From c8afdcd6ecfae970dd2ab0575706ff3c553adf63 Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Sat, 11 Aug 2018 19:19:56 +0100
Subject: [PATCH] Turn EwasmAPI into a trait

---
 src/lib.rs | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 23663f2..62aca6d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -587,3 +587,68 @@ pub fn selfdestruct(address: &Address) -> ! {
         native::ethereum_selfDestruct(address.bytes.as_ptr() as *const u32);
     }
 }
+
+pub trait EwasmAPI: Send + Sync {
+    fn consume_gas(mut self, amount: u64);
+    fn gas_left(self) -> u64;
+    fn current_address() -> [u8; 20];
+}
+
+#[derive(Debug)]
+pub struct NativeImpl;
+
+#[derive(Debug)]
+pub struct TestImpl {
+    gas: u64,
+}
+
+impl Default for TestImpl {
+    fn default() -> TestImpl {
+        TestImpl { gas: 0 }
+    }
+}
+
+/*
+trait TestSetter {
+   fn set_gas(mut self, amount: u64);
+}
+
+impl TestSetter for TestImpl {
+   fn set_gas(mut self, amount: u64) {
+       self.gas = amount
+   }
+}
+*/
+
+impl EwasmAPI for NativeImpl {
+    fn consume_gas(self, amount: u64) {}
+    fn gas_left(self) -> u64 {
+        0
+    }
+    fn current_address() -> [u8; 20] {
+        [0u8; 20]
+    }
+}
+
+impl EwasmAPI for TestImpl {
+    fn consume_gas(mut self, amount: u64) {
+        self.gas
+    }
+    fn gas_left(self) -> u64 {
+        self.gas
+    }
+    fn current_address() -> [u8; 20] {
+        [0u8; 20]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{EwasmAPI, TestImpl};
+
+    #[test]
+    fn consume_gas_func() {
+        assert_eq!(0, EwasmAPI::gas_left(<TestImpl>::default()));
+        assert_eq!(TestImpl::default().gas_left(), 0);
+    }
+}