feat: char and integral_constant types

6 files changed, 35 insertions, 0 deletions

diff --git a/ast.h b/ast.h
index e18b5d9..da409be 100644
--- a/ast.h
+++ b/ast.h
@@ -17,6 +17,8 @@ enum NodeKind
     TYPE_ARRAY,
     TYPE_CONDITIONAL,
     TYPE_DECLTYPE,
+    TYPE_CHAR,
+    TYPE_CHAR_CONSTANT,
     VALUE_DIFFERENCE,
     VALUE_SUM,
     VALUE_PRODUCT,
diff --git a/eval.c b/eval.c
index 2f79a5d..170b122 100644
--- a/eval.c
+++ b/eval.c
@@ -130,6 +130,13 @@ static int evaluate_type(struct Machine* machine, const struct Node* node, struc
         case TYPE_INT32: out->kind = KIND_INT32; return 0;
         case TYPE_BYTE: out->kind = KIND_BYTE; return 0;
         case TYPE_SIZE: out->kind = KIND_SIZE; return 0;
+        case TYPE_CHAR: out->kind = KIND_CHAR; return 0;
+        case TYPE_CHAR_CONSTANT:
+            if (evaluate_value(machine, node->first, &out->number))
+                return 1;
+
+            out->kind = KIND_CHAR_CONSTANT;
+            return 0;
         case TYPE_REMOVE_CV: return evaluate_type(machine, node->first, out);
         case TYPE_ARRAY:
             if (evaluate_type(machine, node->first, &element) ||
@@ -248,6 +255,8 @@ static enum RunStatus emit(struct Machine* machine, const struct Node* node)
         case KIND_BYTE: (void)printf("byte\n"); break;
         case KIND_SIZE: (void)printf("size_t\n"); break;
         case KIND_ARRAY: (void)printf("array[%" PRId64 "]\n", type.number); break;
+        case KIND_CHAR: (void)printf("char\n"); break;
+        case KIND_CHAR_CONSTANT: (void)printf("%c\n", (char)type.number); break;
         case KIND_VALUE: (void)printf("%" PRId64 "\n", type.number); break;
     }
 
diff --git a/eval.h b/eval.h
index eba8244..eb3fe1d 100644
--- a/eval.h
+++ b/eval.h
@@ -14,6 +14,8 @@ enum TypeKind
     KIND_BYTE,
     KIND_SIZE,
     KIND_ARRAY,
+    KIND_CHAR,
+    KIND_CHAR_CONSTANT,
     KIND_VALUE
 };
 
diff --git a/examples/chars.sfinae b/examples/chars.sfinae
new file mode 100644
index 0000000..b38118b
--- /dev/null
+++ b/examples/chars.sfinae
@@ -0,0 +1,16 @@
+// ::integral_constant<::char, V> is a type that says one character
+// there are no character values, so it says its own distance from '\0'
+
+::emit<::integral_constant<::char, ::difference<'h', '\0'>>>::commit;
+::emit<::integral_constant<::char, ::difference<'i', '\0'>>>::commit;
+
+// ::char on its own is a type like any other, and says its name
+::emit<::remove_cv_t<::char>>::commit;
+
+// two character types are the same type when they say the same thing
+::static_assert<
+    ::is_same<
+        ::integral_constant<::char, ::difference<'a', '\0'>>,
+        ::integral_constant<::char, ::sum<::difference<'a', 'b'>, ::difference<'b', '\0'>>>
+    >::value
+>::commit;
diff --git a/sfinae.l b/sfinae.l
index c8099c9..f5b9cf1 100644
--- a/sfinae.l
+++ b/sfinae.l
@@ -46,6 +46,7 @@ static int fail(const char* message)
 "int32_t"               return TOK_INT32;
 "byte"                  return TOK_BYTE;
 "size_t"                return TOK_SIZE_T;
+"char"                  return TOK_CHAR_T;
 "remove_cv_t"           return TOK_REMOVE_CV;
 "decltype"              return TOK_DECLTYPE;
 "difference"            return TOK_DIFFERENCE;
diff --git a/sfinae.y b/sfinae.y
index 341be36..aa7650b 100644
--- a/sfinae.y
+++ b/sfinae.y
@@ -32,6 +32,7 @@ void yyerror(const char* message);
 %token TOK_INT32
 %token TOK_BYTE
 %token TOK_SIZE_T
+%token TOK_CHAR_T
 %token TOK_REMOVE_CV
 %token TOK_DECLTYPE
 %token TOK_DIFFERENCE
@@ -138,6 +139,10 @@ type
         { $$ = node_ternary(TYPE_CONDITIONAL, $4, $6, $8); }
     | TOK_COLONCOLON TOK_DECLTYPE '(' value ')'
         { $$ = node_unary(TYPE_DECLTYPE, $4); }
+    | TOK_COLONCOLON TOK_CHAR_T
+        { $$ = node_leaf(TYPE_CHAR); }
+    | TOK_COLONCOLON TOK_INTEGRAL_CONSTANT '<' TOK_COLONCOLON TOK_CHAR_T ',' value '>'
+        { $$ = node_unary(TYPE_CHAR_CONSTANT, $7); }
     ;
 
 value