com.helger.html.js.JSMarshaller Maven / Gradle / Ivy
/**
* Copyright (C) 2014-2016 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* 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.helger.html.js;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import com.helger.commons.collection.ArrayHelper;
import com.helger.commons.collection.ext.CommonsHashSet;
import com.helger.commons.collection.ext.ICommonsSet;
import com.helger.commons.string.StringHelper;
/**
* JavaScript String helper
*
* @author Philip Helger
*/
@Immutable
public final class JSMarshaller
{
private static final char [] CHARS_TO_MASK = new char [] { '"', '\'', '\\', '/', '\t', '\r', '\n', '\f' };
private static final char [] CHARS_TO_MASK_REGEX = new char [] { '\\',
'^',
'$',
'*',
'+',
'?',
'|',
'.',
'-',
'[',
']',
'(',
')',
'{',
'}' };
private static final char MASK_CHAR = '\\';
private static final char MASK_CHAR_REGEX = '\\';
/**
* All reserved keywords of JS. see here
* technically the last few are not reserved words but they cannot be used as
* identifiers.
*/
private static final ICommonsSet RESERVED_KEYWORDS = new CommonsHashSet <> ("break",
"case",
"catch",
"continue",
"debugger",
"default",
"delete",
"do",
"else",
"finally",
"for",
"function",
"if",
"in",
"instanceof",
"new",
"return",
"switch",
"this",
"throw",
"try",
"typeof",
"var",
"void",
"while",
"with",
"class",
"enum",
"export",
"extends",
"import",
"super",
// non-reserved
"true",
"false",
"null",
"undefined");
private JSMarshaller ()
{}
/**
* Turn special characters into escaped characters conforming to JavaScript.
* Handles complete character set defined in HTML 4.01 recommendation.
* Reference: Core JavaScript 1.5 Guide
*
* @param sInput
* the input string
* @return the escaped string
*/
@Nullable
public static String javaScriptEscape (@Nullable final String sInput)
{
if (StringHelper.hasNoText (sInput))
return sInput;
final char [] aInput = sInput.toCharArray ();
if (!StringHelper.containsAny (aInput, CHARS_TO_MASK))
return sInput;
final char [] ret = new char [aInput.length * 2];
int nIndex = 0;
char cPrevChar = '\u0000';
for (final char cCurrent : aInput)
{
switch (cCurrent)
{
case '"':
case '\'':
case '\\':
case '/':
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = cCurrent;
break;
case '\t':
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = 't';
break;
case '\n':
if (cPrevChar != '\r')
{
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = 'n';
}
break;
case '\r':
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = 'n';
break;
case '\f':
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = 'f';
break;
default:
ret[nIndex++] = cCurrent;
break;
}
cPrevChar = cCurrent;
}
return new String (ret, 0, nIndex);
}
@Nonnull
public static String javaScriptEscapeForRegEx (final char cInput)
{
if (ArrayHelper.contains (CHARS_TO_MASK_REGEX, cInput))
return new StringBuilder (2).append (MASK_CHAR_REGEX).append (cInput).toString ();
return Character.toString (cInput);
}
/**
* Turn special regular expression characters into escaped characters
* conforming to JavaScript.
* Reference: MDN Regular Expressions
*
* @param sInput
* the input string
* @return the escaped string
*/
@Nullable
public static String javaScriptEscapeForRegEx (@Nullable final String sInput)
{
if (StringHelper.hasNoText (sInput))
return sInput;
final char [] aInput = sInput.toCharArray ();
if (!StringHelper.containsAny (aInput, CHARS_TO_MASK_REGEX))
return sInput;
// At last each character has one masking character
final char [] ret = new char [aInput.length * 2];
int nIndex = 0;
for (final char cCurrent : aInput)
if (ArrayHelper.contains (CHARS_TO_MASK_REGEX, cCurrent))
{
ret[nIndex++] = MASK_CHAR_REGEX;
ret[nIndex++] = cCurrent;
}
else
ret[nIndex++] = cCurrent;
return new String (ret, 0, nIndex);
}
/**
* Unescape a previously escaped string.
* Important: this is not a 100% reversion of
* {@link #javaScriptEscape(String)} since the escaping method drops any '\r'
* character and it will therefore not be unescaped!
*
* @param sInput
* The string to be unescaped. May be null.
* @return The unescaped string.
* @see #javaScriptEscape(String)
*/
@Nullable
public static String javaScriptUnescape (@Nullable final String sInput)
{
if (StringHelper.hasNoText (sInput))
return sInput;
final char [] aInput = sInput.toCharArray ();
if (!ArrayHelper.contains (aInput, MASK_CHAR))
return sInput;
final char [] ret = new char [aInput.length];
int nIndex = 0;
char cPrevChar = '\u0000';
for (int i = 0; i < aInput.length; i++)
{
final char cCurrent = aInput[i];
if (cPrevChar == MASK_CHAR)
{
switch (cCurrent)
{
case '"':
case '\'':
case '\\':
case '/':
ret[nIndex++] = cCurrent;
break;
case 't':
ret[nIndex++] = '\t';
break;
case 'n':
ret[nIndex++] = '\n';
break;
case 'f':
ret[nIndex++] = '\f';
break;
case 'x':
final char cHex1 = aInput[++i];
final char cHex2 = aInput[++i];
ret[nIndex++] = (char) StringHelper.getHexByte (cHex1, cHex2);
break;
default:
ret[nIndex++] = MASK_CHAR;
ret[nIndex++] = cCurrent;
break;
}
cPrevChar = 0;
}
else
{
if (cCurrent != MASK_CHAR)
ret[nIndex++] = cCurrent;
cPrevChar = cCurrent;
}
}
// Last char is a mask char? append!
if (cPrevChar == MASK_CHAR)
ret[nIndex++] = MASK_CHAR;
return new String (ret, 0, nIndex);
}
public static boolean isJSIdentifier (@Nullable final String s)
{
if (StringHelper.hasNoText (s))
return false;
// Reserved word?
if (RESERVED_KEYWORDS.contains (s))
return false;
final char [] aChars = s.toCharArray ();
for (int i = 0; i < aChars.length; ++i)
{
if (i == 0)
{
if (!Character.isJavaIdentifierStart (aChars[i]))
return false;
}
else
{
if (!Character.isJavaIdentifierPart (aChars[i]))
return false;
}
}
return true;
}
}
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