CODEWITHSUNDEEP
javaunicodeutf-16javacc
java.is.for.desktop
java.is.for.desktop

Reputation: 11216

Java, JavaCC: How to parse characters outside the BMP?

I am referring to the XML 1.1 spec.

Look at the definition of NameStartChar:

NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]

If I interpret this correctly, the last range (#x10000-#xEFFFF) goes beyond the UTF16 range of Java's char type. So it must be UTF32, right? So, I need to check pairs of char against this range, instead of single chars, right?

My questions are:

Thank you!

NOTE: Don't worry, I am not trying to write an own XML-parser.
EDIT: I am writing a parser, which would check if text input from miscellaneous (non-XML) text formats would match valid XML names.

Upvotes: 7

Views: 1736

Answers (2)

Kirby
Kirby

Reputation: 15855

I've found http://www.fileformat.info/info/unicode/char/10000/index.htm to be a handy site for learning about Unicode characters.

For example, u+10000 and u+10FFFF are 

String first = "\uD800\uDC00"; // u10000
String last = "\uDBFF\uDFFF"; // u10FFFF

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500555

Have a look at Character.toCodePoint(char, char) which will convert a surrogate pair into a full range code point. String.codePointAt may well be useful to you, too.

There's a lot of other surrogate support within Character and String. To know exactly which methods to call, we'd need to know the exact details of your situation.

Upvotes: 4

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