Merge pull request #253 from paritytech/show

Show function signature and code example

examples/show.rs

@@ -0,0 +1,36 @@
+extern crate parity_wasm;
+
+use std::env;
+
+fn main() {
+	let args = env::args().collect::<Vec<_>>();
+	if args.len() != 3 {
+		println!("Usage: {} <wasm file> <index of function>", args[0]);
+		return;
+	}
+
+	let module = parity_wasm::deserialize_file(&args[1]).expect("Failed to load module");
+	let function_index = args[2].parse::<usize>().expect("Failed to parse function index");
+
+	if module.code_section().is_none() {
+		println!("no code in module!");
+		std::process::exit(1);
+	}
+
+	let sig = match module.function_section().unwrap().entries().get(function_index) {
+		Some(s) => s,
+		None => {
+			println!("no such function in module!");
+			std::process::exit(1)
+		}
+	};
+
+	let sig_type = &module.type_section().expect("No type section: module malformed").types()[sig.type_ref() as usize];
+	let code = &module.code_section().expect("Already checked, impossible").bodies()[function_index];
+
+	println!("signature: {:?}", sig_type);
+	println!("code: ");
+	for instruction in code.code().elements() {
+		println!("{}", instruction);
+	}
+}