Class: LL::ConfigurationCompiler

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# File 'lib/ll/configuration_compiler.rb', line 114

def generate_action_bodies(grammar)
  bodies = {}
  index  = 0

  grammar.rules.each do |rule|
    rule.branches.each do |branch|
      if branch.ruby_code
        code = branch.ruby_code

      # If a branch only contains a single, non-epsilon step we can just
      # return that value as-is. This makes parsing code a little bit
      # easier.
      elsif !branch.ruby_code and branch.steps.length == 1 \
      and !branch.steps[0].is_a?(Epsilon)
        code = 'val[0]'

      else
        code = DEFAULT_RUBY_CODE
      end

      bodies[:_rule_#{index}"] = code

      index += 1
    end
  end

  return bodies
end

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# File 'lib/ll/configuration_compiler.rb', line 93

def generate_actions(grammar)
  actions = []
  index   = 0

  grammar.rules.each do |rule|
    rule.branches.each do |branch|
      args = branch.steps.reject { |step| step.is_a?(Epsilon) }.length

      actions << [:_rule_#{index}", args]

      index += 1
    end
  end

  return actions
end

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# File 'lib/ll/configuration_compiler.rb', line 57

def generate_name(grammar)
  return grammar.name.split('::').last
end

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# File 'lib/ll/configuration_compiler.rb', line 65

def generate_namespace(grammar)
  parts = grammar.name.split('::')

  return parts.length > 1 ? parts[0..-2] : []
end

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# File 'lib/ll/configuration_compiler.rb', line 149

def generate_rules(grammar)
  rules        = []
  action_index = 0
  rule_indices = grammar.rule_indices
  term_indices = grammar.terminal_indices

  grammar.rules.each_with_index do |rule, rule_index|
    rule.branches.each do |branch|
      row = [TYPES[:action], action_index]

      action_index += 1

      branch.steps.reverse_each do |step|
        if step.is_a?(Terminal)
          row << TYPES[:terminal]
          row << term_indices[step] + 1

        elsif step.is_a?(Rule)
          row << TYPES[:rule]
          row << rule_indices[step]

        elsif step.is_a?(Epsilon)
          row << TYPES[:epsilon]
          row << 0

        elsif step.is_a?(Operator)
          row << TYPES[step.type]
          row << rule_indices[step.receiver]

          unless SKIP_VALUE_STACK.include?(step.type)
            row << TYPES[:add_value_stack]
            row << 0
          end
        end
      end

      rules << row
    end
  end

  return rules
end

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# File 'lib/ll/configuration_compiler.rb', line 206

def generate_table(grammar)
  branch_index = 0
  term_indices = grammar.terminal_indices
  columns      = grammar.terminals.length + 1

  table = Array.new(grammar.rules.length) do
    Array.new(columns, -1)
  end

  grammar.rules.each_with_index do |rule, rule_index|
    rule.branches.each do |branch|
      branch.first_set.each do |step|
        # For terminals we'll base the column index on the terminal index.
        if step.is_a?(Terminal)
          terminal_index = term_indices[step]

          table[rule_index][terminal_index + 1] = branch_index

        # For the rest (= epsilon) we'll update all columns that haven't
        # been updated yet.
        else
          table[rule_index].each_with_index do |col, col_index|
            table[rule_index][col_index] = branch_index if col == -1
          end
        end
      end

      branch_index += 1
    end
  end

  return table
end

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# File 'lib/ll/configuration_compiler.rb', line 79

def generate_terminals(grammar)
  terminals = [:$EOF]

  grammar.terminals.each do |term|
    terminals << term.name.to_sym
  end

  return terminals
end