feat(es/minifier): Add CLI for debugging (#2273)

swc_ecma_minifier:
 - Add a binary to help development.

ecmascript/minifier/Cargo.toml

@@ -9,6 +9,10 @@ name = "swc_ecma_minifier"
 repository = "https://github.com/swc-project/swc.git"
 version = "0.27.3"
 
+[[bin]]
+name = "cli"
+path = "./src/cli/bin.rs"
+
 [features]
 debug = []
 

ecmascript/minifier/src/cli/bin.rs

@@ -0,0 +1,79 @@
+use std::{env::args, io, path::Path};
+use swc_common::{input::SourceFileInput, sync::Lrc, FilePathMapping, Mark, SourceMap};
+use swc_ecma_ast::Module;
+use swc_ecma_codegen::text_writer::JsWriter;
+use swc_ecma_minifier::{
+    optimize,
+    option::{ExtraOptions, MinifyOptions},
+};
+use swc_ecma_parser::{error::Error as ParseError, lexer::Lexer, Parser};
+use swc_ecma_transforms::{fixer, hygiene::hygiene_with_config, resolver_with_mark};
+use swc_ecma_visit::FoldWith;
+
+fn parse_js(cm: &Lrc<SourceMap>, filename: String) -> Result<Module, ParseError> {
+    let fm = cm
+        .load_file(Path::new(&filename))
+        .expect("Failed to load file");
+
+    let lexer = Lexer::new(
+        Default::default(),
+        Default::default(),
+        SourceFileInput::from(&*fm),
+        None,
+    );
+    let mut parser = Parser::new_from(lexer);
+
+    parser.parse_module()
+}
+
+fn print_js(cm: Lrc<SourceMap>, module: &Module) {
+    let stdout = io::stdout();
+
+    let mut emitter = swc_ecma_codegen::Emitter {
+        cfg: swc_ecma_codegen::Config { minify: true },
+        cm: cm.clone(),
+        comments: None,
+        wr: Box::new(JsWriter::new(cm.clone(), "\n", &stdout, None)),
+    };
+    emitter.emit_module(module).unwrap();
+
+    print!("\n");
+}
+
+fn run_cli(filename: String) -> Result<(), ParseError> {
+    swc_common::GLOBALS.set(&swc_common::Globals::new(), || {
+        let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+
+        let top_level_mark = Mark::fresh(Mark::root());
+        let program = parse_js(&cm, filename)?.fold_with(&mut resolver_with_mark(top_level_mark));
+
+        let output = optimize(
+            program,
+            cm.clone(),
+            None,
+            None,
+            &MinifyOptions {
+                compress: Some(Default::default()),
+                mangle: Some(Default::default()),
+                ..Default::default()
+            },
+            &ExtraOptions { top_level_mark },
+        );
+
+        let output = output
+            .fold_with(&mut hygiene_with_config(Default::default()))
+            .fold_with(&mut fixer(None));
+
+        print_js(cm.clone(), &output);
+
+        Ok(())
+    })
+}
+
+fn main() {
+    let filename = args().nth(1).expect("Usage: cargo run [filename.js]");
+
+    if let Err(error) = run_cli(filename) {
+        println!("{:?}", error);
+    }
+}