1  # coding: utf-8
   2  # frozen_string_literal: true
   3 
   4 
   5 
   6  module Umu
   7 
   8  module ConcreteSyntax
   9 
  10  module Core
  11 
  12  module Expression
  13 
  14  module Nary
  15 
  16  module Branch
  17 
  18  module Rule
  19 
  20  module Abstraction
  21 
  22  class Abstract < Umu::Abstraction::Model
  23      def line_num
  24          self.loc.line_num
  25      end
  26 
  27 
  28      def desugar_poly_rule(_env)
  29          raise X::InternalSubclassResponsibility
  30      end
  31  end
  32 
  33 
  34 
  35  class HasHead < Abstract
  36      attr_reader :head, :body_expr
  37 
  38 
  39      def initialize(loc, head, body_expr)
  40          ASSERT.kind_of head,        Umu::Abstraction::Model
  41          ASSERT.kind_of body_expr,   CSCE::Abstract
  42 
  43          super(loc)
  44 
  45          @head       = head
  46          @body_expr  = body_expr
  47      end
  48 
  49 
  50      def to_s
  51          format "%s -> %s", self.head.to_s, self.body_expr.to_s
  52      end
  53 
  54 
  55      def pretty_print(q)
  56          q.pp self.head
  57          q.text ' -> '
  58          q.pp self.body_expr
  59      end
  60  end
  61 
  62  end # Umu::ConcreteSyntax::Core::Expression::Nary::Branch::Rule::Abstraction
  63 
  64  end # Umu::ConcreteSyntax::Core::Expression::Nary::Branch::Rule
  65 
  66 
  67 
  68  class Abstract < Expression::Abstract
  69      attr_reader :expr, :fst_rule, :snd_rules, :opt_else_expr
  70 
  71 
  72      def initialize(loc, expr, fst_rule, snd_rules, opt_else_expr)
  73          ASSERT.kind_of      expr,           CSCE::Abstract
  74          ASSERT.kind_of      fst_rule,
  75                                  CSCEN::Branch::Rule::Abstraction::Abstract
  76          ASSERT.kind_of      snd_rules,      ::Array
  77          ASSERT.opt_kind_of  opt_else_expr,  CSCE::Abstract
  78 
  79          super(loc)
  80 
  81          @expr       = expr
  82          @fst_rule   = fst_rule
  83          @snd_rules  = snd_rules
  84          @opt_else_expr  = opt_else_expr
  85      end
  86 
  87 
  88      def to_s
  89          format("%%%s %s %%OF { %s %s}",
  90              __keyword__.upcase,
  91 
  92              self.expr.to_s,
  93 
  94              self.rules.map(&:to_s).join(' | '),
  95              (
  96                  if self.opt_else_expr
  97                      format("%%ELSE -> %s", self.opt_else_expr.to_s)
  98                  else
  99                      ''
 100                  end
 101              )
 102          )
 103      end
 104 
 105 
 106      def pretty_print(q)
 107          q.text format("%%%s ", __keyword__.upcase)
 108          q.pp self.expr
 109          q.text ' %OF {'
 110 
 111          q.breakable
 112 
 113          self.rules.each do |rule|
 114              q.breakable
 115 
 116              PRT.group q, bb:'| ' do
 117                  q.pp rule
 118              end
 119          end
 120 
 121          if self.opt_else_expr
 122              else_expr = self.opt_else_expr
 123 
 124              q.breakable ' '
 125 
 126              PRT.group q, bb:'%ELSE -> ' do
 127                  q.pp else_expr
 128              end
 129          end
 130 
 131          q.breakable
 132 
 133          q.text '}'
 134      end
 135 
 136 
 137      def rules
 138          [self.fst_rule] + self.snd_rules
 139      end
 140 
 141 
 142      def desugar_body_expr(env, rule)
 143          ASSERT.kind_of rule, Nary::Branch::Rule::Abstraction::HasHead
 144 
 145          body_expr = rule.body_expr.desugar(env)
 146 
 147          ASSERT.kind_of body_expr, ASCE::Abstract
 148      end
 149 
 150 
 151      def desugar_else_expr(env)
 152          else_expr = if self.opt_else_expr
 153              self.opt_else_expr.desugar(env)
 154          else
 155              ASCE.make_raise(
 156                  self.loc,
 157                  X::UnmatchError,
 158                  ASCE.make_string(self.loc, "No rules matched")
 159              )
 160          end
 161 
 162          ASSERT.kind_of else_expr, ASCE::Abstract
 163      end
 164 
 165 
 166  private
 167 
 168      def __keyword__
 169          raise X::InternalSubclassResponsibility
 170      end
 171  end
 172 
 173  end # Umu::ConcreteSyntax::Core::Expression::Nary::Branch
 174 
 175  end # Umu::ConcreteSyntax::Core::Expression::Nary
 176 
 177  end # Umu::ConcreteSyntax::Core::Expression
 178 
 179  end # Umu::ConcreteSyntax::Core
 180 
 181  end # Umu::ConcreteSyntax
 182 
 183  end # Umu