1 files changed, 56 insertions, 0 deletions
diff --git a/internal/interpreter/interpreter.ha b/internal/interpreter/interpreter.ha
new file mode 100644
index 0000000..5e92461
--- /dev/null
+++ b/internal/interpreter/interpreter.ha
@@ -0,0 +1,56 @@
+use internal::parser;
+use strconv;
+use strings;
+
+export type variable = (str, str);
+export type interpreter = struct {
+	vars: []variable,
+};
+
+export type error = !(interperror | nomem);
+export type interperror = !str;
+
+export fn interpret(it: *interpreter, tree: parser::ast) void = {
+	match (tree.value) {
+	case parser::assign =>
+		assign(it, tree.children)!;
+	};
+};
+
+fn assign(it: *interpreter, nodes: []parser::ast) (void | error) = {
+	const varname = nodes[0].value as parser::varname;
+	const operation = nodes[1].value as parser::operation;
+
+	let value = 0;
+
+	let stack: []int = [];
+
+	for (let i = 0z; i < len(operation.stack); i += 1) {
+		const arg = operation.stack[i];
+		match (arg) {
+		case let i: int =>
+			append(stack, i)?;
+		case let o: parser::operator =>
+			if (len(stack) >= 2) {
+				let last = len(stack) - 1;
+				let val = switch (o) {
+				case parser::operator::ADD =>
+					yield stack[last] + stack[last-1];
+				case parser::operator::SUBTRACT =>
+					yield stack[last] - stack[last-1];
+				case parser::operator::MULTIPLY =>
+					yield stack[last] * stack[last-1];
+				case parser::operator::DIVIDE =>
+					yield stack[last] / stack[last-1];
+				};
+				delete(stack[last-1..]);
+				append(stack, val)?;
+			} else {
+				return "Invalid operation": interperror;
+			};
+		};
+	};
+
+	let last = len(stack) - 1;
+	append(it.vars, (varname, strings::dup(strconv::itos(stack[last]))?))?;
+};