diff options
Diffstat (limited to 'java/src')
| -rw-r--r-- | java/src/com/android/inputmethod/latin/utils/CsvUtils.java | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/java/src/com/android/inputmethod/latin/utils/CsvUtils.java b/java/src/com/android/inputmethod/latin/utils/CsvUtils.java new file mode 100644 index 000000000..999c2f0de --- /dev/null +++ b/java/src/com/android/inputmethod/latin/utils/CsvUtils.java @@ -0,0 +1,319 @@ +/* + * Copyright (C) 2013 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.utils; + +import com.android.inputmethod.annotations.UsedForTesting; +import com.android.inputmethod.latin.CollectionUtils; + +import java.util.ArrayList; + +/** + * Utility methods for parsing and serializing Comma-Separated Values. The public APIs of this + * utility class are {@link #split(String)}, {@link #split(int,String)}, {@link #join(String)}, + * {@link #join(int,String...)}, and {@link #join(int,int[],String...)}. + * + * This class implements CSV parsing and serializing methods conforming to RFC 4180 with an + * exception: + * These methods can't handle new line code escaped in double quotes. + */ +@UsedForTesting +public final class CsvUtils { + private CsvUtils() { + // This utility class is not publicly instantiable. + } + + public static final int SPLIT_FLAGS_NONE = 0x0; + /** + * A flag for {@link #split(int,String)}. If this flag is specified, the method will trim + * spaces around fields before splitting. Note that this behavior doesn't conform to RFC 4180. + */ + public static final int SPLIT_FLAGS_TRIM_SPACES = 0x1; + + public static final int JOIN_FLAGS_NONE = 0x0; + /** + * A flag for {@link #join(int,String...)} and {@link #join(int,int[],String...)}. If this + * flag is specified, these methods surround each field with double quotes before joining. + */ + public static final int JOIN_FLAGS_ALWAYS_QUOTED = 0x1; + /** + * A flag for {@link #join(int,String...)} and {@link #join(int,int[],String...)}. If this + * flag is specified, these methods add an extra space just after the comma separator. Note that + * this behavior doesn't conform to RFC 4180. + */ + public static final int JOIN_FLAGS_EXTRA_SPACE = 0x2; + + // Note that none of these characters match high or low surrogate characters, so we need not + // take care of matching by code point. + private static final char COMMA = ','; + private static final char SPACE = ' '; + private static final char QUOTE = '"'; + + @SuppressWarnings("serial") + public static class CsvParseException extends RuntimeException { + public CsvParseException(final String message) { + super(message); + } + } + + /** + * Find the first non-space character in the text. + * + * @param text the text to be searched. + * @param fromIndex the index to start the search from, inclusive. + * @return the index of the first occurrence of the non-space character in the + * <code>text</code> that is greater than or equal to <code>fromIndex</code>, or the length of + * the <code>text</code> if the character does not occur. + */ + private static int indexOfNonSpace(final String text, final int fromIndex) { + final int length = text.length(); + if (fromIndex < 0 || fromIndex > length) { + throw new IllegalArgumentException("text=" + text + " fromIndex=" + fromIndex); + } + int index = fromIndex; + while (index < length && text.charAt(index) == SPACE) { + index++; + } + return index; + } + + /** + * Find the last non-space character in the text. + * + * @param text the text to be searched. + * @param fromIndex the index to start the search from, exclusive. + * @param toIndex the index to end the search at, inclusive. Usually <code>toIndex</code> + * points a non-space character. + * @return the index of the last occurrence of the non-space character in the + * <code>text</code>, exclusive. It is less than <code>fromIndex</code> and greater than + * <code>toIndex</code>, or <code>toIndex</code> if the character does not occur. + */ + private static int lastIndexOfNonSpace(final String text, final int fromIndex, + final int toIndex) { + if (toIndex < 0 || fromIndex > text.length() || fromIndex < toIndex) { + throw new IllegalArgumentException( + "text=" + text + " fromIndex=" + fromIndex + " toIndex=" + toIndex); + } + int index = fromIndex; + while (index > toIndex && text.charAt(index - 1) == SPACE) { + index--; + } + return index; + } + + /** + * Find the index of a comma separator. The search takes account of quoted fields and escape + * quotes. + * + * @param text the text to be searched. + * @param fromIndex the index to start the search from, inclusive. + * @return the index of the comma separator, exclusive. + */ + private static int indexOfSeparatorComma(final String text, final int fromIndex) { + final int length = text.length(); + if (fromIndex < 0 || fromIndex > length) { + throw new IllegalArgumentException("text=" + text + " fromIndex=" + fromIndex); + } + final boolean isQuoted = (length - fromIndex > 0 && text.charAt(fromIndex) == QUOTE); + for (int index = fromIndex + (isQuoted ? 1 : 0); index < length; index++) { + final char c = text.charAt(index); + if (c == COMMA && !isQuoted) { + return index; + } + if (c == QUOTE) { + final int nextIndex = index + 1; + if (nextIndex < length && text.charAt(nextIndex) == QUOTE) { + // Quoted quote. + index = nextIndex; + continue; + } + // Closing quote. + final int endIndex = text.indexOf(COMMA, nextIndex); + return endIndex < 0 ? length : endIndex; + } + } + return length; + } + + /** + * Removing any enclosing QUOTEs (U+0022), and convert any two consecutive QUOTEs into + * one QUOTE. + * + * @param text the CSV field text that may have enclosing QUOTEs and escaped QUOTE character. + * @return the text that has been removed enclosing quotes and converted two consecutive QUOTEs + * into one QUOTE. + */ + @UsedForTesting + /* private */ static String unescapeField(final String text) { + StringBuilder sb = null; + final int length = text.length(); + final boolean isQuoted = (length > 0 && text.charAt(0) == QUOTE); + int start = isQuoted ? 1 : 0; + int end = start; + while (start <= length && (end = text.indexOf(QUOTE, start)) >= start) { + final int nextIndex = end + 1; + if (nextIndex == length && isQuoted) { + // Closing quote. + break; + } + if (nextIndex < length && text.charAt(nextIndex) == QUOTE) { + if (!isQuoted) { + throw new CsvParseException("Escaped quote in text"); + } + // Quoted quote. + if (sb == null) { + sb = new StringBuilder(); + } + sb.append(text.substring(start, nextIndex)); + start = nextIndex + 1; + } else { + throw new CsvParseException( + isQuoted ? "Raw quote in quoted text" : "Raw quote in text"); + } + } + if (end < 0 && isQuoted) { + throw new CsvParseException("Unterminated quote"); + } + if (end < 0) { + end = length; + } + if (sb != null && start < length) { + sb.append(text.substring(start, end)); + } + return sb == null ? text.substring(start, end) : sb.toString(); + } + + /** + * Split the CSV text into fields. The leading and trailing spaces of the each field can be + * trimmed optionally. + * + * @param splitFlags flags for split behavior. {@link #SPLIT_FLAGS_TRIM_SPACES} will trim + * spaces around each fields. + * @param line the text of CSV fields. + * @return the array of unescaped CVS fields. + * @throws CsvParseException + */ + @UsedForTesting + public static String[] split(final int splitFlags, final String line) throws CsvParseException { + final boolean trimSpaces = (splitFlags & SPLIT_FLAGS_TRIM_SPACES) != 0; + final ArrayList<String> fields = CollectionUtils.newArrayList(); + final int length = line.length(); + int start = 0; + do { + final int csvStart = trimSpaces ? indexOfNonSpace(line, start) : start; + final int end = indexOfSeparatorComma(line, csvStart); + final int csvEnd = trimSpaces ? lastIndexOfNonSpace(line, end, csvStart) : end; + final String csvText = unescapeField(line.substring(csvStart, csvEnd)); + fields.add(csvText); + start = end + 1; + } while (start <= length); + return fields.toArray(new String[fields.size()]); + } + + @UsedForTesting + public static String[] split(final String line) throws CsvParseException { + return split(SPLIT_FLAGS_NONE, line); + } + + /** + * Convert the raw CSV field text to the escaped text. It adds enclosing QUOTEs (U+0022) if the + * raw value contains any QUOTE or comma. Also it converts any QUOTE character into two + * consecutive QUOTE characters. + * + * @param text the raw CSV field text to be escaped. + * @param alwaysQuoted true if the escaped text should always be enclosed by QUOTEs. + * @return the escaped text. + */ + @UsedForTesting + /* private */ static String escapeField(final String text, final boolean alwaysQuoted) { + StringBuilder sb = null; + boolean needsQuoted = alwaysQuoted; + final int length = text.length(); + int indexToBeAppended = 0; + for (int index = indexToBeAppended; index < length; index++) { + final char c = text.charAt(index); + if (c == COMMA) { + needsQuoted = true; + } else if (c == QUOTE) { + needsQuoted = true; + if (sb == null) { + sb = new StringBuilder(); + } + sb.append(text.substring(indexToBeAppended, index)); + indexToBeAppended = index + 1; + sb.append(QUOTE); // escaping quote. + sb.append(QUOTE); // escaped quote. + } + } + if (sb != null && indexToBeAppended < length) { + sb.append(text.substring(indexToBeAppended)); + } + final String escapedText = (sb == null) ? text : sb.toString(); + return needsQuoted ? QUOTE + escapedText + QUOTE : escapedText; + } + + private static final String SPACES = " "; + + private static void padToColumn(final StringBuilder sb, final int column) { + int padding; + while ((padding = column - sb.length()) > 0) { + final String spaces = SPACES.substring(0, Math.min(padding, SPACES.length())); + sb.append(spaces); + } + } + + /** + * Join CSV text fields with comma. The column positions of the fields can be specified + * optionally. Surround each fields with double quotes before joining. + * + * @param joinFlags flags for join behavior. {@link #JOIN_FLAGS_EXTRA_SPACE} will add an extra + * space after each comma separator. {@link #JOIN_FLAGS_ALWAYS_QUOTED} will always add + * surrounding quotes to each element. + * @param columnPositions the array of column positions of the fields. It can be shorter than + * <code>fields</code> or null. Note that specifying the array column positions of the fields + * doesn't conform to RFC 4180. + * @param fields the CSV text fields. + * @return the string of the joined and escaped <code>fields</code>. + */ + @UsedForTesting + public static String join(final int joinFlags, final int columnPositions[], + final String... fields) { + final boolean alwaysQuoted = (joinFlags & JOIN_FLAGS_ALWAYS_QUOTED) != 0; + final String separator = COMMA + ((joinFlags & JOIN_FLAGS_EXTRA_SPACE) != 0 ? " " : ""); + final StringBuilder sb = new StringBuilder(); + for (int index = 0; index < fields.length; index++) { + if (index > 0) { + sb.append(separator); + } + if (columnPositions != null && index < columnPositions.length) { + padToColumn(sb, columnPositions[index]); + } + final String escapedText = escapeField(fields[index], alwaysQuoted); + sb.append(escapedText); + } + return sb.toString(); + } + + @UsedForTesting + public static String join(final int joinFlags, final String... fields) { + return join(joinFlags, null, fields); + } + + @UsedForTesting + public static String join(final String... fields) { + return join(JOIN_FLAGS_NONE, null, fields); + } +} |