Class: StyleScript::Scope

Inherits:
Object
  • Object
show all
Defined in:
lib/style_script/scope.rb

Overview

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.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(parent, expressions, function) ⇒ Scope

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.



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# File 'lib/style_script/scope.rb', line 13

def initialize(parent, expressions, function)
  @parent, @expressions, @function = parent, expressions, function
  @variables = {}
  @temp_variable = @parent ? @parent.temp_variable.dup : '__a'
end

Instance Attribute Details

#expressions ⇒ Object (readonly)

Returns the value of attribute expressions.



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# File 'lib/style_script/scope.rb', line 8

def expressions
  @expressions
end

#function ⇒ Object (readonly)

Returns the value of attribute function.



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# File 'lib/style_script/scope.rb', line 8

def function
  @function
end

#parent ⇒ Object (readonly)

Returns the value of attribute parent.



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# File 'lib/style_script/scope.rb', line 8

def parent
  @parent
end

#temp_variable ⇒ Object (readonly)

Returns the value of attribute temp_variable.



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# File 'lib/style_script/scope.rb', line 8

def temp_variable
  @temp_variable
end

#variables ⇒ Object (readonly)

Returns the value of attribute variables.



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# File 'lib/style_script/scope.rb', line 8

def variables
  @variables
end

Instance Method Details

#assign(name, value, top = false) ⇒ Object

Ensure that an assignment is made at the top of scope (or top-level scope, if requested).



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# File 'lib/style_script/scope.rb', line 53

def assign(name, value, top=false)
  return @parent.assign(name, value, top) if top && @parent
  @variables[name.to_sym] = Value.new(value)
end

#assigned_variables ⇒ Object

Return the list of variables that are supposed to be assigned at the top of scope.



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# File 'lib/style_script/scope.rb', line 77

def assigned_variables
  @variables.select {|k, v| v.is_a?(Value) }.sort_by {|pair| pair[0].to_s }
end

#assignments?(body) ⇒ Boolean

Does this scope reference any assignments that need to be declared at the top of the given function body?

Returns:

  • (Boolean) 


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# File 'lib/style_script/scope.rb', line 66

def assignments?(body)
  !assigned_variables.empty? && body == @expressions
end

#check(name) ⇒ Object

Just check to see if a variable has already been declared.



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# File 'lib/style_script/scope.rb', line 34

def check(name)
  return true if @variables[name.to_sym]
  !!(@parent && @parent.check(name))
end

#compiled_assignments ⇒ Object 



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# File 'lib/style_script/scope.rb', line 85

def compiled_assignments
  assigned_variables.map {|name, val| "#{name} = #{val}"}.join(', ')
end

#compiled_declarations ⇒ Object 



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# File 'lib/style_script/scope.rb', line 81

def compiled_declarations
  declared_variables.join(', ')
end

#declarations?(body) ⇒ Boolean

Does this scope reference any variables that need to be declared in the given function body?

Returns:

  • (Boolean) 


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# File 'lib/style_script/scope.rb', line 60

def declarations?(body)
  !declared_variables.empty? && body == @expressions
end

#declared_variables ⇒ Object

Return the list of variables first declared in current scope.



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# File 'lib/style_script/scope.rb', line 71

def declared_variables
  @variables.select {|k, v| v == :var }.map {|pair| pair[0].to_s }.sort
end

#find(name, remote = false) ⇒ Object

Look up a variable in lexical scope, or declare it if not found.



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# File 'lib/style_script/scope.rb', line 20

def find(name, remote=false)
  found = check(name)
  return found if found || remote
  @variables[name.to_sym] = :var
  found
end

#free_variable ⇒ Object

Find an available, short, name for a compiler-generated variable.



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# File 'lib/style_script/scope.rb', line 45

def free_variable
  @temp_variable.succ! while check(@temp_variable)
  @variables[@temp_variable.to_sym] = :var
  Value.new(@temp_variable.dup)
end

#inspect ⇒ Object 



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# File 'lib/style_script/scope.rb', line 89

def inspect
  "<Scope:#{__id__} #{@variables.inspect}>"
end

#parameter(name) ⇒ Object

Define a local variable as originating from a parameter in current scope – no var required.



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# File 'lib/style_script/scope.rb', line 29

def parameter(name)
  @variables[name.to_sym] = :param
end

#reset(name) ⇒ Object

You can reset a found variable on the immediate scope.



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# File 'lib/style_script/scope.rb', line 40

def reset(name)
  @variables[name.to_sym] = false
end