xo-reader: simplify: adopt exprseq_xs + drop .admits_definition()

src/reader/define_xs.cpp

@@ -15,6 +15,7 @@ namespace xo {
               def_expr_{std::move(def_expr)}
         {}
 
+#ifdef OBSOLETE
         bool
         define_xs::admits_definition() const
         {
@@ -41,6 +42,7 @@ namespace xo {
 
             return false;
         }
+#endif
 
         bool
         define_xs::admits_symbol() const {

src/reader/exprseq_xs.cpp

@@ -5,6 +5,17 @@
 
 namespace xo {
     namespace scm {
+        std::unique_ptr<exprseq_xs>
+        exprseq_xs::expect_toplevel_expression_sequence()
+        {
+            return std::make_unique<exprseq_xs>(exprseq_xs());
+        }
+
+        exprseq_xs::exprseq_xs()
+            : exprstate(exprstatetype::expect_toplevel_expression_sequence)
+        {
+        }
+
         void
         exprseq_xs::on_def_token(const token_type & /*tk*/,
                                  exprstatestack * p_stack)
@@ -29,5 +40,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-
 /* end exprseq_xs.cpp */

src/reader/exprstate.cpp

@@ -323,8 +323,11 @@ namespace xo {
 
         void
         exprstate::on_def_token(const token_type & tk,
-                                exprstatestack * p_stack)
+                                exprstatestack * /*p_stack*/)
         {
+            this->illegal_input_error("exprstate::on_def_token", tk);
+
+#ifdef OBSOLETE
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
@@ -347,6 +350,7 @@ namespace xo {
              *   def pi : f64 = 3.14159265
              *   def sq(x : f64) -> f64 { (x * x) }
              */
+#endif
         }
 
         void

src/reader/paren_xs.cpp

@@ -14,8 +14,10 @@ namespace xo {
             return std::make_unique<paren_xs>(paren_xs());
         }
 
+#ifdef OBSOLETE
         bool
         paren_xs::admits_definition() const { return false; }
+#endif
 
         bool
         paren_xs::admits_symbol() const { return true; }

src/reader/parser.cpp

@@ -5,6 +5,7 @@
 
 #include "parser.hpp"
 #include "define_xs.hpp"
+#include "exprseq_xs.hpp"
 #include "xo/expression/DefineExpr.hpp"
 #include "xo/expression/Constant.hpp"
 #include "xo/expression/ConvertExpr.hpp"
@@ -30,7 +31,7 @@ namespace xo {
         void
         parser::begin_translation_unit() {
             xs_stack_.push_exprstate
-                (exprstate::expect_toplevel_expression_sequence());
+                (exprseq_xs::expect_toplevel_expression_sequence());
         }
 
         rp<Expression>

src/reader/progress_xs.cpp

@@ -14,8 +14,10 @@ namespace xo {
               gen_expr_{std::move(valex)}
         {}
 
+#ifdef OBSOLETE
         bool
         progress_xs::admits_definition() const { return false; }
+#endif
 
         bool
         progress_xs::admits_symbol() const { return false; }