Move StringUtils under common.

Bug: 18108776
Change-Id: Ia46a4102a0e86e71118ca5e641f9f531998e166b

1 files changed, 629 insertions, 0 deletions

diff --git a/common/src/com/android/inputmethod/latin/common/StringUtils.java b/common/src/com/android/inputmethod/latin/common/StringUtils.java
new file mode 100644
index 000000000..bbe46644d
--- /dev/null
+++ b/common/src/com/android/inputmethod/latin/common/StringUtils.java
@@ -0,0 +1,629 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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 License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.common;
+
+import com.android.inputmethod.annotations.UsedForTesting;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Locale;
+
+public final class StringUtils {
+    public static final int CAPITALIZE_NONE = 0;  // No caps, or mixed case
+    public static final int CAPITALIZE_FIRST = 1; // First only
+    public static final int CAPITALIZE_ALL = 2;   // All caps
+
+    private static final String EMPTY_STRING = "";
+
+    private static final char CHAR_LINE_FEED = 0X000A;
+    private static final char CHAR_VERTICAL_TAB = 0X000B;
+    private static final char CHAR_FORM_FEED = 0X000C;
+    private static final char CHAR_CARRIAGE_RETURN = 0X000D;
+    private static final char CHAR_NEXT_LINE = 0X0085;
+    private static final char CHAR_LINE_SEPARATOR = 0X2028;
+    private static final char CHAR_PARAGRAPH_SEPARATOR = 0X2029;
+
+    private StringUtils() {
+        // This utility class is not publicly instantiable.
+    }
+
+    // Taken from android.text.TextUtils. We are extensively using this method in many places,
+    // some of which don't have the android libraries available.
+    /**
+     * Returns true if the string is null or 0-length.
+     * @param str the string to be examined
+     * @return true if str is null or zero length
+     */
+    public static boolean isEmpty(CharSequence str) {
+        if (str == null || str.length() == 0)
+            return true;
+        else
+            return false;
+    }
+
+    // Taken from android.text.TextUtils to cut the dependency to the Android framework.
+    /**
+     * Returns a string containing the tokens joined by delimiters.
+     * @param tokens an array objects to be joined. Strings will be formed from
+     *     the objects by calling object.toString().
+     */
+    public static String join(CharSequence delimiter, Iterable tokens) {
+        StringBuilder sb = new StringBuilder();
+        boolean firstTime = true;
+        for (Object token: tokens) {
+            if (firstTime) {
+                firstTime = false;
+            } else {
+                sb.append(delimiter);
+            }
+            sb.append(token);
+        }
+        return sb.toString();
+    }
+
+    // Taken from android.text.TextUtils to cut the dependency to the Android framework.
+    /**
+     * Returns true if a and b are equal, including if they are both null.
+     * <p><i>Note: In platform versions 1.1 and earlier, this method only worked well if
+     * both the arguments were instances of String.</i></p>
+     * @param a first CharSequence to check
+     * @param b second CharSequence to check
+     * @return true if a and b are equal
+     */
+    public static boolean equals(CharSequence a, CharSequence b) {
+        if (a == b) return true;
+        int length;
+        if (a != null && b != null && (length = a.length()) == b.length()) {
+            if (a instanceof String && b instanceof String) {
+                return a.equals(b);
+            } else {
+                for (int i = 0; i < length; i++) {
+                    if (a.charAt(i) != b.charAt(i)) return false;
+                }
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static int codePointCount(final CharSequence text) {
+        if (isEmpty(text)) return 0;
+        return Character.codePointCount(text, 0, text.length());
+    }
+
+    public static String newSingleCodePointString(int codePoint) {
+        if (Character.charCount(codePoint) == 1) {
+            // Optimization: avoid creating a temporary array for characters that are
+            // represented by a single char value
+            return String.valueOf((char) codePoint);
+        }
+        // For surrogate pair
+        return new String(Character.toChars(codePoint));
+    }
+
+    public static boolean containsInArray(final String text, final String[] array) {
+        for (final String element : array) {
+            if (text.equals(element)) return true;
+        }
+        return false;
+    }
+
+    /**
+     * Comma-Splittable Text is similar to Comma-Separated Values (CSV) but has much simpler syntax.
+     * Unlike CSV, Comma-Splittable Text has no escaping mechanism, so that the text can't contain
+     * a comma character in it.
+     */
+    private static final String SEPARATOR_FOR_COMMA_SPLITTABLE_TEXT = ",";
+
+    public static boolean containsInCommaSplittableText(final String text,
+            final String extraValues) {
+        if (isEmpty(extraValues)) {
+            return false;
+        }
+        return containsInArray(text, extraValues.split(SEPARATOR_FOR_COMMA_SPLITTABLE_TEXT));
+    }
+
+    public static String removeFromCommaSplittableTextIfExists(final String text,
+            final String extraValues) {
+        if (isEmpty(extraValues)) {
+            return EMPTY_STRING;
+        }
+        final String[] elements = extraValues.split(SEPARATOR_FOR_COMMA_SPLITTABLE_TEXT);
+        if (!containsInArray(text, elements)) {
+            return extraValues;
+        }
+        final ArrayList<String> result = new ArrayList<>(elements.length - 1);
+        for (final String element : elements) {
+            if (!text.equals(element)) {
+                result.add(element);
+            }
+        }
+        return join(SEPARATOR_FOR_COMMA_SPLITTABLE_TEXT, result);
+    }
+
+    /**
+     * Remove duplicates from an array of strings.
+     *
+     * This method will always keep the first occurrence of all strings at their position
+     * in the array, removing the subsequent ones.
+     */
+    public static void removeDupes(final ArrayList<String> suggestions) {
+        if (suggestions.size() < 2) return;
+        int i = 1;
+        // Don't cache suggestions.size(), since we may be removing items
+        while (i < suggestions.size()) {
+            final String cur = suggestions.get(i);
+            // Compare each suggestion with each previous suggestion
+            for (int j = 0; j < i; j++) {
+                final String previous = suggestions.get(j);
+                if (equals(cur, previous)) {
+                    suggestions.remove(i);
+                    i--;
+                    break;
+                }
+            }
+            i++;
+        }
+    }
+
+    public static String capitalizeFirstCodePoint(final String s, final Locale locale) {
+        if (s.length() <= 1) {
+            return s.toUpperCase(locale);
+        }
+        // Please refer to the comment below in
+        // {@link #capitalizeFirstAndDowncaseRest(String,Locale)} as this has the same shortcomings
+        final int cutoff = s.offsetByCodePoints(0, 1);
+        return s.substring(0, cutoff).toUpperCase(locale) + s.substring(cutoff);
+    }
+
+    public static String capitalizeFirstAndDowncaseRest(final String s, final Locale locale) {
+        if (s.length() <= 1) {
+            return s.toUpperCase(locale);
+        }
+        // TODO: fix the bugs below
+        // - This does not work for Greek, because it returns upper case instead of title case.
+        // - It does not work for Serbian, because it fails to account for the "lj" character,
+        // which should be "Lj" in title case and "LJ" in upper case.
+        // - It does not work for Dutch, because it fails to account for the "ij" digraph when it's
+        // written as two separate code points. They are two different characters but both should
+        // be capitalized as "IJ" as if they were a single letter in most words (not all). If the
+        // unicode char for the ligature is used however, it works.
+        final int cutoff = s.offsetByCodePoints(0, 1);
+        return s.substring(0, cutoff).toUpperCase(locale) + s.substring(cutoff).toLowerCase(locale);
+    }
+
+    private static final int[] EMPTY_CODEPOINTS = {};
+
+    public static int[] toCodePointArray(final CharSequence charSequence) {
+        return toCodePointArray(charSequence, 0, charSequence.length());
+    }
+
+    /**
+     * Converts a range of a string to an array of code points.
+     * @param charSequence the source string.
+     * @param startIndex the start index inside the string in java chars, inclusive.
+     * @param endIndex the end index inside the string in java chars, exclusive.
+     * @return a new array of code points. At most endIndex - startIndex, but possibly less.
+     */
+    public static int[] toCodePointArray(final CharSequence charSequence,
+            final int startIndex, final int endIndex) {
+        final int length = charSequence.length();
+        if (length <= 0) {
+            return EMPTY_CODEPOINTS;
+        }
+        final int[] codePoints =
+                new int[Character.codePointCount(charSequence, startIndex, endIndex)];
+        copyCodePointsAndReturnCodePointCount(codePoints, charSequence, startIndex, endIndex,
+                false /* downCase */);
+        return codePoints;
+    }
+
+    /**
+     * Copies the codepoints in a CharSequence to an int array.
+     *
+     * This method assumes there is enough space in the array to store the code points. The size
+     * can be measured with Character#codePointCount(CharSequence, int, int) before passing to this
+     * method. If the int array is too small, an ArrayIndexOutOfBoundsException will be thrown.
+     * Also, this method makes no effort to be thread-safe. Do not modify the CharSequence while
+     * this method is running, or the behavior is undefined.
+     * This method can optionally downcase code points before copying them, but it pays no attention
+     * to locale while doing so.
+     *
+     * @param destination the int array.
+     * @param charSequence the CharSequence.
+     * @param startIndex the start index inside the string in java chars, inclusive.
+     * @param endIndex the end index inside the string in java chars, exclusive.
+     * @param downCase if this is true, code points will be downcased before being copied.
+     * @return the number of copied code points.
+     */
+    public static int copyCodePointsAndReturnCodePointCount(final int[] destination,
+            final CharSequence charSequence, final int startIndex, final int endIndex,
+            final boolean downCase) {
+        int destIndex = 0;
+        for (int index = startIndex; index < endIndex;
+                index = Character.offsetByCodePoints(charSequence, index, 1)) {
+            final int codePoint = Character.codePointAt(charSequence, index);
+            // TODO: stop using this, as it's not aware of the locale and does not always do
+            // the right thing.
+            destination[destIndex] = downCase ? Character.toLowerCase(codePoint) : codePoint;
+            destIndex++;
+        }
+        return destIndex;
+    }
+
+    public static int[] toSortedCodePointArray(final String string) {
+        final int[] codePoints = toCodePointArray(string);
+        Arrays.sort(codePoints);
+        return codePoints;
+    }
+
+    /**
+     * Construct a String from a code point array
+     *
+     * @param codePoints a code point array that is null terminated when its logical length is
+     * shorter than the array length.
+     * @return a string constructed from the code point array.
+     */
+    public static String getStringFromNullTerminatedCodePointArray(final int[] codePoints) {
+        int stringLength = codePoints.length;
+        for (int i = 0; i < codePoints.length; i++) {
+            if (codePoints[i] == 0) {
+                stringLength = i;
+                break;
+            }
+        }
+        return new String(codePoints, 0 /* offset */, stringLength);
+    }
+
+    // This method assumes the text is not null. For the empty string, it returns CAPITALIZE_NONE.
+    public static int getCapitalizationType(final String text) {
+        // If the first char is not uppercase, then the word is either all lower case or
+        // camel case, and in either case we return CAPITALIZE_NONE.
+        final int len = text.length();
+        int index = 0;
+        for (; index < len; index = text.offsetByCodePoints(index, 1)) {
+            if (Character.isLetter(text.codePointAt(index))) {
+                break;
+            }
+        }
+        if (index == len) return CAPITALIZE_NONE;
+        if (!Character.isUpperCase(text.codePointAt(index))) {
+            return CAPITALIZE_NONE;
+        }
+        int capsCount = 1;
+        int letterCount = 1;
+        for (index = text.offsetByCodePoints(index, 1); index < len;
+                index = text.offsetByCodePoints(index, 1)) {
+            if (1 != capsCount && letterCount != capsCount) break;
+            final int codePoint = text.codePointAt(index);
+            if (Character.isUpperCase(codePoint)) {
+                ++capsCount;
+                ++letterCount;
+            } else if (Character.isLetter(codePoint)) {
+                // We need to discount non-letters since they may not be upper-case, but may
+                // still be part of a word (e.g. single quote or dash, as in "IT'S" or "FULL-TIME")
+                ++letterCount;
+            }
+        }
+        // We know the first char is upper case. So we want to test if either every letter other
+        // than the first is lower case, or if they are all upper case. If the string is exactly
+        // one char long, then we will arrive here with letterCount 1, and this is correct, too.
+        if (1 == capsCount) return CAPITALIZE_FIRST;
+        return (letterCount == capsCount ? CAPITALIZE_ALL : CAPITALIZE_NONE);
+    }
+
+    public static boolean isIdenticalAfterUpcase(final String text) {
+        final int length = text.length();
+        int i = 0;
+        while (i < length) {
+            final int codePoint = text.codePointAt(i);
+            if (Character.isLetter(codePoint) && !Character.isUpperCase(codePoint)) {
+                return false;
+            }
+            i += Character.charCount(codePoint);
+        }
+        return true;
+    }
+
+    public static boolean isIdenticalAfterDowncase(final String text) {
+        final int length = text.length();
+        int i = 0;
+        while (i < length) {
+            final int codePoint = text.codePointAt(i);
+            if (Character.isLetter(codePoint) && !Character.isLowerCase(codePoint)) {
+                return false;
+            }
+            i += Character.charCount(codePoint);
+        }
+        return true;
+    }
+
+    public static boolean isIdenticalAfterCapitalizeEachWord(final String text,
+            final int[] sortedSeparators) {
+        boolean needsCapsNext = true;
+        final int len = text.length();
+        for (int i = 0; i < len; i = text.offsetByCodePoints(i, 1)) {
+            final int codePoint = text.codePointAt(i);
+            if (Character.isLetter(codePoint)) {
+                if ((needsCapsNext && !Character.isUpperCase(codePoint))
+                        || (!needsCapsNext && !Character.isLowerCase(codePoint))) {
+                    return false;
+                }
+            }
+            // We need a capital letter next if this is a separator.
+            needsCapsNext = (Arrays.binarySearch(sortedSeparators, codePoint) >= 0);
+        }
+        return true;
+    }
+
+    // TODO: like capitalizeFirst*, this does not work perfectly for Dutch because of the IJ digraph
+    // which should be capitalized together in *some* cases.
+    public static String capitalizeEachWord(final String text, final int[] sortedSeparators,
+            final Locale locale) {
+        final StringBuilder builder = new StringBuilder();
+        boolean needsCapsNext = true;
+        final int len = text.length();
+        for (int i = 0; i < len; i = text.offsetByCodePoints(i, 1)) {
+            final String nextChar = text.substring(i, text.offsetByCodePoints(i, 1));
+            if (needsCapsNext) {
+                builder.append(nextChar.toUpperCase(locale));
+            } else {
+                builder.append(nextChar.toLowerCase(locale));
+            }
+            // We need a capital letter next if this is a separator.
+            needsCapsNext = (Arrays.binarySearch(sortedSeparators, nextChar.codePointAt(0)) >= 0);
+        }
+        return builder.toString();
+    }
+
+    /**
+     * Approximates whether the text before the cursor looks like a URL.
+     *
+     * This is not foolproof, but it should work well in the practice.
+     * Essentially it walks backward from the cursor until it finds something that's not a letter,
+     * digit, or common URL symbol like underscore. If it hasn't found a period yet, then it
+     * does not look like a URL.
+     * If the text:
+     * - starts with www and contains a period
+     * - starts with a slash preceded by either a slash, whitespace, or start-of-string
+     * Then it looks like a URL and we return true. Otherwise, we return false.
+     *
+     * Note: this method is called quite often, and should be fast.
+     *
+     * TODO: This will return that "abc./def" and ".abc/def" look like URLs to keep down the
+     * code complexity, but ideally it should not. It's acceptable for now.
+     */
+    public static boolean lastPartLooksLikeURL(final CharSequence text) {
+        int i = text.length();
+        if (0 == i) return false;
+        int wCount = 0;
+        int slashCount = 0;
+        boolean hasSlash = false;
+        boolean hasPeriod = false;
+        int codePoint = 0;
+        while (i > 0) {
+            codePoint = Character.codePointBefore(text, i);
+            if (codePoint < Constants.CODE_PERIOD || codePoint > 'z') {
+                // Handwavy heuristic to see if that's a URL character. Anything between period
+                // and z. This includes all lower- and upper-case ascii letters, period,
+                // underscore, arrobase, question mark, equal sign. It excludes spaces, exclamation
+                // marks, double quotes...
+                // Anything that's not a URL-like character causes us to break from here and
+                // evaluate normally.
+                break;
+            }
+            if (Constants.CODE_PERIOD == codePoint) {
+                hasPeriod = true;
+            }
+            if (Constants.CODE_SLASH == codePoint) {
+                hasSlash = true;
+                if (2 == ++slashCount) {
+                    return true;
+                }
+            } else {
+                slashCount = 0;
+            }
+            if ('w' == codePoint) {
+                ++wCount;
+            } else {
+                wCount = 0;
+            }
+            i = Character.offsetByCodePoints(text, i, -1);
+        }
+        // End of the text run.
+        // If it starts with www and includes a period, then it looks like a URL.
+        if (wCount >= 3 && hasPeriod) return true;
+        // If it starts with a slash, and the code point before is whitespace, it looks like an URL.
+        if (1 == slashCount && (0 == i || Character.isWhitespace(codePoint))) return true;
+        // If it has both a period and a slash, it looks like an URL.
+        if (hasPeriod && hasSlash) return true;
+        // Otherwise, it doesn't look like an URL.
+        return false;
+    }
+
+    /**
+     * Examines the string and returns whether we're inside a double quote.
+     *
+     * This is used to decide whether we should put an automatic space before or after a double
+     * quote character. If we're inside a quotation, then we want to close it, so we want a space
+     * after and not before. Otherwise, we want to open the quotation, so we want a space before
+     * and not after. Exception: after a digit, we never want a space because the "inch" or
+     * "minutes" use cases is dominant after digits.
+     * In the practice, we determine whether we are in a quotation or not by finding the previous
+     * double quote character, and looking at whether it's followed by whitespace. If so, that
+     * was a closing quotation mark, so we're not inside a double quote. If it's not followed
+     * by whitespace, then it was an opening quotation mark, and we're inside a quotation.
+     *
+     * @param text the text to examine.
+     * @return whether we're inside a double quote.
+     */
+    public static boolean isInsideDoubleQuoteOrAfterDigit(final CharSequence text) {
+        int i = text.length();
+        if (0 == i) return false;
+        int codePoint = Character.codePointBefore(text, i);
+        if (Character.isDigit(codePoint)) return true;
+        int prevCodePoint = 0;
+        while (i > 0) {
+            codePoint = Character.codePointBefore(text, i);
+            if (Constants.CODE_DOUBLE_QUOTE == codePoint) {
+                // If we see a double quote followed by whitespace, then that
+                // was a closing quote.
+                if (Character.isWhitespace(prevCodePoint)) return false;
+            }
+            if (Character.isWhitespace(codePoint) && Constants.CODE_DOUBLE_QUOTE == prevCodePoint) {
+                // If we see a double quote preceded by whitespace, then that
+                // was an opening quote. No need to continue seeking.
+                return true;
+            }
+            i -= Character.charCount(codePoint);
+            prevCodePoint = codePoint;
+        }
+        // We reached the start of text. If the first char is a double quote, then we're inside
+        // a double quote. Otherwise we're not.
+        return Constants.CODE_DOUBLE_QUOTE == codePoint;
+    }
+
+    public static boolean isEmptyStringOrWhiteSpaces(final String s) {
+        final int N = codePointCount(s);
+        for (int i = 0; i < N; ++i) {
+            if (!Character.isWhitespace(s.codePointAt(i))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @UsedForTesting
+    public static String byteArrayToHexString(final byte[] bytes) {
+        if (bytes == null || bytes.length == 0) {
+            return EMPTY_STRING;
+        }
+        final StringBuilder sb = new StringBuilder();
+        for (byte b : bytes) {
+            sb.append(String.format("%02x", b & 0xff));
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Convert hex string to byte array. The string length must be an even number.
+     */
+    @UsedForTesting
+    public static byte[] hexStringToByteArray(final String hexString) {
+        if (isEmpty(hexString)) {
+            return null;
+        }
+        final int N = hexString.length();
+        if (N % 2 != 0) {
+            throw new NumberFormatException("Input hex string length must be an even number."
+                    + " Length = " + N);
+        }
+        final byte[] bytes = new byte[N / 2];
+        for (int i = 0; i < N; i += 2) {
+            bytes[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)
+                    + Character.digit(hexString.charAt(i + 1), 16));
+        }
+        return bytes;
+    }
+
+    public static String toUpperCaseOfStringForLocale(final String text,
+            final boolean needsToUpperCase, final Locale locale) {
+        if (text == null || !needsToUpperCase) return text;
+        return text.toUpperCase(locale);
+    }
+
+    public static int toUpperCaseOfCodeForLocale(final int code, final boolean needsToUpperCase,
+            final Locale locale) {
+        if (!Constants.isLetterCode(code) || !needsToUpperCase) return code;
+        final String text = newSingleCodePointString(code);
+        final String casedText = toUpperCaseOfStringForLocale(
+                text, needsToUpperCase, locale);
+        return codePointCount(casedText) == 1
+                ? casedText.codePointAt(0) : Constants.CODE_UNSPECIFIED;
+    }
+
+    public static int getTrailingSingleQuotesCount(final CharSequence charSequence) {
+        final int lastIndex = charSequence.length() - 1;
+        int i = lastIndex;
+        while (i >= 0 && charSequence.charAt(i) == Constants.CODE_SINGLE_QUOTE) {
+            --i;
+        }
+        return lastIndex - i;
+    }
+
+    public static class Stringizer<E> {
+        public String stringize(final E element) {
+            return element != null ? element.toString() : "null";
+        }
+
+        public final String join(final E[] array) {
+            return joinStringArray(toStringArray(array), null /* delimiter */);
+        }
+
+        public final String join(final E[] array, final String delimiter) {
+            return joinStringArray(toStringArray(array), delimiter);
+        }
+
+        protected String[] toStringArray(final E[] array) {
+            final String[] stringArray = new String[array.length];
+            for (int index = 0; index < array.length; index++) {
+                stringArray[index] = stringize(array[index]);
+            }
+            return stringArray;
+        }
+
+        protected String joinStringArray(final String[] stringArray, final String delimiter) {
+            if (stringArray == null) {
+                return "null";
+            }
+            if (delimiter == null) {
+                return Arrays.toString(stringArray);
+            }
+            final StringBuilder sb = new StringBuilder();
+            for (int index = 0; index < stringArray.length; index++) {
+                sb.append(index == 0 ? "[" : delimiter);
+                sb.append(stringArray[index]);
+            }
+            return sb + "]";
+        }
+    }
+
+    /**
+     * Returns whether the last composed word contains line-breaking character (e.g. CR or LF).
+     * @param text the text to be examined.
+     * @return {@code true} if the last composed word contains line-breaking separator.
+     */
+    public static boolean hasLineBreakCharacter(final String text) {
+        if (isEmpty(text)) {
+            return false;
+        }
+        for (int i = text.length() - 1; i >= 0; --i) {
+            final char c = text.charAt(i);
+            switch (c) {
+                case CHAR_LINE_FEED:
+                case CHAR_VERTICAL_TAB:
+                case CHAR_FORM_FEED:
+                case CHAR_CARRIAGE_RETURN:
+                case CHAR_NEXT_LINE:
+                case CHAR_LINE_SEPARATOR:
+                case CHAR_PARAGRAPH_SEPARATOR:
+                    return true;
+            }
+        }
+        return false;
+    }
+}