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# The CoffeeScript parser is generated by [Jison](http://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)](http://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](http://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](http://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](http://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
return [patternString, '$$ = $1;', options] unless action
action = if match = unwrap.exec action then match[1] else "(#{action}())"
# All runtime functions we need are defined on "yy"
action = action.replace /\bnew /g, '$&yy.'
action = action.replace /\b(?:Block\.wrap|extend)\b/g, 'yy.$&'
# Returns a function which adds location data to the first parameter passed
# in, and returns the parameter. If the parameter is not a node, it will
# just be passed through unaffected.
addLocationDataFn = (first, last) ->
if not last
"yy.addLocationDataFn(@#{first})"
else
"yy.addLocationDataFn(@#{first}, @#{last})"
action = action.replace /LOC\(([0-9]*)\)/g, addLocationDataFn('$1')
action = action.replace /LOC\(([0-9]*),\s*([0-9]*)\)/g, addLocationDataFn('$1', '$2')
[patternString, "$$ = #{addLocationDataFn(1, patternCount)}(#{action});", 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 Block
o 'Body'
]
# 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.
Line: [
o 'Expression'
o 'Statement'
]
# Pure statements which cannot be expressions.
Statement: [
o 'Return'
o 'Comment'
o 'STATEMENT', -> new Literal $1
]
# 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 'Invocation'
o 'Code'
o 'Operation'
o 'Assign'
o 'If'
o 'Try'
o 'While'
o 'For'
o 'Switch'
o 'Class'
o 'Throw'
]
# 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
]
# A literal identifier, a variable name or property.
Identifier: [
o 'IDENTIFIER', -> new Literal $1
]
# Alphanumerics are separated from the other **Literal** matchers because
# they can also serve as keys in object literals.
AlphaNumeric: [
o 'NUMBER', -> new Literal $1
o 'String'
]
String: [
o 'STRING', -> new Literal $1
o 'STRING_START Body STRING_END', -> new Parens $2
]
Regex: [
o 'REGEX', -> new Literal $1
o 'REGEX_START Invocation REGEX_END', -> $2
]
# All of our immediate values. Generally these can be passed straight
# through and printed to JavaScript.
Literal: [
o 'AlphaNumeric'
o 'JS', -> new Literal $1
o 'Regex'
o 'DEBUGGER', -> new Literal $1
o 'UNDEFINED', -> new Undefined
o 'NULL', -> new Null
o 'BOOL', -> new Bool $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 'ObjAssignable : Expression', -> new Assign LOC(1)(new Value($1)), $3, 'object'
o 'ObjAssignable :
INDENT Expression OUTDENT', -> new Assign LOC(1)(new Value($1)), $4, 'object'
o 'Comment'
]
ObjAssignable: [
o 'Identifier'
o 'AlphaNumeric'
o 'ThisProperty'
]
# A return statement from a function body.
Return: [
o 'RETURN Expression', -> new Return $2
o 'RETURN', -> new Return
]
# A block comment.
Comment: [
o 'HERECOMMENT', -> new Comment $1
]
# 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
o 'FuncGlyph Block', -> new Code [], $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 '->', -> 'func'
o '=>', -> 'boundfunc'
]
# 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 = 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
]
# Variables and properties that can be assigned to.
SimpleAssignable: [
o 'Identifier', -> new Value $1
o 'Value Accessor', -> $1.add $2
o 'Invocation Accessor', -> new Value $1, [].concat $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 'This'
]
# The general group of accessors into an object, by property, by prototype
# or by array index or slice.
Accessor: [
o '. Identifier', -> new Access $2
o '?. Identifier', -> new Access $2, 'soak'
o ':: Identifier', -> [LOC(1)(new Access new Literal('prototype')), LOC(2)(new Access $2)]
o '?:: Identifier', -> [LOC(1)(new Access new Literal('prototype'), 'soak'), LOC(2)(new Access $2)]
o '::', -> new Access new Literal 'prototype'
o 'Index'
]
# Indexing into an object or array using bracket notation.
Index: [
o 'INDEX_START IndexValue INDEX_END', -> $2
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
]
# Ordinary function invocation, or a chained series of calls.
Invocation: [
o 'Value OptFuncExist Arguments', -> new Call $1, $3, $2
o 'Invocation OptFuncExist Arguments', -> new Call $1, $3, $2
o 'SUPER', -> new Call 'super', [new Splat new Literal 'arguments']
o 'SUPER Arguments', -> new Call 'super', $2
]
# An optional existence check on a function.
OptFuncExist: [
o '', -> no
o 'FUNC_EXIST', -> yes
]
# The list of arguments to a function call.
Arguments: [
o 'CALL_START CALL_END', -> []
o 'CALL_START ArgList OptComma CALL_END', -> $2
]
# A reference to the *this* current object.
This: [
o 'THIS', -> new Value new Literal 'this'
o '@', -> new Value new Literal 'this'
]
# A reference to a property on *this*.
ThisProperty: [
o '@ Identifier', -> new Value LOC(1)(new Literal('this')), [LOC(2)(new Access($2))], 'this'
]
# The array literal.
Array: [
o '[ ]', -> new Arr []
o '[ ArgList OptComma ]', -> new Arr $2
]
# Inclusive and exclusive range dots.
RangeDots: [
o '..', -> 'inclusive'
o '...', -> 'exclusive'
]
# The CoffeeScript range literal.
Range: [
o '[ Expression RangeDots Expression ]', -> new Range $2, $4, $3
]
# Array slice literals.
Slice: [
o 'Expression RangeDots Expression', -> new Range $1, $3, $2
o 'Expression RangeDots', -> new Range $1, null, $2
o 'RangeDots Expression', -> new Range null, $2, $1
o 'RangeDots', -> new Range null, null, $1
]
# The **ArgList** is both the list of objects passed into a function call,
# as well as the contents of an array literal
# (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 'Splat'
o '...', -> new Expansion
]
# 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 'SimpleArgs , Expression', -> [].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[0], $3[1]
o 'TRY Block FINALLY Block', -> new Try $2, null, null, $4
o 'TRY Block Catch FINALLY Block', -> new Try $2, $3[0], $3[1], $5
]
# A catch clause names its error and runs a block of code.
Catch: [
o 'CATCH Identifier Block', -> [$2, $3]
o 'CATCH Object Block', -> [LOC(2)(new Value($2)), $3]
o 'CATCH Block', -> [null, $2]
]
# Throw an exception object.
Throw: [
o 'THROW Expression', -> new Throw $2
]
# 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.
WhileSource: [
o 'WHILE Expression', -> new While $2
o 'WHILE Expression 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
]
# 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 'Statement WhileSource', -> $2.addBody LOC(1) Block.wrap([$1])
o 'Expression WhileSource', -> $2.addBody LOC(1) Block.wrap([$1])
o 'Loop', -> $1
]
Loop: [
o 'LOOP Block', -> new While(LOC(1) new Literal 'true').addBody $2
o 'LOOP Expression', -> new While(LOC(1) new Literal 'true').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', -> new For $1, $2
o 'Expression ForBody', -> new For $1, $2
o 'ForBody Block', -> new For $2, $1
]
ForBody: [
o 'FOR Range', -> source: (LOC(2) new Value($2))
o 'FOR Range BY Expression', -> source: (LOC(2) new Value($2)), step: $4
o 'ForStart ForSource', -> $2.own = $1.own; $2.name = $1[0]; $2.index = $1[1]; $2
]
ForStart: [
o 'FOR ForVariables', -> $2
o 'FOR OWN ForVariables', -> $3.own = yes; $3
]
# 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 'FOROF Expression WHEN Expression', -> source: $2, guard: $4, object: yes
o 'FORIN Expression BY Expression', -> source: $2, step: $4
o 'FORIN Expression WHEN Expression BY Expression', -> source: $2, guard: $4, step: $6
o 'FORIN Expression BY Expression WHEN Expression', -> source: $2, step: $4, guard: $6
]
Switch: [
o 'SWITCH Expression INDENT Whens OUTDENT', -> new Switch $2, $4
o 'SWITCH Expression INDENT Whens ELSE Block OUTDENT', -> new Switch $2, $4, $6
o 'SWITCH INDENT Whens OUTDENT', -> new Switch null, $3
o 'SWITCH INDENT Whens ELSE Block OUTDENT', -> new Switch null, $3, $5
]
Whens: [
o 'When'
o 'Whens When', -> $1.concat $2
]
# An individual **When** clause, with action.
When: [
o 'LEADING_WHEN SimpleArgs Block', -> [[$2, $3]]
o 'LEADING_WHEN SimpleArgs Block TERMINATOR', -> [[$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, statement: true
o 'Expression POST_IF Expression', -> new If $3, LOC(1)(Block.wrap [$1]), type: $2, statement: 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.
Operation: [
o 'UNARY 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 'YIELD Statement', -> new Op $1 , $2
o 'YIELD Expression', -> new Op $1 , $2
o 'YIELD FROM Expression', -> new Op $1.concat($2) , $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](http://jashkenas.github.com/coffee-script/#existence).
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, $1, $3
o 'Expression LOGIC Expression', -> new Op $2, $1, $3
o 'Expression RELATION Expression', ->
if $2.charAt(0) is '!'
new Op($2[1..], $1, $3).invert()
else
new Op $2, $1, $3
o 'SimpleAssignable COMPOUND_ASSIGN
Expression', -> new Assign $1, $3, $2
o 'SimpleAssignable COMPOUND_ASSIGN
INDENT Expression OUTDENT', -> new Assign $1, $4, $2
o 'SimpleAssignable COMPOUND_ASSIGN TERMINATOR
Expression', -> new Assign $1, $4, $2
o 'SimpleAssignable EXTENDS Expression', -> new Extends $1, $3
]
# 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 = [
['left', '.', '?.', '::', '?::']
['left', 'CALL_START', 'CALL_END']
['nonassoc', '++', '--']
['left', '?']
['right', 'UNARY']
['right', '**']
['right', 'UNARY_MATH']
['left', 'MATH']
['left', '+', '-']
['left', 'SHIFT']
['left', 'RELATION']
['left', 'COMPARE']
['left', 'LOGIC']
['nonassoc', 'INDENT', 'OUTDENT']
['right', 'YIELD']
['right', '=', ':', 'COMPOUND_ASSIGN', 'RETURN', 'THROW', 'EXTENDS']
['right', 'FORIN', 'FOROF', 'BY', 'WHEN']
['right', 'IF', 'ELSE', 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'SUPER', 'CLASS']
['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'
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