Merge pull request #81 from NikVolf/exports-example

Exports example

examples/exports.rs

@@ -0,0 +1,45 @@
+extern crate parity_wasm;
+
+use std::env::args;
+
+use parity_wasm::elements::{Internal, External, Type, FunctionType, Module};
+
+fn type_by_index(module: &Module, index: usize) -> FunctionType {
+    let function_section = module.function_section().expect("No function section found");
+    let type_section = module.type_section().expect("No type section found");
+
+    let import_section_len: usize = match module.import_section() {
+            Some(import) => 
+                import.entries().iter().filter(|entry| match entry.external() {
+                    &External::Function(_) => true,
+                    _ => false,
+                    }).count(),
+            None => 0,
+        };
+    let function_index_in_section = index - import_section_len;
+    let func_type_ref: usize = function_section.entries()[function_index_in_section].type_ref() as usize;
+    match type_section.types()[func_type_ref] {
+        Type::Function(ref func_type) => func_type.clone(),
+    }
+}
+
+fn main() {
+    let args: Vec<_> = args().collect();
+    if args.len() < 2 {
+        println!("Prints export function names with and their types");
+        println!("Usage: {} <wasm file>", args[0]);
+        return;
+    }
+    let module = parity_wasm::deserialize_file(&args[1]).expect("File to be deserialized");
+    let export_section = module.export_section().expect("No export section found");
+    let exports: Vec<String> = export_section.entries().iter()
+        .filter_map(|entry|
+            match *entry.internal() {
+                Internal::Function(index) => Some((entry.field(), index as usize)),
+                _ => None
+            })
+        .map(|(field, index)| format!("{:}: {:?}", field, type_by_index(&module, index).params())).collect();
+    for export in exports {
+        println!("{:}", export);
+    }
+}