perf: Do not allocate if visitors are not used (#391)

Cargo.toml

@@ -24,7 +24,6 @@ cipher                      = "0.4.4"
 clap                        = "4.5.4"
 convert_case                = "0.6.0"
 default-from-serde          = "0.1"
-fxhash                      = "0.2.1"
 handlebars                  = "5.1.2"
 hex                         = "0.4.3"
 langtag                     = "0.3.2"
@@ -71,6 +70,7 @@ testing                     = "5.0.0"
 tracing                     = "0.1.40"
 widestring                  = "1.0.2"
 
+rustc-hash                   = "2.1.0"
 swc_icu_messageformat_parser = { version = "1.0.0", path = "./crates/swc_icu_messageformat_parser" }
 
 

packages/emotion/CHANGELOG.md

@@ -1,5 +1,11 @@
 # @swc/plugin-emotion
 
+## 8.1.0
+
+### Minor Changes
+
+- 05a2458: Improve performance greatly
+
 ## 8.0.4
 
 ### Patch Changes

packages/emotion/Cargo.toml

@@ -17,6 +17,7 @@ crate-type = ["cdylib", "rlib"]
 [dependencies]
 serde            = { workspace = true }
 serde_json       = { workspace = true }
+swc_atoms        = { workspace = true }
 swc_common       = { workspace = true, features = ["concurrent"] }
 swc_core         = { workspace = true, features = ["ecma_plugin_transform"] }
 swc_ecma_ast     = { workspace = true }

packages/emotion/README.md

@@ -34,6 +34,12 @@ Source code for plugin itself (not transforms) are copied from https://github.co
 
 # @swc/plugin-emotion
 
+## 8.1.0
+
+### Minor Changes
+
+- 05a2458: Improve performance greatly
+
 ## 8.0.4
 
 ### Patch Changes

packages/emotion/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@swc/plugin-emotion",
-  "version": "8.0.4",
+  "version": "8.1.0",
   "description": "SWC plugin for emotion css-in-js library",
   "main": "swc_plugin_emotion.wasm",
   "scripts": {

packages/emotion/src/lib.rs

@@ -3,6 +3,7 @@
 use std::path::Path;
 
 use serde::Deserialize;
+use swc_atoms::{atom, Atom};
 use swc_common::{plugin::metadata::TransformPluginMetadataContextKind, SourceMapper, Spanned};
 use swc_ecma_ast::Program;
 use swc_emotion::EmotionOptions;
@@ -23,7 +24,7 @@ enum EmotionJsAutoLabel {
 struct EmotionJsOptions {
     source_map: Option<bool>,
     auto_label: Option<EmotionJsAutoLabel>,
-    label_format: Option<String>,
+    label_format: Option<Atom>,
     #[serde(flatten)]
     extra: swc_emotion::EmotionOptions,
 }
@@ -44,7 +45,7 @@ impl EmotionJsOptions {
                     EmotionJsAutoLabel::DevOnly => matches!(env_name, "development"),
                 },
             ),
-            label_format: Some(self.label_format.unwrap_or_else(|| "[local]".to_string())),
+            label_format: Some(self.label_format.unwrap_or_else(|| atom!("[local]"))),
             ..self.extra
         }
     }

packages/emotion/transform/Cargo.toml

@@ -7,28 +7,29 @@ license      = { workspace = true }
 name         = "swc_emotion"
 repository   = { workspace = true }
 rust-version = { workspace = true }
-version      = "0.74.1"
+version      = "0.74.2"
 
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-base64           = { workspace = true }
-byteorder        = { workspace = true }
-fxhash           = { workspace = true }
-once_cell        = { workspace = true }
-radix_fmt        = { workspace = true }
-regex            = { workspace = true }
-serde            = { workspace = true }
-sourcemap        = { workspace = true }
-swc_atoms        = { workspace = true }
-swc_common       = { workspace = true }
-swc_ecma_ast     = { workspace = true }
-swc_ecma_codegen = { workspace = true }
-swc_ecma_utils   = { workspace = true }
-swc_ecma_visit   = { workspace = true }
-swc_trace_macro  = { workspace = true }
-tracing          = { workspace = true }
+base64              = { workspace = true }
+byteorder           = { workspace = true }
+once_cell           = { workspace = true }
+radix_fmt           = { workspace = true }
+regex               = { workspace = true }
+rustc-hash          = { workspace = true }
+serde               = { workspace = true }
+sourcemap           = { workspace = true }
+swc_atoms           = { workspace = true }
+swc_common          = { workspace = true }
+swc_ecma_ast        = { workspace = true }
+swc_ecma_codegen    = { workspace = true }
+swc_ecma_transforms = { workspace = true }
+swc_ecma_utils      = { workspace = true }
+swc_ecma_visit      = { workspace = true }
+swc_trace_macro     = { workspace = true }
+tracing             = { workspace = true }
 
 [dev-dependencies]
 serde_json                  = { workspace = true }

packages/emotion/transform/src/import_map.rs

@@ -1,14 +1,14 @@
+use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
 use swc_atoms::JsWord;
-use swc_common::collections::AHashMap;
 
 use crate::{EmotionModuleConfig, ExportItem};
 
 /// key: `importSource`
-pub type ImportMap = AHashMap<JsWord, ImportMapValue>;
+pub type ImportMap = FxHashMap<JsWord, ImportMapValue>;
 
 /// key: `localExportName`
-pub type ImportMapValue = AHashMap<JsWord, ImportItemConfig>;
+pub type ImportMapValue = FxHashMap<JsWord, ImportItemConfig>;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase", deny_unknown_fields)]

packages/emotion/transform/src/lib.rs

@@ -5,12 +5,12 @@ use std::{
 };
 
 use base64::Engine;
-use fxhash::FxHashMap;
 use once_cell::sync::Lazy;
 use regex::{Regex, RegexBuilder};
+use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
 use sourcemap::{RawToken, SourceMap as RawSourcemap};
-use swc_atoms::JsWord;
+use swc_atoms::{atom, Atom};
 use swc_common::{comments::Comments, util::take::Take, BytePos, SourceMapperDyn, DUMMY_SP};
 use swc_ecma_ast::{
     ArrayLit, CallExpr, Callee, ClassDecl, ClassMethod, ClassProp, Expr, ExprOrSpread, FnDecl, Id,
@@ -20,7 +20,7 @@ use swc_ecma_ast::{
     SourceMapperExt, SpreadElement, Tpl, VarDeclarator,
 };
 use swc_ecma_utils::ExprFactory;
-use swc_ecma_visit::{fold_pass, Fold, FoldWith};
+use swc_ecma_visit::{Fold, FoldWith, Visit, VisitWith};
 use swc_trace_macro::swc_trace;
 
 pub use crate::import_map::*;
@@ -104,13 +104,17 @@ static MULTI_LINE_COMMENT: Lazy<Regex> = Lazy::new(|| {
 static SPACE_AROUND_COLON: Lazy<Regex> =
     Lazy::new(|| Regex::new(r"\s*(?P<s>[:;,\{,\}])\s*").unwrap());
 
+fn default_label_format() -> Atom {
+    atom!("[local]")
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct EmotionOptions {
     pub enabled: Option<bool>,
     pub sourcemap: Option<bool>,
     pub auto_label: Option<bool>,
-    pub label_format: Option<String>,
+    pub label_format: Option<Atom>,
     pub import_map: Option<ImportMap>,
 }
 
@@ -120,15 +124,15 @@ impl Default for EmotionOptions {
             enabled: Some(false),
             sourcemap: Some(true),
             auto_label: Some(true),
-            label_format: Some("[local]".to_owned()),
+            label_format: Some(default_label_format()),
             import_map: None,
         }
     }
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct EmotionModuleConfig {
-    module_name: JsWord,
+    module_name: Atom,
     exported_names: Vec<ExportItem>,
     default_export: Option<ExprKind>,
 }
@@ -168,13 +172,7 @@ pub fn emotion<C: Comments>(
     cm: Arc<SourceMapperDyn>,
     comments: C,
 ) -> impl Pass {
-    fold_pass(EmotionTransformer::new(
-        emotion_options,
-        path,
-        src_file_hash,
-        cm,
-        comments,
-    ))
+    EmotionTransformer::new(emotion_options, path, src_file_hash, cm, comments)
 }
 
 pub struct EmotionTransformer<C: Comments> {
@@ -258,7 +256,7 @@ impl<C: Comments> EmotionTransformer<C> {
             self.options
                 .label_format
                 .clone()
-                .unwrap_or_else(|| "[local]".to_owned())
+                .unwrap_or_else(default_label_format)
         );
         if let Some(current_context) = &self.current_context {
             label = label.replace("[local]", &self.sanitize_label_part(current_context));
@@ -989,6 +987,45 @@ fn remove_space_around_colon(input: &str, is_first_item: bool, is_last_item: boo
     )
 }
 
+impl<C> Pass for EmotionTransformer<C>
+where
+    C: Comments,
+{
+    fn process(&mut self, program: &mut swc_ecma_ast::Program) {
+        let mut checker = ShouldWorkChecker {
+            should_work: false,
+            registered_imports: &self.registered_imports,
+        };
+        program.visit_with(&mut checker);
+        if !checker.should_work {
+            return;
+        }
+
+        program.map_with_mut(|p| p.fold_with(self));
+    }
+}
+
+struct ShouldWorkChecker<'a> {
+    should_work: bool,
+
+    registered_imports: &'a [EmotionModuleConfig],
+}
+
+impl Visit for ShouldWorkChecker<'_> {
+    fn visit_import_decl(&mut self, i: &ImportDecl) {
+        if self
+            .registered_imports
+            .iter()
+            .any(|item| item.module_name == i.src.value)
+        {
+            self.should_work = true;
+            return;
+        }
+
+        i.visit_children_with(self);
+    }
+}
+
 #[cfg(test)]
 mod test_emotion {
     use super::minify_css_string;