org.yaml.snakeyaml.external.com.google.gdata.util.common.base

## Class PercentEscaper

- java.lang.Object
- - org.yaml.snakeyaml.external.com.google.gdata.util.common.base.UnicodeEscaper
  - - org.yaml.snakeyaml.external.com.google.gdata.util.common.base.PercentEscaper

All Implemented Interfaces:
  Escaper

    public class PercentEscaper
    extends UnicodeEscaper

A `UnicodeEscaper` that escapes some set of Java characters using the URI percent encoding scheme. The set of safe characters (those which remain unescaped) can be specified on construction.

For details on escaping URIs for use in web pages, see section 2.4 of RFC 3986.

In most cases this class should not need to be used directly. If you have no special requirements for escaping your URIs, you should use either `CharEscapers#uriEscaper()` or `CharEscapers#uriEscaper(boolean)`.

When encoding a String, the following rules apply:

- The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain the same.
- Any additionally specified safe characters remain the same.
- If `plusForSpace` was specified, the space character " " is converted into a plus sign "+".
- All other characters are converted into one or more bytes using UTF-8 encoding and each byte is then represented by the 3-character string "%XY", where "XY" is the two-digit, uppercase, hexadecimal representation of the byte value.

RFC 2396 specifies the set of unreserved characters as "-", "_", ".", "!", "~", "*", "'", "(" and ")". It goes on to state:

Unreserved characters can be escaped without changing the semantics of the URI, but this should not be done unless the URI is being used in a context that does not allow the unescaped character to appear.

For performance reasons the only currently supported character encoding of this class is UTF-8.

Note: This escaper produces uppercase hexidecimal sequences. From RFC 3986:
"URI producers and normalizers should use uppercase hexadecimal digits for all percent-encodings."

### Field Summary

Fields
`static java.lang.String` `SAFECHARS_URLENCODER` A string of safe characters that mimics the behavior of `URLEncoder`.
`static java.lang.String` `SAFEPATHCHARS_URLENCODER` A string of characters that do not need to be encoded when used in URI path segments, as specified in RFC 3986.
`static java.lang.String` `SAFEQUERYSTRINGCHARS_URLENCODER` A string of characters that do not need to be encoded when used in URI query strings, as specified in RFC 3986.

### Constructor Summary

Constructors
Constructor and Description
`PercentEscaper(java.lang.String safeChars, boolean plusForSpace)` Constructs a URI escaper with the specified safe characters and optional handling of the space character.

### Method Summary

Methods
`protected char[]` `escape(int cp)` Escapes the given Unicode code point in UTF-8.
`java.lang.String` `escape(java.lang.String s)` Returns the escaped form of a given literal string.
`protected int` `nextEscapeIndex(java.lang.CharSequence csq, int index, int end)` Scans a sub-sequence of characters from a given `CharSequence`, returning the index of the next character that requires escaping.

### Methods inherited from class org.yaml.snakeyaml.external.com.google.gdata.util.common.base.UnicodeEscaper

`codePointAt, escape, escapeSlow`

### Methods inherited from class java.lang.Object

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

### Field Detail

#### SAFECHARS_URLENCODER

    public static final java.lang.String SAFECHARS_URLENCODER

A string of safe characters that mimics the behavior of `URLEncoder`.

See Also:
  Constant Field Values

#### SAFEPATHCHARS_URLENCODER

    public static final java.lang.String SAFEPATHCHARS_URLENCODER

A string of characters that do not need to be encoded when used in URI path segments, as specified in RFC 3986. Note that some of these characters do need to be escaped when used in other parts of the URI.

See Also:
  Constant Field Values

#### SAFEQUERYSTRINGCHARS_URLENCODER

    public static final java.lang.String SAFEQUERYSTRINGCHARS_URLENCODER

A string of characters that do not need to be encoded when used in URI query strings, as specified in RFC 3986. Note that some of these characters do need to be escaped when used in other parts of the URI.

See Also:
  Constant Field Values

### Constructor Detail

#### PercentEscaper

    public PercentEscaper(java.lang.String safeChars,
                  boolean plusForSpace)

Constructs a URI escaper with the specified safe characters and optional handling of the space character.

Parameters:
  `safeChars` - a non null string specifying additional safe characters for this escaper (the ranges 0..9, a..z and A..Z are always safe and should not be specified here)
  `plusForSpace` - true if ASCII space should be escaped to `+` rather than `%20`
Throws:
  `java.lang.IllegalArgumentException` - if any of the parameters were invalid

### Method Detail

#### nextEscapeIndex

    protected int nextEscapeIndex(java.lang.CharSequence csq,
                      int index,
                      int end)

Description copied from class: `UnicodeEscaper`
Scans a sub-sequence of characters from a given `CharSequence`, returning the index of the next character that requires escaping.

Note: When implementing an escaper, it is a good idea to override this method for efficiency. The base class implementation determines successive Unicode code points and invokes `UnicodeEscaper.escape(int)` for each of them. If the semantics of your escaper are such that code points in the supplementary range are either all escaped or all unescaped, this method can be implemented more efficiently using `CharSequence.charAt(int)`.

Note however that if your escaper does not escape characters in the supplementary range, you should either continue to validate the correctness of any surrogate characters encountered or provide a clear warning to users that your escaper does not validate its input.

See `PercentEscaper` for an example.

Overrides:
  `nextEscapeIndex` in class `UnicodeEscaper`
Parameters:
  `csq` - a sequence of characters
  `index` - the index of the first character to be scanned
  `end` - the index immediately after the last character to be scanned

#### escape

    public java.lang.String escape(java.lang.String s)

Description copied from class: `UnicodeEscaper`
Returns the escaped form of a given literal string.

If you are escaping input in arbitrary successive chunks, then it is not generally safe to use this method. If an input string ends with an unmatched high surrogate character, then this method will throw `IllegalArgumentException`. You should either ensure your input is valid UTF-16 before calling this method or use an escaped `Appendable` (as returned by `UnicodeEscaper.escape(Appendable)`) which can cope with arbitrarily split input.

Note: When implementing an escaper it is a good idea to override this method for efficiency by inlining the implementation of `UnicodeEscaper.nextEscapeIndex(CharSequence, int, int)` directly. Doing this for `PercentEscaper` more than doubled the performance for unescaped strings (as measured by `CharEscapersBenchmark`).

Specified by:
  `escape` in interface `Escaper`
Overrides:
  `escape` in class `UnicodeEscaper`
Parameters:
  `s` - the literal string to be escaped
Returns:
  the escaped form of `string`

#### escape

    protected char[] escape(int cp)

Escapes the given Unicode code point in UTF-8.

Specified by:
  `escape` in class `UnicodeEscaper`
Parameters:
  `cp` - the Unicode code point to escape if necessary
Returns:
  the replacement characters, or `null` if no escaping was needed