1 files changed, 96 insertions, 0 deletions
diff --git a/state.hpp b/state.hpp
new file mode 100644
index 0000000..03d0084
--- /dev/null
+++ b/state.hpp
@@ -0,0 +1,96 @@
+/**
+ * Alee Forth: A portable and concise Forth implementation in modern C++.
+ * Copyright (C) 2023  Clyne Sullivan <clyne@bitgloo.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef ALEEFORTH_STATE_HPP
+#define ALEEFORTH_STATE_HPP
+
+#include "dictionary.hpp"
+#include "types.hpp"
+
+#include <cstddef>
+#include <iterator>
+
+constexpr unsigned DataStackSize = 12;
+constexpr unsigned ReturnStackSize = 12;
+
+class State
+{
+    Cell dstack[DataStackSize] = {};
+    Cell rstack[ReturnStackSize] = {};
+    Cell *dsp = dstack - 1;
+    Cell *rsp = rstack - 1;
+
+public:
+    bool compiling = false;
+    Addr ip = 0;
+    Pass pass = Pass::None;
+    Dictionary& dict;
+
+    constexpr State(Dictionary& d): dict(d) {}
+
+    Cell beyondip() const {
+	return dict.read(ip + 1);
+    }
+
+    void pushr(Cell value) {
+	if (rsize() == ReturnStackSize)
+            throw;
+        *++rsp = value;
+    }
+
+    Cell popr() {
+	if (rsize() == 0)
+            throw;
+	return *rsp--;
+    }
+
+    void push(Cell value) {
+	if (size() == DataStackSize)
+            throw;
+        *++dsp = value;
+    }
+
+    Cell pop() {
+	if (size() == 0)
+            throw;
+	return *dsp--;
+    }
+
+    Cell& top() {
+	if (size() == 0)
+            throw;
+	return *dsp;
+    }
+
+    Cell& pick(std::size_t i) {
+	if (i >= size())
+	    throw;
+	return *(dsp - i);
+    }
+
+    std::size_t size() const noexcept {
+	return std::distance(dstack, static_cast<const Cell *>(dsp)) + 1;
+    }
+
+    std::size_t rsize() const noexcept {
+	return std::distance(rstack, static_cast<const Cell *>(rsp)) + 1;
+    }
+};
+
+#endif // ALEEFORTH_STATE_HPP
+