Build and test wasm on CI

cli/src/wasm.rs

@@ -1,11 +1,14 @@
 use super::error::{Error, Result};
 use super::generate::parse_grammar::GrammarJSON;
+use std::ffi::{OsStr, OsString};
 use std::fs;
 use std::path::Path;
 use std::process::Command;
 
 pub fn compile_language_to_wasm(language_dir: &Path) -> Result<()> {
     let src_dir = language_dir.join("src");
+
+    // Parse the grammar.json to find out the language name.
     let grammar_json_path = src_dir.join("grammar.json");
     let grammar_json = fs::read_to_string(&grammar_json_path).map_err(|e| {
         format!(
@@ -19,11 +22,30 @@ pub fn compile_language_to_wasm(language_dir: &Path) -> Result<()> {
             grammar_json_path, e
         )
     })?;
+    let output_filename = format!("tree-sitter-{}.wasm", grammar.name);
 
-    let mut command = Command::new("emcc");
+    // Get the current user id so that files created in the docker container will have
+    // the same owner.
+    let user_id_output = Command::new("id")
+        .arg("-u")
+        .output()
+        .map_err(|e| format!("Failed to get get current user id {}", e))?;
+    let user_id = String::from_utf8_lossy(&user_id_output.stdout);
+    let user_id = user_id.trim();
+
+    // Use `emscripten-slim` docker image with the parser directory mounted as a volume.
+    let mut command = Command::new("docker");
+    let mut volume_string = OsString::from(language_dir);
+    volume_string.push(":/src");
+    command.args(&["run", "--rm"]);
+    command.args(&[OsStr::new("--volume"), &volume_string]);
+    command.args(&["--user", user_id, "trzeci/emscripten-slim"]);
+
+    // Run emscripten in the container
     command.args(&[
+        "emcc",
         "-o",
-        &format!("tree-sitter-{}.wasm", grammar.name),
+        &output_filename,
         "-Os",
         "-s",
         "WASM=1",
@@ -31,14 +53,15 @@ pub fn compile_language_to_wasm(language_dir: &Path) -> Result<()> {
         "SIDE_MODULE=1",
         "-s",
         &format!("EXPORTED_FUNCTIONS=[\"_tree_sitter_{}\"]", grammar.name),
+        "-I",
+        "src",
     ]);
-    command.arg("-I").arg(&src_dir);
 
-    // Find source files to compile
-    let entries = fs::read_dir(&src_dir)
+    // Find source files to pass to emscripten
+    let src_entries = fs::read_dir(&src_dir)
         .map_err(|e| format!("Failed to read source directory {:?} - {}", src_dir, e))?;
 
-    for entry in entries {
+    for entry in src_entries {
         let entry = entry?;
         let file_name = entry.file_name();
 
@@ -53,20 +76,24 @@ pub fn compile_language_to_wasm(language_dir: &Path) -> Result<()> {
         // Compile any .c, .cc, or .cpp files
         if let Some(extension) = Path::new(&file_name).extension().and_then(|s| s.to_str()) {
             if extension == "c" || extension == "cc" || extension == "cpp" {
-                command.arg(entry.path());
+                command.arg(Path::new("src").join(entry.file_name()));
             }
         }
     }
 
     let output = command
         .output()
-        .map_err(|e| format!("Failed to run emcc command - {}", e))?;
-    if output.status.success() {
-        Ok(())
-    } else {
-        Err(Error::from(format!(
+        .map_err(|e| format!("Failed to run docker emcc command - {}", e))?;
+    if !output.status.success() {
+        return Err(Error::from(format!(
             "emcc command failed - {}",
             String::from_utf8_lossy(&output.stderr)
-        )))
+        )));
     }
+
+    // Move the created `.wasm` file into the current working directory.
+    fs::rename(&language_dir.join(&output_filename), &output_filename)
+        .map_err(|e| format!("Couldn't find output file {:?} - {}", output_filename, e))?;
+
+    Ok(())
 }