feat(furc): introduce while loop statement

Refs: #2

furc/src/front/parser.cpp

@@ -2,9 +2,10 @@
 
 #include "furc/ast/declaration.hpp" // IWYU pragma: keep
 #include "furc/ast/expression.hpp"  // IWYU pragma: keep
-#include "furc/ast/literal.hpp"     // IWYU pragma: keep
-#include "furc/ast/program.hpp"     // IWYU pragma: keep
-#include "furc/ast/statement.hpp"   // IWYU pragma: keep
+#include "furc/ast/fwd.hpp"
+#include "furc/ast/literal.hpp"   // IWYU pragma: keep
+#include "furc/ast/program.hpp"   // IWYU pragma: keep
+#include "furc/ast/statement.hpp" // IWYU pragma: keep
 
 #include <fstream>
 #include <iostream>
@@ -145,6 +146,24 @@ ast::statement_node_r parser::parse_statement() {
                 std::move(cond.value()),
                 std::move(then.value()));
         }
+        case keyword_token::While: {
+            auto tok = next_token();
+            auto err = eat_token(token_t::LParen);
+            if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
+
+            auto cond = parse_expression();
+            if (cond.has_error()) return ast::statement_node_r(ast::error{ cond.error().location });
+
+            err = eat_token(token_t::RParen);
+            if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
+
+            auto body = parse_statement();
+            if (body.has_error()) return ast::statement_node_r(ast::error{ body.error().location });
+
+            return m_arena.allocate_shared<ast::while_statement_node>(location,
+                std::move(cond.value()),
+                std::move(body.value()));
+        }
         case keyword_token::None:
         case keyword_token::Func:
         default: break;
@@ -438,4 +457,4 @@ token_r parser::eat_token(token_t type) {
     return token;
 }
 
-} // namespace furc::front
+} // namespace furc::front