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Diffstat (limited to 'javaparser-core/src/main/java/com/github/javaparser/utils/StringEscapeUtils.java')
| -rw-r--r-- | javaparser-core/src/main/java/com/github/javaparser/utils/StringEscapeUtils.java | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/javaparser-core/src/main/java/com/github/javaparser/utils/StringEscapeUtils.java b/javaparser-core/src/main/java/com/github/javaparser/utils/StringEscapeUtils.java new file mode 100644 index 000000000..a9732b906 --- /dev/null +++ b/javaparser-core/src/main/java/com/github/javaparser/utils/StringEscapeUtils.java @@ -0,0 +1,435 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.github.javaparser.utils; + +import java.io.IOException; +import java.io.StringWriter; +import java.io.Writer; +import java.util.HashMap; +import java.util.HashSet; + +/** + * Adapted from apache commons-lang3 project. + * <p> + * Unescapes escaped chars in strings. + */ +public class StringEscapeUtils { + + private StringEscapeUtils() { + } + + /** + * <p>Escapes the characters in a {@code String} using Java String rules.</p> + * <p> + * <p>Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p> + * <p> + * <p>So a tab becomes the characters {@code '\\'} and + * {@code 't'}.</p> + * <p> + * <p>The only difference between Java strings and JavaScript strings + * is that in JavaScript, a single quote and forward-slash (/) are escaped.</p> + * <p> + * <p>Example:</p> + * <pre> + * input string: He didn't say, "Stop!" + * output string: He didn't say, \"Stop!\" + * </pre> + * + * @param input String to escape values in, may be null + * @return String with escaped values, {@code null} if null string input + */ + public static String escapeJava(final String input) { + return ESCAPE_JAVA.translate(input); + } + + /** + * <p>Unescapes any Java literals found in the {@code String}. + * For example, it will turn a sequence of {@code '\'} and + * {@code 'n'} into a newline character, unless the {@code '\'} + * is preceded by another {@code '\'}.</p> + * + * @param input the {@code String} to unescape, may be null + * @return a new unescaped {@code String}, {@code null} if null string input + */ + public static String unescapeJava(final String input) { + return UNESCAPE_JAVA.translate(input); + } + + private static final String[][] JAVA_CTRL_CHARS_UNESCAPE = { + {"\\b", "\b"}, + {"\\n", "\n"}, + {"\\t", "\t"}, + {"\\f", "\f"}, + {"\\r", "\r"} + }; + + private static final String[][] JAVA_CTRL_CHARS_ESCAPE = { + {"\b", "\\b"}, + {"\n", "\\n"}, + {"\t", "\\t"}, + {"\f", "\\f"}, + {"\r", "\\r"} + }; + + private static final CharSequenceTranslator ESCAPE_JAVA = + new AggregateTranslator( + new LookupTranslator( + new String[][]{ + {"\"", "\\\""}, + {"\\", "\\\\"}, + }), + new LookupTranslator(JAVA_CTRL_CHARS_ESCAPE.clone()) + ); + + private static final CharSequenceTranslator UNESCAPE_JAVA = + new AggregateTranslator( + new OctalUnescaper(), + new UnicodeUnescaper(), + new LookupTranslator(JAVA_CTRL_CHARS_UNESCAPE.clone()), + new LookupTranslator( + new String[][]{ + {"\\\\", "\\"}, + {"\\\"", "\""}, + {"\\'", "'"}, + {"\\", ""} + }) + ); + + /** + * Adapted from apache commons-lang3 project. + * <p> + * An API for translating text. + * Its core use is to escape and unescape text. Because escaping and unescaping + * is completely contextual, the API does not present two separate signatures. + * + * @since 3.0 + */ + private static abstract class CharSequenceTranslator { + + /** + * Translate a set of codepoints, represented by an int index into a CharSequence, + * into another set of codepoints. The number of codepoints consumed must be returned, + * and the only IOExceptions thrown must be from interacting with the Writer so that + * the top level API may reliably ignore StringWriter IOExceptions. + * + * @param input CharSequence that is being translated + * @param index int representing the current point of translation + * @param out Writer to translate the text to + * @return int count of codepoints consumed + * @throws IOException if and only if the Writer produces an IOException + */ + public abstract int translate(CharSequence input, int index, Writer out) throws IOException; + + /** + * Helper for non-Writer usage. + * + * @param input CharSequence to be translated + * @return String output of translation + */ + public final String translate(final CharSequence input) { + if (input == null) { + return null; + } + try { + final StringWriter writer = new StringWriter(input.length() * 2); + translate(input, writer); + return writer.toString(); + } catch (final IOException ioe) { + // this should never ever happen while writing to a StringWriter + throw new RuntimeException(ioe); + } + } + + /** + * Translate an input onto a Writer. This is intentionally final as its algorithm is + * tightly coupled with the abstract method of this class. + * + * @param input CharSequence that is being translated + * @param out Writer to translate the text to + * @throws IOException if and only if the Writer produces an IOException + */ + public final void translate(final CharSequence input, final Writer out) throws IOException { + if (out == null) { + throw new IllegalArgumentException("The Writer must not be null"); + } + if (input == null) { + return; + } + int pos = 0; + final int len = input.length(); + while (pos < len) { + final int consumed = translate(input, pos, out); + if (consumed == 0) { + // inlined implementation of Character.toChars(Character.codePointAt(input, pos)) + // avoids allocating temp char arrays and duplicate checks + char c1 = input.charAt(pos); + out.write(c1); + pos++; + if (Character.isHighSurrogate(c1) && pos < len) { + char c2 = input.charAt(pos); + if (Character.isLowSurrogate(c2)) { + out.write(c2); + pos++; + } + } + continue; + } + // contract with translators is that they have to understand codepoints + // and they just took care of a surrogate pair + for (int pt = 0; pt < consumed; pt++) { + pos += Character.charCount(Character.codePointAt(input, pos)); + } + } + } + + /** + * Helper method to create a merger of this translator with another set of + * translators. Useful in customizing the standard functionality. + * + * @param translators CharSequenceTranslator array of translators to merge with this one + * @return CharSequenceTranslator merging this translator with the others + */ + public final CharSequenceTranslator with(final CharSequenceTranslator... translators) { + final CharSequenceTranslator[] newArray = new CharSequenceTranslator[translators.length + 1]; + newArray[0] = this; + System.arraycopy(translators, 0, newArray, 1, translators.length); + return new AggregateTranslator(newArray); + } + + } + + /** + * Adapted from apache commons-lang3 project. + * <p> + * Translates a value using a lookup table. + * + * @since 3.0 + */ + private static class LookupTranslator extends CharSequenceTranslator { + + private final HashMap<String, String> lookupMap; + private final HashSet<Character> prefixSet; + private final int shortest; + private final int longest; + + /** + * Define the lookup table to be used in translation + * <p> + * Note that, as of Lang 3.1, the key to the lookup table is converted to a + * java.lang.String. This is because we need the key to support hashCode and + * equals(Object), allowing it to be the key for a HashMap. See LANG-882. + * + * @param lookup CharSequence[][] table of size [*][2] + */ + public LookupTranslator(final CharSequence[]... lookup) { + lookupMap = new HashMap<>(); + prefixSet = new HashSet<>(); + int _shortest = Integer.MAX_VALUE; + int _longest = 0; + if (lookup != null) { + for (final CharSequence[] seq : lookup) { + this.lookupMap.put(seq[0].toString(), seq[1].toString()); + this.prefixSet.add(seq[0].charAt(0)); + final int sz = seq[0].length(); + if (sz < _shortest) { + _shortest = sz; + } + if (sz > _longest) { + _longest = sz; + } + } + } + shortest = _shortest; + longest = _longest; + } + + /** + * {@inheritDoc} + */ + @Override + public int translate(final CharSequence input, final int index, final Writer out) throws IOException { + // check if translation exists for the input at position index + if (prefixSet.contains(input.charAt(index))) { + int max = longest; + if (index + longest > input.length()) { + max = input.length() - index; + } + // implement greedy algorithm by trying maximum match first + for (int i = max; i >= shortest; i--) { + final CharSequence subSeq = input.subSequence(index, index + i); + final String result = lookupMap.get(subSeq.toString()); + + if (result != null) { + out.write(result); + return i; + } + } + } + return 0; + } + } + + /** + * Adapted from apache commons-lang3 project. + * <p> + * Executes a sequence of translators one after the other. Execution ends whenever + * the first translator consumes codepoints from the input. + * + * @since 3.0 + */ + private static class AggregateTranslator extends CharSequenceTranslator { + + private final CharSequenceTranslator[] translators; + + /** + * Specify the translators to be used at creation time. + * + * @param translators CharSequenceTranslator array to aggregate + */ + public AggregateTranslator(final CharSequenceTranslator... translators) { + this.translators = translators == null ? null : translators.clone(); + } + + /** + * The first translator to consume codepoints from the input is the 'winner'. + * Execution stops with the number of consumed codepoints being returned. + * {@inheritDoc} + */ + @Override + public int translate(final CharSequence input, final int index, final Writer out) throws IOException { + for (final CharSequenceTranslator translator : translators) { + final int consumed = translator.translate(input, index, out); + if (consumed != 0) { + return consumed; + } + } + return 0; + } + + } + + /** + * Adapted from apache commons-lang3 project. + * <p> + * Translate escaped octal Strings back to their octal values. + * <p> + * For example, "\45" should go back to being the specific value (a %). + * <p> + * Note that this currently only supports the viable range of octal for Java; namely + * 1 to 377. This is because parsing Java is the main use case. + * + * @since 3.0 + */ + private static class OctalUnescaper extends CharSequenceTranslator { + + /** + * {@inheritDoc} + */ + @Override + public int translate(final CharSequence input, final int index, final Writer out) throws IOException { + final int remaining = input.length() - index - 1; // how many characters left, ignoring the first \ + final StringBuilder builder = new StringBuilder(); + if (input.charAt(index) == '\\' && remaining > 0 && isOctalDigit(input.charAt(index + 1))) { + final int next = index + 1; + final int next2 = index + 2; + final int next3 = index + 3; + + // we know this is good as we checked it in the if block above + builder.append(input.charAt(next)); + + if (remaining > 1 && isOctalDigit(input.charAt(next2))) { + builder.append(input.charAt(next2)); + if (remaining > 2 && isZeroToThree(input.charAt(next)) && isOctalDigit(input.charAt(next3))) { + builder.append(input.charAt(next3)); + } + } + + out.write(Integer.parseInt(builder.toString(), 8)); + return 1 + builder.length(); + } + return 0; + } + + /** + * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to + * 7. + * + * @param ch the char to check + * @return true if the given char is the character representation of one of the digits from 0 to 7 + */ + private boolean isOctalDigit(final char ch) { + return ch >= '0' && ch <= '7'; + } + + /** + * Checks if the given char is the character representation of one of the digit from 0 to 3. + * + * @param ch the char to check + * @return true if the given char is the character representation of one of the digits from 0 to 3 + */ + private boolean isZeroToThree(final char ch) { + return ch >= '0' && ch <= '3'; + } + } + + /** + * Adapted from apache commons-lang3 project. + * <p> + * Translates escaped Unicode values of the form \\u+\d\d\d\d back to + * Unicode. It supports multiple 'u' characters and will work with or + * without the +. + * + * @since 3.0 + */ + private static class UnicodeUnescaper extends CharSequenceTranslator { + + /** + * {@inheritDoc} + */ + @Override + public int translate(final CharSequence input, final int index, final Writer out) throws IOException { + if (input.charAt(index) == '\\' && index + 1 < input.length() && input.charAt(index + 1) == 'u') { + // consume optional additional 'u' chars + int i = 2; + while (index + i < input.length() && input.charAt(index + i) == 'u') { + i++; + } + + if (index + i < input.length() && input.charAt(index + i) == '+') { + i++; + } + + if (index + i + 4 <= input.length()) { + // Get 4 hex digits + final CharSequence unicode = input.subSequence(index + i, index + i + 4); + + try { + final int value = Integer.parseInt(unicode.toString(), 16); + out.write((char) value); + } catch (final NumberFormatException nfe) { + throw new IllegalArgumentException("Unable to parse unicode value: " + unicode, nfe); + } + return i + 4; + } + throw new IllegalArgumentException("Less than 4 hex digits in unicode value: '" + input.subSequence(index, input.length()) + + "' due to end of CharSequence"); + } + return 0; + } + } + +}
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