Modularize implementation

1 files changed, 38 insertions, 0 deletions

diff --git a/src/stack.d b/src/stack.d
new file mode 100644
index 0000000..756dafc
--- /dev/null
+++ b/src/stack.d
@@ -0,0 +1,38 @@
+module src.stack;
+
+import std.variant;
+import std.string;
+import std.container : SList;
+
+static import src.definition;
+
+alias Token = Algebraic!(int, string);
+alias Stack = SList;
+
+Stack!Token stack;
+
+Token top(ref Stack!Token stack) {
+	if ( stack.empty ) {
+		throw new Exception("stack is empty");
+	} else {
+		return stack.front;
+	}
+}
+
+Token pop(ref Stack!Token stack) {
+	Token token = stack.top;
+	stack.removeFront;
+	return token;
+}
+
+void push(ref Stack!Token stack, int value) {
+	if ( !src.definition.handle(value) ) {
+		stack.insertFront(Token(value));
+	}
+}
+
+void push(ref Stack!Token stack, string word) {
+	if ( !src.definition.handle(word) ) {
+		stack.insertFront(Token(word));
+	}
+}