Add partial replacements.

src/line-replace.js

@@ -5,58 +5,68 @@ const stream = require('stream')
 const rename = util.promisify(fs.rename)
 const unlink = util.promisify(fs.unlink)
 
-function lineReplace({ file, line, text, addNewLine = true, callback }) {
-  const readStream = fs.createReadStream(file)
-  const tempFile = `${file}.tmp`
-  const writeStream = fs.createWriteStream(tempFile)
-  const rl = readline.createInterface(readStream, stream)
-  let replacedText
-
-  readStream.on('error', async ({ message }) => {
-    await unlink(tempFile)
-    callback({ error: message, file, line, replacedText, text })
-  })
-
-  writeStream.on('error', async ({ message }) => {
-    await unlink(tempFile)
-    callback({ error: message, file, line, replacedText, text })
-  })
-
-  rl.on('error', async ({ message }) => {
-    await unlink(tempFile)
-    callback({ error: message, file, line, replacedText, text })
-  })
-
-  let currentLine = 0
-  rl.on('line', (originalLine) => {
-    ++currentLine
-
-    // Replace.
-    if (currentLine === line) {
-      replacedText = originalLine
-      if (addNewLine) return writeStream.write(`${text}\n`)
-      return writeStream.write(`${text}`)
-    }
-
-    // Save original line.
-    writeStream.write(`${originalLine}\n`)
-  })
-
-  rl.on('close', () => {
-    // Finish writing to temp file and replace files.
-    // Replace original file with fixed file (the temp file).
-    writeStream.end(async () => {
-      try {
-        await unlink(file) // Delete original file.
-        await rename(tempFile, file) // Rename temp file with original file name.
-      } catch (error) {
-        callback({ error, file, line, replacedText, text })
-        return
+function lineReplace({ file, line, text, addNewLine = true, textToReplace }) {
+
+  return new Promise((resolve, reject) => {
+    const readStream = fs.createReadStream(file)
+    const tempFile = `${file}.tmp`
+    const writeStream = fs.createWriteStream(tempFile)
+    const rl = readline.createInterface(readStream, stream)
+
+    let replacedText
+
+    readStream.on('error', async ({ message }) => {
+      await unlink(tempFile)
+      reject({ error: message, file, line, replacedText, text })
+    })
+
+    writeStream.on('error', async ({ message }) => {
+      await unlink(tempFile)
+      reject({ error: message, file, line, replacedText, text })
+    })
+
+    rl.on('error', async ({ message }) => {
+      await unlink(tempFile)
+      reject({ error: message, file, line, replacedText, text })
+    })
+
+    let currentLine = 0
+    rl.on('line', (originalLine) => {
+      ++currentLine
+
+      // Replace.
+      if (currentLine === line) {
+        let output;
+        if (textToReplace) {
+          replacedText = textToReplace
+          output = originalLine.replace(textToReplace, text)
+        } else {
+          replacedText = originalLine
+          output = text
+        }
+        if (addNewLine) return writeStream.write(`${output}\n`)
+        return writeStream.write(`${output}`)
       }
 
-      callback({ file, line, replacedText, text })
+      // Save original line.
+      writeStream.write(`${originalLine}\n`)
+    })
+
+    rl.on('close', () => {
+      // Finish writing to temp file and replace files.
+      // Replace original file with fixed file (the temp file).
+      writeStream.end(async () => {
+        try {
+          await unlink(file) // Delete original file.
+          await rename(tempFile, file) // Rename temp file with original file name.
+        } catch (error) {
+          reject({ error, file, line, replacedText, text })
+        }
+
+        resolve({ file, line, replacedText, text })
+      })
     })
-  })
+  });
 }
 
 module.exports = lineReplace