Create a new default character set mapping instance. This class is the parent
class of all of the charmapping subclasses, and only implements basic US-ASCII
mapping. The subclasses implement all other charsets, some algorithmically, and
some in a table-based way. Use CharmapFactory to create the correct
subclass instance for the desired charmap.
All mappings are done to or from Unicode in the UTF-16 encoding, which is the base
character set and encoding used by Javascript itself. In order to convert
between two non-Unicode character sets, you must chain two charmap instances together
to first map to Unicode and then back to the second charset.
The options parameter controls which mapping is constructed and its behaviours. The
current list of supported options are:
- missing - specify what to do if a mapping is missing for a particular
character. For example, if you are mapping Unicode characters to a particular native
character set that does not support particular Unicode characters, the mapper will
follow the behaviour specified in this property. Valid values are:
- skip - skip any characters that do not exist in the target charset
- placeholder - put a static placeholder character in the output string
wherever there is an unknown character in the input string. Use the placeholder
parameter to specify which character to use in this case
- escape - use an escape sequence to represent the unknown character
The default value for the missing property if not otherwise specified is "escape"
so that information is not lost.
- placeholder - specify the placeholder character to use when the
mapper cannot map a particular input character to the output string. If this
option is not specified, then the '?' (question mark) character is used where
possible.
- escapeStyle - what style of escape sequences should be used to
escape unknown characters in the input when mapping to native, and what
style of espcae sequences should be parsed when mapping to Unicode. Valid
values are:
- html - Escape the characters as HTML entities. This would use
the standard HTML 5.0 (or later) entity names where possible, and numeric
entities in all other cases. Eg. an "e" with an acute accent would be
"é"
- js - Use the Javascript escape style. Eg. an "e" with an acute
accent would be "\u00E9". This can also be specified as "c#" as
it uses a similar escape syntax.
- c - Use the C/C++ escape style, which is similar to the the
Javascript style, but uses an "x" in place of the "u". Eg. an "e" with an
acute accent would be "\x00E9". This can also be specified as "c++".
- java - Use the Java escape style. This is very similar to the
the Javascript style, but the backslash has to be escaped twice. Eg. an
"e" with an acute accent would be "\\u00E9". This can also be specified
as "ruby", as Ruby uses a similar escape syntax with double backslashes.
- perl - Use the Perl escape style. Eg. an "e" with an acute
accent would be "\N{U+00E9}"
The default if this style is not specified is "js" for Javascript.
If this copy of ilib is pre-assembled and all the data is already available,
or if the data was already previously loaded, then this constructor will call
the onLoad callback immediately when the initialization is done.
If the onLoad option is not given, this class will only attempt to load any
missing data synchronously.