libs/spirit/doc/lex/quick_reference.qbk
[/==============================================================================
Copyright (C) 2001-2011 Joel de Guzman
Copyright (C) 2001-2011 Hartmut Kaiser
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
===============================================================================/]
This quick reference section is provided for convenience. You can use
this section as a sort of a "cheat-sheet" on the most commonly used Lex
components. It is not intended to be complete, but should give you an
easy way to recall a particular component without having to dig through
pages and pages of reference documentation.
[/////////////////////////////////////////////////////////////////////////////]
[section Common Notation]
[variablelist Notation
[[`L`] [Lexer type]]
[[`l, a, b, c, d`] [Lexer objects]]
[[`Iterator`] [The type of an iterator referring to the underlying
input sequence]]
[[`IdType`] [The token id type]]
[[`Context`] [The lexer components `Context` type]]
[[`ch`] [Character-class specific character (See __char_class_types__)]]
[[`Ch`] [Character-class specific character type (See __char_class_types__)]]
[[`str`] [Character-class specific string (See __char_class_types__)]]
[[`Str`] [Character-class specific string type (See __char_class_types__)]]
[[`Attrib`] [An attribute type]]
[[`fa`] [A semantic action function with a signature:
`void f(Iterator&, Iterator&, pass_flag&, Idtype&, Context&)`.]]
]
[endsect]
[/////////////////////////////////////////////////////////////////////////////]
[section:lexers Primitive Lexer Components]
[table
[[Expression] [Attribute] [Description]]
[[`ch`] [n/a] [Matches `ch`]]
[[`char_(ch)`] [n/a] [Matches `ch`]]
[[`str`] [n/a] [Matches regular expression `str`]]
[[`string(str)`] [n/a] [Matches regular expression `str`]]
[[`token_def<Attrib>`] [`Attrib`] [Matches the immediate argument]]
[[`a | b`] [n/a] [Matches any of the expressions `a` or `b`]]
[[`l[fa]`] [Attribute of `l`] [Call semantic action `fa` (after matching `l`).]]
]
[note The column /Attribute/ in the table above lists the parser attribute
exposed by the lexer component if it is used as a parser (see
__attribute__). A 'n/a' in this columns means the lexer component is not
usable as a parser.]
[endsect]
[/////////////////////////////////////////////////////////////////////////////]
[section Semantic Actions]
Has the form:
l[f]
where `f` is a function with the signatures:
void f();
void f(Iterator&, Iterator&);
void f(Iterator&, Iterator&, pass_flag&);
void f(Iterator&, Iterator&, pass_flag&, Idtype&);
void f(Iterator&, Iterator&, pass_flag&, Idtype&, Context&);
You can use __boost_bind__ to bind member functions. For function
objects, the allowed signatures are:
void operator()(unused_type, unused_type, unused_type, unused_type, unused_type) const;
void operator()(Iterator&, Iterator&, unused_type, unused_type, unused_type) const;
void operator()(Iterator&, Iterator&, pass_flag&, unused_type, unused_type) const;
void operator()(Iterator&, Iterator&, pass_flag&, Idtype&, unused_type) const;
void operator()(Iterator&, Iterator&, pass_flag&, Idtype&, Context&) const;
The `unused_type` is used in the signatures above to signify 'don't
care'.
For more information see __lex_actions__.
[endsect]
[/////////////////////////////////////////////////////////////////////////////]
[section Phoenix]
__phoenix__ makes it easier to attach semantic actions. You just
inline your lambda expressions:
l[phoenix-lambda-expression]
__lex__ provides some __phoenix__ placeholders to access important
information from the `Context` that are otherwise difficult to extract.
[variablelist Spirit.Lex specific Phoenix placeholders
[[`_start, _end`] [Iterators pointing to the begin and the end of the
matched input sequence.]]
[[`_pass`] [Assign `lex::pass_flags::pass_fail` to `_pass` to force the current match to fail.]]
[[`_tokenid`] [The token id of the matched token.]]
[[`_val`] [The token value of the matched token.]]
[[`_state`] [The lexer state the token has been matched in.]]
[[`_eoi`] [Iterator referring to the current end of the input sequence.]]
]
[tip All of the placeholders in the list above (except `_eoi`) can be changed
from the inside of the semantic action allowing to modify the lexer
behavior. They are defined in the namespace `boost::spirit::lex`.]
For more information see __lex_actions__.
[endsect]
