If CSS file has no @tailwind rules, don't consider it a context dependency

Author: adamwathan

src/index.js

@@ -31,18 +31,7 @@ module.exports = (configOrPath = {}) => {
           })
         }
 
-        // TODO: Maybe we only set up a context + run context dependent plugins
-        // on files that contain @tailwind rules? I don't know.
-        let foundTailwind = false
-        root.walkAtRules('tailwind', (rule) => {
-          foundTailwind = true
-        })
-
-        let context = null
-
-        if (foundTailwind) {
-          context = setupContext(configOrPath)(result, root)
-        }
+        let context = setupContext(configOrPath)(result, root)
 
         if (context.configPath !== null) {
           registerDependency(context.configPath)

src/lib/expandTailwindAtRules.js

@@ -206,8 +206,7 @@ function expandTailwindAtRules(context, registerDependency) {
     if (env.DEBUG) {
       console.log('Changed files: ', context.changedFiles.size)
       console.log('Potential classes: ', candidates.size)
-      console.log('Active contexts: ', sharedState.contextMap.size)
-      // console.log('Context source map: ', sharedState.contextSourcesMap)
+      console.log('Active contexts: ', sharedState.contextSourcesMap.size)
       console.log('Content match entries', contentMatchCache.size)
     }
 

src/lib/setupContext.js

@@ -544,20 +544,33 @@ function cleanupContext(context) {
 // plugins) then return it
 function setupContext(configOrPath) {
   return (result, root) => {
+    let foundTailwind = false
+
+    root.walkAtRules('tailwind', (rule) => {
+      foundTailwind = true
+    })
+
     let sourcePath = result.opts.from
     let [tailwindConfig, userConfigPath, tailwindConfigHash] = getTailwindConfig(configOrPath)
 
     let contextDependencies = new Set()
-    contextDependencies.add(sourcePath)
 
-    if (userConfigPath !== null) {
-      contextDependencies.add(userConfigPath)
+    // If there are no @tailwind rules, we don't consider this CSS file or it's dependencies
+    // to be dependencies of the context. Can reuse the context even if they change.
+    // We may want to think about `@layer` being part of this trigger too, but it's tough
+    // because it's impossible for a layer in one file to end up in the actual @tailwind rule
+    // in another file since independent sources are effectively isolated.
+    if (foundTailwind) {
+      contextDependencies.add(sourcePath)
+      for (let message of result.messages) {
+        if (message.type === 'dependency') {
+          contextDependencies.add(message.file)
+        }
+      }
     }
 
-    for (let message of result.messages) {
-      if (message.type === 'dependency') {
-        contextDependencies.add(message.file)
-      }
+    if (userConfigPath !== null) {
+      contextDependencies.add(userConfigPath)
     }
 
     let contextDependenciesChanged =
@@ -572,29 +585,26 @@ function setupContext(configOrPath) {
     }
 
     // If the config file used already exists in the cache, return that.
-    console.log('dependencies changed: ', contextDependenciesChanged)
-    console.log(tailwindConfigHash)
-    console.log(configContextMap.keys())
-    console.log(configContextMap.has(tailwindConfigHash))
-
-    // DAMN YOU CONTEXTDEPENDENCIESCHANGED
-    // Ideas:
-    // - Can we incorporate the presence of @tailwind rules somehow? If it has no Tailwind rules, be
-    // more lenient about the dependencies changing?
     if (!contextDependenciesChanged && configContextMap.has(tailwindConfigHash)) {
       let context = configContextMap.get(tailwindConfigHash)
       contextSourcesMap.get(context).add(sourcePath)
       contextMap.set(sourcePath, context)
       return context
     }
 
-    // TODO: Update this to no longer associate this path with its old context
-    // and clean up that context if no one else is using it.
+    // If this source is in the context map, get the old context.
+    // Remove this source from the context sources for the old context,
+    // and clean up that context if no one else is using it. This can be
+    // called by many processes in rapid succession, so we check for presence
+    // first because the first process to run this code will wipe it out first.
     if (contextMap.has(sourcePath)) {
       let oldContext = contextMap.get(sourcePath)
-      contextSourcesMap.get(oldContext).remove(sourcePath)
-      if (contextSourcesMap.get(oldContext).size === 0) {
-        cleanupContext(oldContext)
+      if (contextSourcesMap.has(oldContext)) {
+        contextSourcesMap.get(oldContext).remove(sourcePath)
+        if (contextSourcesMap.get(oldContext).size === 0) {
+          contextSourcesMap.delete(oldContext)
+          cleanupContext(oldContext)
+        }
       }
     }
 
@@ -646,12 +656,6 @@ function setupContext(configOrPath) {
       }
     }
 
-    let prev = null
-    for (let [key, value] of contextSourcesMap) {
-      console.log(key === prev)
-      prev = key
-    }
-
     rebootWatcher(context)
 
     let corePluginList = Object.entries(corePlugins)