add skip_empty_output method to call intrinsic

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+- Add skip_empty_output intrinsic
+
 ## 0.5.20
 
 - Accepts `-` character in expression's parsing expect at the beginning of the expression. (Ex: `-test` is failing, `test-8` is not)

substreams/src/externs.rs

@@ -1,6 +1,7 @@
 #[cfg(target_arch = "wasm32")]
 #[link(wasm_import_module = "env")]
 extern "C" {
+    pub fn skip_empty_output();
     pub fn output(ptr: *const u8, len: u32);
     pub fn register_panic(
         msg_ptr: *const u8,

substreams/src/lib.rs

@@ -177,6 +177,14 @@ pub fn output<M: prost::Message>(msg: M) {
     }
 }
 
+#[cfg_attr(not(target_arch = "wasm32"), allow(unused_variables))]
+pub fn skip_empty_output() {
+    #[cfg(target_arch = "wasm32")]
+    unsafe {
+        externs::skip_empty_output()
+    }
+}
+
 #[cfg_attr(not(target_arch = "wasm32"), allow(unused_variables))]
 pub fn output_raw(data: Vec<u8>) {
     #[cfg(target_arch = "wasm32")]