Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Click here to view the latest version of this page.
PrevUpHomeNext

Qi Seek Parser Directive

Description

The seek[] parser-directive skips all input until the subject parser matches. On failure, the current position is the end of the input.

Header
// forwards to <boost/spirit/repository/home/qi/directive/seek.hpp>
#include <boost/spirit/repository/include/qi_seek.hpp>

Also, see Include Structure.

Namespace

Name

boost::spirit::repository::qi::seek

Model of

UnaryParser

Notation

a

A Parser.

Expression Semantics

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

Expression

Semantics

seek[a]

Advances until the parser a matches.

Attributes

See Compound Attribute Notation.

Expression

Attribute

seek[a]

a: A --> seek[a]: A
a: Unused --> seek[a]: Unused

Complexity

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

Example

The following example shows a simple use case of the seek[] directive, seeking all the ints preceding by '#'. (For the full source of the example, see seek.cpp)

Some namespace aliases:

namespace qi = boost::spirit::qi;
namespace ka = boost::spirit::karma;
namespace repo = boost::spirit::repository;

The input iterators and the attribute to store the result:

iterator it = line.begin();
iterator end = line.end();
std::vector<int> val;

Parsing and showing the result:

if (qi::phrase_parse(it, end, +repo::qi::seek["#" >> qi::int_], qi::space, val))
{
    std::cout << "-------------------------------- \n";
    std::cout << "Parsing succeeded, got: "
              << ka::format("[ " << ka::int_ % ", " << " ]\n", val);
    std::cout << "---------------------------------\n";
}

Input:

1 will not be outputted while #2, ##3 and # 4 will.

Output:

--------------------------------
Parsing succeeded, got: [ 2, 3, 4 ]
---------------------------------

PrevUpHomeNext