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jashkenas--coffeescript/test/strict.coffee
Simon Lydell 8ab15d7372 Fix #1500, #1574, #3318: Name generated vars uniquely
Any variables generated by CoffeeScript are now made sure to be named to
something not present in the source code being compiled. This way you can no
longer interfere with them, either on purpose or by mistake. (#1500, #1574)

For example, `({a}, _arg) ->` now compiles correctly. (#1574)

As opposed to the somewhat complex implementations discussed in #1500, this
commit takes a very simple approach by saving all used variables names using a
single pass over the token stream. Any generated variables are then made sure
not to exist in that list.

`(@a) -> a` used to be equivalent to `(@a) -> @a`, but now throws a runtime
`ReferenceError` instead (unless `a` exists in an upper scope of course). (#3318)

`(@a) ->` used to compile to `(function(a) { this.a = a; })`. Now it compiles to
`(function(_at_a) { this.a = _at_a; })`. (But you cannot access `_at_a` either,
of course.)

Because of the above, `(@a, a) ->` is now valid; `@a` and `a` are not duplicate
parameters.

Duplicate this-parameters with a reserved word, such as `(@case, @case) ->`,
used to compile but now throws, just like regular duplicate parameters.
2015-01-10 23:25:01 +01:00

173 lines
5.4 KiB
CoffeeScript

# Strict Early Errors
# -------------------
# The following are prohibited under ES5's `strict` mode
# * `Octal Integer Literals`
# * `Octal Escape Sequences`
# * duplicate property definitions in `Object Literal`s
# * duplicate formal parameter
# * `delete` operand is a variable
# * `delete` operand is a parameter
# * `delete` operand is `undefined`
# * `Future Reserved Word`s as identifiers: implements, interface, let, package, private, protected, public, static, yield
# * `eval` or `arguments` as `catch` identifier
# * `eval` or `arguments` as formal parameter
# * `eval` or `arguments` as function declaration identifier
# * `eval` or `arguments` as LHS of assignment
# * `eval` or `arguments` as the operand of a post/pre-fix inc/dec-rement expression
# helper to assert that code complies with strict prohibitions
strict = (code, msg) ->
throws (-> CoffeeScript.compile code), null, msg ? code
strictOk = (code, msg) ->
doesNotThrow (-> CoffeeScript.compile code), msg ? code
test "octal integer literals prohibited", ->
strict '01'
strict '07777'
# decimals with a leading '0' are also prohibited
strict '09'
strict '079'
strictOk '`01`'
test "octal escape sequences prohibited", ->
strict '"\\1"'
strict '"\\7"'
strict '"\\001"'
strict '"\\777"'
strict '"_\\1"'
strict '"\\1_"'
strict '"_\\1_"'
strict '"\\\\\\1"'
strictOk '"\\0"'
eq "\x00", "\0"
strictOk '"\\08"'
eq "\x008", "\08"
strictOk '"\\0\\8"'
eq "\x008", "\0\8"
strictOk '"\\8"'
eq "8", "\8"
strictOk '"\\\\1"'
eq "\\" + "1", "\\1"
strictOk '"\\\\\\\\1"'
eq "\\\\" + "1", "\\\\1"
strictOk "`'\\1'`"
eq "\\" + "1", `"\\1"`
# Also test other string types.
strict "'\\\\\\1'"
eq "\x008", '\08'
eq "\\\\" + "1", '\\\\1'
strict "'''\\\\\\1'''"
eq "\x008", '''\08'''
eq "\\\\" + "1", '''\\\\1'''
strict '"""\\\\\\1"""'
eq "\x008", """\08"""
eq "\\\\" + "1", """\\\\1"""
test "duplicate formal parameters are prohibited", ->
nonce = {}
# a Param can be an Identifier, ThisProperty( @-param ), Array, or Object
# a Param can also be a splat (...) or an assignment (param=value)
# the following function expressions should throw errors
strict '(_,_)->', 'param, param'
strict '(_,_...)->', 'param, param...'
strict '(_,_ = true)->', 'param, param='
strict '(@_,@_)->', 'two @params'
strict '(@case,@case)->', 'two @reserved'
strict '(_,{_})->', 'param, {param}'
strict '({_,_})->', '{param, param}'
strict '(_,[_])->', 'param, [param]'
strict '([_,_])->', '[param, param]'
strict '(_,[_]=true)->', 'param, [param]='
strict '(_,[@_,{_}])->', 'param, [@param, {param}]'
strict '(_,[_,{@_}])->', 'param, [param, {@param}]'
strict '(_,[_,{_}])->', 'param, [param, {param}]'
strict '(_,[_,{__}])->', 'param, [param, {param2}]'
strict '(_,[__,{_}])->', 'param, [param2, {param}]'
strict '(__,[_,{_}])->', 'param, [param2, {param2}]'
strict '(0:a,1:a)->', '0:param,1:param'
strict '({0:a,1:a})->', '{0:param,1:param}'
# the following function expressions should **not** throw errors
strictOk '(_,@_)->'
strictOk '(@_,_...)->'
strictOk '(_,@_ = true)->'
strictOk '(@_,{_})->'
strictOk '({_,@_})->'
strictOk '([_,@_])->'
strictOk '({},_arg)->'
strictOk '({},{})->'
strictOk '([]...,_arg)->'
strictOk '({}...,_arg)->'
strictOk '({}...,[],_arg)->'
strictOk '([]...,{},_arg)->'
strictOk '(@case,_case)->'
strictOk '(@case,_case...)->'
strictOk '(@case...,_case)->'
strictOk '(_case,@case)->'
strictOk '(_case,@case...)->'
strictOk '(a:a)->'
strictOk '(a:a,a:b)->'
test "`delete` operand restrictions", ->
strict 'a = 1; delete a'
strictOk 'delete a' #noop
strict '(a) -> delete a'
strict '(a...) -> delete a'
strict '(a = 1) -> delete a'
strict '([a]) -> delete a'
strict '({a}) -> delete a'
test "`Future Reserved Word`s, `eval` and `arguments` restrictions", ->
access = (keyword, check = strict) ->
check "#{keyword}.a = 1"
check "#{keyword}[0] = 1"
assign = (keyword, check = strict) ->
check "#{keyword} = 1"
check "#{keyword} += 1"
check "#{keyword} -= 1"
check "#{keyword} *= 1"
check "#{keyword} /= 1"
check "#{keyword} ?= 1"
check "{keyword}++"
check "++{keyword}"
check "{keyword}--"
check "--{keyword}"
destruct = (keyword, check = strict) ->
check "{#{keyword}}"
check "o = {#{keyword}}"
invoke = (keyword, check = strict) ->
check "#{keyword} yes"
check "do #{keyword}"
fnDecl = (keyword, check = strict) ->
check "class #{keyword}"
param = (keyword, check = strict) ->
check "(#{keyword}) ->"
check "({#{keyword}}) ->"
prop = (keyword, check = strict) ->
check "a.#{keyword} = 1"
tryCatch = (keyword, check = strict) ->
check "try new Error catch #{keyword}"
future = 'implements interface let package private protected public static'.split ' '
for keyword in future
access keyword
assign keyword
destruct keyword
invoke keyword
fnDecl keyword
param keyword
prop keyword, strictOk
tryCatch keyword
for keyword in ['eval', 'arguments']
access keyword, strictOk
assign keyword
destruct keyword, strictOk
invoke keyword, strictOk
fnDecl keyword
param keyword
prop keyword, strictOk
tryCatch keyword