scope.coffee | |
|---|---|
this.exports: this unless process? | |
| Scope objects form a tree corresponding to the shape of the function definitions present in the script. They provide lexical scope, to determine whether a variable has been seen before or if it needs to be declared. Initialize a scope with its parent, for lookups up the chain, as well as the Expressions body where it should declare its variables, and the function that it wraps. | exports.Scope: class Scope
constructor: (parent, expressions, method) ->
[@parent, @expressions, @method]: [parent, expressions, method]
@variables: {}
@temp_var: if @parent then @parent.temp_var else '_a' |
| Look up a variable in lexical scope, or declare it if not found. | find: (name) ->
return true if @check name
@variables[name]: 'var'
false |
| Define a local variable as originating from a parameter in current scope -- no var required. | parameter: (name) ->
@variables[name]: 'param' |
| Just check to see if a variable has already been declared. | check: (name) ->
return true if @variables[name]
!!(@parent and @parent.check(name)) |
| You can reset a found variable on the immediate scope. | reset: (name) ->
delete @variables[name] |
| Find an available, short, name for a compiler-generated variable. | free_variable: ->
while @check @temp_var
ordinal: 1 + parseInt @temp_var.substr(1), 36
@temp_var: '_' + ordinal.toString(36).replace(/\d/g, 'a')
@variables[@temp_var]: 'var'
@temp_var |
| Ensure that an assignment is made at the top of scope (or top-level scope, if requested). | assign: (name, value, top_level) ->
return @parent.assign(name, value, top_level) if top_level and @parent
@variables[name]: {value: value, assigned: true} |
| Does this scope reference any variables that need to be declared in the given function body? | has_declarations: (body) ->
body is @expressions and @declared_variables().length |
| Does this scope reference any assignments that need to be declared at the top of the given function body? | has_assignments: (body) ->
body is @expressions and @assigned_variables().length |
| Return the list of variables first declared in current scope. | declared_variables: ->
(key for key, val of @variables when val is 'var').sort() |
| Return the list of variables that are supposed to be assigned at the top of scope. | assigned_variables: ->
"$key = ${val.value}" for key, val of @variables when val.assigned |
| Compile the string representing all of the declared variables for this scope. | compiled_declarations: ->
@declared_variables().join ', ' |
| Compile the string performing all of the variable assignments for this scope. | compiled_assignments: ->
@assigned_variables().join ', '
|