ICU-8175 Add some utilities for working with CharSequences. @internal for now.

X-SVN-Rev: 29206

.gitattributes

@@ -227,6 +227,7 @@ icu4j/main/classes/core/.project -text
 icu4j/main/classes/core/.settings/org.eclipse.core.resources.prefs -text
 icu4j/main/classes/core/.settings/org.eclipse.jdt.core.prefs -text
 icu4j/main/classes/core/manifest.stub -text
+icu4j/main/classes/core/src/com/ibm/icu/lang/CharSequences.java -text
 icu4j/main/classes/currdata/.externalToolBuilders/copy-data-currdata.launch -text
 icu4j/main/classes/currdata/.settings/org.eclipse.core.resources.prefs -text
 icu4j/main/classes/currdata/.settings/org.eclipse.jdt.core.prefs -text

icu4j/main/classes/core/src/com/ibm/icu/lang/CharSequences.java

@@ -0,0 +1,100 @@
+/*
+ *******************************************************************************
+ * Copyright (C) 2010, Google, International Business Machines Corporation and         *
+ * others. All Rights Reserved.                                                *
+ *******************************************************************************
+ */
+package com.ibm.icu.lang;
+
+/**
+ * A number of utilities for dealing with CharSequences and related classes.
+ * @author markdavis
+ * @internal
+ */
+public class CharSequences {
+    
+    /**
+     * Utility function for comparing codepoint to string without generating new
+     * string.
+     * 
+     * @param codepoint
+     * @param other
+     * @return true if the codepoint equals the string
+     * @internal
+     */
+    public static final boolean equals(int codepoint, CharSequence other) {
+        if (other == null) {
+            return false;
+        }
+        switch (other.length()) {
+        case 1: return codepoint == other.charAt(0);
+        case 2: return codepoint > 0xFFFF && codepoint == Character.codePointAt(other, 0);
+        default: return false;
+        }
+    }
+
+    /**
+     * Utility function for comparing objects that may be null
+     * string.
+     * @internal
+     */
+    public static final <T extends Object> boolean equals(T a, T b) {
+        return a == null ? b == null
+                : b == null ? false
+                        : a.equals(b);
+    }
+    
+    /** Are we on a character boundary?
+     * @internal
+     */
+    public static boolean onCharacterBoundary(CharSequence s, int i) {
+        return i <= 0 
+        || i >= s.length() 
+        || !Character.isHighSurrogate(s.charAt(i-1))
+        || !Character.isLowSurrogate(s.charAt(i));
+    }
+    
+    /**
+     * Find code point in string.
+     * @param s
+     * @param codePoint
+     * @return
+     * @internal
+     */
+    public static int indexOf(CharSequence s, int codePoint) {
+        int cp;
+        for (int i = 0; i < s.length(); i += Character.charCount(cp)) {
+            cp = Character.codePointAt(s, i);
+            if (cp == codePoint) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * Utility function for simplified, more robust loops, such as:
+     * <pre>
+     *   for (int codePoint : CharSequences.codePoints(string)) {
+     *     doSomethingWith(codePoint);
+     *   }
+     * </pre>
+     * @internal
+     */
+    public static int[] codePoints(CharSequence s) {
+        int[] result = new int[s.length()]; // common case
+        int j = 0;
+        int cp;
+        for (int i = 0; i < s.length(); i += Character.charCount(cp)) {
+            cp = Character.codePointAt(s, i);
+            result[j++] = cp;
+        }
+        if (j == result.length) {
+            return result;
+        }
+        int[] shortResult = new int[j];
+        System.arraycopy(result, 0, shortResult, 0, j);
+        return shortResult;
+    }
+
+}