fe::Parser< Tok, Tag, K, S > Class Template Reference

The blueprint for a recursive descent/ ascent parser using a K lookahead of Tokens. More...

#include <fe/parser.h>

Classes
class	Tracker

Protected Member Functions
Construction
void	init (const std::filesystem::path *path)
Tracker
Track Location in the source file. Use like this: auto track = tracker(); auto foo = parse_foo(); auto bar = parse_bar(); auto foobar = new FooBar(track, foo, bar);
Tracker	tracker ()
	Factory method to build a Parser::Tracker.
Tracker	tracker (Pos begin)
	As above but start tracking at begin.
Tracker	tracker (Loc begin)
Shift Token
Tok	ahead (size_t i=0) const
Tok	lex ()
	Invoke Lexer to retrieve next Token.
Tok	accept (Tag tag)
	If Parser::ahead() is a tag, consume and return it, otherwise yield std::nullopt.
Tok	expect (Tag tag, std::string_view ctxt)
	Parser::lex Parser::ahead() which must be a tag.
Tok	eat (Tag tag)
	Consume Parser::ahead which must be a tag; asserts otherwise.

Protected Attributes
Ring< Tok, K >	ahead_
Loc	curr_

Detailed Description

template<class Tok, class Tag, size_t K, class S>
requires (std::is_convertible_v<Tok, bool> || std::is_constructible_v<bool, Tok>) || std::is_default_constructible_v<Tok>
class fe::Parser< Tok, Tag, K, S >

The blueprint for a recursive descent/ ascent parser using a K lookahead of Tokens.

Parser::accept and Parser::expect indicate failure by constructing a Token with its default constructor. Provide a conversion operator to bool to check for an error:

class Tok {
public:
    enum class Tag {
        Nil,
        // ...
    };
    // ...
    explicit bool operator() const { return tag_ != Tag::Nil; }
    // ...
};
 
// Your Parser:
if (auto tok = accept(Tok::Tag::My_Tag)) {
    do_something(tok);
}

Definition at line 31 of file parser.h.

Member Function Documentation

accept()

template<class Tok, class Tag, size_t K, class S>

Tok fe::Parser< Tok, Tag, K, S >::accept ( Tag tag )

inlineprotected

If Parser::ahead() is a tag, consume and return it, otherwise yield std::nullopt.

Definition at line 92 of file parser.h.

References ahead(), and lex().

ahead()

template<class Tok, class Tag, size_t K, class S>

Tok fe::Parser< Tok, Tag, K, S >::ahead ( size_t i = 0 ) const

inlineprotected

Get lookahead.

Definition at line 81 of file parser.h.

References ahead_.

Referenced by accept(), eat(), expect(), lex(), and tracker().

eat()

template<class Tok, class Tag, size_t K, class S>

Tok fe::Parser< Tok, Tag, K, S >::eat ( Tag tag )

inlineprotected

Consume Parser::ahead which must be a tag; asserts otherwise.

Definition at line 106 of file parser.h.

References ahead(), and lex().

expect()

template<class Tok, class Tag, size_t K, class S>

Tok fe::Parser< Tok, Tag, K, S >::expect ( Tag tag, std::string_view ctxt )

inlineprotected

Parser::lex Parser::ahead() which must be a tag.

Issue error with ctxt otherwise.

Definition at line 99 of file parser.h.

References ahead(), and lex().

init()

template<class Tok, class Tag, size_t K, class S>

void fe::Parser< Tok, Tag, K, S >::init ( const std::filesystem::path * path )

inlineprotected

Definition at line 39 of file parser.h.

References ahead_, and curr_.

lex()

template<class Tok, class Tag, size_t K, class S>

Tok fe::Parser< Tok, Tag, K, S >::lex ( )

inlineprotected

Invoke Lexer to retrieve next Token.

Definition at line 84 of file parser.h.

References ahead(), ahead_, curr_, and lex().

Referenced by accept(), eat(), expect(), and lex().

tracker() [1/3]

template<class Tok, class Tag, size_t K, class S>

Tracker fe::Parser< Tok, Tag, K, S >::tracker ( )

inlineprotected

Factory method to build a Parser::Tracker.

Definition at line 73 of file parser.h.

References ahead(), and curr_.

tracker() [2/3]

template<class Tok, class Tag, size_t K, class S>

Tracker fe::Parser< Tok, Tag, K, S >::tracker ( Loc begin )

inlineprotected

Definition at line 75 of file parser.h.

References fe::Loc::begin, and curr_.

tracker() [3/3]

template<class Tok, class Tag, size_t K, class S>

Tracker fe::Parser< Tok, Tag, K, S >::tracker ( Pos begin )

inlineprotected

As above but start tracking at begin.

Definition at line 74 of file parser.h.

References curr_.

Member Data Documentation

ahead_

template<class Tok, class Tag, size_t K, class S>

Ring<Tok, K> fe::Parser< Tok, Tag, K, S >::ahead_

protected

Definition at line 112 of file parser.h.

Referenced by ahead(), init(), and lex().

curr_

template<class Tok, class Tag, size_t K, class S>

Loc fe::Parser< Tok, Tag, K, S >::curr_

protected

Definition at line 113 of file parser.h.

Referenced by init(), lex(), tracker(), tracker(), and tracker().

---

The documentation for this class was generated from the following file:

• fe/parser.h