From d89c25701381b393839ff38f93f198c4105b2c21 Mon Sep 17 00:00:00 2001
From: johannst <johannes.stoelp@gmail.com>
Date: Fri, 18 Sep 2020 01:36:00 +0200
Subject: move yielding into Thread base class + make user fn a pure virtual fn
 and require user to derive from Thread

---
 example/test.cc | 28 ++++++++--------------------
 lib/matcha.cc   | 12 ++++++------
 lib/matcha.h    | 18 +++++++++++-------
 3 files changed, 25 insertions(+), 33 deletions(-)

diff --git a/example/test.cc b/example/test.cc
index 7307bec..b436708 100644
--- a/example/test.cc
+++ b/example/test.cc
@@ -3,30 +3,18 @@
 #include <cassert>
 #include <cstdio>
 
-Thread* gThread1 = nullptr;
-
-void thread1_1() {
-    puts("thread1_1");
-}
-
-void thread1() {
-    puts("start thread1");
-    thread1_1();
-    puts("finish thread1");
-
-    assert(gThread1 != nullptr);
-    yield_from(*gThread1);
-}
+struct Thread1 : public Thread {
+    virtual void threadFn() override {
+        puts("start threadFn -> yield()");
+        yield();
+        puts("return from yield() -> finish threadFn");
+    }
+} gThread1;
 
 int main() {
     puts("start main thread");
 
-    Thread t(thread1);
-    gThread1 = &t;
-
-    yield_to(t);
-
-    gThread1 = nullptr;
+    gThread1.yield_to();
 
     puts("finish main thread");
     return 0;
diff --git a/lib/matcha.cc b/lib/matcha.cc
index 3f7cd7b..561a08f 100644
--- a/lib/matcha.cc
+++ b/lib/matcha.cc
@@ -14,7 +14,7 @@ long get_pagesize() {
     return sysconf(_SC_PAGESIZE);
 }
 
-Thread::Thread(void (*fn)()) : mUserFn(fn) {
+Thread::Thread() {
     const long PAGE_SIZE = get_pagesize();
     const long STACK_SIZE = 8 * PAGE_SIZE;
 
@@ -53,16 +53,16 @@ void Thread::entry(void* obj) {
     Thread* t = static_cast<Thread*>(obj);
 
     puts("thread entry");
-    t->mUserFn();
+    t->threadFn();
     puts("thread done");
 }
 
 void* gOriginalStack;
 
-void yield_to(const Thread& t) {
-    yield(t.mStackPtr, &gOriginalStack);
+void Thread::yield() {
+    ::yield(gOriginalStack, &mStackPtr);
 }
 
-void yield_from(Thread& t) {
-    yield(gOriginalStack, &t.mStackPtr);
+void Thread::yield_to() const {
+    ::yield(mStackPtr, &gOriginalStack);
 }
diff --git a/lib/matcha.h b/lib/matcha.h
index 905107f..1506081 100644
--- a/lib/matcha.h
+++ b/lib/matcha.h
@@ -1,14 +1,18 @@
 struct Thread {
     Thread(const Thread&) = delete;
     Thread& operator=(const Thread&) = delete;
-    Thread(void (*fn)());
+    Thread();
 
-    static void entry(void* obj);
+    virtual void threadFn() = 0;
+
+    // use from executor
+    void yield_to() const;
+
+  protected:
+    // use in thread
+    void yield();
 
-    // private:
+  private:
+    static void entry(void* obj);
     void* mStackPtr;
-    void (*mUserFn)();
 };
-
-void yield_to(const Thread& t);
-void yield_from(Thread& t);
-- 
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