Extract variable management, move into `state` package

1 files changed, 41 insertions, 0 deletions

diff --git a/source/state/variable.d b/source/state/variable.d
new file mode 100644
index 0000000..f77e207
--- /dev/null
+++ b/source/state/variable.d
@@ -0,0 +1,41 @@
+module state.variable;
+
+import std.variant;
+
+import state.stack;
+
+bool handle(string word) {
+	switch ( word ) {
+		case "$" : binary_op_variable_bind;   return true;
+		case "@" : unary_op_variable_resolve; return true;
+		default  :                            return false;
+	}
+}
+
+bool handle(Token token) {
+	return token.visit!(
+		(int        ) => false,
+		(bool       ) => false,
+		(string word) => handle(word)
+	);
+}
+
+private {
+
+Token[string] variables;
+
+void binary_op_variable_bind() {
+	string name     = stack.pop.get!string;
+	Token  value    = stack.pop;
+	variables[name] = value;
+}
+
+void unary_op_variable_resolve() {
+	string name = stack.pop.get!string;
+
+	if ( name in variables ) {
+		stack.push(variables[name]);
+	}
+}
+
+}