class RDF::Query::Solution

An RDF query solution.

@example Iterating over every binding in the solution

solution.each_binding  { |name, value| puts value.inspect }
solution.each_variable { |variable| puts variable.value.inspect }

@example Iterating over every value in the solution

solution.each_value    { |value| puts value.inspect }

@example Checking whether a variable is bound or unbound

solution.bound?(:title)
solution.unbound?(:mbox)

@example Retrieving the value of a bound variable

solution[:mbox]
solution.mbox

@example Retrieving all bindings in the solution as a `Hash`

solution.to_hash       #=> {mbox: "jrhacker@example.org", ...}

Attributes

bindings[R]

@private

Public Class Methods

new(bindings = {}, &block) click to toggle source

Initializes the query solution.

@param [Hash{Symbol => RDF::Term}] bindings @yield [solution]

# File lib/rdf/query/solution.rb, line 38
def initialize(bindings = {}, &block)
  @bindings = bindings.to_hash

  if block_given?
    case block.arity
      when 1 then block.call(self)
      else instance_eval(&block)
    end
  end
end

Public Instance Methods

==(other)
Alias for: eql?
[](name) click to toggle source

Returns the value of the variable `name`.

@param [Symbol, to_sym] name

the variable name

@return [RDF::Term]

# File lib/rdf/query/solution.rb, line 135
def [](name)
  @bindings[name.to_sym]
end
[]=(name, value) click to toggle source

Binds or rebinds the variable `name` to the given `value`.

@param [Symbol, to_sym] name

the variable name

@param [RDF::Term] value @return [RDF::Term] @since 0.3.0

# File lib/rdf/query/solution.rb, line 147
def []=(name, value)
  @bindings[name.to_sym] = value.is_a?(RDF::Term) ? value : RDF::Literal(value)
end
bound?(name) click to toggle source

Returns `true` if the variable `name` is bound in this solution.

@param [Symbol, to_sym] name

the variable name

@return [Boolean] `true` or `false`

# File lib/rdf/query/solution.rb, line 115
def bound?(name)
  !unbound?(name)
end
compatible?(other) click to toggle source

Compatible Mappings

Two solution mappings u1 and u2 are compatible if, for every variable v in dom(u1) and in dom(u2), u1(v) = u2(v).

@param [RDF::Query::Solution, to_hash] other

another query solution or hash bindings

@return [Boolean] @see www.w3.org/TR/2013/REC-sparql11-query-20130321/#defn_algCompatibleMapping

# File lib/rdf/query/solution.rb, line 192
def compatible?(other)
  @bindings.all? do |k, v|
    !other.to_hash.has_key?(k) || other[k].eql?(v)
  end
end
disjoint?(other) click to toggle source

Disjoint mapping

A solution is disjoint with another solution if it shares no common variables in their domains.

@param [RDF::Query::Solution] other @return [Boolean] @see www.w3.org/TR/2013/REC-sparql11-query-20130321/#defn_algMinus

# File lib/rdf/query/solution.rb, line 206
def disjoint?(other)
  @bindings.none? do |k, v|
    v && other.to_hash.has_key?(k) && other[k].eql?(v)
  end
end
dup() click to toggle source

Duplicate solution, preserving patterns @return [RDF::Statement]

# File lib/rdf/query/solution.rb, line 179
def dup
  merge({})
end
each(&block)
Alias for: each_binding
each_binding(&block) click to toggle source

Enumerates over every variable binding in this solution.

@yield [name, value] @yieldparam [Symbol] name @yieldparam [RDF::Term] value @return [Enumerator]

# File lib/rdf/query/solution.rb, line 59
def each_binding(&block)
  @bindings.each(&block)
end
Also aliased as: each
each_key(&block)
Alias for: each_name
each_name(&block) click to toggle source

Enumerates over every variable name in this solution.

@yield [name] @yieldparam [Symbol] name @return [Enumerator]

# File lib/rdf/query/solution.rb, line 70
def each_name(&block)
  @bindings.each_key(&block)
end
Also aliased as: each_key
each_value(&block) click to toggle source

Enumerates over every variable value in this solution.

@yield [value] @yieldparam [RDF::Term] value @return [Enumerator]

# File lib/rdf/query/solution.rb, line 81
def each_value(&block)
  @bindings.each_value(&block)
end
each_variable() { |variable| ... } click to toggle source

Enumerates over every variable in this solution.

@yield [variable] @yieldparam [Variable] @return [Enumerator]

# File lib/rdf/query/solution.rb, line 103
def each_variable
  @bindings.each do |name, value|
    yield Variable.new(name, value)
  end
end
eql?(other) click to toggle source

Equivalence of solution

# File lib/rdf/query/solution.rb, line 247
def eql?(other)
  other.is_a?(Solution) && @bindings.eql?(other.bindings)
end
Also aliased as: ==
has_variables?(variables) click to toggle source

Returns `true` if this solution contains bindings for any of the given `variables`.

@param [Array<Symbol, to_sym>] variables

an array of variables to check

@return [Boolean] `true` or `false` @since 0.3.0

# File lib/rdf/query/solution.rb, line 93
def has_variables?(variables)
  variables.any? { |variable| bound?(variable) }
end
hash() click to toggle source

Integer hash of this solution @return [Integer]

# File lib/rdf/query/solution.rb, line 241
def hash
  @bindings.hash
end
inspect() click to toggle source

@return [String]

# File lib/rdf/query/solution.rb, line 260
def inspect
  sprintf("#<%s:%#0x(%s)>", self.class.name, __id__, @bindings.inspect)
end
isomorphic_with?(other) click to toggle source

Isomorphic Mappings Two solution mappings u1 and u2 are isomorphic if, for every variable v in dom(u1) and in dom(u2), u1(v) = u2(v).

@param [RDF::Query::Solution, to_hash] other

another query solution or hash bindings

@return [Boolean]

# File lib/rdf/query/solution.rb, line 220
def isomorphic_with?(other)
  @bindings.all? do |k, v|
    !other.to_hash.has_key?(k) || other[k].eql?(v)
  end
end
merge(other) click to toggle source

Merges the bindings from the given `other` query solution with a copy of this one.

@param [RDF::Query::Solution, to_hash] other

another query solution or hash bindings

@return [RDF::Query::Solution] @since 0.3.0

# File lib/rdf/query/solution.rb, line 172
def merge(other)
  self.class.new(@bindings.dup).merge!(other)
end
merge!(other) click to toggle source

Merges the bindings from the given `other` query solution into this one, overwriting any existing ones having the same name.

@param [RDF::Query::Solution, to_hash] other

another query solution or hash bindings

@return [void] self @since 0.3.0

# File lib/rdf/query/solution.rb, line 159
def merge!(other)
  @bindings.merge!(other.to_hash)
  self
end
to_a() click to toggle source

@return [Array<Array(Symbol, RDF::Term)>}

# File lib/rdf/query/solution.rb, line 228
def to_a
  @bindings.to_a
end
to_hash() click to toggle source

@return [Hash{Symbol => RDF::Term}}

# File lib/rdf/query/solution.rb, line 234
def to_hash
  @bindings.dup
end
unbound?(name) click to toggle source

Returns `true` if the variable `name` is unbound in this solution.

@param [Symbol, to_sym] name

the variable name

@return [Boolean] `true` or `false`

# File lib/rdf/query/solution.rb, line 125
def unbound?(name)
  @bindings[name.to_sym].nil?
end

Protected Instance Methods

method_missing(name, *args, &block) click to toggle source

@param [Symbol] name @return [RDF::Term]

Calls superclass method
# File lib/rdf/query/solution.rb, line 269
def method_missing(name, *args, &block)
  if args.empty? && @bindings.has_key?(name.to_sym)
    @bindings[name.to_sym]
  else
    super # raises NoMethodError
  end
end
respond_to_missing?(name, include_private = false) click to toggle source

@return [Boolean]

Calls superclass method
# File lib/rdf/query/solution.rb, line 279
def respond_to_missing?(name, include_private = false)
  @bindings.has_key?(name.to_sym) || super
end