com.helger.html.markdown.MarkdownHelper 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.markdown;
import java.util.Locale;
import javax.annotation.CheckForSigned;
import javax.annotation.Nonnull;
import com.helger.commons.collection.ArrayHelper;
import com.helger.commons.random.RandomHelper;
/**
* Utilities.
*
* @author René Jeschke <[email protected]>
*/
final class MarkdownHelper
{
private static final char [] ESCAPE_CHARS = new char [] { '\\',
'[',
']',
'(',
')',
'{',
'}',
'#',
'"',
'\'',
'.',
'>',
'<',
'*',
'+',
'-',
'_',
'!',
'`',
'^' };
/**
* @return A pseudo random number between 0 and 1023
*/
public static int rnd ()
{
return RandomHelper.getRandom ().nextInt (1024);
}
/**
* Skips spaces in the given String.
*
* @param in
* Input String.
* @param start
* Starting position.
* @return The new position or -1 if EOL has been reached.
*/
public static int skipSpaces (final String in, final int start)
{
int pos = start;
while (pos < in.length () && (in.charAt (pos) == ' ' || in.charAt (pos) == '\n'))
pos++;
return pos < in.length () ? pos : -1;
}
public static boolean isEscapeChar (final char ch)
{
return ArrayHelper.contains (ESCAPE_CHARS, ch);
}
/**
* Processed the given escape sequence.
*
* @param out
* The StringBuilder to write to.
* @param ch
* The character.
* @param pos
* Current parsing position.
* @return The new position.
*/
private static int _escape (final StringBuilder out, final char ch, final int pos)
{
if (isEscapeChar (ch))
{
out.append (ch);
return pos + 1;
}
out.append ('\\');
return pos;
}
/**
* Reads characters until any 'end' character is encountered.
*
* @param out
* The StringBuilder to write to.
* @param in
* The Input String.
* @param start
* Starting position.
* @param end
* End characters.
* @return The new position or -1 if no 'end' char was found.
*/
public static int readUntil (final StringBuilder out, final String in, final int start, final char... end)
{
int pos = start;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
if (ch == '\\' && pos + 1 < in.length ())
{
pos = _escape (out, in.charAt (pos + 1), pos);
}
else
{
boolean endReached = false;
for (final char element : end)
{
if (ch == element)
{
endReached = true;
break;
}
}
if (endReached)
break;
out.append (ch);
}
pos++;
}
return pos == in.length () ? -1 : pos;
}
/**
* Reads characters until the 'end' character is encountered.
*
* @param out
* The StringBuilder to write to.
* @param in
* The Input String.
* @param start
* Starting position.
* @param end
* End characters.
* @return The new position or -1 if no 'end' char was found.
*/
public static int readUntil (final StringBuilder out, final String in, final int start, final char end)
{
int pos = start;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
if (ch == '\\' && pos + 1 < in.length ())
{
pos = _escape (out, in.charAt (pos + 1), pos);
}
else
{
if (ch == end)
break;
out.append (ch);
}
pos++;
}
return pos == in.length () ? -1 : pos;
}
/**
* Reads a markdown link.
*
* @param out
* The StringBuilder to write to.
* @param in
* Input String.
* @param start
* Starting position.
* @return The new position or -1 if this is no valid markdown link.
*/
public static int readMdLink (final StringBuilder out, final String in, final int start)
{
int pos = start;
int counter = 1;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
if (ch == '\\' && pos + 1 < in.length ())
{
pos = _escape (out, in.charAt (pos + 1), pos);
}
else
{
boolean endReached = false;
switch (ch)
{
case '(':
counter++;
break;
case ' ':
if (counter == 1)
endReached = true;
break;
case ')':
counter--;
if (counter == 0)
endReached = true;
break;
default:
break;
}
if (endReached)
break;
out.append (ch);
}
pos++;
}
return pos == in.length () ? -1 : pos;
}
/**
* Reads a markdown link ID.
*
* @param out
* The StringBuilder to write to.
* @param in
* Input String.
* @param start
* Starting position.
* @return The new position or -1 if this is no valid markdown link ID.
*/
public static int readMdLinkId (final StringBuilder out, final String in, final int start)
{
int pos = start;
int counter = 1;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
boolean endReached = false;
switch (ch)
{
case '\n':
out.append (' ');
break;
case '[':
counter++;
out.append (ch);
break;
case ']':
counter--;
if (counter == 0)
endReached = true;
else
out.append (ch);
break;
default:
out.append (ch);
break;
}
if (endReached)
break;
pos++;
}
return pos == in.length () ? -1 : pos;
}
/**
* Reads characters until any 'end' character is encountered, ignoring escape
* sequences.
*
* @param out
* The StringBuilder to write to.
* @param in
* The Input String.
* @param start
* Starting position.
* @param end
* End characters.
* @return The new position or -1 if no 'end' char was found.
*/
private static int _readRawUntil (final StringBuilder out, final String in, final int start, final char... end)
{
int pos = start;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
boolean endReached = false;
for (final char element : end)
{
if (ch == element)
{
endReached = true;
break;
}
}
if (endReached)
break;
out.append (ch);
pos++;
}
return pos == in.length () ? -1 : pos;
}
/**
* Reads characters until the end character is encountered, ignoring escape
* sequences.
*
* @param out
* The StringBuilder to write to.
* @param in
* The Input String.
* @param start
* Starting position.
* @param end
* End characters.
* @return The new position or -1 if no 'end' char was found.
*/
public static int readRawUntil (final StringBuilder out, final String in, final int start, final char end)
{
int pos = start;
while (pos < in.length ())
{
final char ch = in.charAt (pos);
if (ch == end)
break;
out.append (ch);
pos++;
}
return (pos == in.length ()) ? -1 : pos;
}
/**
* Append the given char as a decimal HTML entity.
*
* @param out
* The StringBuilder to write to.
* @param value
* The character.
*/
private static void _appendDecEntity (final StringBuilder out, final char value)
{
out.append ("&#").append ((int) value).append (';');
}
/**
* Append the given char as a hexadecimal HTML entity.
*
* @param out
* The StringBuilder to write to.
* @param value
* The character.
*/
private static void _appendHexEntity (final StringBuilder out, final char value)
{
out.append ("&#x").append (Integer.toHexString (value)).append (';');
}
/**
* Appends the given mailto link using obfuscation.
*
* @param out
* The StringBuilder to write to.
* @param in
* Input String.
* @param start
* Input String starting position.
* @param end
* Input String end position.
*/
public static void appendMailto (final StringBuilder out, final String in, final int start, final int end)
{
for (int i = start; i < end; i++)
{
final char c = in.charAt (i);
final int r = rnd ();
switch (c)
{
case '&':
case '<':
case '>':
case '"':
case '\'':
case '@':
if (r < 512)
_appendDecEntity (out, c);
else
_appendHexEntity (out, c);
break;
default:
if (r < 32)
out.append (c);
else
if (r < 520)
_appendDecEntity (out, c);
else
_appendHexEntity (out, c);
break;
}
}
}
/**
* Extracts the tag from an XML element.
*
* @param in
* Input String.
* @return XML tag name
*/
@Nonnull
public static String getXMLTag (final String in)
{
final StringBuilder aSB = new StringBuilder ();
int pos = 1;
if (in.charAt (1) == '/')
pos++;
while (Character.isLetterOrDigit (in.charAt (pos)))
aSB.append (in.charAt (pos++));
return aSB.toString ().toLowerCase (Locale.US);
}
/**
* Reads an XML element.
*
* @param aSB
* The StringBuilder to write to.
* @param sIn
* Input String.
* @param nStart
* Starting position.
* @param bSafeMode
* Whether to escape unsafe HTML tags or not
* @return The new position or -1 if this is no valid XML element.
*/
@CheckForSigned
public static int readXMLElement (final StringBuilder aSB,
final String sIn,
final int nStart,
final boolean bSafeMode)
{
try
{
if (sIn.charAt (nStart + 1) == '!')
{
aSB.append ("');
if (pos == -1)
return -1;
final String tag = temp.toString ().trim ().toLowerCase (Locale.US);
if (MarkdownHTML.isUnsafeHtmlElement (tag))
{
aSB.append ("<");
if (bIsCloseTag)
aSB.append ('/');
aSB.append (temp);
}
else
{
aSB.append ('<');
if (bIsCloseTag)
aSB.append ('/');
aSB.append (temp);
}
}
else
{
aSB.append ('<');
if (bIsCloseTag)
aSB.append ('/');
pos = _readRawUntil (aSB, sIn, pos, ' ', '/', '>');
}
if (pos == -1)
return -1;
pos = _readRawUntil (aSB, sIn, pos, '/', '>');
if (sIn.charAt (pos) == '/')
{
aSB.append (" /");
pos = readRawUntil (aSB, sIn, pos + 1, '>');
if (pos == -1)
return -1;
}
if (sIn.charAt (pos) == '>')
{
aSB.append ('>');
return pos + 1;
}
}
catch (final StringIndexOutOfBoundsException e)
{
return -1;
}
return -1;
}
/**
* Removes trailing ` and trims spaces.
*
* @param fenceLine
* Fenced code block starting line
* @return Rest of the line after trimming and backtick removal
* @since 0.7
*/
@Nonnull
public static String getMetaFromFence (final String fenceLine)
{
for (int i = 0; i < fenceLine.length (); i++)
{
final char c = fenceLine.charAt (i);
if (!Character.isWhitespace (c) && c != '`' && c != '~' && c != '%')
{
return fenceLine.substring (i).trim ();
}
}
return "";
}
}
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