Class: ActiveFacts::CQL::Compiler::Clause

Inherits:
Object
  • Object
show all
Defined in:
lib/activefacts/cql/compiler/clause.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(phrases, qualifiers = [], context_note = nil) ⇒ Clause

Returns a new instance of Clause.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 16

def initialize phrases, qualifiers = [], context_note = nil
  @phrases = phrases
  refs.each { |ref| ref.clause = self }
  @certainty = true
  @qualifiers = qualifiers
  @context_note = context_note
end

Instance Attribute Details

#certainty ⇒ Object

nil, true, false -> maybe, definitely, not



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# File 'lib/activefacts/cql/compiler/clause.rb', line 8

def certainty
  @certainty
end

#conjunction ⇒ Object

one of ‘and’, ‘,’, ‘or’, ‘where’



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# File 'lib/activefacts/cql/compiler/clause.rb', line 9

def conjunction
  @conjunction
end

#context_note ⇒ Object

Returns the value of attribute context_note.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 7

def context_note
  @context_note
end

#fact ⇒ Object

When binding fact instances the fact goes here



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# File 'lib/activefacts/cql/compiler/clause.rb', line 13

def fact
  @fact
end

#fact_type ⇒ Object

Returns the value of attribute fact_type.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 10

def fact_type
  @fact_type
end

#objectified_as ⇒ Object

The Reference which objectified this fact type



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# File 'lib/activefacts/cql/compiler/clause.rb', line 14

def objectified_as
  @objectified_as
end

#phrases ⇒ Object (readonly)

Returns the value of attribute phrases.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 6

def phrases
  @phrases
end

#qualifiers ⇒ Object

Returns the value of attribute qualifiers.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 7

def qualifiers
  @qualifiers
end

#reading ⇒ Object (readonly)

These are the Metamodel objects



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# File 'lib/activefacts/cql/compiler/clause.rb', line 11

def reading
  @reading
end

#role_sequence ⇒ Object (readonly)

These are the Metamodel objects



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# File 'lib/activefacts/cql/compiler/clause.rb', line 11

def role_sequence
  @role_sequence
end

#side_effects ⇒ Object (readonly)

How to adjust the phrases if this fact_type match is accepted



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# File 'lib/activefacts/cql/compiler/clause.rb', line 12

def side_effects
  @side_effects
end

Instance Method Details

#adjust_for_match ⇒ Object

When we match an existing reading, we might have matched using additional adjectives. These adjectives have been removed from the phrases. If there are any remaining adjectives, we need to make a new RoleSequence, otherwise we can use the existing one.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 651

def adjust_for_match
  return unless @applied_side_effects
  new_role_sequence_needed = @applied_side_effects.residual_adjectives

  role_phrases = []
  reading_words = []
  new_role_sequence_needed = false
  @phrases.each do |phrase|
    if phrase.respond_to?(:player)
      role_phrases << phrase
      reading_words << "{#{phrase.role_ref.ordinal}}"
      if phrase.role_name != phrase.role_ref.role.role_name ||
          phrase.leading_adjective ||
          phrase.trailing_adjective
        debug :matching, "phrase in matched clause has residual adjectives or role name, so needs a new role_sequence" if @fact_type.all_reading.size > 0
        new_role_sequence_needed = true
      end
    else
      reading_words << phrase
      false
    end
  end

  debug :matching, "Clause '#{reading_words*' '}' #{new_role_sequence_needed ? 'requires' : 'does not require'} a new Role Sequence"

  constellation = @fact_type.constellation
  reading_text = reading_words*" "
  if new_role_sequence_needed
    @role_sequence = constellation.RoleSequence(:new)
    extra_adjectives = []
    role_phrases.each_with_index do |rp, i|
      role_ref = constellation.RoleRef(@role_sequence, i, :role => rp.role_ref.role)
      if a = rp.leading_adjective
        role_ref.leading_adjective = a
        extra_adjectives << a+"-"
      end
      if a = rp.trailing_adjective
        role_ref.trailing_adjective = a
        extra_adjectives << "-"+a
      end
      if (a = rp.role_name) && (e = rp.role_ref.role.role_name) && a != e
        raise "Can't create new reading '#{reading_text}' for '#{reading.expand}' with alternate role name #{a}"
        extra_adjectives << "(as #{a})"
      end
    end
    debug :matching, "Making new role sequence for new reading #{reading_text} due to #{extra_adjectives.inspect}"
  else
    # Use existing RoleSequence
    @role_sequence = role_phrases[0].role_ref.role_sequence
    if @role_sequence.all_reading.detect{|r| r.text == reading_text }
      debug :matching, "No need to re-create identical reading for #{reading_text}"
      return @role_sequence
    else
      debug :matching, "Using existing role sequence for new reading '#{reading_text}'"
    end
  end
  if @fact_type.all_reading.
    detect do |r|
      r.text == reading_text and
      r.role_sequence.all_role_ref_in_order.map{|rr| rr.role.object_type} ==
        @role_sequence.all_role_ref_in_order.map{|rr| rr.role.object_type}
    end
    # raise "Reading '#{@reading.expand}' already exists, so why are we creating a duplicate (with #{extra_adjectives.inspect})?"
  else
    constellation.Reading(@fact_type, @fact_type.all_reading.size, :role_sequence => @role_sequence, :text => reading_text, :is_negative => (certainty == false))
  end
  @role_sequence
end

#apply_side_effects(context, side_effects) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 517

def apply_side_effects(context, side_effects)
  @applied_side_effects = side_effects
  # Enact the side-effects of this match (delete the consumed adjectives):
  # Since this deletes words from the phrases, we do it in reverse order.
  debug :matching, "Apply side-effects" do
    side_effects.apply_all do |side_effect|
      phrase = side_effect.phrase

      # We re-use the role_ref if possible (no extra adjectives were used, no rolename or step, etc).
      debug :matching, "side-effect means binding #{phrase.inspect} matches role ref #{side_effect.role_ref.role.object_type.name}"
      phrase.role_ref = side_effect.role_ref

      changed = false

      # Where this phrase has leading or trailing adjectives that are in excess of those of
      # the role_ref, those must be local, and we'll need to extract them.

      if rra = side_effect.role_ref.trailing_adjective
        debug :matching, "Deleting matched trailing adjective '#{rra}'#{side_effect.absorbed_followers>0 ? " in #{side_effect.absorbed_followers} followers" : ""}, cost is #{side_effect.cost}"
        side_effect.cancel_cost side_effect.absorbed_followers

        # These adjective(s) matched either an adjective here, or a follower word, or both.
        if a = phrase.trailing_adjective
          if a.size >= rra.size
            a = a[rra.size+1..-1]
            phrase.trailing_adjective = a == '' ? nil : a
            changed = true
          end
        elsif side_effect.absorbed_followers > 0
          # The following statement is incorrect. The absorbed adjective is what caused the match.
          # This phrase is absorbing non-hyphenated adjective(s), which changes its binding
          # phrase.trailing_adjective =
          @phrases.slice!(side_effect.num+1, side_effect.absorbed_followers)*' '
          changed = true
        end
      end

      if rra = side_effect.role_ref.leading_adjective
        debug :matching, "Deleting matched leading adjective '#{rra}'#{side_effect.absorbed_precursors>0 ? " in #{side_effect.absorbed_precursors} precursors" : ""}, cost is #{side_effect.cost}"
        side_effect.cancel_cost side_effect.absorbed_precursors

        # These adjective(s) matched either an adjective here, or a precursor word, or both.
        if a = phrase.leading_adjective
          if a.size >= rra.size
            a = a[0...-rra.size]
            phrase.leading_adjective = a == '' ? nil : a
            changed = true
          end
        elsif side_effect.absorbed_precursors > 0
          # The following statement is incorrect. The absorbed adjective is what caused the match.
          # This phrase is absorbing non-hyphenated adjective(s), which changes its binding
          #phrase.leading_adjective =
          @phrases.slice!(side_effect.num-side_effect.absorbed_precursors, side_effect.absorbed_precursors)*' '
          changed = true
        end
      end
      if changed
        phrase.rebind context
      end

    end
  end
end

#bind(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 97

def bind context
  role_names = refs.map{ |ref| ref.role_name }.compact

  # Check uniqueness of role names and subscripts within this clause:
  role_names.each do |rn|
    next if role_names.select{|rn2| rn2 == rn}.size == 1
    raise "Duplicate role #{rn.is_a?(Integer) ? "subscript" : "name"} '#{rn}' in clause"
  end

  refs.each do |ref|
    ref.bind context
  end
end

#clause_matches(fact_type, reading, phrases = @phrases) ⇒ Object

The Reading passed has the same players as this Clause. Does it match? Twisty curves. This is a complex bit of code! Find whether the phrases of this clause match the fact type reading, which may require absorbing unmarked adjectives.

If it does match, make the required changes and set @ref to the matching role ref. Adjectives that were used to match are removed (and leaving any additional adjectives intact).

Approach:

Match each element where element means:
  a role player phrase (perhaps with adjectives)
    Our phrase must either be
      a player that contains the same adjectives as in the reading.
      a word (unmarked leading adjective) that introduces a sequence
        of adjectives leading up to a matching player
    trailing adjectives, both marked and unmarked, are absorbed too.
  a word that matches the reading's



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# File 'lib/activefacts/cql/compiler/clause.rb', line 331

def clause_matches(fact_type, reading, phrases = @phrases)
  implicitly_negated = false
  side_effects = []    # An array of items for each role, describing any side-effects of the match.
  intervening_words = nil
  residual_adjectives = false

  # The following form of negation is, e.g., where "Person was invited to no Party",
  # as opposed to where "Person was not invited to that Party". Quite different meaning,
  # because a free Party variable is required, but the join step is still disallowed.
  # REVISIT: I'll create the free variable when I implement some/that binding
  # REVISIT: the verbaliser will need to know about a negated step to a free variable
  implicitly_negated = true if refs.detect{|ref| q = ref.quantifier and q.is_zero }

  debug :matching_fails, "Does '#{phrases.inspect}' match '#{reading.expand}'" do
    phrase_num = 0
    reading_parts = reading.text.split(/\s+/)
    reading_parts.each do |element|
      phrase = phrases[phrase_num]
      if phrase == 'not'
        raise "Stop playing games with your double negatives: #{phrases.inspect}" if implicitly_negated
        debug :matching, "Negation detected"
        implicitly_negated = true
        phrase = phrases[phrase_num += 1]
      end
      if element !~ /\{(\d+)\}/
        # Just a word; it must match
        unless phrase == element
          debug :matching_fails, "Mismatched ordinary word #{phrases[phrase_num].inspect} (wanted #{element})"
          return nil
        end
        phrase_num += 1
        next
      else
        role_ref = reading.role_sequence.all_role_ref.sort_by{|rr| rr.ordinal}[$1.to_i]
      end

      player = role_ref.role.object_type

      # Figure out what's next in this phrase (the next player and the words leading up to it)
      next_player_phrase = nil
      intervening_words = []
      while (phrase = phrases[phrase_num])
        phrase_num += 1
        if phrase.respond_to?(:player)
          next_player_phrase = phrase
          next_player_phrase_num = phrase_num-1
          break
        else
          intervening_words << phrase
        end
      end
      return nil unless next_player_phrase  # reading has more players than we do.
      next_player = next_player_phrase.player

      # The next player must match:
      common_supertype = nil
      if next_player != player
        # This relies on the supertypes being in breadth-first order:
        common_supertype = (next_player.supertypes_transitive & player.supertypes_transitive)[0]
        if !common_supertype
          debug :matching_fails, "Reading discounted because next player #{player.name} doesn't match #{next_player.name}"
          return nil
        end

        debug :matching_fails, "Subtype step is required between #{player.name} and #{next_player_phrase.player.name} via common supertype #{common_supertype.name}"
      else
        if !next_player_phrase
          next    # Contraction succeeded so far
        end
      end

      # It's the right player. Do the adjectives match? This must include the intervening_words, if any.

      role_has_residual_adjectives = false
      absorbed_precursors = 0
      if la = role_ref.leading_adjective and !la.empty?
        # The leading adjectives must match, one way or another
        la = la.split(/\s+/)
		if (la[0, intervening_words.size] == intervening_words)		# Exact match
		  iw = intervening_words
		else
		  # We may have hyphenated adjectives. Break them up to check:
		  iw = intervening_words.map{|w| w.split(/-/)}.flatten
		  return nil unless la[0,iw.size] == iw
		end

        # Any intervening_words matched, see what remains
        la.slice!(0, iw.size)

        # If there were intervening_words, the remaining reading adjectives must match the phrase's leading_adjective exactly.
        phrase_la = (next_player_phrase.leading_adjective||'').split(/\s+/)
        return nil if !iw.empty? && la != phrase_la
        # If not, the phrase's leading_adjectives must *end* with the reading's
        return nil if phrase_la[-la.size..-1] != la
        role_has_residual_adjectives = true if phrase_la.size > la.size
        # The leading adjectives and the player matched! Check the trailing adjectives.
        absorbed_precursors = intervening_words.size
        intervening_words = []
      elsif intervening_words.size > 0 || next_player_phrase.leading_adjective
        role_has_residual_adjectives = true
      end

      absorbed_followers = 0
      if ta = role_ref.trailing_adjective and !ta.empty?
        ta = ta.split(/\s+/)  # These are the trailing adjectives to match

        phrase_ta = (next_player_phrase.trailing_adjective||'').split(/\s+/)
        i = 0   # Pad the phrases up to the size of the trailing_adjectives
        while phrase_ta.size < ta.size
          break unless (word = phrases[phrase_num+i]).is_a?(String)
          phrase_ta << word
          i += 1
        end
        # ta is the adjectives in the fact type being matched
        # phrase_ta is the explicit adjectives augmented with implicit ones to the same size
        return nil if ta != phrase_ta[0,ta.size]
        role_has_residual_adjectives = true if phrase_ta.size > ta.size
        absorbed_followers = i
        phrase_num += i # Skip following words that were consumed as trailing adjectives
      elsif next_player_phrase.trailing_adjective
        role_has_residual_adjectives = true
      end

      # REVISIT: I'm not even sure I should be caring about role names here.
      # Role names are on roles, and are only useful within the fact type definition.
      # At some point, we need to worry about role names on clauses within fact type derivations,
      # which means they'll move to the Role Ref class; but even then they only match within the
      # definition that creates that Role Ref.
=begin
      if a = (!phrase.role_name.is_a?(Integer) && phrase.role_name) and
          e = role_ref.role.role_name and
          a != e
        debug :matching, "Role names #{e.inspect} for #{player.name} and #{a.inspect} for #{next_player_phrase.player.name} don't match"
        return nil
      end
=end

      residual_adjectives ||= role_has_residual_adjectives
      if residual_adjectives && next_player_phrase.binding.refs.size == 1
        # This makes matching order-dependent, because there may be no "other purpose"
        # until another reading has been matched and the roles rebound.
        debug :matching_fails, "Residual adjectives have no other purpose, so this match fails"
        return nil
      end

      # The phrases matched this reading's next role_ref, save data to apply the side-effects:
      side_effects << ClauseMatchSideEffect.new(next_player_phrase, role_ref, next_player_phrase_num, absorbed_precursors, absorbed_followers, common_supertype, role_has_residual_adjectives)
    end

    if phrase_num != phrases.size || !intervening_words.empty?
      debug :matching_fails, "Extra words #{(intervening_words + phrases[phrase_num..-1]).inspect}"
      return nil
    end

    if fact_type.is_a?(Metamodel::TypeInheritance)
      # There may be only one subtyping step on a TypeInheritance fact type.
      ti_steps = side_effects.select{|side_effect| side_effect.common_supertype}
      if ti_steps.size > 1   # Not allowed
        debug :matching_fails, "Can't have more than one subtyping step on a TypeInheritance fact type"
        return nil
      end

      if ti = ti_steps[0]
        # The Type Inheritance step must continue in the same direction as this reading.
        allowed = fact_type.supertype == ti.role_ref.role.object_type ?
            fact_type.subtype.supertypes_transitive :
            fact_type.supertype.subtypes_transitive
        if !allowed.include?(ti.common_supertype)
          debug :matching_fails, "Implicit subtyping step extends in the wrong direction"
          return nil
        end
      end
    end

    debug :matching, "Matched reading '#{reading.expand}' (with #{
          side_effects.map{|side_effect|
            side_effect.absorbed_precursors+side_effect.absorbed_followers + (side_effect.common_supertype ? 1 : 0)
          }.inspect
        } side effects)#{residual_adjectives ? ' and residual adjectives' : ''}"
  end
  # There will be one side_effects for each role player
  @certainty = !@certainty if implicitly_negated
  @certainty = !@certainty if reading.is_negative
  ClauseMatchSideEffects.new(fact_type, self, residual_adjectives, side_effects, implicitly_negated)
end

#display ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 36

def display
  to_s
end

#identify_other_players(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 81

def identify_other_players context
  refs.each do |ref|
    ref.identify_other_players(context)
    # Include players in nested clauses, if any
    ref.nested_clauses.each{|clause| clause.identify_other_players(context)} if ref.nested_clauses
  end
end

#identify_players_with_role_name(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 75

def identify_players_with_role_name context
  refs.each do |ref|
    ref.identify_players_with_role_name(context)
  end
end

#includes_literals ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 89

def includes_literals
  refs.detect{|ref| ref.literal || (ja = ref.nested_clauses and ja.detect{|jr| jr.includes_literals })}
end

#inspect(phrases = nil) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 40

def inspect phrases = nil
  to_s(phrases||@phrases)
end

#is_equality_comparison ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 93

def is_equality_comparison
  false
end

#is_existential_type ⇒ Object

A clause that contains only the name of a ObjectType and no literal or reading text refers only to the existence of that ObjectType (as opposed to an instance of the object_type).



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# File 'lib/activefacts/cql/compiler/clause.rb', line 30

def is_existential_type
  @phrases.size == 1 and
    @phrases[0].is_a?(Reference) and
    !@phrases[0].literal
end

#is_naked_object_type ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 745

def is_naked_object_type
  @phrases.size == 1 && refs.size == 1
end

#make_embedded_constraints(vocabulary) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 720

def make_embedded_constraints vocabulary
  refs.each do |ref|
    next unless ref.quantifier
    # puts "Quantifier #{ref.inspect} not implemented as a presence constraint"
    ref.make_embedded_presence_constraint vocabulary
  end

  if @qualifiers && @qualifiers.size > 0
    # We shouldn't make a new ring constraint if there's already one over this ring.
    existing_rcs = 
      @role_sequence.all_role_ref.map{|rr| rr.role.all_ring_constraint.to_a }.flatten.uniq
    unless existing_rcs[0]
      rc = RingConstraint.new(@role_sequence, @qualifiers)
      rc.vocabulary = vocabulary
      rc.constellation = vocabulary.constellation
      rc.compile
    else
      # Ignore the fact that the ring might be of a different type.
    end

    # REVISIT: Check maybe and other qualifiers:
    debug :constraint, "Need to make constraints for #{@qualifiers.inspect}" if @qualifiers.size > 0 or @certainty != true
  end
end

#make_fact_type(vocabulary) ⇒ Object

Make a new fact type with roles for this clause. Don’t assign @fact_type; that will happen when the reading is added



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# File 'lib/activefacts/cql/compiler/clause.rb', line 583

def make_fact_type vocabulary
  fact_type = vocabulary.constellation.FactType(:new)
  debug :matching, "Making new fact type for #{@phrases.inspect}" do
    @phrases.each do |phrase|
      next unless phrase.respond_to?(:player)
      phrase.role = vocabulary.constellation.Role(fact_type, fact_type.all_role.size, :object_type => phrase.player, :concept => :new)
      phrase.role.role_name = phrase.role_name if phrase.role_name && phrase.role_name.is_a?(String)
    end
  end
  fact_type
end

#make_reading(vocabulary, fact_type) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 595

def make_reading vocabulary, fact_type
  @fact_type = fact_type
  constellation = vocabulary.constellation
  @role_sequence = constellation.RoleSequence(:new)
  reading_words = @phrases.clone
  index = 0
  debug :matching, "Making new reading for #{@phrases.inspect}" do
    reading_words.map! do |phrase|
      if phrase.respond_to?(:player)
        # phrase.role will be set if this reading was used to make_fact_type.
        # Otherwise we have to find the existing role via the Binding. This is pretty ugly.
        unless phrase.role
          # Find another binding for this phrase which already has a role_ref to the same fact type:
          ref = phrase.binding.refs.detect{|ref| ref.role_ref && ref.role_ref.role.fact_type == fact_type}
          role_ref = ref.role_ref
          phrase.role = role_ref.role
        end
        rr = constellation.RoleRef(@role_sequence, index, :role => phrase.role)
        phrase.role_ref = rr

        if la = phrase.leading_adjective
          # If we have used one or more adjective to match an existing reading, that has already been removed.
          rr.leading_adjective = la
        end
        if ta = phrase.trailing_adjective
          rr.trailing_adjective = ta
        end

        if phrase.value_constraint
          raise "The role #{rr.inspect} already has a value constraint" if rr.role.role_value_constraint
          phrase.value_constraint.constellation = fact_type.constellation
          rr.role.role_value_constraint = phrase.value_constraint.compile
        end

        index += 1
        "{#{index-1}}"
      else
        phrase
      end
    end
    if existing = @fact_type.all_reading.detect{|r|
        r.text == reading_words*' ' and
          r.role_sequence.all_role_ref_in_order.map{|rr| rr.role.object_type} ==
            role_sequence.all_role_ref_in_order.map{|rr| rr.role.object_type}
      }
      existing
      #raise "Reading '#{existing.expand}' already exists, so why are we creating a duplicate?"
    end
    r = constellation.Reading(@fact_type, @fact_type.all_reading.size, :role_sequence => @role_sequence, :text => reading_words*" ", :is_negative => (certainty == false))
    r
  end
end

#match_existing_fact_type(context, options = {}) ⇒ Object

This method chooses the existing fact type which matches most closely. It returns nil if there is none, or a ClauseMatchSideEffects object if matched.

As this match may not necessarily be used (depending on the side effects), no change is made to this Clause object - those will be done later.



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# File 'lib/activefacts/cql/compiler/clause.rb', line 129

def match_existing_fact_type context, options = {}
  raise "Cannot match a clause that contains no object types" if refs.size == 0
  raise "Internal error, clause already matched, should not match again" if @fact_type
  # If we fail to match, try a left contraction (or save this for a subsequent left contraction):
  left_contract_this_onto = context.left_contractable_clause
  new_conjunction = (conjunction == nil || conjunction == ',')
  changed_conjunction = (lcc = context.left_contraction_conjunction) && lcc != conjunction
  if context.left_contraction_allowed && (new_conjunction || changed_conjunction)
    # Conjunctions are that/who, where, comparison-operator, ','
    debug :matching, "A left contraction will be against #{self.inspect}, conjunction is #{conjunction.inspect}"
    context.left_contractable_clause = self
    left_contract_this_onto = nil # Can't left-contract this clause
  end
  context.left_contraction_conjunction = new_conjunction ? nil : @conjunction

  phrases = @phrases
  vrs = []+refs

  # A left contraction is where the first player in the previous clause continues as first player of this clause
  contracted_left = false
  can_contract_right = false
  left_insertion = nil
  right_insertion = nil
  supposed_roles = []   # Arrange to unbind incorrect references supposed due to contraction
  contract_left = proc do
    contracted_from = left_contract_this_onto.refs[0]
    contraction_player = contracted_from.player
    contracted_role = Reference.new(contraction_player.name)
    supposed_roles << contracted_role
    left_insertion = contracted_role.inspect+' '
    contracted_role.player = contracted_from.player
    contracted_role.role_name = contracted_from.role_name
    contracted_role.bind(context)
    vrs.unshift contracted_role
    contracted_left = true
    phrases = [contracted_role]+phrases
    debug :matching, "Failed to match #{inspect}. Trying again using left contraction onto #{contraction_player.name}"
  end

  contract_right = proc do
    contracted_from = left_contract_this_onto.refs[-1]
    contraction_player = contracted_from.player
    contracted_role = Reference.new(contraction_player.name)
    supposed_roles << contracted_role
    right_insertion = ' '+contracted_role.inspect
    contracted_role.player = contracted_from.player
    contracted_role.role_name = contracted_from.role_name
    contracted_role.bind(context)
    vrs.push contracted_role
    phrases = phrases+[contracted_role]
    debug :matching, "Failed to match #{inspect}. Trying again using right contraction onto #{contraction_player.name}"
  end

  begin
    players = vrs.map{|vr| vr.player}

    if players.size == 0
      can_contract_right = left_contract_this_onto.refs.size == 2
      contract_left.call
      redo
    end

    raise "Must identify players before matching fact types" if players.include? nil
    raise "A fact type must involve at least one object type, but there are none in '#{inspect}'" if players.size == 0 && !left_contract_this_onto

    player_names = players.map{|p| p.name}

    debug :matching, "Looking for existing #{players.size}-ary fact types matching '#{inspect(phrases)}'" do
      debug :matching, "Players are '#{player_names.inspect}'"

      # Match existing fact types in nested clauses first:
      # (not for contractions) REVISIT: Why not?
      if !contracted_left
        vrs.each do |ref|
          next if ref.is_a?(Operation)
          next unless steps = ref.nested_clauses and !steps.empty?
          ref.nested_clauses.each do |oj|
            ft = oj.match_existing_fact_type(context)
            raise "Unrecognised fact type #{oj.display}" unless ft
            if (ft && ft.entity_type == ref.player)
              ref.objectification_of = ft
              oj.objectified_as = ref
            end
          end
          raise "#{ref.inspect} contains objectification steps that do not objectify it" unless ref.objectification_of
        end
      end

      # For each role player, find the compatible types (the set of all subtypes and supertypes).
      # For a player that's an objectification, we don't allow implicit supertype steps
      player_related_types =
        vrs.zip(players).map do |ref, player|
          disallow_subtyping = ref && ref.objectification_of || options[:exact_type]
          ((disallow_subtyping ? [] : player.supertypes_transitive) +
            player.subtypes_transitive).uniq
        end

      debug :matching, "Players must match '#{player_related_types.map{|pa| pa.map{|p|p.name}}.inspect}'"

      start_obj = player_related_types[0] || [left_contract_this_onto.refs[-1].player]
      # The candidate fact types have the right number of role players of related types.
      # If any role is played by a supertype or subtype of the required type, there's an implicit subtyping steps
      # REVISIT: A double contraction results in player_related_types being empty here
      candidate_fact_types =
        start_obj.map do |related_type|
          related_type.all_role.select do |role|
            # next if role.fact_type.all_reading.size == 0
            next if role.fact_type.is_a?(ActiveFacts::Metamodel::LinkFactType)
            next if role.fact_type.all_role.size != players.size      # Wrong number of players

		    compatible_readings = role.fact_type.compatible_readings(player_related_types)
		    next unless compatible_readings.size > 0
		    debug :matching_fails, "These readings are compatible: #{compatible_readings.map(&:expand).inspect}"
            true
          end.
            map{ |role| role.fact_type}
        end.flatten.uniq

      # If there is more than one possible exact match (same adjectives) with different subyping, the implicit query is ambiguous and is not allowed

      debug :matching, "Looking amongst #{candidate_fact_types.size} existing fact types for one matching #{left_insertion}'#{inspect}'#{right_insertion}" do
        matches = {}
        candidate_fact_types.map do |fact_type|
          fact_type.all_reading.map do |reading|
            next unless side_effects = clause_matches(fact_type, reading, phrases)
            matches[reading] = side_effects if side_effects
          end
        end

        # REVISIT: Side effects that leave extra adjectives should only be allowed if the
        # same extra adjectives exist in some other clause in the same declaration.
        # The extra adjectives are then necessary to associate the two role players
        # when consumed adjectives were required to bind to the underlying fact types.
        # This requires the final decision on fact type matching to be postponed until
        # the whole declaration has been processed and the extra adjectives can be matched.

        best_matches = matches.keys.sort_by{|match|
          # Between equivalents, prefer the one without steps on the first role
          (m = matches[match]).cost*2 + ((!(e = m.role_side_effects[0]) || e.cost) == 0 ? 0 : 1)
        }
        debug :matching_fails, "Found #{matches.size} valid matches#{matches.size > 0 ? ', best is '+best_matches[0].expand : ''}"

        if matches.size > 1
          first = matches[best_matches[0]]
          cost = first.cost
          equal_best = matches.select{|k,m| m.cost == cost}

          if equal_best.size > 1 and equal_best.detect{|k,m| !m.fact_type.is_a?(Metamodel::TypeInheritance)}
            # Complain if there's more than one equivalent cost match (unless all are TypeInheritance):
            raise "#{@phrases.inspect} could match any of the following:\n\t"+
              best_matches.map { |reading| reading.expand + " with " + matches[reading].describe } * "\n\t"
          end
        end

        if matches.size >= 1
          @reading = best_matches[0]
          @side_effects = matches[@reading]
          @fact_type = @side_effects.fact_type
          debug :matching, "Matched '#{@fact_type.default_reading}'"
          @phrases = phrases
          apply_side_effects(context, @side_effects)
          return @fact_type
        end

      end
      debug :matching, "No fact type matched, candidates were '#{candidate_fact_types.map{|ft| ft.default_reading}*"', '"}'"
    end
    if left_contract_this_onto
      if !contracted_left
        contract_left.call
        redo
      elsif can_contract_right
        contract_right.call
        can_contract_right = false
        redo
      end
    end
  end until true  # Once through, unless we hit a redo
  supposed_roles.each do |role|
    role.unbind context
  end
  @fact_type = nil
end

#phrases_match(phrases) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 111

def phrases_match(phrases)
  @phrases.zip(phrases).each do |mine, theirs|
    return false if mine.is_a?(Reference) != theirs.is_a?(Reference)
    if mine.is_a?(Reference)
      return false unless mine.key == theirs.key
    else
      return false unless mine == theirs
    end
  end
  true
end

#refs ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 24

def refs
  @phrases.select{|r| r.respond_to?(:player)}
end

#to_s(phrases = nil) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/clause.rb', line 44

def to_s phrases = nil
  phrases ||= @phrases
  "#{
    @qualifiers && @qualifiers.size > 0 ? @qualifiers.sort.inspect+' ' : nil
  }#{
    case @certainty
    when nil; 'maybe '
    when false; 'negated '
    # else 'definitely '
    end
  }#{
    quotes = false
    phrases.inject(""){|s, p|
      if String === p
        s + (quotes ? '' : (quotes = true; '"')) + p.to_s + ' '
#              REVISIT: Add something here when I re-add functions
#              elsif FunctionCallChain === p
#                s[0..-2] + (quotes ? (quotes = false; '" ') : '') + p.to_s
      else # if Reference === p
        s[0..-2] + (quotes ? (quotes = false; '" ') : '') + p.to_s +
          ((oj = p.nested_clauses) ?  ' ('+ oj.map{|c| ((j=c.conjunction) ? j+' ' : '') + c.to_s}*' ' + ')' : '') +
        ' '
#              else
#                raise "Unexpected phrase type in clause: #{p.to_s}"
      end
    }.sub(/ $/,'') + (quotes ? '"' : '')
  }#{
    @context_note && ' ' + @context_note.inspect
  }"
end