From a2a93a383046c349d51475ba2e23d0b8609c1e9e Mon Sep 17 00:00:00 2001
From: Ilya Ryzhenkov <orangy@jetbrains.com>
Date: Wed, 28 May 2014 15:50:15 +0400
Subject: [PATCH] Fix String.dropWhile & String.takeWhile

---
 libraries/stdlib/src/generated/_Filtering.kt           |  6 +++---
 libraries/stdlib/test/text/StringJVMTest.kt            | 10 ++++++----
 .../tools/kotlin-stdlib-gen/src/templates/Filtering.kt |  6 +++---
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/libraries/stdlib/src/generated/_Filtering.kt b/libraries/stdlib/src/generated/_Filtering.kt
index 881dd979fc1..f6e08fa2531 100644
--- a/libraries/stdlib/src/generated/_Filtering.kt
+++ b/libraries/stdlib/src/generated/_Filtering.kt
@@ -354,7 +354,7 @@ public fun <T> Stream<T>.dropWhile(predicate: (T) -> Boolean): Stream<T> {
  * Returns a list containing all elements except first elements that satisfy the given *predicate*
  */
 public inline fun String.dropWhile(predicate: (Char) -> Boolean): String {
-    for (index in 0..length)
+    for (index in 0..length - 1)
         if (!predicate(get(index))) {
             return substring(index)
         }
@@ -1240,10 +1240,10 @@ public fun <T> Stream<T>.takeWhile(predicate: (T) -> Boolean): Stream<T> {
  * Returns a list containing first elements satisfying the given *predicate*
  */
 public inline fun String.takeWhile(predicate: (Char) -> Boolean): String {
-    for (index in 0..length)
+    for (index in 0..length - 1)
         if (!predicate(get(index))) {
             return substring(0, index)
         }
-    return ""
+    return this
 }
 
diff --git a/libraries/stdlib/test/text/StringJVMTest.kt b/libraries/stdlib/test/text/StringJVMTest.kt
index b90a9c1ba24..528bb07f89c 100644
--- a/libraries/stdlib/test/text/StringJVMTest.kt
+++ b/libraries/stdlib/test/text/StringJVMTest.kt
@@ -240,8 +240,9 @@ class StringJVMTest {
 
     test fun dropWhile() {
         val data = "ab1cd2"
-        val result = data.dropWhile { it.isJavaLetter() }
-        assertEquals("1cd2", result)
+        assertEquals("1cd2", data.dropWhile { it.isJavaLetter() })
+        assertEquals("", data.dropWhile { true })
+        assertEquals("ab1cd2", data.dropWhile { false })
     }
 
     test fun drop() {
@@ -255,8 +256,9 @@ class StringJVMTest {
 
     test fun takeWhile() {
         val data = "ab1cd2"
-        val result = data.takeWhile { it.isJavaLetter() }
-        assertEquals("ab", result)
+        assertEquals("ab", data.takeWhile { it.isJavaLetter() })
+        assertEquals("", data.takeWhile { false })
+        assertEquals("ab1cd2", data.takeWhile { true })
     }
 
     test fun take() {
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
index 949ad834695..5a17166734d 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
@@ -113,7 +113,7 @@ fun filtering(): List<GenericFunction> {
         returns(Strings) { "String" }
         body(Strings) {
             """
-            for (index in 0..length)
+            for (index in 0..length - 1)
                 if (!predicate(get(index))) {
                     return substring(index)
                 }
@@ -161,11 +161,11 @@ fun filtering(): List<GenericFunction> {
         returns(Strings) { "String" }
         body(Strings) {
             """
-            for (index in 0..length)
+            for (index in 0..length - 1)
                 if (!predicate(get(index))) {
                     return substring(0, index)
                 }
-            return ""
+            return this
             """
         }