From d79d42e10a75c2c4bd82cffdda229da65712b1a1 Mon Sep 17 00:00:00 2001
From: Tad Hardesty <tad@platymuus.com>
Date: Tue, 2 Apr 2019 18:29:14 -0700
Subject: [PATCH] Further restructure langserver::io for WebAssembly

---
 src/langserver/io/mod.rs              | 15 +++++++
 src/langserver/{io.rs => io/stdio.rs} | 63 ++++++---------------------
 src/langserver/io/wasm.rs             | 42 ++++++++++++++++++
 src/langserver/main.rs                | 18 +-------
 4 files changed, 73 insertions(+), 65 deletions(-)
 create mode 100644 src/langserver/io/mod.rs
 rename src/langserver/{io.rs => io/stdio.rs} (54%)
 create mode 100644 src/langserver/io/wasm.rs

diff --git a/src/langserver/io/mod.rs b/src/langserver/io/mod.rs
new file mode 100644
index 00000000..bd4dc590
--- /dev/null
+++ b/src/langserver/io/mod.rs
@@ -0,0 +1,15 @@
+//! Pluggable backends for input/output handling.
+
+pub trait RequestRead {
+    fn read(&self) -> Option<String>;
+}
+
+pub trait ResponseWrite {
+    fn write(&self, output: String);
+}
+
+#[cfg_attr(target_arch="wasm32", path="wasm.rs")]
+#[cfg_attr(not(target_arch="wasm32"), path="stdio.rs")]
+mod system;
+
+pub use self::system::*;
diff --git a/src/langserver/io.rs b/src/langserver/io/stdio.rs
similarity index 54%
rename from src/langserver/io.rs
rename to src/langserver/io/stdio.rs
index ccb40f38..affb5ced 100644
--- a/src/langserver/io.rs
+++ b/src/langserver/io/stdio.rs
@@ -1,16 +1,22 @@
-// Based loosely on RLS's input/output code
+//! I/O backend for standard targets.
+//!
+//! JSON-RPC over stdin/stdout with Content-Length headers.
 
+use Engine;
+use io::{RequestRead, ResponseWrite};
 use std::io::{self, Read, Write};
 
-pub trait RequestRead {
-    fn read(&self) -> Option<String>;
+pub fn io_main() {
+    let stdio = StdIo;
+    let context = Default::default();
+    let mut engine = Engine::new(&stdio, &context);
+    loop {
+        let message = stdio.read().expect("request bad read");
+        engine.handle_input(&message);
+    }
 }
 
-pub trait ResponseWrite {
-    fn write(&self, output: String);
-}
-
-pub struct StdIo;
+struct StdIo;
 
 impl RequestRead for StdIo {
     fn read(&self) -> Option<String> {
@@ -62,44 +68,3 @@ impl ResponseWrite for StdIo {
         stdout_lock.flush().unwrap();
     }
 }
-
-#[cfg(target_arch="wasm32")]
-#[allow(unsafe_code)]
-pub mod wasm {
-    use Engine;
-    use super::ResponseWrite;
-
-    extern {
-        fn handle_output(ptr: *const u8, len: usize);
-    }
-
-    struct WasmIo;
-
-    impl ResponseWrite for WasmIo {
-        fn write(&self, output: String) {
-            unsafe {
-                handle_output(output.as_ptr(), output.len());
-            }
-        }
-    }
-
-    static mut ENGINE_PTR: *mut Engine<WasmIo> = 0 as *mut Engine<WasmIo>;
-
-    pub fn main() {
-        let wasmio = Box::leak(Box::new(WasmIo));
-        let context = Box::leak(Box::new(Default::default()));
-        let engine = Box::new(Engine::new(wasmio, context));
-        unsafe {
-            ENGINE_PTR = Box::into_raw(engine);
-        }
-    }
-
-    #[no_mangle]
-    pub unsafe extern fn handle_input(ptr: *const u8, len: usize) {
-        assert!(!ENGINE_PTR.is_null());
-        let engine = &mut *ENGINE_PTR;
-        let slice = std::slice::from_raw_parts(ptr, len);
-        let text = std::str::from_utf8(slice).expect("input is not utf-8");
-        engine.handle_input(text);
-    }
-}
diff --git a/src/langserver/io/wasm.rs b/src/langserver/io/wasm.rs
new file mode 100644
index 00000000..ea0f631b
--- /dev/null
+++ b/src/langserver/io/wasm.rs
@@ -0,0 +1,42 @@
+//! I/O backend for WebAssembly target.
+//!
+//! `main()` creates an engine that will respond to calls to `handle_input()`,
+//! which will then call `handle_output()` with output messages.
+#![allow(unsafe_code)]
+
+use Engine;
+use super::ResponseWrite;
+
+pub fn io_main() {
+    let wasmio = Box::leak(Box::new(WasmIo));
+    let context = Box::leak(Box::new(Default::default()));
+    let engine = Box::new(Engine::new(wasmio, context));
+    unsafe {
+        ENGINE_PTR = Box::into_raw(engine);
+    }
+}
+
+static mut ENGINE_PTR: *mut Engine<WasmIo> = 0 as *mut Engine<WasmIo>;
+
+#[no_mangle]
+pub unsafe extern fn handle_input(ptr: *const u8, len: usize) {
+    assert!(!ENGINE_PTR.is_null());
+    let engine = &mut *ENGINE_PTR;
+    let slice = std::slice::from_raw_parts(ptr, len);
+    let text = std::str::from_utf8(slice).expect("input is not utf-8");
+    engine.handle_input(text);
+}
+
+struct WasmIo;
+
+impl ResponseWrite for WasmIo {
+    fn write(&self, output: String) {
+        unsafe {
+            handle_output(output.as_ptr(), output.len());
+        }
+    }
+}
+
+extern {
+    fn handle_output(ptr: *const u8, len: usize);
+}
diff --git a/src/langserver/main.rs b/src/langserver/main.rs
index e17b0ec5..a924b880 100644
--- a/src/langserver/main.rs
+++ b/src/langserver/main.rs
@@ -6,6 +6,7 @@
 //! * https://microsoft.github.io/language-server-protocol/specification
 //! * https://github.com/rust-lang-nursery/rls
 #![deny(unsafe_code)]
+#![cfg_attr(not(target_arch="wasm32"), forbid(unsafe_code))]
 
 extern crate url;
 extern crate serde;
@@ -60,22 +61,7 @@ fn main() {
         Err(e) => eprintln!("dir check failure: {}", e),
     }
 
-    #[cfg(not(target_arch="wasm32"))]
-    {
-        let stdio = io::StdIo;
-        let context = Default::default();
-        let mut engine = Engine::new(&stdio, &context);
-        loop {
-            use io::RequestRead;
-            let message = stdio.read().expect("request bad read");
-            engine.handle_input(&message);
-        }
-    }
-
-    #[cfg(target_arch="wasm32")]
-    {
-        io::wasm::main();
-    }
+    io::io_main();
 }
 
 const VERSION: Option<jsonrpc::Version> = Some(jsonrpc::Version::V2);