com.google.common.escape

Class ArrayBasedCharEscaper

java.lang.Object

com.google.common.escape.Escaper

com.google.common.escape.CharEscaper

com.google.common.escape.ArrayBasedCharEscaper

@Beta
 @GwtCompatible
public abstract class ArrayBasedCharEscaper
extends CharEscaper

A CharEscaper that uses an array to quickly look up replacement characters for a given char value. An additional safe range is provided that determines whether char values without specific replacements are to be considered safe and left unescaped or should be escaped in a general way.

A good example of usage of this class is for Java source code escaping where the replacement array contains information about special ASCII characters such as \\t and \\n while escapeUnsafe(char) is overridden to handle general escaping of the form \\uxxxx.

The size of the data structure used by ArrayBasedCharEscaper is proportional to the highest valued character that requires escaping. For example a replacement map containing the single character '\u1000' will require approximately 16K of memory. If you need to create multiple escaper instances that have the same character replacement mapping consider using ArrayBasedEscaperMap.

Since:

15.0

Author:

Sven Mawson, David Beaumont

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ArrayBasedCharEscaper(ArrayBasedEscaperMap escaperMap, char safeMin, char safeMax) Creates a new ArrayBasedCharEscaper instance with the given replacement map and specified safe range.
protected	ArrayBasedCharEscaper(Map<Character,String> replacementMap, char safeMin, char safeMax) Creates a new ArrayBasedCharEscaper instance with the given replacement map and specified safe range.

Method Summary

Modifier and Type	Method and Description
protected char[]	escape(char c) Escapes a single character using the replacement array and safe range values.
String	escape(String s) Returns the escaped form of a given literal string.
protected abstract char[]	escapeUnsafe(char c) Escapes a char value that has no direct explicit value in the replacement array and lies outside the stated safe range.

Methods inherited from class com.google.common.escape.CharEscaper

escapeSlow

Methods inherited from class com.google.common.escape.Escaper

asFunction

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayBasedCharEscaper

protected ArrayBasedCharEscaper(Map<Character,String> replacementMap,
                                char safeMin,
                                char safeMax)

Creates a new ArrayBasedCharEscaper instance with the given replacement map and specified safe range. If safeMax < safeMin then no characters are considered safe.

If a character has no mapped replacement then it is checked against the safe range. If it lies outside that, then escapeUnsafe(char) is called, otherwise no escaping is performed.

Parameters:

replacementMap - a map of characters to their escaped representations

safeMin - the lowest character value in the safe range

safeMax - the highest character value in the safe range

ArrayBasedCharEscaper

protected ArrayBasedCharEscaper(ArrayBasedEscaperMap escaperMap,
                                char safeMin,
                                char safeMax)

Creates a new ArrayBasedCharEscaper instance with the given replacement map and specified safe range. If safeMax < safeMin then no characters are considered safe. This initializer is useful when explicit instances of ArrayBasedEscaperMap are used to allow the sharing of large replacement mappings.

If a character has no mapped replacement then it is checked against the safe range. If it lies outside that, then escapeUnsafe(char) is called, otherwise no escaping is performed.

Parameters:

escaperMap - the mapping of characters to be escaped

safeMin - the lowest character value in the safe range

safeMax - the highest character value in the safe range

Method Detail

escape

public final String escape(String s)

Description copied from class: CharEscaper

Returns the escaped form of a given literal string.

Overrides:

escape in class CharEscaper

Parameters:

s - the literal string to be escaped

Returns:

the escaped form of string

escape

protected final char[] escape(char c)

Escapes a single character using the replacement array and safe range values. If the given character does not have an explicit replacement and lies outside the safe range then escapeUnsafe(char) is called.

Specified by:

escape in class CharEscaper

Parameters:

c - the character to escape if necessary

Returns:

the replacement characters, or null if no escaping was needed

escapeUnsafe

protected abstract char[] escapeUnsafe(char c)

Escapes a char value that has no direct explicit value in the replacement array and lies outside the stated safe range. Subclasses should override this method to provide generalized escaping for characters.

Note that arrays returned by this method must not be modified once they have been returned. However it is acceptable to return the same array multiple times (even for different input characters).

Parameters:

c - the character to escape

Returns:

the replacement characters, or null if no escaping was required