Class: Lox::Environment

Inherits:
Object
  • Object
show all
Defined in:
lib/loxby/helpers/environment.rb

Overview

Stores namespaces for a Lox interpreter. Environments can be nested (for scope).

Instance Method Summary collapse

Constructor Details

#initialize(enclosing = nil) ⇒ Environment

Returns a new instance of Environment.



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# File 'lib/loxby/helpers/environment.rb', line 9

def initialize(enclosing = nil)
  @enclosing = enclosing
  @values = {}
end

Instance Method Details

#[](name) ⇒ Object 



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# File 'lib/loxby/helpers/environment.rb', line 34

def [](name)
  if @values[name.lexeme]
    @values[name.lexeme]
  elsif declared? name
    raise Lox::RunError.new(name, "Declared variable not initialized: '#{name.lexeme}'")
  elsif @enclosing
    @enclosing[name]
  else
    raise undefined_variable(name)
  end
end

#[]=(name, value) ⇒ Object Also known as: define 



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# File 'lib/loxby/helpers/environment.rb', line 18

def []=(name, value)
  set name.lexeme, value
end

#assign(name, value) ⇒ Object 



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# File 'lib/loxby/helpers/environment.rb', line 46

def assign(name, value)
  if declared? name
    self[name] = value
  elsif @enclosing
    @enclosing.assign(name, value)
  else
    raise undefined_variable(name)
  end
end

#declared?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/loxby/helpers/environment.rb', line 28

def declared?(name)
  # We can't check for a dummy value
  # since loxby uses `nil` as well
  @values.keys.member? name.lexeme
end

#set(name, value) ⇒ Object

Used to set a static association. For example:

env.set 'static_function_name', static_function



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# File 'lib/loxby/helpers/environment.rb', line 24

def set(name, value)
  @values[name] = value
end

#undefined_variable(name) ⇒ Object 



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# File 'lib/loxby/helpers/environment.rb', line 14

def undefined_variable(name)
  Lox::RunError.new(name, "Undefined variable '#{name.lexeme}'")
end