Add two simple Modula-2 operations

This adds a couple of simple Modula-2 operations.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* m2-lang.c (eval_op_m2_high, eval_op_m2_subscript): No longer
	static.
	* m2-exp.h: New file.

3 files changed, 93 insertions, 2 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ccd8d46..fcacb6d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2021-03-08  Tom Tromey  <tom@tromey.com>
 
+	* m2-lang.c (eval_op_m2_high, eval_op_m2_subscript): No longer
+	static.
+	* m2-exp.h: New file.
+
+2021-03-08  Tom Tromey  <tom@tromey.com>
+
 	* rust-lang.c (rust_aggregate_operation::evaluate): New method.
 	* rust-exp.h (class rust_aggregate_operation): New.
 
diff --git a/gdb/m2-exp.h b/gdb/m2-exp.h
new file mode 100644
index 0000000..e034963
--- /dev/null
+++ b/gdb/m2-exp.h
@@ -0,0 +1,84 @@
+/* Definitions for Modula-2 expressions
+
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef M2_EXP_H
+#define M2_EXP_H
+
+#include "expop.h"
+
+extern struct value *eval_op_m2_high (struct type *expect_type,
+				      struct expression *exp,
+				      enum noside noside,
+				      struct value *arg1);
+extern struct value *eval_op_m2_subscript (struct type *expect_type,
+					   struct expression *exp,
+					   enum noside noside,
+					   struct value *arg1,
+					   struct value *arg2);
+
+namespace expr
+{
+
+/* The Modula-2 "HIGH" operation.  */
+class m2_unop_high_operation
+  : public tuple_holding_operation<operation_up>
+{
+public:
+
+  using tuple_holding_operation::tuple_holding_operation;
+
+  value *evaluate (struct type *expect_type,
+		   struct expression *exp,
+		   enum noside noside) override
+  {
+    value *arg1 = std::get<0> (m_storage)->evaluate_with_coercion (exp,
+								   noside);
+    return eval_op_m2_high (expect_type, exp, noside, arg1);
+  }
+
+  enum exp_opcode opcode () const override
+  { return UNOP_HIGH; }
+};
+
+/* Subscripting for Modula-2.  */
+class m2_binop_subscript_operation
+  : public tuple_holding_operation<operation_up, operation_up>
+{
+public:
+
+  using tuple_holding_operation::tuple_holding_operation;
+
+  value *evaluate (struct type *expect_type,
+		   struct expression *exp,
+		   enum noside noside) override
+  {
+    value *arg1 = std::get<0> (m_storage)->evaluate_with_coercion (exp,
+								   noside);
+    value *arg2 = std::get<1> (m_storage)->evaluate_with_coercion (exp,
+								   noside);
+    return eval_op_m2_subscript (expect_type, exp, noside, arg1, arg2);
+  }
+
+  enum exp_opcode opcode () const override
+  { return BINOP_SUBSCRIPT; }
+};
+
+} /* namespace expr */
+
+#endif /* M2_EXP_H */
diff --git a/gdb/m2-lang.c b/gdb/m2-lang.c
index 5748b60..e286613 100644
--- a/gdb/m2-lang.c
+++ b/gdb/m2-lang.c
@@ -28,10 +28,11 @@
 #include "c-lang.h"
 #include "valprint.h"
 #include "gdbarch.h"
+#include "m2-exp.h"
 
 /* A helper function for UNOP_HIGH.  */
 
-static struct value *
+struct value *
 eval_op_m2_high (struct type *expect_type, struct expression *exp,
 		 enum noside noside,
 		 struct value *arg1)
@@ -62,7 +63,7 @@ eval_op_m2_high (struct type *expect_type, struct expression *exp,
 
 /* A helper function for BINOP_SUBSCRIPT.  */
 
-static struct value *
+struct value *
 eval_op_m2_subscript (struct type *expect_type, struct expression *exp,
 		      enum noside noside,
 		      struct value *arg1, struct value *arg2)