Refactor to add abstraction around the JS source (#407)

* Add abstraction around the JS source * Add module documentation
bytecodealliance · Jun 23, 2023 · bcbed2d · bcbed2d
1 parent a5e14ce
commit bcbed2d
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Showing 4 changed files with 74 additions and 34 deletions.
diff --git a/crates/cli/src/js.rs b/crates/cli/src/js.rs
@@ -0,0 +1,51 @@
+/// Higher-level representation of JavaScript.
+///
+/// This is intended to be used to derive different representations of source
+/// code. For example, as a byte array, a string, QuickJS bytecode, compressed
+/// bytes, or attributes of the source code like what it exports.
+use anyhow::{Context, Result};
+use brotli::enc::{self, BrotliEncoderParams};
+use std::{
+    fs::File,
+    io::{Cursor, Read},
+    path::Path,
+};
+
+use crate::bytecode;
+
+pub struct JS {
+    source_code: Vec<u8>,
+}
+
+impl JS {
+    pub fn from_file(path: &Path) -> Result<JS> {
+        let mut input_file = File::open(path)
+            .with_context(|| format!("Failed to open input file {}", path.display()))?;
+        let mut contents: Vec<u8> = vec![];
+        input_file.read_to_end(&mut contents)?;
+        Ok(JS {
+            source_code: contents,
+        })
+    }
+
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.source_code
+    }
+
+    pub fn compile(&self) -> Result<Vec<u8>> {
+        bytecode::compile_source(&self.source_code)
+    }
+
+    pub fn compress(&self) -> Result<Vec<u8>> {
+        let mut compressed_source_code: Vec<u8> = vec![];
+        enc::BrotliCompress(
+            &mut Cursor::new(&self.source_code),
+            &mut compressed_source_code,
+            &BrotliEncoderParams {
+                quality: 11,
+                ..Default::default()
+            },
+        )?;
+        Ok(compressed_source_code)
+    }
+}
diff --git a/crates/cli/src/main.rs b/crates/cli/src/main.rs
@@ -1,14 +1,16 @@
 mod bytecode;
 mod commands;
+mod js;
 mod module_generator;
 mod opt;
 mod transform;
 
 use crate::commands::{Command, CompileCommandOpts, EmitProviderCommandOpts};
-use anyhow::{bail, Context, Result};
+use anyhow::{bail, Result};
+use js::JS;
 use std::env;
 use std::fs::File;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::path::Path;
 use std::process::Stdio;
 use std::{fs, process::Command as OsCommand};
@@ -54,7 +56,7 @@ fn create_statically_linked_module(opts: &CompileCommandOpts) -> Result<()> {
         return Ok(());
     }
 
-    let contents = read_input_file(&opts.input)?;
+    let js = JS::from_file(&opts.input)?;
 
     let self_cmd = env::args().next().unwrap();
 
@@ -67,39 +69,30 @@ fn create_statically_linked_module(opts: &CompileCommandOpts) -> Result<()> {
             .arg(&opts.output)
             .stdin(Stdio::piped())
             .spawn()?;
-        command.stdin.take().unwrap().write_all(&contents)?;
+        command.stdin.take().unwrap().write_all(js.as_bytes())?;
         let status = command.wait()?;
         if !status.success() {
             bail!("Couldn't create wasm from input");
         }
     }
 
-    add_producers_and_source_code_sections(&opts.output, &contents)?;
+    add_producers_and_source_code_sections(&opts.output, &js)?;
 
     Ok(())
 }
 
-fn add_producers_and_source_code_sections<P: AsRef<Path>>(file: P, contents: &[u8]) -> Result<()> {
+fn add_producers_and_source_code_sections<P: AsRef<Path>>(file: P, js: &JS) -> Result<()> {
     let mut module = Module::from_file_with_config(&file, &transform::module_config())?;
     transform::add_producers_section(&mut module.producers);
-    module.customs.add(SourceCodeSection::new(contents)?);
+    module.customs.add(SourceCodeSection::new(js)?);
     module.emit_wasm_file(&file)?;
     Ok(())
 }
 
 fn create_dynamically_linked_module(opts: &CompileCommandOpts) -> Result<()> {
-    let js_source_code = read_input_file(&opts.input)?;
-    let quickjs_bytecode = bytecode::compile_source(&js_source_code)?;
-    let wasm_module = module_generator::generate_module(quickjs_bytecode, &js_source_code)?;
+    let js = JS::from_file(&opts.input)?;
+    let wasm_module = module_generator::generate_module(&js)?;
     let mut output_file = fs::File::create(&opts.output)?;
     output_file.write_all(&wasm_module)?;
     Ok(())
 }
-
-fn read_input_file(path: &Path) -> Result<Vec<u8>> {
-    let mut input_file = fs::File::open(path)
-        .with_context(|| format!("Failed to open input file {}", path.display()))?;
-    let mut contents: Vec<u8> = vec![];
-    input_file.read_to_end(&mut contents)?;
-    Ok(contents)
-}
diff --git a/crates/cli/src/module_generator.rs b/crates/cli/src/module_generator.rs
@@ -1,7 +1,10 @@
 use anyhow::Result;
 use walrus::{DataKind, FunctionBuilder, Module, ValType};
 
-use crate::transform::{self, SourceCodeSection};
+use crate::{
+    js::JS,
+    transform::{self, SourceCodeSection},
+};
 
 // Run the calling code with the `dump_wat` feature enabled to print the WAT to stdout
 //
@@ -31,7 +34,7 @@ use crate::transform::{self, SourceCodeSection};
 //     (export "_start" (func 2))
 //     (data (;0;) "\02\04\18function.mjs\0econsole\06log\18Hello world!\0f\bc\03\00\00\00\00\0e\00\06\01\a0\01\00\00\00\03\00\00\17\00\08\ea\02)8\df\00\00\00B\e0\00\00\00\04\e1\00\00\00$\01\00)\bc\03\01\02\01\17")
 // )
-pub fn generate_module(bytecode: Vec<u8>, js_src: &[u8]) -> Result<Vec<u8>> {
+pub fn generate_module(js: &JS) -> Result<Vec<u8>> {
     let mut module = Module::with_config(transform::module_config());
 
     const IMPORT_NAMESPACE: &str = "javy_quickjs_provider_v1";
@@ -53,8 +56,9 @@ pub fn generate_module(bytecode: Vec<u8>, js_src: &[u8]) -> Result<Vec<u8>> {
     let (memory, _) = module.add_import_memory(IMPORT_NAMESPACE, "memory", false, 0, None);
 
     transform::add_producers_section(&mut module.producers);
-    module.customs.add(SourceCodeSection::new(js_src)?);
+    module.customs.add(SourceCodeSection::new(js)?);
 
+    let bytecode = js.compile()?;
     let bytecode_len: i32 = bytecode.len().try_into()?;
     let bytecode_data = module.data.add(DataKind::Passive, bytecode);
 

diff --git a/crates/cli/src/transform.rs b/crates/cli/src/transform.rs
@@ -1,27 +1,19 @@
-use std::{borrow::Cow, io::Cursor};
+use std::borrow::Cow;
 
 use anyhow::Result;
-use brotli::enc::{self, BrotliEncoderParams};
 use walrus::{CustomSection, IdsToIndices, ModuleConfig, ModuleProducers};
 
+use crate::js::JS;
+
 #[derive(Debug)]
 pub struct SourceCodeSection {
     compressed_source_code: Vec<u8>,
 }
 
 impl SourceCodeSection {
-    pub fn new(source_code: &[u8]) -> Result<SourceCodeSection> {
-        let mut compressed_source_code: Vec<u8> = vec![];
-        enc::BrotliCompress(
-            &mut Cursor::new(source_code),
-            &mut compressed_source_code,
-            &BrotliEncoderParams {
-                quality: 11,
-                ..Default::default()
-            },
-        )?;
+    pub fn new(js: &JS) -> Result<SourceCodeSection> {
         Ok(SourceCodeSection {
-            compressed_source_code,
+            compressed_source_code: js.compress()?,
         })
     }
 }