added parsing for function literals

src/ast/expressions/function.cpp

@@ -0,0 +1,35 @@
+#include "function.hpp"
+
+#include <sstream>
+
+namespace ast {
+    function_literal::function_literal(token::token token)
+        : token(std::move(token)),
+          block(nullptr) {};
+
+    std::string function_literal::token_literal() const {
+        return token.literal;
+    };
+
+    std::string function_literal::str() const {
+        std::stringstream ss;
+        ss << "fn (";
+        bool first = true;
+        for (auto& param : parameters) {
+            if (!first)
+                ss << ", ";
+            ss << param->str();
+            first = false;
+        }
+        ss << ")";
+        ss << block->str();
+        return ss.str();
+    };
+
+    function_literal::~function_literal() {
+        for (auto& param : parameters)
+            delete param;
+        if (block != nullptr)
+            delete block;
+    }
+} // namespace ast