Parser Directive Inhibiting Case Sensitivity (no_case[])

Parser Directive Inhibiting Case Sensitivity (`no_case[]`)

Description

The no_case[] directive does not consume any input. The actual matching is done by its subject parser. It's purpose is to force matching of the subject parser (and all its children) to be case insensitive.

Header

// forwards to <boost/spirit/home/qi/directive/no_case.hpp>
#include <boost/spirit/include/qi_no_case.hpp>

Also, see Include Structure.

Namespace

Name
`ns::no_case`

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

Model of

The model of no_case is the model of its subject parser.

Notation

a: A Parser.
ns: A Character Encoding Namespace.

Expression Semantics

Semantics of an expression is defined only where it differs from, or is not defined in the subject's concept.

Expression	Semantics
`ns::no_case[a]`	Force matching of the subject parser, `a` (and all its children) to be case insensitive

Attributes

See Compound Attribute Notation.

Expression	Attribute
`ns::no_case[a]`	a: A --> ns::no_case[a]: A a: Unused --> ns::no_case[a]: Unused

Expression

Attribute

ns::no_case[a]

a: A --> ns::no_case[a]: A
a: Unused --> ns::no_case[a]: Unused

Complexity

The complexity is defined by the complexity of the subject parser, a

Example

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

Some using declarations:

using boost::spirit::ascii::no_case;
using boost::spirit::ascii::char_;
using boost::spirit::ascii::alnum;
using boost::spirit::qi::symbols;

Simple usage of no_case[]:

test_parser("X", no_case[char_('x')]);
test_parser("6", no_case[alnum]);

A more sophisticated use case of no_case[] in conjunction with a symbol table (see symbols<> for more details):

symbols<char, int> sym;

sym.add
    ("apple", 1)    // symbol strings are added in lowercase...
    ("banana", 2)
    ("orange", 3)
;

int i;
// ...because sym is used for case-insensitive parsing
test_parser_attr("Apple", no_case[ sym ], i);
std::cout << i << std::endl;
test_parser_attr("ORANGE", no_case[ sym ], i);
std::cout << i << std::endl;