Add small Lisp evaluator for the benefit of new GUI.

1 files changed, 116 insertions, 0 deletions

diff --git a/src/include/Lisp.H b/src/include/Lisp.H
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+// Copyright (C) 2013, Gabriel Dos Reis.
+// All rights reserved.
+// Written by Gabriel Dos Reis.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     - Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//
+//     - Redistributions in binary form must reproduce the above copyright
+//       notice, this list of conditions and the following disclaimer in
+//       the documentation and/or other materials provided with the
+//       distribution.
+//
+//     - Neither the name of OpenAxiom nor the names of its contributors
+//       may be used to endorse or promote products derived from this
+//       software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// --% Author: Gabriel Dos Reis
+// --% Abstract:
+// --%    Very simple support for some core Lisp-like operations.
+
+#ifndef OPENAXIOM_LISP_included
+#define OPENAXIOM_LISP_included
+
+#include <list>
+#include <open-axiom/sexpr>
+#include <open-axiom/vm>
+#include <map>
+#include <open-axiom/diagnostics>
+#include <iosfwd>
+#include <unordered_set>
+
+namespace std {
+   template<>
+   struct hash<OpenAxiom::VM::Scope>  {
+      hash<OpenAxiom::VM::String>::result_type
+      operator()(const OpenAxiom::VM::Scope& s) const {
+         return h(s.name());
+      }
+      hash<OpenAxiom::VM::String> h;
+   };
+
+   template<>
+   struct equal_to<OpenAxiom::VM::Scope> {
+      using arg_type = OpenAxiom::VM::Scope;
+      bool operator()(const arg_type& x, const arg_type& y) const {
+         return p(x.name(), y.name());
+      }
+         equal_to<OpenAxiom::VM::String> p;
+   };
+}
+
+namespace OpenAxiom {
+   namespace Lisp {
+      using namespace VM;
+
+      // -- Unimplemented features
+      struct Unimplemented : Diagnostics::BasicError {
+         explicit Unimplemented(const std::string&);
+      };
+
+      // -- Integer overflow
+      struct IntegerOverflow : Diagnostics::BasicError {
+         explicit IntegerOverflow(const std::string&);
+      };
+      
+      // -- Environments.
+      using Environment = std::map<Symbol*, Value>;
+
+      // -- Anchor maps
+      using AnchorTable = std::map<Ordinal, Value>;
+
+      // -- Evaluator --
+      struct Evaluator : VM::BasicContext {
+         Evaluator();
+         Scope* keyword_namespace() { return &keys; }
+         Scope* active_namespace() { return ns; }
+         Value toplevel_form(const Sexpr::Syntax*);
+         Value make_value(const Sexpr::Syntax*);
+         Environment* global_environment();
+      private:
+         Scope keys;
+         std::unordered_set<Scope> packages;
+         Scope* ns;
+         std::list<Environment> env_stack;
+         AnchorTable anchor_map;
+      };
+
+      // -- Format a value onto an output stream.
+      void format(Value, std::ostream&);
+      std::string show(Value);
+
+      // -- Retracts
+      Fixnum retract_to_fixnum(Value);
+      Pair retract_to_pair(Value);
+      Symbol* retract_to_symbol(Value);
+   }
+}
+
+#endif  // OPENAXIOM_LISP_included
+