File.useLines and Reader.readLines.

libraries/stdlib/src/kotlin/io/FileReadWrite.kt

@@ -207,11 +207,11 @@ public fun File.outputStream(): FileOutputStream {
 }
 
 /**
- * Reads the file content as a list of lines. By default uses UTF-8 charset.
+ * Reads the file content as a list of lines.
  *
  * Do not use this function for huge files.
  *
- * @param charset character set to use.
+ * @param charset character set to use. By default uses UTF-8 charset.
  * @return list of file lines.
  */
 public fun File.readLines(charset: Charset = Charsets.UTF_8): List<String> {
@@ -220,3 +220,12 @@ public fun File.readLines(charset: Charset = Charsets.UTF_8): List<String> {
     return result
 }
 
+/**
+ * Calls the [block] callback giving it a sequence of all the lines in this file and closes the reader once
+ * the processing is complete.
+
+ * @param charset character set to use. By default uses UTF-8 charset.
+ * @return the value returned by [block].
+ */
+public inline fun <T> File.useLines(charset: Charset = Charsets.UTF_8, block: (Sequence<String>) -> T): T =
+        bufferedReader(charset).use { block(it.lineSequence()) }

libraries/stdlib/src/kotlin/io/ReadWrite.kt

@@ -24,6 +24,17 @@ public fun Writer.buffered(bufferSize: Int = defaultBufferSize): BufferedWriter
  */
 public fun Reader.forEachLine(block: (String) -> Unit): Unit = useLines { it.forEach(block) }
 
+/**
+ * Reads this reader content as a list of lines.
+ *
+ * Do not use this function for huge files.
+ */
+public fun Reader.readLines(): List<String> {
+    val result = arrayListOf<String>()
+    forEachLine { result.add(it) }
+    return result
+}
+
 /**
  * Calls the [block] callback giving it a sequence of all the lines in this file and closes the reader once
  * the processing is complete.

libraries/stdlib/test/io/ReadWrite.kt

@@ -41,7 +41,14 @@ class ReadWriteTest {
         sample().forEachLine {
             list.add(it)
         }
-        assertEquals(arrayListOf("Hello", "World"), list)
+        assertEquals(listOf("Hello", "World"), list)
+
+        assertEquals(listOf("Hello", "World"), sample().readLines())
+
+        sample().useLines {
+            assertEquals(listOf("Hello", "World"), it.toList())
+        }
+
 
         var reader = StringReader("")
         var c = 0
@@ -78,10 +85,17 @@ class ReadWriteTest {
             assertTrue(arr.contains('W'.toByte()))
         }
         val list = ArrayList<String>()
-        file.forEachLine("UTF8", {
+        file.forEachLine(Charsets.UTF_8, {
             list.add(it)
         })
         assertEquals(arrayListOf("Hello", "World"), list)
+
+        assertEquals(arrayListOf("Hello", "World"), file.readLines())
+
+        file.useLines {
+            assertEquals(arrayListOf("Hello", "World"), it.toList())
+        }
+
         val text = file.inputStream().reader().readText()
         assertTrue(text.contains("Hello"))
         assertTrue(text.contains("World"))