ]

  # Inclusive and exclusive range dots.
  RangeDots: [
    o '..',                                     -> exclusive: no
    o '...',                                    -> exclusive: yes
  ]

  # The CoffeeScript range literal.
  Range: [
    o '[ Expression RangeDots Expression ]',      -> new Range $2, $4, if $3.exclusive then 'exclusive' else 'inclusive'
    o '[ ExpressionLine RangeDots Expression ]',  -> new Range $2, $4, if $3.exclusive then 'exclusive' else 'inclusive'
  ]

  # Array slice literals.
  Slice: [
    o 'Expression RangeDots Expression',        -> new Range $1, $3, if $2.exclusive then 'exclusive' else 'inclusive'
    o 'Expression RangeDots',                   -> new Range $1, null, if $2.exclusive then 'exclusive' else 'inclusive'
    o 'ExpressionLine RangeDots Expression',    -> new Range $1, $3, if $2.exclusive then 'exclusive' else 'inclusive'
    o 'ExpressionLine RangeDots',               -> new Range $1, null, if $2.exclusive then 'exclusive' else 'inclusive'
    o 'RangeDots Expression',                   -> new Range null, $2, if $1.exclusive then 'exclusive' else 'inclusive'
    o 'RangeDots',                              -> new Range null, null, if $1.exclusive then 'exclusive' else 'inclusive'
  ]

  # The **ArgList** is the list of objects passed into a function call
  # (i.e. comma-separated expressions). Newlines work as well.
  ArgList: [
    o 'Arg',                                              -> [$1]
    o 'ArgList , Arg',                                    -> $1.concat $3
    o 'ArgList OptComma TERMINATOR Arg',                  -> $1.concat $4
    o 'INDENT ArgList OptComma OUTDENT',                  -> $2
    o 'ArgList OptComma INDENT ArgList OptComma OUTDENT', -> $1.concat $4
  ]

  # Valid arguments are Blocks or Splats.
  Arg: [
    o 'Expression'
    o 'ExpressionLine'
    o 'Splat'
    o '...',                                     -> new Expansion
  ]

  # The **ArgElisionList** is the list of objects, contents of an array literal
  # (i.e. comma-separated expressions and elisions). Newlines work as well.
  ArgElisionList: [
    o 'ArgElision'
    o 'ArgElisionList , ArgElision',                                          -> $1.concat $3
    o 'ArgElisionList OptComma TERMINATOR ArgElision',                        -> $1.concat $4
    o 'INDENT ArgElisionList OptElisions OUTDENT',                            -> $2.concat $3
    o 'ArgElisionList OptElisions INDENT ArgElisionList OptElisions OUTDENT', -> $1.concat $2, $4, $5
  ]

  ArgElision: [
    o 'Arg',                  -> [$1]
    o 'Elisions Arg',         -> $1.concat $2
  ]

  OptElisions: [
    o 'OptComma',             -> []
    o ', Elisions',           -> [].concat $2
  ]

  Elisions: [
    o 'Elision',              -> [$1]
    o 'Elisions Elision',     -> $1.concat $2
  ]

  Elision: [
    o ',',                    -> new Elision
    o 'Elision TERMINATOR',   -> $1
  ]

  # Just simple, comma-separated, required arguments (no fancy syntax). We need
  # this to be separate from the **ArgList** for use in **Switch** blocks, where
  # having the newlines wouldn't make sense.
  SimpleArgs: [
    o 'Expression'
    o 'ExpressionLine'
    o 'SimpleArgs , Expression',                -> [].concat $1, $3
    o 'SimpleArgs , ExpressionLine',            -> [].concat $1, $3
  ]

  # The variants of *try/catch/finally* exception handling blocks.
  Try: [
    o 'TRY Block',                              -> new Try $2
    o 'TRY Block Catch',                        -> new Try $2, $3
    o 'TRY Block FINALLY Block',                -> new Try $2, null, $4, LOC(3)(new Literal $3)
    o 'TRY Block Catch FINALLY Block',          -> new Try $2, $3, $5, LOC(4)(new Literal $4)
  ]

  # A catch clause names its error and runs a block of code.
  Catch: [
    o 'CATCH Identifier Block',                 -> new Catch $3, $2
    o 'CATCH Object Block',                     -> new Catch $3, LOC(2)(new Value($2))
    o 'CATCH Block',                            -> new Catch $2
  ]

  # Throw an exception object.
  Throw: [
    o 'THROW Expression',                       -> new Throw $2
    o 'THROW INDENT Object OUTDENT',            -> new Throw new Value $3
  ]

  # Parenthetical expressions. Note that the **Parenthetical** is a **Value**,
  # not an **Expression**, so if you need to use an expression in a place
  # where only values are accepted, wrapping it in parentheses will always do
  # the trick.
  Parenthetical: [
    o '( Body )',                               -> new Parens $2
    o '( INDENT Body OUTDENT )',                -> new Parens $3
  ]

  # The condition portion of a while loop.
  WhileLineSource: [
    o 'WHILE ExpressionLine',                       -> new While $2
    o 'WHILE ExpressionLine WHEN ExpressionLine',   -> new While $2, guard: $4
    o 'UNTIL ExpressionLine',                       -> new While $2, invert: true
    o 'UNTIL ExpressionLine WHEN ExpressionLine',   -> new While $2, invert: true, guard: $4
  ]

  WhileSource: [
    o 'WHILE Expression',                       -> new While $2
    o 'WHILE Expression WHEN Expression',       -> new While $2, guard: $4
    o 'WHILE ExpressionLine WHEN Expression',   -> new While $2, guard: $4
    o 'UNTIL Expression',                       -> new While $2, invert: true
    o 'UNTIL Expression WHEN Expression',       -> new While $2, invert: true, guard: $4
    o 'UNTIL ExpressionLine WHEN Expression',   -> new While $2, invert: true, guard: $4
  ]

  # The while loop can either be normal, with a block of expressions to execute,
  # or postfix, with a single expression. There is no do..while.
  While: [
    o 'WhileSource Block',                      -> $1.addBody $2
    o 'WhileLineSource Block',                  -> $1.addBody $2
    o 'Statement  WhileSource',                 -> (Object.assign $2, postfix: yes).addBody LOC(1) Block.wrap([$1])
    o 'Expression WhileSource',                 -> (Object.assign $2, postfix: yes).addBody LOC(1) Block.wrap([$1])
    o 'Loop',                                   -> $1
  ]

  Loop: [
    o 'LOOP Block',                             -> new While(LOC(1)(new BooleanLiteral 'true'), isLoop: yes).addBody $2
    o 'LOOP Expression',                        -> new While(LOC(1)(new BooleanLiteral 'true'), isLoop: yes).addBody LOC(2) Block.wrap [$2]
  ]

  # Array, object, and range comprehensions, at the most generic level.
  # Comprehensions can either be normal, with a block of expressions to execute,
  # or postfix, with a single expression.
  For: [
    o 'Statement    ForBody',  -> $2.postfix = yes; $2.addBody $1
    o 'Expression   ForBody',  -> $2.postfix = yes; $2.addBody $1
    o 'ForBody      Block',    -> $1.addBody $2
    o 'ForLineBody  Block',    -> $1.addBody $2
  ]

  ForBody: [
    o 'FOR Range',                -> new For [], source: (LOC(2) new Value($2))
    o 'FOR Range BY Expression',  -> new For [], source: (LOC(2) new Value($2)), step: $4
    o 'ForStart ForSource',       -> $1.addSource $2
  ]

  ForLineBody: [
    o 'FOR Range BY ExpressionLine',  -> new For [], source: (LOC(2) new Value($2)), step: $4
    o 'ForStart ForLineSource',       -> $1.addSource $2
  ]

  ForStart: [
    o 'FOR ForVariables',        -> new For [], name: $2[0], index: $2[1]
    o 'FOR AWAIT ForVariables',  ->
        [name, index] = $3
        new For [], {name, index, await: yes, awaitTag: (LOC(2) new Literal($2))}
    o 'FOR OWN ForVariables',    ->
        [name, index] = $3
        new For [], {name, index, own: yes, ownTag: (LOC(2) new Literal($2))}
  ]

  # An array of all accepted values for a variable inside the loop.
  # This enables support for pattern matching.
  ForValue: [
    o 'Identifier'
    o 'ThisProperty'
    o 'Array',                                  -> new Value $1
    o 'Object',                                 -> new Value $1
  ]

  # An array or range comprehension has variables for the current element
  # and (optional) reference to the current index. Or, *key, value*, in the case
  # of object comprehensions.
  ForVariables: [
    o 'ForValue',                               -> [$1]
    o 'ForValue , ForValue',                    -> [$1, $3]
  ]

  # The source of a comprehension is an array or object with an optional guard
  # clause. If it’s an array comprehension, you can also choose to step through
  # in fixed-size increments.
  ForSource: [
    o 'FORIN Expression',                                           -> source: $2
    o 'FOROF Expression',                                           -> source: $2, object: yes
    o 'FORIN Expression WHEN Expression',                           -> source: $2, guard: $4
    o 'FORIN ExpressionLine WHEN Expression',                       -> source: $2, guard: $4
    o 'FOROF Expression WHEN Expression',                           -> source: $2, guard: $4, object: yes
    o 'FOROF ExpressionLine WHEN Expression',                       -> source: $2, guard: $4, object: yes
    o 'FORIN Expression BY Expression',                             -> source: $2, step:  $4
    o 'FORIN ExpressionLine BY Expression',                         -> source: $2, step:  $4
    o 'FORIN Expression WHEN Expression BY Expression',             -> source: $2, guard: $4, step: $6
    o 'FORIN ExpressionLine WHEN Expression BY Expression',         -> source: $2, guard: $4, step: $6
    o 'FORIN Expression WHEN ExpressionLine BY Expression',         -> source: $2, guard: $4, step: $6
    o 'FORIN ExpressionLine WHEN ExpressionLine BY Expression',     -> source: $2, guard: $4, step: $6
    o 'FORIN Expression BY Expression WHEN Expression',             -> source: $2, step:  $4, guard: $6
    o 'FORIN ExpressionLine BY Expression WHEN Expression',         -> source: $2, step:  $4, guard: $6
    o 'FORIN Expression BY ExpressionLine WHEN Expression',         -> source: $2, step:  $4, guard: $6
    o 'FORIN ExpressionLine BY ExpressionLine WHEN Expression',     -> source: $2, step:  $4, guard: $6
    o 'FORFROM Expression',                                         -> source: $2, from: yes
    o 'FORFROM Expression WHEN Expression',                         -> source: $2, guard: $4, from: yes
    o 'FORFROM ExpressionLine WHEN Expression',                     -> source: $2, guard: $4, from: yes
  ]

  ForLineSource: [
    o 'FORIN ExpressionLine',                                       -> source: $2
    o 'FOROF ExpressionLine',                                       -> source: $2, object: yes
    o 'FORIN Expression WHEN ExpressionLine',                       -> source: $2, guard: $4
    o 'FORIN ExpressionLine WHEN ExpressionLine',                   -> source: $2, guard: $4
    o 'FOROF Expression WHEN ExpressionLine',                       -> source: $2, guard: $4, object: yes
    o 'FOROF ExpressionLine WHEN ExpressionLine',                   -> source: $2, guard: $4, object: yes
    o 'FORIN Expression BY ExpressionLine',                         -> source: $2, step:  $4
    o 'FORIN ExpressionLine BY ExpressionLine',                     -> source: $2, step:  $4
    o 'FORIN Expression WHEN Expression BY ExpressionLine',         -> source: $2, guard: $4, step: $6
    o 'FORIN ExpressionLine WHEN Expression BY ExpressionLine',     -> source: $2, guard: $4, step: $6
    o 'FORIN Expression WHEN ExpressionLine BY ExpressionLine',     -> source: $2, guard: $4, step: $6
    o 'FORIN ExpressionLine WHEN ExpressionLine BY ExpressionLine', -> source: $2, guard: $4, step: $6
    o 'FORIN Expression BY Expression WHEN ExpressionLine',         -> source: $2, step:  $4, guard: $6
    o 'FORIN ExpressionLine BY Expression WHEN ExpressionLine',     -> source: $2, step:  $4, guard: $6
    o 'FORIN Expression BY ExpressionLine WHEN ExpressionLine',     -> source: $2, step:  $4, guard: $6
    o 'FORIN ExpressionLine BY ExpressionLine WHEN ExpressionLine', -> source: $2, step:  $4, guard: $6
    o 'FORFROM ExpressionLine',                                     -> source: $2, from: yes
    o 'FORFROM Expression WHEN ExpressionLine',                     -> source: $2, guard: $4, from: yes
    o 'FORFROM ExpressionLine WHEN ExpressionLine',                 -> source: $2, guard: $4, from: yes
  ]

  Switch: [
    o 'SWITCH Expression INDENT Whens OUTDENT',                -> new Switch $2, $4
    o 'SWITCH ExpressionLine INDENT Whens OUTDENT',            -> new Switch $2, $4
    o 'SWITCH Expression INDENT Whens ELSE Block OUTDENT',     -> new Switch $2, $4, LOC(5,6) $6
    o 'SWITCH ExpressionLine INDENT Whens ELSE Block OUTDENT', -> new Switch $2, $4, LOC(5,6) $6
    o 'SWITCH INDENT Whens OUTDENT',                           -> new Switch null, $3
    o 'SWITCH INDENT Whens ELSE Block OUTDENT',                -> new Switch null, $3, LOC(4,5) $5
  ]

  Whens: [
    o 'When',                                   -> [$1]
    o 'Whens When',                             -> $1.concat $2
  ]

  # An individual **When** clause, with action.
  When: [
    o 'LEADING_WHEN SimpleArgs Block',            -> new SwitchWhen $2, $3
    o 'LEADING_WHEN SimpleArgs Block TERMINATOR', -> LOC(1, 3) new SwitchWhen $2, $3
  ]

  # The most basic form of *if* is a condition and an action. The following
  # if-related rules are broken up along these lines in order to avoid
  # ambiguity.
  IfBlock: [
    o 'IF Expression Block',                    -> new If $2, $3, type: $1
    o 'IfBlock ELSE IF Expression Block',       -> $1.addElse LOC(3,5) new If $4, $5, type: $3
  ]

  # The full complement of *if* expressions, including postfix one-liner
  # *if* and *unless*.
  If: [
    o 'IfBlock'
    o 'IfBlock ELSE Block',                     -> $1.addElse $3
    o 'Statement  POST_IF Expression',          -> new If $3, LOC(1)(Block.wrap [$1]), type: $2, postfix: true
    o 'Expression POST_IF Expression',          -> new If $3, LOC(1)(Block.wrap [$1]), type: $2, postfix: true
  ]

  IfBlockLine: [
    o 'IF ExpressionLine Block',                  -> new If $2, $3, type: $1
    o 'IfBlockLine ELSE IF ExpressionLine Block', -> $1.addElse LOC(3,5) new If $4, $5, type: $3
  ]

  IfLine: [
    o 'IfBlockLine'
    o 'IfBlockLine ELSE Block',               -> $1.addElse $3
    o 'Statement  POST_IF ExpressionLine',    -> new If $3, LOC(1)(Block.wrap [$1]), type: $2, postfix: true
    o 'Expression POST_IF ExpressionLine',    -> new If $3, LOC(1)(Block.wrap [$1]), type: $2, postfix: true
  ]

  # Arithmetic and logical operators, working on one or more operands.
  # Here they are grouped by order of precedence. The actual precedence rules
  # are defined at the bottom of the page. It would be shorter if we could
  # combine most of these rules into a single generic *Operand OpSymbol Operand*
  # -type rule, but in order to make the precedence binding possible, separate
  # rules are necessary.
  OperationLine: [
    o 'UNARY ExpressionLine',                   -> new Op $1, $2
    o 'DO ExpressionLine',                      -> new Op $1, $2
    o 'DO_IIFE CodeLine',                       -> new Op $1, $2
  ]

  Operation: [
    o 'UNARY Expression',                       -> new Op $1.toString(), $2, undefined, undefined, originalOperator: $1.original
    o 'DO Expression',                          -> new Op $1, $2
    o 'UNARY_MATH Expression',                  -> new Op $1, $2
    o '-     Expression',                      (-> new Op '-', $2), prec: 'UNARY_MATH'
    o '+     Expression',                      (-> new Op '+', $2), prec: 'UNARY_MATH'

    o 'AWAIT Expression',                       -> new Op $1, $2
    o 'AWAIT INDENT Object OUTDENT',            -> new Op $1, $3

    o '-- SimpleAssignable',                    -> new Op '--', $2
    o '++ SimpleAssignable',                    -> new Op '++', $2
    o 'SimpleAssignable --',                    -> new Op '--', $1, null, true
    o 'SimpleAssignable ++',                    -> new Op '++', $1, null, true

    # [The existential operator](https://coffeescript.org/#existential-operator).
    o 'Expression ?',                           -> new Existence $1

    o 'Expression +  Expression',               -> new Op '+' , $1, $3
    o 'Expression -  Expression',               -> new Op '-' , $1, $3

    o 'Expression MATH     Expression',         -> new Op $2, $1, $3
    o 'Expression **       Expression',         -> new Op $2, $1, $3
    o 'Expression SHIFT    Expression',         -> new Op $2, $1, $3
    o 'Expression COMPARE  Expression',         -> new Op $2.toString(), $1, $3, undefined, originalOperator: $2.original
    o 'Expression &        Expression',         -> new Op $2, $1, $3
    o 'Expression ^        Expression',         -> new Op $2, $1, $3
    o 'Expression |        Expression',         -> new Op $2, $1, $3
    o 'Expression &&       Expression',         -> new Op $2.toString(), $1, $3, undefined, originalOperator: $2.original
    o 'Expression ||       Expression',         -> new Op $2.toString(), $1, $3, undefined, originalOperator: $2.original
    o 'Expression BIN?     Expression',         -> new Op $2, $1, $3
    o 'Expression RELATION Expression',         -> new Op $2.toString(), $1, $3, undefined, invertOperator: $2.invert?.original ? $2.invert

    o 'SimpleAssignable COMPOUND_ASSIGN
       Expression',                             -> new Assign $1, $3, $2.toString(), originalContext: $2.original
    o 'SimpleAssignable COMPOUND_ASSIGN
       INDENT Expression OUTDENT',              -> new Assign $1, $4, $2.toString(), originalContext: $2.original
    o 'SimpleAssignable COMPOUND_ASSIGN TERMINATOR
       Expression',                             -> new Assign $1, $4, $2.toString(), originalContext: $2.original
  ]

  DoIife: [
    o 'DO_IIFE Code',                           -> new Op $1 , $2
  ]

# Precedence
# ----------

# Operators at the top of this list have higher precedence than the ones lower
# down. Following these rules is what makes `2 + 3 * 4` parse as:
#
#     2 + (3 * 4)
#
# And not:
#
#     (2 + 3) * 4
operators = [
  ['right',     'DO_IIFE']
  ['left',      '.', '?.', '::', '?::']
  ['left',      'CALL_START', 'CALL_END']
  ['nonassoc',  '++', '--']
  ['left',      '?']
  ['right',     'UNARY', 'DO']
  ['right',     'AWAIT']
  ['right',     '**']
  ['right',     'UNARY_MATH']
  ['left',      'MATH']
  ['left',      '+', '-']
  ['left',      'SHIFT']
  ['left',      'RELATION']
  ['left',      'COMPARE']
  ['left',      '&']
  ['left',      '^']
  ['left',      '|']
  ['left',      '&&']
  ['left',      '||']
  ['left',      'BIN?']
  ['nonassoc',  'INDENT', 'OUTDENT']
  ['right',     'YIELD']
  ['right',     '=', ':', 'COMPOUND_ASSIGN', 'RETURN', 'THROW', 'EXTENDS']
  ['right',     'FORIN', 'FOROF', 'FORFROM', 'BY', 'WHEN']
  ['right',     'IF', 'ELSE', 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'SUPER', 'CLASS', 'IMPORT', 'EXPORT', 'DYNAMIC_IMPORT']
  ['left',      'POST_IF']
]

# Wrapping Up
# -----------

# Finally, now that we have our **grammar** and our **operators**, we can create
# our **Jison.Parser**. We do this by processing all of our rules, recording all
# terminals (every symbol which does not appear as the name of a rule above)
# as "tokens".
tokens = []
for name, alternatives of grammar
  grammar[name] = for alt in alternatives
    for token in alt[0].split ' '
      tokens.push token unless grammar[token]
    alt[1] = "return #{alt[1]}" if name is 'Root'
    alt

# Initialize the **Parser** with our list of terminal **tokens**, our **grammar**
# rules, and the name of the root. Reverse the operators because Jison orders
# precedence from low to high, and we have it high to low
# (as in [Yacc](http://dinosaur.compilertools.net/yacc/index.html)).
exports.parser = new Parser
  tokens      : tokens.join ' '
  bnf         : grammar
  operators   : operators.reverse()
  startSymbol : 'Root'