feat: scaffold crate structure and implement core macros

Add the project skeleton, LICENSE files, README, Makefile, doc
examples, and the initial implementation of `#[func]`, `invoke!`,
and `select!` procedural macros.

4 files changed, 181 insertions, 0 deletions

diff --git a/test/src/lib.rs b/test/src/lib.rs
new file mode 100644
index 0000000..5e91425
--- /dev/null
+++ b/test/src/lib.rs
@@ -0,0 +1,3 @@
+include!("test_func.rs");
+include!("test_invoke.rs");
+include!("test_select.rs");
diff --git a/test/src/test_func.rs b/test/src/test_func.rs
new file mode 100644
index 0000000..71fe365
--- /dev/null
+++ b/test/src/test_func.rs
@@ -0,0 +1,36 @@
+#[might_be_async::func]
+fn identity(x: i32) -> i32 {
+    x
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_func_identity() {
+    assert_eq!(identity(42), 42);
+}
+
+#[might_be_async::func]
+fn first<T: PartialEq + Clone>(a: T, _b: T) -> T
+where
+    T: std::fmt::Debug,
+{
+    a.clone()
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_func_generic() {
+    assert_eq!(first(1, 2), 1);
+    assert_eq!(first("a", "b"), "a");
+}
+
+#[might_be_async::func("custom_ft")]
+fn triple(x: i32) -> i32 {
+    x * 3
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_func_custom_feature() {
+    assert_eq!(triple(3), 9);
+}
diff --git a/test/src/test_invoke.rs b/test/src/test_invoke.rs
new file mode 100644
index 0000000..b8506e9
--- /dev/null
+++ b/test/src/test_invoke.rs
@@ -0,0 +1,50 @@
+// ─── 测试 1: 默认 feature 名 ─────────────────────────────────────────────────
+//
+// 不指定 feature → 用 Cargo.toml 的 default_feature_name = "metadata_async"
+//
+// 展开（feature "metadata_async" 关闭时）：
+//   { #[cfg(feature = "metadata_async")] { double(5).await }
+//     #[cfg(not(feature = "metadata_async"))] { double(5) } }
+
+#[cfg(not(feature = "metadata_async"))]
+fn double(x: i32) -> i32 {
+    x * 2
+}
+
+#[cfg(feature = "metadata_async")]
+async fn double(x: i32) -> i32 {
+    x * 2
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_invoke_default() {
+    assert_eq!(might_be_async::invoke!(double(5)), 10);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_invoke_default() {
+    let result = futures::executor::block_on(async { might_be_async::invoke!(double(5)) });
+    assert_eq!(result, 10);
+}
+
+#[might_be_async::func]
+fn square(x: i32) -> i32 {
+    x * x
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_invoke_explicit() {
+    assert_eq!(might_be_async::invoke!("metadata_async" => square(6)), 36);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_invoke_explicit() {
+    let result = futures::executor::block_on(async {
+        might_be_async::invoke!("metadata_async" => square(6))
+    });
+    assert_eq!(result, 36);
+}
diff --git a/test/src/test_select.rs b/test/src/test_select.rs
new file mode 100644
index 0000000..2cf3bfe
--- /dev/null
+++ b/test/src/test_select.rs
@@ -0,0 +1,92 @@
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_explicit() {
+    let r = might_be_async::select! { "metadata_async" => { 1 } else ! => { 2 } };
+    assert_eq!(r, 2);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_explicit() {
+    let r = might_be_async::select! { "metadata_async" => { 1 } else ! => { 2 } };
+    assert_eq!(r, 1);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_not() {
+    let r = might_be_async::select! { "metadata_async" => { 10 } else ! => { 20 } };
+    assert_eq!(r, 20);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_not() {
+    let r = might_be_async::select! { "metadata_async" => { 10 } else ! => { 20 } };
+    assert_eq!(r, 10);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_not_first() {
+    let r = might_be_async::select! { ! => { 30 } else "metadata_async" => { 40 } };
+    assert_eq!(r, 30);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_not_first() {
+    let r = might_be_async::select! { ! => { 30 } else "metadata_async" => { 40 } };
+    assert_eq!(r, 40);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_both_explicit() {
+    let r = might_be_async::select! { "metadata_async" => { 100 } else "custom_ft" => { 200 } };
+    assert_eq!(r, 100);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_implicit() {
+    let r = might_be_async::select! { { 1 + 2 } else { 3 + 4 } };
+    assert_eq!(r, 7);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_implicit() {
+    let r = futures::executor::block_on(async {
+        might_be_async::select! { { 1 + 2 } else { 3 + 4 } }
+    });
+    assert_eq!(r, 3);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_mixed_explicit_first() {
+    let r = might_be_async::select! { "metadata_async" => { 100 } else { 200 } };
+    assert_eq!(r, 200);
+}
+
+#[cfg(feature = "metadata_async")]
+#[test]
+fn test_select_mixed_explicit_first() {
+    let r = might_be_async::select! { "metadata_async" => { 100 } else { 200 } };
+    assert_eq!(r, 100);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_metadata_default() {
+    let r = might_be_async::select! { { 50 } else { 60 } };
+    assert_eq!(r, 60);
+}
+
+#[cfg(not(feature = "metadata_async"))]
+#[test]
+fn test_select_metadata_two_not() {
+    let r = might_be_async::select! { ! => { 70 } else ! => { 80 } };
+    assert_eq!(r, 80);
+}