feat: add scheduler module and refactor built-in module loading into shared modules.c

Introduce a new scheduler module with fiber-based cooperative multitasking, including native bindings for resume operations and a Wren class for scheduling callables. Refactor the existing timer module and CLI code to use a centralized built-in module registry in modules.c, replacing direct includes of timer.h and timer.wren.inc. Update Xcode project and Makefile to compile the new scheduler.c, modules.c, and their generated .wren.inc sources.

src/module/scheduler.c

@@ -0,0 +1,42 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "uv.h"
+
+#include "scheduler.h"
+#include "wren.h"
+#include "vm.h"
+
+// This method resumes a fiber that is suspended waiting on an asynchronous
+// operation. The first resumes it with zero arguments, and the second passes
+// one.
+static WrenValue* resume;
+static WrenValue* resumeWithArg;
+
+static void captureMethods(WrenVM* vm)
+{
+  resume = wrenGetMethod(vm, "scheduler", "Scheduler", "resume_(_)");
+  resumeWithArg = wrenGetMethod(vm, "scheduler", "Scheduler", "resume_(_,_)");
+}
+
+WrenForeignMethodFn schedulerBindForeign(
+    WrenVM* vm, const char* className, bool isStatic, const char* signature)
+{
+  if (strcmp(className, "Scheduler") != 0) return NULL;
+  
+  if (isStatic && strcmp(signature, "captureMethods_()") == 0) return captureMethods;
+  
+  return NULL;
+}
+
+void schedulerResume(WrenValue* fiber)
+{
+  wrenCall(getVM(), resume, NULL, "v", fiber);
+  wrenReleaseValue(getVM(), fiber);
+}
+
+void schedulerReleaseMethods()
+{
+  if (resume != NULL) wrenReleaseValue(getVM(), resume);
+  if (resumeWithArg != NULL) wrenReleaseValue(getVM(), resumeWithArg);
+}

src/module/scheduler.h

@@ -0,0 +1,13 @@
+#ifndef scheduler_h
+#define scheduler_h
+
+#include "wren.h"
+
+WrenForeignMethodFn schedulerBindForeign(
+    WrenVM* vm, const char* className, bool isStatic, const char* signature);
+
+void schedulerResume(WrenValue* fiber);
+
+void schedulerReleaseMethods();
+
+#endif

src/module/scheduler.wren

@@ -0,0 +1,26 @@
+class Scheduler {
+  static add(callable) {
+    if (__scheduled == null) __scheduled = []
+
+    __scheduled.add(Fiber.new {
+      callable.call()
+      runNextScheduled_()
+    })
+  }
+
+  // Called by native code.
+  static resume_(fiber) { fiber.transfer() }
+  static resume_(fiber, arg) { fiber.transfer(arg) }
+
+  static runNextScheduled_() {
+    if (__scheduled == null || __scheduled.isEmpty) {
+      return Fiber.suspend()
+    } else {
+      return __scheduled.removeAt(0).transfer()
+    }
+  }
+
+  foreign static captureMethods_()
+}
+
+Scheduler.captureMethods_()

src/module/scheduler.wren.inc

@@ -0,0 +1,28 @@
+// Generated automatically from src/module/scheduler.wren. Do not edit.
+static const char* schedulerModuleSource =
+"class Scheduler {\n"
+"  static add(callable) {\n"
+"    if (__scheduled == null) __scheduled = []\n"
+"\n"
+"    __scheduled.add(Fiber.new {\n"
+"      callable.call()\n"
+"      runNextScheduled_()\n"
+"    })\n"
+"  }\n"
+"\n"
+"  // Called by native code.\n"
+"  static resume_(fiber) { fiber.transfer() }\n"
+"  static resume_(fiber, arg) { fiber.transfer(arg) }\n"
+"\n"
+"  static runNextScheduled_() {\n"
+"    if (__scheduled == null || __scheduled.isEmpty) {\n"
+"      return Fiber.suspend()\n"
+"    } else {\n"
+"      return __scheduled.removeAt(0).transfer()\n"
+"    }\n"
+"  }\n"
+"\n"
+"  foreign static captureMethods_()\n"
+"}\n"
+"\n"
+"Scheduler.captureMethods_()\n";

src/module/timer.c

@@ -3,14 +3,10 @@
 
 #include "uv.h"
 
+#include "scheduler.h"
 #include "timer.h"
-#include "wren.h"
 #include "vm.h"
-
-#include "timer.wren.inc"
-
-// The Wren method to call when a timer has completed.
-static WrenValue* resumeTimer;
+#include "wren.h"
 
 // Called by libuv when the timer finished closing.
 static void timerCloseCallback(uv_handle_t* handle)
@@ -27,18 +23,11 @@ static void timerCallback(uv_timer_t* handle)
   uv_close((uv_handle_t*)handle, timerCloseCallback);
 
   // Run the fiber that was sleeping.
-  wrenCall(getVM(), resumeTimer, NULL, "v", fiber);
-  wrenReleaseValue(getVM(), fiber);
+  schedulerResume(fiber);
 }
 
 static void startTimer(WrenVM* vm)
 {
-  // If we haven't looked up the resume method yet, grab it now.
-  if (resumeTimer == NULL)
-  {
-    resumeTimer = wrenGetMethod(vm, "timer", "Timer", "resumeTimer_(_)");
-  }
-
   int milliseconds = (int)wrenGetArgumentDouble(vm, 1);
   WrenValue* fiber = wrenGetArgumentValue(vm, 2);
 
@@ -50,15 +39,6 @@ static void startTimer(WrenVM* vm)
   uv_timer_start(handle, timerCallback, milliseconds, 0);
 }
 
-char* timerGetSource()
-{
-  size_t length = strlen(timerModuleSource);
-  char* copy = (char*)malloc(length + 1);
-  strncpy(copy, timerModuleSource, length + 1);
-
-  return copy;
-}
-
 WrenForeignMethodFn timerBindForeign(
     WrenVM* vm, const char* className, bool isStatic, const char* signature)
 {
@@ -68,8 +48,3 @@ WrenForeignMethodFn timerBindForeign(
 
   return NULL;
 }
-
-void timerReleaseMethods()
-{
-  if (resumeTimer != NULL) wrenReleaseValue(getVM(), resumeTimer);
-}

src/module/timer.h

@@ -3,11 +3,7 @@
 
 #include "wren.h"
 
-char* timerGetSource();
-
 WrenForeignMethodFn timerBindForeign(
     WrenVM* vm, const char* className, bool isStatic, const char* signature);
 
-void timerReleaseMethods();
-
 #endif

src/module/timer.wren

@@ -1,34 +1,13 @@
+import "scheduler" for Scheduler
+
 class Timer {
   static sleep(milliseconds) {
     if (!(milliseconds is Num)) Fiber.abort("Milliseconds must be a number.")
     if (milliseconds < 0) Fiber.abort("Milliseconds cannot be negative.")
+
     startTimer_(milliseconds, Fiber.current)
-
-    runNextScheduled_()
-  }
-
-  // TODO: Once the CLI modules are more fleshed out, find a better place to
-  // put this.
-  static schedule(callable) {
-    if (__scheduled == null) __scheduled = []
-    __scheduled.add(Fiber.new {
-      callable.call()
-      runNextScheduled_()
-    })
+    Scheduler.runNextScheduled_()
   }
 
   foreign static startTimer_(milliseconds, fiber)
-
-  // Called by native code.
-  static resumeTimer_(fiber) {
-    fiber.transfer()
-  }
-
-  static runNextScheduled_() {
-    if (__scheduled == null || __scheduled.isEmpty) {
-      Fiber.suspend()
-    } else {
-      __scheduled.removeAt(0).transfer()
-    }
-  }
 }

src/module/timer.wren.inc

@@ -1,36 +1,15 @@
 // Generated automatically from src/module/timer.wren. Do not edit.
 static const char* timerModuleSource =
+"import \"scheduler\" for Scheduler\n"
+"\n"
 "class Timer {\n"
 "  static sleep(milliseconds) {\n"
 "    if (!(milliseconds is Num)) Fiber.abort(\"Milliseconds must be a number.\")\n"
 "    if (milliseconds < 0) Fiber.abort(\"Milliseconds cannot be negative.\")\n"
+"\n"
 "    startTimer_(milliseconds, Fiber.current)\n"
-"\n"
-"    runNextScheduled_()\n"
-"  }\n"
-"\n"
-"  // TODO: Once the CLI modules are more fleshed out, find a better place to\n"
-"  // put this.\n"
-"  static schedule(callable) {\n"
-"    if (__scheduled == null) __scheduled = []\n"
-"    __scheduled.add(Fiber.new {\n"
-"      callable.call()\n"
-"      runNextScheduled_()\n"
-"    })\n"
+"    Scheduler.runNextScheduled_()\n"
 "  }\n"
 "\n"
 "  foreign static startTimer_(milliseconds, fiber)\n"
-"\n"
-"  // Called by native code.\n"
-"  static resumeTimer_(fiber) {\n"
-"    fiber.transfer()\n"
-"  }\n"
-"\n"
-"  static runNextScheduled_() {\n"
-"    if (__scheduled == null || __scheduled.isEmpty) {\n"
-"      Fiber.suspend()\n"
-"    } else {\n"
-"      __scheduled.removeAt(0).transfer()\n"
-"    }\n"
-"  }\n"
 "}\n";