include fetch arg for wasm2es6js

crates/cli-support/src/wasm2es6js.rs

@@ -1,6 +1,7 @@
 extern crate base64;
 
 use std::collections::HashSet;
+use std::path::PathBuf;
 
 use parity_wasm::elements::*;
 
@@ -8,17 +9,23 @@ use super::Error;
 
 pub struct Config {
     base64: bool,
+    fetch: bool,
+    file_name: String,
 }
 
 pub struct Output {
     module: Module,
     base64: bool,
+    fetch: bool,
+    file_name: String,
 }
 
 impl Config {
     pub fn new() -> Config {
         Config {
             base64: false,
+            fetch: false,
+            file_name: String::new(),
         }
     }
 
@@ -26,15 +33,28 @@ impl Config {
         self.base64 = base64;
         self
     }
+    
+    pub fn fetch(&mut self, fetch: bool, in_path: &PathBuf) -> &mut Self {
+        self.fetch = fetch;
+        self.file_name = match in_path.file_name() {
+            Some(os_str) => os_str.to_str().unwrap_or("").to_string(),
+            None => String::new()
+        };
+        self
+    }
 
     pub fn generate(&mut self, wasm: &[u8]) -> Result<Output, Error> {
-        assert!(self.base64);
+        if !self.base64 && !self.fetch {
+            panic!()
+        }
         let module = deserialize_buffer(wasm).map_err(|e| {
             ::Error(format!("{:?}", e))
         })?;
         Ok(Output {
             module,
             base64: self.base64,
+            fetch: self.fetch,
+            file_name: self.file_name.clone(),
         })
     }
 }
@@ -180,35 +200,51 @@ impl Output {
                 ));
             }
         }
-
-        let wasm = serialize(self.module)
-            .expect("failed to serialize");
-
-        format!("
-            {js_imports}
-            let wasm;
-            let bytes;
-            const base64 = \"{base64}\";
-            if (typeof Buffer === 'undefined') {{
-                bytes = Uint8Array.from(atob(base64), c => c.charCodeAt(0));
-            }} else {{
-                bytes = Buffer.from(base64, 'base64');
-            }}
-            {mem_export}
-            export const booted = WebAssembly.instantiate(bytes, {{ {imports} }})
+        let inst = format!("WebAssembly.instantiate(bytes,{{ {imports} }})
                 .then(obj => {{
                     wasm = obj.instance;
                     {memory}
-                }});
-
+                }})", 
+                imports = imports,
+                memory = if export_mem { "memory = wasm.exports.memory;" } else { "" },
+            );
+        let (bytes, booted) = if self.base64 {
+            let wasm = serialize(self.module)
+                .expect("failed to serialize");
+            (
+                format!("
+                    let bytes;
+                    const base64 = \"{base64}\";
+                    if (typeof Buffer === 'undefined') {{
+                        bytes = Uint8Array.from(atob(base64), c => c.charCodeAt(0));
+                    }} else {{
+                        bytes = Buffer.from(base64, 'base64');
+                    }}", base64 = base64::encode(&wasm)),
+                inst
+            )
+        } else if self.fetch {
+            (
+                String::new(),
+                format!("fetch('/{name}')
+                .then(res => res.arrayBuffer())
+                .then(bytes => {inst})", name = self.file_name, inst = inst)
+            )
+        } else {
+            panic!("the option --base64 or --fetch is required");
+        };
+        format!("
+            {js_imports}
+            let wasm;
+            {bytes}
+            {mem_export}
+            export const booted = {booted};
             {exports}
         ",
-            base64 = base64::encode(&wasm),
+            bytes = bytes,
+            booted = booted,
             js_imports = js_imports,
-            imports = imports,
             exports = exports,
             mem_export = if export_mem { "export let memory;" } else { "" },
-            memory = if export_mem { "memory = wasm.exports.memory;" } else { "" },
         )
     }
 }

crates/cli/src/bin/wasm2es6js.rs

@@ -22,6 +22,7 @@ Options:
     -o --output FILE        File to place output in
     --typescript            Output a `*.d.ts` file next to the JS output
     --base64                Inline the wasm module using base64 encoding
+    --fetch                 Load module via `fetch()` instead of default webpack implementation
 
 Note that this is not intended to produce a production-ready output module
 but rather is intended purely as a temporary \"hack\" until it's standard in
@@ -33,6 +34,7 @@ struct Args {
     flag_output: Option<PathBuf>,
     flag_typescript: bool,
     flag_base64: bool,
+    flag_fetch: bool,
     arg_input: PathBuf,
 }
 
@@ -41,8 +43,8 @@ fn main() {
         .and_then(|d| d.deserialize())
         .unwrap_or_else(|e| e.exit());
 
-    if !args.flag_base64 {
-        panic!("unfortunately only works right now with base64");
+    if !args.flag_base64 && !args.flag_fetch {
+        panic!("unfortunately only works right now with base64 or fetch");
     }
 
     let mut wasm = Vec::new();
@@ -51,6 +53,7 @@ fn main() {
 
     let object = wasm_bindgen_cli_support::wasm2es6js::Config::new()
         .base64(args.flag_base64)
+        .fetch(args.flag_fetch, &args.arg_input)
         .generate(&wasm)
         .expect("failed to parse wasm");