Convert Decoder.decode_code_point return type to a SumType

assets/parser.d.erb

@@ -2,8 +2,8 @@
 module <%= @grammar.modulename %>;
 
 <% end %>
-
 import std.stdio;
+import std.sumtype;
 
 <% @grammar.code_blocks.each do |code| %>
 <%= code %>
@@ -56,7 +56,7 @@ class <%= @classname %>
 
     alias CodePoint = uint;
 
-    static immutable string token_names[] = [
+    static immutable string[] token_names = [
 <% @grammar.tokens.each_with_index do |token, index| %>
         "<%= token.name %>",
 <% end %>
@@ -71,54 +71,23 @@ class <%= @classname %>
 
     static class Decoder
     {
-        struct Result
+        struct Success
         {
-            enum Type
-            {
-                SUCCESS,
-                EOF,
-                DECODE_ERROR,
-            }
-            private Type type;
             CodePoint code_point;
             uint code_point_length;
-
-            static Result success(CodePoint code_point, uint code_point_length)
-            {
-                return Result(Type.SUCCESS, code_point, code_point_length);
         }
+        struct EOF {}
+        struct DecodeError {}
 
-            bool is_success()
+        static SumType!(
-            {
+                Success,
-                return type == Type.SUCCESS;
+                EOF,
-            }
+                DecodeError)
-
+            decode_code_point(string input)
-            static Result eof()
-            {
-                return Result(Type.EOF);
-            }
-
-            bool is_eof()
-            {
-                return type == Type.EOF;
-            }
-
-            static Result decode_error()
-            {
-                return Result(Type.DECODE_ERROR);
-            }
-
-            bool is_decode_error()
-            {
-                return type == Type.DECODE_ERROR;
-            }
-        }
-
-        static Result decode_code_point(string input)
         {
             if (input.length == 0u)
             {
-                return Result.eof();
+                return cast(ReturnType!decode_code_point)EOF();
             }
             char c = input[0];
             CodePoint code_point;
@@ -158,11 +127,11 @@ class <%= @classname %>
                 }
                 else
                 {
-                    return Result.decode_error();
+                    return cast(ReturnType!decode_code_point)DecodeError();
                 }
                 if (input.length <= following_bytes)
                 {
-                    return Result.decode_error();
+                    return cast(ReturnType!decode_code_point)DecodeError();
                 }
                 code_point_length = following_bytes + 1u;
                 for (size_t i = 0u; i < following_bytes; i++)
@@ -170,12 +139,12 @@ class <%= @classname %>
                     char b = input[i + 1u];
                     if ((b & 0xC0u) != 0x80u)
                     {
-                        return Result.decode_error();
+                        return cast(ReturnType!decode_code_point)DecodeError();
                     }
                     code_point = (code_point << 6u) | (b & 0x3Fu);
                 }
             }
-            return Result.success(code_point, code_point_length);
+            return cast(ReturnType!decode_code_point)Success(code_point, code_point_length);
         }
     }
 
@@ -237,13 +206,13 @@ class <%= @classname %>
         }
 
 <% transition_table, state_table, mode_table = @lexer.build_tables %>
-        private static immutable Transition transitions[] = [
+        private static immutable Transition[] transitions = [
 <% transition_table.each do |transition_table_entry| %>
             Transition(<%= transition_table_entry[:first] %>u, <%= transition_table_entry[:last] %>u, <%= transition_table_entry[:destination] %>u),
 <% end %>
         ];
 
-        private static immutable State states[] = [
+        private static immutable State[] states = [
 <% state_table.each do |state_table_entry| %>
             State(<%= state_table_entry[:transition_table_index] %>u,
                   <%= state_table_entry[:n_transitions] %>u,
@@ -261,7 +230,7 @@ class <%= @classname %>
 <% end %>
         ];
 
-        private static immutable Mode modes[] = [
+        private static immutable Mode[] modes = [
 <% mode_table.each do |mode_table_entry| %>
             Mode(<%= mode_table_entry[:state_table_offset] %>),
 <% end %>
@@ -498,14 +467,10 @@ class <%= @classname %>
             uint current_state = modes[m_mode].state_table_offset;
             for (;;)
             {
-                auto decoded = Decoder.decode_code_point(m_input[(m_input_position + attempt_match.length)..(m_input.length)]);
-                if (decoded.is_decode_error())
-                {
-                    return FindLongestMatchResult.decode_error();
-                }
                 bool lex_continue = false;
-                if (decoded.is_eof())
+                Decoder.decode_code_point(m_input[(m_input_position + attempt_match.length)..(m_input.length)]).match!(
-                {
+                        (Decoder.DecodeError de) {return FindLongestMatchResult.decode_error();},
+                        (Decoder.EOF e) {
                             /* We hit EOF. */
                             if (longest_match.length > 0)
                             {
@@ -522,9 +487,8 @@ class <%= @classname %>
                                 /* Valid EOF return. */
                                 return FindLongestMatchResult.eof();
                             }
-                }
+                        },
-                else
+                        (Decoder.Success decoded) {
-                {
                             auto transition_result = transition(current_state, decoded.code_point);
                             if (transition_result.found())
                             {
@@ -554,7 +518,7 @@ class <%= @classname %>
                             {
                                 return FindLongestMatchResult.unexpected_input(attempt_match.length + decoded.code_point_length);
                             }
-                }
+                        });
             }
         }
 
@@ -642,19 +606,19 @@ class <%= @classname %>
         }
 
 <% state_table, shift_table, reduce_table = @parser.build_tables %>
-        private static immutable Shift shifts[] = [
+        private static immutable Shift[] shifts = [
 <%   shift_table.each do |shift| %>
             Shift(<%= shift[:token_id] %>u, <%= shift[:state_id] %>u),
 <%   end %>
         ];
 
-        private static immutable Reduce reduces[] = [
+        private static immutable Reduce[] reduces = [
 <%   reduce_table.each do |reduce| %>
             Reduce(<%= reduce[:token_id] %>u, <%= reduce[:rule_id] %>u, <%= reduce[:rule_set_id] %>u, <%= reduce[:n_states] %>u),
 <%   end %>
         ];
 
-        private static immutable State states[] = [
+        private static immutable State[] states = [
 <%   state_table.each do |state| %>
             State(<%= state[:shift_index] %>u, <%= state[:n_shifts] %>u, <%= state[:reduce_index] %>u, <%= state[:n_reduces] %>u),
 <%   end %>

spec/propane_spec.rb

@@ -20,7 +20,7 @@ describe Propane do
   end
 
   def compile(*test_files)
-    result = system(*%w[gdc -funittest -o spec/run/testparser spec/run/testparser.d -Ispec], *test_files)
+    result = system(*%w[ldc2 --unittest -of spec/run/testparser spec/run/testparser.d -Ispec], *test_files)
     expect(result).to be_truthy
   end
 
@@ -28,6 +28,7 @@ describe Propane do
     stdout, stderr, status = Open3.capture3("spec/run/testparser")
     File.binwrite("spec/run/.stderr", stderr)
     File.binwrite("spec/run/.stdout", stdout)
+    stderr.sub!(/^.*modules passed unittests\n/, "")
     Results.new(stdout, stderr, status)
   end