Merge pull request #70 from ewasm/entry-macro

Macro for declaring entry point

Author: axic

README.md

@@ -18,6 +18,20 @@ In your project, include the prelude:
 use ewasm_api::prelude::*;
 ```
 
+Additionally there is support for some macros to make creating contracts easier:
+```rust
+#[macro_use]
+extern crate ewasm_api;
+
+use ewasm_api::prelude::*;
+
+fn entry() {
+    // The actual contract code goes here.
+}
+
+ewasm_entry_point!(entry);
+```
+
 Other modules are available as well, outside of the prelude. Refer to the documentation for more info.
 
 `ewasm-rust-api` builds with various feature sets:

src/lib.rs

@@ -14,18 +14,29 @@
 //! - `experimental`: Exposes the experimental bignum system library API.
 //!
 //! # Examples
-//! ```ignore
-//! extern crate ewasm_api;
+//! ```
+//! use ewasm_api::prelude::*;
+//!
+//! fn entry() {
+//!     let a: Hash = block_hash(1);
+//!     finish_data(&a.bytes);
+//! }
+//!
+//! ewasm_entry_point!(entry);
+//! ```
 //!
-//! use ewasm_api::{Hash, block_hash, finish_data};
+//! Using lower-level primitives:
+//! ```ignore
+//! use ewasm_api::{types::Hash, block_hash, finish_data};
 //!
 //! #[cfg(target_arch = "wasm32")]
 //! #[no_mangle]
 //! pub extern "C" fn main() {
-//!     let a: Hash = block_hash(1);
+//!     let a: types::Hash = block_hash(1);
 //!     finish_data(&a.bytes);
 //! }
 //! ```
+//!
 
 #[macro_use]
 extern crate cfg_if;
@@ -85,6 +96,19 @@ pub mod prelude {
     pub use crate::eth2;
 }
 
+/// Declare entry point for a contract. Expects a Rust function name to be executed.
+/// This will only compile in when using the wasm32 target.
+#[macro_export]
+macro_rules! ewasm_entry_point {
+    ($name:ident) => {
+        #[cfg(target_arch = "wasm32")]
+        #[no_mangle]
+        pub extern "C" fn main() {
+            $name()
+        }
+    };
+}
+
 /// Enum representing an error code for EEI calls. Currently used by `codeCopy`, `callDataCopy`,
 /// `externalCodeCopy`, and `returnDataCopy`.
 pub enum Error {