Class: Depager::Grammar

Inherits:
Object
  • Object
show all
Defined in:
lib/depager/grammar.rb

Direct Known Subclasses

LALR::Grammar

Defined Under Namespace

Classes: SymbolSet

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(rulelist, terms, nonterms, precs = nil) ⇒ Grammar

Returns a new instance of Grammar.



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# File 'lib/depager/grammar.rb', line 7

def initialize(rulelist, terms, nonterms, precs = nil)
  @precs    = precs
  @nonterms = nonterms.invert
  @terms    = terms.invert
  @syms     = nonterms.invert.merge(terms.invert)

  @rulelist = rulelist
  @lhs_to_rule = []
  @nonterms.size.times { |i| @lhs_to_rule[i] = [] }
  @empty_rules = {}
  @rulelist.each_with_index do |rule, rx|
    rule.grammar = self
    rule.n = rx
    @lhs_to_rule[rule.lhs] << rule
    @empty_rules[rule.lhs] = rule.n if rule.rhs.empty?
  end
  make_sym_mask
  make_sym_first
  initialize_depend
end

Instance Attribute Details

#f0e ⇒ Object

Returns the value of attribute f0e.



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# File 'lib/depager/grammar.rb', line 5

def f0e
  @f0e
end

#first1 ⇒ Object

Returns the value of attribute first1.



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# File 'lib/depager/grammar.rb', line 5

def first1
  @first1
end

#lhs_to_rule ⇒ Object

Returns the value of attribute lhs_to_rule.



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# File 'lib/depager/grammar.rb', line 5

def lhs_to_rule
  @lhs_to_rule
end

#mask_sym ⇒ Object (readonly)

Returns the value of attribute mask_sym.



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# File 'lib/depager/grammar.rb', line 55

def mask_sym
  @mask_sym
end

#nonterms ⇒ Object

Returns the value of attribute nonterms.



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# File 'lib/depager/grammar.rb', line 5

def nonterms
  @nonterms
end

#precs ⇒ Object

Returns the value of attribute precs.



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# File 'lib/depager/grammar.rb', line 5

def precs
  @precs
end

#rulelist ⇒ Object

Returns the value of attribute rulelist.



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# File 'lib/depager/grammar.rb', line 5

def rulelist
  @rulelist
end

#syms ⇒ Object

Returns the value of attribute syms.



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# File 'lib/depager/grammar.rb', line 5

def syms
  @syms
end

#terms ⇒ Object

Returns the value of attribute terms.



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# File 'lib/depager/grammar.rb', line 5

def terms
  @terms
end

Instance Method Details

#[](n) ⇒ Object 



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# File 'lib/depager/grammar.rb', line 118

def [](n)
  @rulelist[n]
end

#first(p) ⇒ Object 



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# File 'lib/depager/grammar.rb', line 92

def first(p)
  return symset([EPS]) if p.empty?

  r = symset
  x = 0
  p.each do |i|
    unless i == EPS
      r.merge! @first1[i]
      break unless @first1[i].include? EPS
    end
    x += 1
  end
  r.delete EPS
  r << EPS if x == p.size

  r
end

#initialize_depend ⇒ Object 



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# File 'lib/depager/grammar.rb', line 28

def initialize_depend; end

#make_sym_first ⇒ Object 



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# File 'lib/depager/grammar.rb', line 57

def make_sym_first
  @first1 = {}
  @syms.each_key do |s|
    @first1[s] = symset

    @first1[s] << s   if term? s
    @first1[s] << EPS if @empty_rules[s]
  end

  begin
    changed = false
    @nonterms.size.times do |lhs|
      @lhs_to_rule[lhs].each do |rule|
        rule.rhs.each do |s|
          unless @first1[s].subset_of?(@first1[lhs])
            # warn "%b\n%b" % [@first1[s].set, @first1[lhs].set]
            # warn "update{"
            # warn "  R:#{symname(s)}:#{@first1[s].inspect}"
            # warn "  L:#{symname(lhs)}:#{@first1[lhs].inspect}"
            @first1[lhs].merge! @first1[s]
            # warn "  L:#{symname(lhs)}:#{@first1[lhs].inspect}"
            # warn "}"
            changed = true
          end
          break unless @first1[s].include? EPS
        end
        if !@first1[lhs].include?(EPS) && rule.rhs.all? { |i| @first1[i].include? EPS }
          @first1[lhs] << EPS
          changed = true
        end
      end
    end
  end while changed
end

#make_sym_mask ⇒ Object 



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# File 'lib/depager/grammar.rb', line 30

def make_sym_mask
  @sym_mask = {}
  @mask_sym = []
  @terms.sort_by { |a, _b| a }.each_with_index do |i, x|
    @sym_mask[i[0]] = 1 << x
    @mask_sym[x] = i[0]
  end

  @sym_mask[EPS] = (1 << @sym_mask.size)
  @mask_sym << EPS
end

#mask_size ⇒ Object 



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# File 'lib/depager/grammar.rb', line 51

def mask_size
  @mask_sym.size
end

#nonterm?(i) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/depager/grammar.rb', line 114

def nonterm?(i)
  i && i < @nonterms.size
end

#sym_mask(sym) ⇒ Object 



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# File 'lib/depager/grammar.rb', line 47

def sym_mask(sym)
  @sym_mask[sym]
end

#symname(sym) ⇒ Object 



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# File 'lib/depager/grammar.rb', line 122

def symname(sym)
  name = @syms[sym]
  return nil        unless sym.is_a? Integer
  return "$start"   if sym == 0
  return "$empty"   if sym == EPS
  return "$end"     if name.nil?
  return "$error"   if name == false
  return name.to_s  if name.is_a? Symbol

  "'#{name}'"
end

#symset(syms = nil) ⇒ Object 



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# File 'lib/depager/grammar.rb', line 42

def symset(syms = nil)
  ss = SymbolSet.new(self)
  syms ? ss.concat_array(syms) : ss
end

#term?(i) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/depager/grammar.rb', line 110

def term?(i)
  i && i >= @nonterms.size
end