Refactor copy API in async/await

lib/copy/copy.js

@@ -36,27 +36,22 @@ async function copy (src, dest, opts = {}) {
 
   if (!include) return
 
-  return checkParentDir(destStat, src, dest, opts)
-}
-
-async function checkParentDir (destStat, src, dest, opts) {
+  // check if the parent of dest exists, and create it if it doesn't exist
   const destParent = path.dirname(dest)
-
   const dirExists = await pathExists(destParent)
-
   if (!dirExists) {
     await mkdirs(destParent)
   }
 
-  return getStats(destStat, src, dest, opts)
+  await getStatsAndPerformCopy(destStat, src, dest, opts)
 }
 
 async function runFilter (src, dest, opts) {
   if (!opts.filter) return true
   return opts.filter(src, dest)
 }
 
-async function getStats (destStat, src, dest, opts) {
+async function getStatsAndPerformCopy (destStat, src, dest, opts) {
   const statFn = opts.dereference ? fs.stat : fs.lstat
   const srcStat = await statFn(src)
 
@@ -101,19 +96,10 @@ async function handleTimestampsAndMode (srcMode, src, dest) {
   if (fileIsNotWritable(srcMode)) {
     await makeFileWritable(dest, srcMode)
   }
-  return setDestTimestampsAndMode(srcMode, src, dest)
-}
 
-function fileIsNotWritable (srcMode) {
-  return (srcMode & 0o200) === 0
-}
+  // Set timestamps and mode correspondingly
 
-function makeFileWritable (dest, srcMode) {
-  return setDestMode(dest, srcMode | 0o200)
-}
-
-async function setDestTimestampsAndMode (srcMode, src, dest) {
-  // The initial srcStat.atime cannot be trusted
+  // Note that The initial srcStat.atime cannot be trusted
   // because it is modified by the read(2) system call
   // (See https://nodejs.org/api/fs.html#fs_stat_time_values)
   const updatedSrcStat = await fs.stat(src)
@@ -122,43 +108,47 @@ async function setDestTimestampsAndMode (srcMode, src, dest) {
   return setDestMode(dest, srcMode)
 }
 
+function fileIsNotWritable (srcMode) {
+  return (srcMode & 0o200) === 0
+}
+
+function makeFileWritable (dest, srcMode) {
+  return setDestMode(dest, srcMode | 0o200)
+}
+
 function setDestMode (dest, srcMode) {
   return fs.chmod(dest, srcMode)
 }
 
 async function onDir (srcStat, destStat, src, dest, opts) {
+  // the dest direcotry might not exist, create it
   if (!destStat) {
     await fs.mkdir(dest)
   }
-  await copyDir(src, dest, opts)
-  if (!destStat) {
-    await setDestMode(dest, srcStat.mode)
-  }
-}
 
-async function copyDir (src, dest, opts) {
   const items = await fs.readdir(src)
-  return copyDirItems(items, src, dest, opts)
-}
 
-function copyDirItems (items, src, dest, opts) {
-  const item = items.pop()
-  if (!item) return
-  return copyDirItem(items, item, src, dest, opts)
-}
+  // loop through the files in the current directory to copy everything
+  for (let i = 0, len = items.length; i < len; i++) {
+    const item = items[i]
 
-async function copyDirItem (items, item, src, dest, opts) {
-  const srcItem = path.join(src, item)
-  const destItem = path.join(dest, item)
+    const srcItem = path.join(src, item)
+    const destItem = path.join(dest, item)
 
-  const include = await runFilter(srcItem, destItem, opts)
-  if (!include) return copyDirItems(items, src, dest, opts)
+    // skip the item if it is matches by the filter function
+    const include = await runFilter(srcItem, destItem, opts)
+    if (!include) continue
 
-  const { destStat } = await stat.checkPathsAsync(srcItem, destItem, 'copy', opts)
+    const { destStat } = await stat.checkPathsAsync(srcItem, destItem, 'copy', opts)
 
-  await getStats(destStat, srcItem, destItem, opts)
+    // If the item is a copyable file, `getStatsAndPerformCopy` will copy it
+    // If the item is a directory, `getStatsAndPerformCopy` will call `onDir` recursively
+    await getStatsAndPerformCopy(destStat, srcItem, destItem, opts)
+  }
 
-  return copyDirItems(items, src, dest, opts)
+  if (!destStat) {
+    await setDestMode(dest, srcStat.mode)
+  }
 }
 
 async function onLink (destStat, src, dest, opts) {
@@ -194,6 +184,7 @@ async function onLink (destStat, src, dest, opts) {
     throw new Error(`Cannot overwrite '${resolvedDest}' with '${resolvedSrc}'.`)
   }
 
+  // copy the link
   await fs.unlink(dest)
   return fs.symlink(resolvedSrc, dest)
 }