Character Classification Parsers (alnum, digit, etc.)

Character Classification Parsers (`alnum`, `digit`, etc.)

Description

The library has the full repertoire of single character parsers for character classification. This includes the usual alnum, alpha, digit, xdigit, etc. parsers. These parsers have an associated Character Encoding Namespace. This is needed when doing basic operations such as inhibiting case sensitivity.

Header

// forwards to <boost/spirit/home/qi/char/char_class.hpp>
#include <boost/spirit/include/qi_char_class.hpp>

Also, see Include Structure.

Namespace

Name
`ns::alnum`
`ns::alpha`
`ns::blank`
`ns::cntrl`
`ns::digit`
`ns::graph`
`ns::lower`
`ns::print`
`ns::punct`
`ns::space`
`ns::upper`
`ns::xdigit`

In the table above, ns represents a Character Encoding Namespace.

Model of

PrimitiveParser

Notation

ns: A Character Encoding Namespace.

Expression Semantics

Semantics of an expression is defined only where it differs from, or is not defined in PrimitiveParser.

Expression	Semantics
`ns::alnum`	Matches alpha-numeric characters
`ns::alpha`	Matches alphabetic characters
`ns::blank`	Matches spaces or tabs
`ns::cntrl`	Matches control characters
`ns::digit`	Matches numeric digits
`ns::graph`	Matches non-space printing characters
`ns::lower`	Matches lower case letters
`ns::print`	Matches printable characters
`ns::punct`	Matches punctuation symbols
`ns::space`	Matches spaces, tabs, returns, and newlines
`ns::upper`	Matches upper case letters
`ns::xdigit`	Matches hexadecimal digits

Attributes

The character type of the Character Encoding Namespace, ns.

Complexity

O(N)

Example

	Note
	The test harness for the example(s) below is presented in the Basics Examples section.

Some using declarations:

using boost::spirit::ascii::alnum;
using boost::spirit::ascii::blank;
using boost::spirit::ascii::digit;
using boost::spirit::ascii::lower;

Basic usage:

test_parser("1", alnum);
test_parser(" ", blank);
test_parser("1", digit);
test_parser("a", lower);