Literate CoffeeScript is a programming language created in 2013 by Jeremy Ashkenas.
| #235on PLDB | 11Years Old | 8kRepos |
git clone https://github.com/jashkenas/coffeescriptBesides being used as an ordinary programming language, CoffeeScript may also be written in “literate” mode. If you name your file with a .litcoffee extension, you can write it as a Markdown document — a document that also happens to be executable CoffeeScript code. The compiler will treat any indented blocks (Markdown’s way of indicating source code) as executable code, and ignore the rest as comments. Code blocks must also be separated from comments by at least one blank line.
The **Scope** class regulates lexical scoping within CoffeeScript. As you
generate code, you create a tree of scopes in the same shape as the nested
function bodies. Each scope knows about the variables declared within it,
and has a reference to its parent enclosing scope. In this way, we know which
variables are new and need to be declared with `var`, and which are shared
with external scopes.
Import the helpers we plan to use.
{extend, last} = require './helpers'
exports.Scope = class Scope
The `root` is the top-level **Scope** object for a given file.
@root: null
Initialize a scope with its parent, for lookups up the chain,
as well as a reference to the **Block** node it belongs to, which is
where it should declare its variables, and a reference to the function that
it belongs to.
constructor: (@parent, @expressions, @method) ->
@variables = [{name: 'arguments', type: 'arguments'}]
@positions = {}
Scope.root = this unless @parent
Adds a new variable or overrides an existing one.
add: (name, type, immediate) ->
return @parent.add name, type, immediate if @shared and not immediate
if Object::hasOwnProperty.call @positions, name
@variables[@positions[name]].type = type
else
@positions[name] = @variables.push({name, type}) - 1
When `super` is called, we need to find the name of the current method we're
in, so that we know how to invoke the same method of the parent class. This
can get complicated if super is being called from an inner function.
`namedMethod` will walk up the scope tree until it either finds the first
function object that has a name filled in, or bottoms out.
namedMethod: ->
return @method if @method.name or !@parent
@parent.namedMethod()
Look up a variable name in lexical scope, and declare it if it does not
already exist.
find: (name) ->
return yes if @check name
@add name, 'var'
no
Reserve a variable name as originating from a function parameter for this
scope. No `var` required for internal references.
parameter: (name) ->
return if @shared and @parent.check name, yes
@add name, 'param'
Just check to see if a variable has already been declared, without reserving,
walks up to the root scope.
check: (name) ->
!!(@type(name) or @parent?.check(name))
Generate a temporary variable name at the given index.
temporary: (name, index) ->
if name.length > 1
'_' + name + if index > 1 then index - 1 else ''
else
'_' + (index + parseInt name, 36).toString(36).replace /\d/g, 'a'
Gets the type of a variable.
type: (name) ->
return v.type for v in @variables when v.name is name
null
If we need to store an intermediate result, find an available name for a
compiler-generated variable. `_var`, `_var2`, and so on...
freeVariable: (name, reserve=true) ->
index = 0
index++ while @check((temp = @temporary name, index))
@add temp, 'var', yes if reserve
temp
Ensure that an assignment is made at the top of this scope
(or at the top-level scope, if requested).
assign: (name, value) ->
@add name, {value, assigned: yes}, yes
@hasAssignments = yes
Does this scope have any declared variables?
hasDeclarations: ->
!!@declaredVariables().length
Return the list of variables first declared in this scope.
declaredVariables: ->
realVars = []
tempVars = []
for v in @variables when v.type is 'var'
(if v.name.charAt(0) is '_' then tempVars else realVars).push v.name
realVars.sort().concat tempVars.sort()
Return the list of assignments that are supposed to be made at the top
of this scope.
assignedVariables: ->
"#{v.name} = #{v.type.value}" for v in @variables when v.type.assigned| Feature | Supported | Example | Token |
|---|---|---|---|
| Semantic Indentation | ✓ |