From 4202e6d8182da0056c56dae1d4c986edfa3733cd Mon Sep 17 00:00:00 2001
From: Ilya Matveev <ilya.matveev@jetbrains.com>
Date: Wed, 14 Jun 2017 14:55:17 +0700
Subject: [PATCH] stdlib: Remove redundant checks from String.lastIndexOf

Kotlin/JVM allows a user to specify a start index greater than
a string length in String.lastIndexOf method. This patch
modifies the Kotlin/Native implementation according to this
behaviour. It also removes other redundant checks.
---
 runtime/src/main/cpp/KString.cpp | 55 ++++++++++++++++----------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/runtime/src/main/cpp/KString.cpp b/runtime/src/main/cpp/KString.cpp
index 30d3883f353..16b9da4209d 100644
--- a/runtime/src/main/cpp/KString.cpp
+++ b/runtime/src/main/cpp/KString.cpp
@@ -1020,9 +1020,12 @@ KInt Kotlin_String_indexOfChar(KString thiz, KChar ch, KInt fromIndex) {
 }
 
 KInt Kotlin_String_lastIndexOfChar(KString thiz, KChar ch, KInt fromIndex) {
-  if (fromIndex < 0 || fromIndex > thiz->count_ || thiz->count_ == 0) {
+  if (fromIndex < 0 || thiz->count_ == 0) {
     return -1;
   }
+  if (fromIndex >= thiz->count_) {
+    fromIndex = thiz->count_ - 1;
+  }
   KInt count = thiz->count_;
   KInt index = fromIndex;
   const KChar* thizRaw = CharArrayAddressOfElementAt(thiz, index);
@@ -1065,35 +1068,33 @@ KInt Kotlin_String_indexOfString(KString thiz, KString other, KInt fromIndex) {
 }
 
 KInt Kotlin_String_lastIndexOfString(KString thiz, KString other, KInt fromIndex) {
-  if (fromIndex < 0 || fromIndex > thiz->count_ || thiz->count_ == 0 ||
-      other->count_ > thiz->count_ - fromIndex) {
-    return -1;
-  }
   KInt count = thiz->count_;
   KInt otherCount = other->count_;
-  KInt start = fromIndex;
-  if (otherCount <= count && start >= 0) {
-    if (otherCount > 0) {
-      if (fromIndex > count - otherCount)
-        start = count - otherCount;
-      KChar firstChar = *CharArrayAddressOfElementAt(other, 0);
-      while (true) {
-        KInt candidate = Kotlin_String_lastIndexOfChar(thiz, firstChar, start);
-        if (candidate == -1) return -1;
-        KInt offsetThiz = candidate;
-        KInt offsetOther = 0;
-        while (++offsetOther < otherCount &&
-               *CharArrayAddressOfElementAt(thiz, ++offsetThiz) ==
-               *CharArrayAddressOfElementAt(other, offsetOther)) {}
-        if (offsetOther == otherCount) {
-          return candidate;
-        }
-        start = candidate - 1;
-      }
-    }
-    return start < count ? start : count;
+
+  if (fromIndex < 0 || otherCount > count) {
+    return -1;
+  }
+  if (otherCount == 0) {
+    return fromIndex < count ? fromIndex : count;
+  }
+
+  KInt start = fromIndex;
+  if (fromIndex > count - otherCount)
+    start = count - otherCount;
+  KChar firstChar = *CharArrayAddressOfElementAt(other, 0);
+  while (true) {
+    KInt candidate = Kotlin_String_lastIndexOfChar(thiz, firstChar, start);
+    if (candidate == -1) return -1;
+    KInt offsetThiz = candidate;
+    KInt offsetOther = 0;
+    while (++offsetOther < otherCount &&
+           *CharArrayAddressOfElementAt(thiz, ++offsetThiz) ==
+           *CharArrayAddressOfElementAt(other, offsetOther)) {}
+    if (offsetOther == otherCount) {
+      return candidate;
+    }
+    start = candidate - 1;
   }
-  return -1;
 }
 
 KInt Kotlin_String_hashCode(KString thiz) {