Class: Porolog::Scope

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

Overview

A Porolog::Scope is a container for Porolog::Predicates. Its purpose is to allow a Ruby program to contain multiple Prolog programs without the Prolog programs interfering with each other.

Author:

  • Luis Esteban

Defined Under Namespace

Classes: Error, NotPredicateError

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Scope

Initializes and registers the Scope.

Parameters:

  • name (Object) —

    the name (or otherwise object) used to register a scope.



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

def initialize(name)
  @name       = name
  @predicates = {}
  
  @@scopes[@name] = self
end

Instance Attribute Details

#name ⇒ Object (readonly)

Name of the Scope.



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# File 'lib/porolog/scope.rb', line 16

class Scope
  
  # Error class for rescuing or detecting any Scope error.
  class Error             < PorologError ; end
  # Error class indicating a non-Predicate was assigned to a Scope.
  class NotPredicateError < Error        ; end
  
  attr_reader :name
  
  # Creates a new Scope unless it already exists.
  # @param name [Symbol, Object] the name (or otherwise object) used to register a scope.
  # @return [Porolog::Scope] new or existing Scope.
  def self.new(name)
    @@scopes[name] || super
  end
  
  # Initializes and registers the Scope.
  # @param name [Object] the name (or otherwise object) used to register a scope.
  def initialize(name)
    @name       = name
    @predicates = {}
    
    @@scopes[@name] = self
  end
  
  # Clears all scopes and re-creates the default Scope.
  # @return [Porolog::Scope] the default Scope.
  def self.reset
    @@scopes = {}
    new(:default)
  end
  
  reset
  
  # Looks up a Scope by its name.
  # @param name [Object] the name (or otherwise object) used to register a scope.
  # @return [Porolog::Scope] the default Scope.
  def self.[](name)
    @@scopes[name]
  end
  
  # Returns the names of all registered Scopes.
  # @return [Array<Symbol>] the names if scopes are named as Symbols (the intended case).
  # @return [Array<Object>] the names if the names are not actually Symbols.
  def self.scopes
    @@scopes.keys
  end
  
  # Looks up a Predicate in the Scope by its name.
  # @param name [Object] the name (or otherwise object) used to register a scope.
  # @return [Porolog::Predicate] the Predicate indicated by the name.
  def [](name)
    @predicates[name.to_sym]
  end
  
  # Assigns a Predicate to the Scope by its name.
  # @param name [Object] the name (or otherwise object) used to register a scope.
  # @param predicate [Porolog::Predicate] a Predicate to be assigned to the Scope.
  # @return [Porolog::Predicate] the Predicate assigned to the Scope.
  # @raise [NotPredicateError] when provided predicate is not actually a Predicate.
  def []=(name, predicate)
    raise NotPredicateError, "#{predicate.inspect} is not a Predicate" unless predicate.is_a?(Predicate)
    @predicates[name.to_sym] = predicate
  end
  
  # Returns the Predicates contained in the Scope.
  # @return [Array<Porolog::Predicate>] Predicates assigned to the Scope.
  def predicates
    @predicates.values
  end
  
end

Class Method Details

.[](name) ⇒ Porolog::Scope

Looks up a Scope by its name.

Parameters:

  • name (Object) —

    the name (or otherwise object) used to register a scope.

Returns:



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

def self.[](name)
  @@scopes[name]
end

.new(name) ⇒ Porolog::Scope

Creates a new Scope unless it already exists.

Parameters:

  • name (Symbol, Object) —

    the name (or otherwise object) used to register a scope.

Returns:



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# File 'lib/porolog/scope.rb', line 28

def self.new(name)
  @@scopes[name] || super
end

.reset ⇒ Porolog::Scope

Clears all scopes and re-creates the default Scope.

Returns:



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# File 'lib/porolog/scope.rb', line 43

def self.reset
  @@scopes = {}
  new(:default)
end

.scopes ⇒ Array<Symbol>, Array<Object>

Returns the names of all registered Scopes.

Returns:

  • (Array<Symbol>) —

    the names if scopes are named as Symbols (the intended case).

  • (Array<Object>) —

    the names if the names are not actually Symbols.



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

def self.scopes
  @@scopes.keys
end

Instance Method Details

#[](name) ⇒ Porolog::Predicate

Looks up a Predicate in the Scope by its name.

Parameters:

  • name (Object) —

    the name (or otherwise object) used to register a scope.

Returns:



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# File 'lib/porolog/scope.rb', line 67

def [](name)
  @predicates[name.to_sym]
end

#[]=(name, predicate) ⇒ Porolog::Predicate

Assigns a Predicate to the Scope by its name.

Parameters:

  • name (Object) —

    the name (or otherwise object) used to register a scope.

  • predicate (Porolog::Predicate) —

    a Predicate to be assigned to the Scope.

Returns:

Raises:



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# File 'lib/porolog/scope.rb', line 76

def []=(name, predicate)
  raise NotPredicateError, "#{predicate.inspect} is not a Predicate" unless predicate.is_a?(Predicate)
  @predicates[name.to_sym] = predicate
end

#predicates ⇒ Array<Porolog::Predicate>

Returns the Predicates contained in the Scope.

Returns:



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# File 'lib/porolog/scope.rb', line 83

def predicates
  @predicates.values
end