Class: Depager::LALR::Table

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(grammar) ⇒ Table

Returns a new instance of Table.



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# File 'lib/depager/lr.rb', line 256

def initialize(grammar)
  @grammar = grammar
  @states = nil
  @warning_list = []

  items
  mkset
  mktable
end

Instance Attribute Details

#action_table ⇒ Object

Returns the value of attribute action_table.



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# File 'lib/depager/lr.rb', line 254

def action_table
  @action_table
end

#defred_after_shift_table ⇒ Object

Returns the value of attribute defred_after_shift_table.



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# File 'lib/depager/lr.rb', line 254

def defred_after_shift_table
  @defred_after_shift_table
end

#defred_table ⇒ Object

Returns the value of attribute defred_table.



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# File 'lib/depager/lr.rb', line 254

def defred_table
  @defred_table
end

#goto_table ⇒ Object

Returns the value of attribute goto_table.



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# File 'lib/depager/lr.rb', line 254

def goto_table
  @goto_table
end

#grammar ⇒ Object

Returns the value of attribute grammar.



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# File 'lib/depager/lr.rb', line 254

def grammar
  @grammar
end

#state_info ⇒ Object (readonly)

Returns the value of attribute state_info.



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# File 'lib/depager/lr.rb', line 475

def state_info
  @state_info
end

#states ⇒ Object

Returns the value of attribute states.



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# File 'lib/depager/lr.rb', line 254

def states
  @states
end

Instance Method Details

#check_table(dp) ⇒ Object 



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# File 'lib/depager/lr.rb', line 434

def check_table(dp)
  @warning_list.each { |i| dp.warning i }

  return unless Depager.debug_mode?

  gen_state_info
  verbose dp if Depager.verbose_mode?
end

#checkconf(newv, oldv, key, g = nil) ⇒ Object 



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# File 'lib/depager/lr.rb', line 314

def checkconf(newv, oldv, key, g = nil)
  return newv unless oldv

  rl   = grammar.rulelist
  syms = grammar.syms
  if oldv == "ACC"
    @warning_list << "'ACC' conflict #{g}."
    return oldv
  end
  # warn "\n-- N:#{newv} O:#{oldv} K:#{grammar.syms[key]} "
  if (newv < 0) && (oldv > 0)
    # warn "-:shift #{grammar.syms[key]} go to #{oldv}"
    r = resolveconf(key, -newv)
    if r > 0
      # warn "+:shift #{grammar.syms[key]} go to #{oldv}"
      oldv
    elsif r < 0
      # warn "+:reduce #{grammar[-newv]}"
      newv
    else
      @warning_list <<
        ("shift/reduce conflict #{syms[key]}.\n  #{g}\n  " \
          "shift : #{syms[key]}\n  " \
          "reduce: #{rl[-newv]}")
      oldv
    end
  elsif (newv > 0) && (oldv < 0)
    r = resolveconf(key, -oldv)
    if r > 0
      # warn "shift"
      newv
    elsif r < 0
      # warn "reduce"
      oldv
    else
      @warning_list <<
        ("shift/reduce conflict #{syms[key]}.\n  #{g}\n  " \
          "shift : #{syms[key]}\n  " \
          "reduce: #{rl[-oldv]}")
      newv
    end
  elsif (newv < 0) && (oldv < 0)
    unless newv == oldv
      @warning_list <<
        ("reduce/reduce conflict #{syms[key]}.\n  #{g}\n  " \
          "reduce: #{rl[-newv]}\n  " \
          "reduce: #{rl[-oldv]}")
      newv
    end
  else
    warn "must not happen"
    newv
  end
end

#gen_state_info ⇒ Object 



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# File 'lib/depager/lr.rb', line 477

def gen_state_info
  g = grammar
  @state_info = []
  @action_table.each_with_index do |s, x|
    shi = ""
    red = ""
    acc = ""
    s.each_with_index do |t, y|
      next unless t

      hd = format("  %-15s", g.symname(y + g.nonterms.size))
      if t == "ACC"
        acc = "#{hd} accept"
      elsif t < 0
        red << "#{hd} reduce using rule #{-t} (#{g.symname g[-t].lhs})\n"
      else
        shi << "#{hd} shift, and goto to state #{t}\n"
      end
    end
    if (t = @defred_table[x])
      as = @defred_after_shift_table[x] ? " [after shift]" : ""
      red << format("  %-15s", "$default") <<
        "reduce using rule #{-t} (#{g.symname g[-t].lhs}) #{as}"
    end

    @state_info << (@states[x].to_s << "\n\n#{shi}\n#{red}\n#{acc}").strip
  end
end

#items ⇒ Object 



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# File 'lib/depager/lr.rb', line 266

def items
  warn "** LR(0) **" if Depager.debug_mode?
  n = 0
  m = 0
  states = [State.new([LRItem[grammar[0], 0]], 0)]
  memo = { states[0] => m }

  while n < states.size
    states[n].mkgoto.each do |x, a|
      unless a.empty?
        if (memo_a = memo[a])
          states[n].gg[x] = states[memo_a]
        else
          m += 1
          a.n = m
          states[m] = a
          memo[a] = m
        end
      end
    end
    n += 1
  end
  @states = states
end

#mkset ⇒ Object 



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# File 'lib/depager/lr.rb', line 443

def mkset
  warn "** LA **" if Depager.debug_mode?
  trn = []
  @states.each do |state|
    state.items.each do |sitem|
      sitem.closure1([TLA]).each do |citem|
        next if citem.n == citem.rule.rhs.size

        gi = state.goto(citem.dotsym).items
        i  = gi.find { |j| j.rule == citem.rule && j.n == citem.n + 1 }
        trn << [sitem, i] if citem.la.include? TLA
        i.la.merge!(citem.la).delete(TLA)
      end
    end
  end

  warn "** LALR(1) **" if Depager.debug_mode?
  @states[0].items[0].la = @grammar.symset([grammar.nonterms.size]) # '$'
  begin
    changed = false
    trn.each do |k, v|
      unless k.la.subset_of?(v.la)
        v.la.merge!(k.la)
        changed
      end
    end
  end while changed
end

#mktable ⇒ Object 



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# File 'lib/depager/lr.rb', line 369

def mktable
  warn "** TABLE **" if Depager.debug_mode?
  taction = (0...@states.size).map { Array.new(grammar.syms.size - grammar.nonterms.size) }
  tgoto = (0...@states.size).map { Array.new(grammar.nonterms.size - 1) }

  @states.each_with_index do |c, i|
    c.gg.each do |k, j|
      next unless k

      if grammar.term? k
        key = k - grammar.nonterms.size
        taction[i][key] = checkconf(j.n, taction[i][key], k, c)
      else
        tgoto[i][k - 1] = j.n
      end
    end
    c.items.each do |j|
      if (j.n == j.rule.rhs.size) && (j.rule.lhs != 0) # $start
        j.la.each do |u|
          key = u - grammar.nonterms.size
          taction[i][key] = checkconf(-j.rule.n, taction[i][key], u, c)
        end
      elsif (efs = grammar.f0e[j.dotsym])
        efs.each do |rn, ef|
          ef.each do |es|
            fst = grammar.symset
            j.la.each do |la|
              fst |= grammar.first [es, *j.dotrest].push(la)
            end
            fst.each do |u|
              key = u - grammar.nonterms.size
              taction[i][key] = checkconf(-rn, taction[i][key], u, c)
            end
          end
        end
      end
      taction[i][0] = "ACC" if j.rule == grammar[0] && j.n == 1 # $start : ...
    end
  end

  @defred_table = []
  taction.each_with_index do |l, x|
    rs = l.select { |i| i.is_a? Integer }.uniq.compact
    rs = rs.select { |i| i < 0 }
    @defred_table[x] = (rs[0] if rs.size == 1)
  end

  @defred_after_shift_table = []
  taction.each_with_index do |l, x|
    rs = l.select { |i| i.is_a? Integer }.uniq.compact
    @defred_after_shift_table[x] = (rs[0] if (rs.size == 1) && (rs[0] < 0))
  end

  taction.each_with_index do |l, x| # rubocop:disable Style/CombinableLoops
    next unless @defred_table[x]

    l.size.times do |i|
      l[i] = nil if l[i] && l[i] < 0
    end
  end

  @action_table = taction
  @goto_table = tgoto
end

#resolveconf(sh, rd) ⇒ Object

-1:reduce sh; 1:shift rd(=key); 0:can’t resolve



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# File 'lib/depager/lr.rb', line 292

def resolveconf(sh, rd)
  precs = grammar.precs
  psh = precs[sh]
  mrt = grammar[rd].rhs.reverse.find { |i| grammar.term?(i) }
  prd = grammar[rd].prec || precs[mrt]

  if psh && prd
    if psh[1] == prd[1]
      # warn :LEFT ? 'reduce' : 'shift'
      psh[0] == :LEFT ? -1 : 1
    elsif psh[1] > prd[1]
      # warn 'reduce'
      -1
    else
      # warn 'shift'
      1
    end
  else
    0
  end
end

#verbose(dp) ⇒ Object 



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# File 'lib/depager/lr.rb', line 506

def verbose(dp)
  g = grammar
  output = []

  if Depager.debug_mode?(:f)
    output << "** FIRST1 **"
    str = g.first1.map do |k, v|
      "#{g.symname k} => #{v.map { |i| g.symname i }.join(' ')}"
    end.join("\n")
    output << "#{str}\n\n"
  end

  if Depager.debug_mode?(:e)
    output << "** Empty Reduction **"
    str = g.f0e.map do |k, v|
      "#{g.symname k} =>\n" << v.map  do |n, f|
        "  #{rulelist[n]} ? #{f.map { |i| g.symname i }.join(' ')}"
      end.join("\n")
    end.join("\n")
    output << "#{str}\n\n"
  end

  if Depager.debug_mode?(:s)
    output << "** SYMBOLS **"
    str = g.syms.map { |k, _| "#{format('%03i', k)} #{g.symname k}" }.sort.join("\n")
    output << "#{str}\n\n"
  end

  if Depager.debug_mode?(:g)
    output << "*** Grammar ***"
    str = g.rulelist.join("\n")
    output << "#{str}\n\n"
  end

  if Depager.debug_mode?(:c)
    output << "*** States ***"
    str = @state_info.join("\n\n").strip
    output << "#{str}\n\n"
  end

  nssize = g.nonterms.size
  if Depager.debug_mode?(:t)
    output << "*** Action Table ***"
    ws = (nssize...g.syms.size).map do |i|
      j = g.symname(i).size
      [j, 6].max
    end
    str = "   |"
    (nssize...g.syms.size).each_with_index do |i, x|
      str << format("%0#{ws[x]}s|", g.symname(i))
    end; str << " $default|\n"

    @action_table.each_with_index do |i, x|
      str << format("%03i|", x)
      i.each_with_index do |j, y|
        str << format("%0#{ws[y]}s|", j)
      end
      str << (format("%04s,%04s|\n", @defred_table[x], @defred_after_shift_table[x]))
    end
    output << "#{str}\n\n"

    output << "*** Goto Table ***"
    ws = (1...nssize).map do |i|
      j = g.symname(i).size
      [j, 6].max
    end
    str = "   |"
    (1...nssize).each_with_index do |i, x|
      str << format("%0#{ws[x]}s|", g.symname(i))
    end; str << "\n"

    @goto_table.each_with_index do |i, x|
      str << format("%03i|", x)
      i.each_with_index do |j, y|
        str << format("%0#{ws[y]}s|", j)
      end
      str << "\n"
    end
    output << "#{str}\n\n"
  end

  File.write("#{File.basename(dp.file.path, '.dr')}.output", output.join("\n"))
end