Add null checks to String methods.

Also did some general cleanup and
fixed String tests to not be optimized by the compiler.

Change-Id: I503aebb5b60764e74406e408985bf57437e88498

user/super/com/google/gwt/emul/java/lang/Character.java

@@ -230,7 +230,7 @@ public static boolean isBmpCodePoint(int codePoint) {
    * TODO: correct Unicode handling.
    */
   public static boolean isDigit(char c) {
-    return String.valueOf(c).nativeMatches(digitRegex());
+    return digitRegex().test(String.valueOf(c));
   }
 
   private static native NativeRegExp digitRegex() /*-{
@@ -245,7 +245,7 @@ public static boolean isHighSurrogate(char ch) {
    * TODO: correct Unicode handling.
    */
   public static boolean isLetter(char c) {
-    return String.valueOf(c).nativeMatches(leterRegex());
+    return leterRegex().test(String.valueOf(c));
   }
 
   private static native NativeRegExp leterRegex() /*-{
@@ -256,7 +256,7 @@ private static native NativeRegExp leterRegex() /*-{
    * TODO: correct Unicode handling.
    */
   public static boolean isLetterOrDigit(char c) {
-    return String.valueOf(c).nativeMatches(leterOrDigitRegex());
+    return leterOrDigitRegex().test(String.valueOf(c));
   }
 
   private static native NativeRegExp leterOrDigitRegex() /*-{
@@ -296,11 +296,11 @@ public static boolean isSpace(char c) {
   }
 
   public static boolean isWhitespace(char ch) {
-    return String.valueOf(ch).nativeMatches(whitespaceRegex());
+    return whitespaceRegex().test(String.valueOf(ch));
   }
 
   public static boolean isWhitespace(int codePoint) {
-    return String.fromCodePoint(codePoint).nativeMatches(whitespaceRegex());
+    return whitespaceRegex().test(String.fromCodePoint(codePoint));
   }
 
   // The regex would just be /\s/, but browsers handle non-breaking spaces inconsistently. Also,

user/super/com/google/gwt/emul/java/lang/String.java

@@ -210,13 +210,6 @@ private static String translateReplaceString(String replaceStr) {
     return replaceStr;
   }
 
-  private static native int compareTo(String thisStr, String otherStr) /*-{
-    if (thisStr == otherStr) {
-      return 0;
-    }
-    return thisStr < otherStr ? -1 : 1;
-  }-*/;
-
   private static Charset getCharset(String charsetName) throws UnsupportedEncodingException {
     try {
       return Charset.forName(charsetName);
@@ -382,15 +375,15 @@ public int codePointCount(int beginIndex, int endIndex) {
 
   @Override
   public int compareTo(String other) {
-    return compareTo(this, other);
+    return JsUtils.compare(checkNotNull(this), checkNotNull(other));
   }
 
   public int compareToIgnoreCase(String other) {
-    return compareTo(toLowerCase(), other.toLowerCase());
+    return toLowerCase().compareTo(other.toLowerCase());
   }
 
   public String concat(String str) {
-    return this + str;
+    return checkNotNull(this) + checkNotNull(str);
   }
 
   public boolean contains(CharSequence s) {
@@ -421,18 +414,15 @@ public boolean equals(Object other) {
   }
 
   public boolean equalsIgnoreCase(String other) {
-    return equalsIgnoreCase(this, other);
-  }
-
-  private static native boolean equalsIgnoreCase(String s, String other) /*-{
+    checkNotNull(this);
     if (other == null) {
       return false;
     }
-    if (s == other) {
+    if (equals(other)) {
       return true;
     }
-    return (s.length == other.length) && (s.toLowerCase() == other.toLowerCase());
-  }-*/;
+    return length() == other.length() && toLowerCase().equals(other.toLowerCase());
+  }
 
   public byte[] getBytes() {
     // default character set for GWT is UTF-8
@@ -450,7 +440,10 @@ public byte[] getBytes(Charset charset) {
   public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
     checkCriticalStringBounds(srcBegin, srcEnd, length());
     checkCriticalStringBounds(dstBegin, dstBegin + (srcEnd - srcBegin), dst.length);
+    getChars0(srcBegin, srcEnd, dst, dstBegin);
+  }
 
+  private void getChars0(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
     while (srcBegin < srcEnd) {
       dst[dstBegin++] = charAt(srcBegin++);
     }
@@ -476,9 +469,9 @@ public int indexOf(String str) {
   public int indexOf(String str, int startIndex) {
     return asNativeString().indexOf(str, startIndex);
   }
-  
+
   public String intern() {
-    return this;
+    return checkNotNull(this);
   }
 
   public boolean isEmpty() {
@@ -516,11 +509,7 @@ public int length() {
    */
   public boolean matches(String regex) {
     // We surround the regex with '^' and '$' because it must match the entire string.
-    return nativeMatches(new NativeRegExp("^(" + regex + ")$"));
-  }
-
-  boolean nativeMatches(NativeRegExp regex) {
-    return regex.test(this);
+    return new NativeRegExp("^(" + regex + ")$").test(this);
   }
 
   public int offsetByCodePoints(int index, int codePointOffset) {
@@ -529,13 +518,11 @@ public int offsetByCodePoints(int index, int codePointOffset) {
 
   public boolean regionMatches(boolean ignoreCase, int toffset, String other,
       int ooffset, int len) {
-    if (other == null) {
-      throw new NullPointerException();
-    }
+    checkNotNull(other);
     if (toffset < 0 || ooffset < 0 || len <= 0) {
       return false;
     }
-    if (toffset + len > this.length() || ooffset + len > other.length()) {
+    if (toffset + len > length() || ooffset + len > other.length()) {
       return false;
     }
 
@@ -692,21 +679,21 @@ public boolean startsWith(String prefix, int toffset) {
 
   @Override
   public CharSequence subSequence(int beginIndex, int endIndex) {
-    return this.substring(beginIndex, endIndex);
+    return substring(beginIndex, endIndex);
   }
 
   public String substring(int beginIndex) {
-    return asNativeString().substr(beginIndex, this.length() - beginIndex);
+    return asNativeString().substr(beginIndex, length() - beginIndex);
   }
 
   public String substring(int beginIndex, int endIndex) {
     return asNativeString().substr(beginIndex, endIndex - beginIndex);
   }
 
   public char[] toCharArray() {
-    int n = this.length();
+    int n = length();
     char[] charArr = new char[n];
-    getChars(0, n, charArr, 0);
+    getChars0(0, n, charArr, 0);
     return charArr;
   }
 
@@ -833,15 +820,15 @@ private static class NativeString {
   }
 
   protected static String $create(String other) {
-    return other;
+    return checkNotNull(other);
   }
 
   protected static String $create(StringBuffer sb) {
-    return String.valueOf(sb);
+    return sb.toString();
   }
 
   protected static String $create(StringBuilder sb) {
-    return String.valueOf(sb);
+    return sb.toString();
   }
 
   @JsMethod

user/super/com/google/gwt/emul/java/lang/StringBuffer.java

@@ -1,12 +1,12 @@
 /*
  * Copyright 2008 Google Inc.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
@@ -15,9 +15,11 @@
  */
 package java.lang;
 
+import static javaemul.internal.InternalPreconditions.checkNotNull;
+
 /**
  * A fast way to create strings using multiple appends.
- * 
+ *
  * This class is an exact clone of {@link StringBuilder} except for the name.
  * Any change made to one should be mirrored in the other.
  */
@@ -28,7 +30,7 @@ public StringBuffer() {
   }
 
   public StringBuffer(CharSequence s) {
-    super(String.valueOf(s));
+    super(s.toString());
   }
 
   /**
@@ -41,7 +43,7 @@ public StringBuffer(int ignoredCapacity) {
   }
 
   public StringBuffer(String s) {
-    super(s);
+    super(checkNotNull(s));
   }
 
   public StringBuffer append(boolean x) {

user/super/com/google/gwt/emul/java/lang/StringBuilder.java

@@ -1,12 +1,12 @@
 /*
  * Copyright 2008 Google Inc.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
@@ -15,9 +15,11 @@
  */
 package java.lang;
 
+import static javaemul.internal.InternalPreconditions.checkNotNull;
+
 /**
  * A fast way to create strings using multiple appends.
- * 
+ *
  * This class is an exact clone of {@link StringBuffer} except for the name.
  * Any change made to one should be mirrored in the other.
  */
@@ -28,7 +30,7 @@ public StringBuilder() {
   }
 
   public StringBuilder(CharSequence s) {
-    super(String.valueOf(s));
+    super(s.toString());
   }
 
   /**
@@ -41,7 +43,7 @@ public StringBuilder(int ignoredCapacity) {
   }
 
   public StringBuilder(String s) {
-    super(s);
+    super(checkNotNull(s));
   }
 
   public StringBuilder append(boolean x) {

user/super/com/google/gwt/emul/javaemul/internal/JsUtils.java

@@ -20,6 +20,10 @@
  */
 public class JsUtils {
 
+  public static native int compare(String a, String b) /*-{
+    return a == b ? 0 : (a < b ? -1 : 1);
+  }-*/;
+
   public static native boolean isFinite(double d) /*-{
     return isFinite(d);
   }-*/;