// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root. package com.yahoo.text; import java.util.OptionalInt; /** * Text utility functions. * * @author bratseth */ public final class Text { private static final boolean[] allowedAsciiChars = new boolean[0x80]; static { allowedAsciiChars[0x0] = false; allowedAsciiChars[0x1] = false; allowedAsciiChars[0x2] = false; allowedAsciiChars[0x3] = false; allowedAsciiChars[0x4] = false; allowedAsciiChars[0x5] = false; allowedAsciiChars[0x6] = false; allowedAsciiChars[0x7] = false; allowedAsciiChars[0x8] = false; allowedAsciiChars[0x9] = true; //tab allowedAsciiChars[0xA] = true; //nl allowedAsciiChars[0xB] = false; allowedAsciiChars[0xC] = false; allowedAsciiChars[0xD] = true; //cr for (int i = 0xE; i < 0x20; i++) { allowedAsciiChars[i] = false; } for (int i = 0x20; i < 0x7F; i++) { allowedAsciiChars[i] = true; //printable ascii chars } allowedAsciiChars[0x7F] = true; //del - discouraged, but allowed } /** No instantiation */ private Text() {} /** * Returns whether the given codepoint is a valid text character, potentially suitable for * purposes such as indexing and display, see http://www.w3.org/TR/2006/REC-xml11-20060816/#charsets */ public static boolean isTextCharacter(int codepoint) { // The link above notes that 0x7F-0x84 and 0x86-0x9F are discouraged, but they are still allowed - // see http://www.w3.org/International/questions/qa-controls if (codepoint < 0x80) return allowedAsciiChars[codepoint]; if (codepoint < 0xFDD0) return true; if (codepoint <= 0xFDDF) return false; if (codepoint < 0x1FFFE) return true; if (codepoint <= 0x1FFFF) return false; if (codepoint < 0x2FFFE) return true; if (codepoint <= 0x2FFFF) return false; if (codepoint < 0x3FFFE) return true; if (codepoint <= 0x3FFFF) return false; if (codepoint < 0x4FFFE) return true; if (codepoint <= 0x4FFFF) return false; if (codepoint < 0x5FFFE) return true; if (codepoint <= 0x5FFFF) return false; if (codepoint < 0x6FFFE) return true; if (codepoint <= 0x6FFFF) return false; if (codepoint < 0x7FFFE) return true; if (codepoint <= 0x7FFFF) return false; if (codepoint < 0x8FFFE) return true; if (codepoint <= 0x8FFFF) return false; if (codepoint < 0x9FFFE) return true; if (codepoint <= 0x9FFFF) return false; if (codepoint < 0xAFFFE) return true; if (codepoint <= 0xAFFFF) return false; if (codepoint < 0xBFFFE) return true; if (codepoint <= 0xBFFFF) return false; if (codepoint < 0xCFFFE) return true; if (codepoint <= 0xCFFFF) return false; if (codepoint < 0xDFFFE) return true; if (codepoint <= 0xDFFFF) return false; if (codepoint < 0xEFFFE) return true; if (codepoint <= 0xEFFFF) return false; if (codepoint < 0xFFFFE) return true; if (codepoint <= 0xFFFFF) return false; if (codepoint < 0x10FFFE) return true; if (codepoint <= 0x10FFFF) return false; return true; } /** * Validates that the given string value only contains text characters and * returns the first illegal code point if one is found. */ public static OptionalInt validateTextString(String string) { for (int i = 0; i < string.length(); ) { int codePoint = string.codePointAt(i); if ( ! Text.isTextCharacter(codePoint)) return OptionalInt.of(codePoint); int charCount = Character.charCount(codePoint); if (Character.isHighSurrogate(string.charAt(i))) { if ( charCount == 1) { return OptionalInt.of(string.codePointAt(i)); } else if ( !Character.isLowSurrogate(string.charAt(i+1))) { return OptionalInt.of(string.codePointAt(i+1)); } } i += charCount; } return OptionalInt.empty(); } /** Returns whether the given code point is displayable. */ public static boolean isDisplayable(int codePoint) { switch (Character.getType(codePoint)) { case Character.CONNECTOR_PUNCTUATION : case Character.DASH_PUNCTUATION : case Character.START_PUNCTUATION : case Character.END_PUNCTUATION : case Character.INITIAL_QUOTE_PUNCTUATION : case Character.FINAL_QUOTE_PUNCTUATION: case Character.OTHER_PUNCTUATION : case Character.LETTER_NUMBER : case Character.OTHER_LETTER : case Character.LOWERCASE_LETTER : case Character.TITLECASE_LETTER : case Character.MODIFIER_LETTER : case Character.UPPERCASE_LETTER : case Character.DECIMAL_DIGIT_NUMBER : case Character.OTHER_NUMBER : case Character.CURRENCY_SYMBOL : case Character.OTHER_SYMBOL : case Character.MATH_SYMBOL : return true; default : return false; } } private static StringBuilder lazy(StringBuilder sb, String s, int i) { if (sb == null) { sb = new StringBuilder(s.substring(0, i)); } sb.append(' '); return sb; } /** Returns a string where any invalid characters in the input string is replaced by spaces */ public static String stripInvalidCharacters(String string) { StringBuilder stripped = null; // lazy, as most string will not need stripping for (int i = 0; i < string.length();) { int codePoint = string.codePointAt(i); int charCount = Character.charCount(codePoint); if ( ! Text.isTextCharacter(codePoint)) { stripped = lazy(stripped, string, i); } else { if (Character.isHighSurrogate(string.charAt(i))) { if (charCount == 1) { stripped = lazy(stripped, string, i); } else if (!Character.isLowSurrogate(string.charAt(i+1))) { stripped = lazy(stripped, string, i); } else { if (stripped != null) { stripped.appendCodePoint(codePoint); } } } else { if (stripped != null) { stripped.appendCodePoint(codePoint); } } } i += charCount; } return stripped != null ? stripped.toString() : string; } /** * Returns a string which is never larger than the given number of characters. * If the string is longer than the given length it will be truncated. * If length is 4 or less the string will be truncated to length. * If length is longer than 4, it will be truncated at length-4 with " ..." added at the end. */ public static String truncate(String s, int length) { if (s.length() <= length) return s; if (length <= 4) return s.substring(0, length); return s.substring(0, length - 4) + " ..."; } }