From cf9aa08aea859924b0e588ee7733c0f560fef311 Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sat, 28 Sep 2024 04:24:37 +0100
Subject: [PATCH] Implement the first IO function "print" to work via
 continuations

---
 src/error.hpp  |  1 +
 src/stdlib.cpp | 31 ++++++++++++++++++++++++++++---
 src/vm.cpp     | 31 +++++++++++++++++++++++++++++--
 3 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/src/error.hpp b/src/error.hpp
index bdd49d3..1d6d8c0 100644
--- a/src/error.hpp
+++ b/src/error.hpp
@@ -23,6 +23,7 @@ enum class ErrorCode {
   SyntaxError,
   RuntimeError,
   Raise,
+  TaskFailed,
 };
 
 class Value;
diff --git a/src/stdlib.cpp b/src/stdlib.cpp
index 311cac6..22632f7 100644
--- a/src/stdlib.cpp
+++ b/src/stdlib.cpp
@@ -307,8 +307,18 @@ Result<StackFrame> stdlib_raise(const StackFrame& stack) {
   auto stack_size = TRY(stack.size());
 
   if (stack_size > 1) {
-    auto accumulator = TRY(stack.get(0));
-    auto res = TRY(stack.set(0, accumulator));
+    auto result = TRY(stack.get(1));
+    if (!result.is<TaskResult>()) return ERROR(TypeMismatch);
+
+    const auto& task_result = *result.to<TaskResult>();
+
+    auto error = TRY(task_result.error());
+
+    if (!error.is<Nil>()) {
+      return ERROR_OBJ(TaskFailed, error);
+    }
+
+    auto res = TRY(stack.set(0, TRY(task_result.result())));
     res = TRY(res.ret(0));
 
     return res;
@@ -376,7 +386,22 @@ Result<Value> stdlib_task_unknown(const Array& params) {
 }
 
 Result<Value> stdlib_task_print(const Array& params) {
-  return ERROR(NotImplemented);
+  auto size = TRY(params.size());
+
+  if (size != 1) {
+    auto err = Value(TRY(Error::create("argument-count-mismatch", "Argument count mismatch")));
+    return ERROR_OBJ(ArgumentCountMismatch, err);
+  }
+
+  auto obj = TRY(params.get(0));
+
+  if (!obj.is<String>()) {
+    auto err = Value(TRY(Error::create("type-mismatch", "Type mismatch")));
+    return ERROR_OBJ(TypeMismatch, err);
+  }
+
+  print_string(*obj.to<String>());
+  return Value(TRY(Nil::create()));
 }
 
 #define STDLIB_TASK(name, id)                                  \
diff --git a/src/vm.cpp b/src/vm.cpp
index d1dd962..9d9cb7f 100644
--- a/src/vm.cpp
+++ b/src/vm.cpp
@@ -284,12 +284,39 @@ Result<StackFrame> VM::handle_raise(const Continuation& cont) {
   // TODO: this should do proper stack unwinding
   auto value = TRY(cont.value());
 
-  std::cout << "Handle raise\n";
-
   if (value.is<Error>()) {
     auto obj = TRY(cont.copy_value());
     return ERROR_OBJ(Raise, obj);
   }
+
+  Value tr;
+
+  if (value.is<Task>()) {
+    auto task_id = value.to<Task>()->task_id();
+    auto params = TRY(value.to<Task>()->params());
+
+    auto res = call_stdlib_task((StdlibTaskId)task_id, params);
+
+    if (res.has_error()) {
+      const auto& err = geterrobj();
+      Value errobj;
+      if (err.is<Nil>()) {
+        errobj = Value(TRY(Error::create("unknown-error", "Unknown error")));
+      } else {
+        errobj = TRY(err.copy());
+      }
+
+      tr = Value(TRY(TaskResult::create(TRY(Nil::create()), errobj)));
+    } else {
+      tr = Value(
+          TRY(TaskResult::create(res.release_value(), TRY(Nil::create()))));
+    }
+
+    auto frame = TRY(cont.frame());
+
+    auto new_frame = frame.set(TRY(frame.size()), tr);
+    return new_frame;
+  }
   return ERROR(TypeMismatch);
 }