real::dfa Class Reference

A multi-rule DFA: maximal-munch (dfa_mode::munch) or which-matched unanchored scan (dfa_mode::which_matched). More...

#include <dfa.hpp>

Collaboration diagram for real::dfa:

Public Member Functions
	dfa (std::span< const detail::program_view > programs, dfa_mode mode=dfa_mode::munch)
	Builds the DFA from compiled programs (the embedder path).
	dfa (std::span< const regex > patterns, dfa_mode mode=dfa_mode::munch)
	Builds the DFA from regexes (a convenience over regex::raw_program).
std::optional< dfa_match >	match (std::string_view rest) const noexcept
	Matches the longest pattern anchored at the start of rest.
std::vector< bool >	which_matched (std::string_view text, bool first_byte_skip=true) const
	Which patterns match the subject at least once (single-pass).
bool	has_first_byte_skip () const noexcept
	True if set-level first-byte skip is armed for which_matched.
bool	is_unanchored () const noexcept
	True if this DFA was built with mid-stream restart (which-matched mode).
std::size_t	state_count () const noexcept
	The number of states in the minimized automaton (includes the dead state).
std::size_t	rule_count () const noexcept
	The number of patterns the DFA was built from.
std::size_t	class_count () const noexcept
	The number of byte-equivalence classes (the reduced alphabet width).

Static Private Member Functions
static std::vector< detail::program_view >	views_of (std::span< const regex > patterns)
	Materializes program views from patterns (helper for the regex ctor).

Private Attributes
detail::dfa_tables	tables_
	The immutable baked tables.

Detailed Description

A multi-rule DFA: maximal-munch (dfa_mode::munch) or which-matched unanchored scan (dfa_mode::which_matched).

Built once (heap-allocated tables), then immutable and cheap to copy-share. match is the lexer munch. which_matched is Stage-2 multi-accept (only valid when built with dfa_mode::which_matched).

Constructor & Destructor Documentation

dfa() [1/2]

real::dfa::dfa ( std::span< const detail::program_view >  programs, dfa_mode  mode = dfa_mode::munch  )

inlineexplicit

Builds the DFA from compiled programs (the embedder path).

Parameters

[in]	programs	The patterns' programs, in priority order (see regex::raw_program).
[in]	mode	Munch (default) or which-matched unanchored multi-accept.

Exceptions

real::dfa_error

if any program holds a non-head zero-width assertion, a lookaround, a code-point class, or a possessive/atomic construct.

dfa() [2/2]

real::dfa::dfa ( std::span< const regex >  patterns, dfa_mode  mode = dfa_mode::munch  )

inlineexplicit

Builds the DFA from regexes (a convenience over regex::raw_program).

Parameters

[in]	patterns	The patterns, in priority order; they must outlive this call.
[in]	mode	Munch (default) or which-matched.

Exceptions

real::dfa_error

if any pattern holds a non-head zero-width assertion, a lookaround, a code-point class, or a possessive/atomic construct.

Member Function Documentation

class_count()

std::size_t real::dfa::class_count ( ) const

inlinenoexcept

The number of byte-equivalence classes (the reduced alphabet width).

Returns

The class count.

has_first_byte_skip()

bool real::dfa::has_first_byte_skip ( ) const

inlinenoexcept

True if set-level first-byte skip is armed for which_matched.

Returns

Whether every rule contributed a valid first-byte set at build time.

is_unanchored()

bool real::dfa::is_unanchored ( ) const

inlinenoexcept

True if this DFA was built with mid-stream restart (which-matched mode).

Returns

Whether the tables carry self-restart transitions.

match()

std::optional< dfa_match > real::dfa::match ( std::string_view  rest ) const

inlinenoexcept

Matches the longest pattern anchored at the start of rest.

Maximal munch: the longest match wins; on equal length the earliest pattern (lowest index passed to the constructor) wins; an empty match never wins.

Parameters

[in]

rest

The text to match at its start.

Returns

The winning rule index and byte length, or std::nullopt if nothing non-empty matches.

rule_count()

std::size_t real::dfa::rule_count ( ) const

inlinenoexcept

The number of patterns the DFA was built from.

Returns

The rule count, which is also the width of which_matched's answer.

state_count()

std::size_t real::dfa::state_count ( ) const

inlinenoexcept

The number of states in the minimized automaton (includes the dead state).

Returns

The state count.

views_of()

static std::vector< detail::program_view > real::dfa::views_of ( std::span< const regex >  patterns )

inlinestaticprivate

Materializes program views from patterns (helper for the regex ctor).

Parameters

[in]

patterns

The compiled regexes, which must outlive the views.

Returns

One view per pattern, in the same order.

which_matched()

std::vector< bool > real::dfa::which_matched ( std::string_view  text, bool  first_byte_skip = true  ) const

inline

Which patterns match the subject at least once (single-pass).

Requires a build with dfa_mode::which_matched. Returns a bitset of length rule_count in construction order. Early-exits when every pattern has hit. Empty matches are excluded (only states that accepted after consuming a byte contribute, via post-move accept masks).

Parameters

[in]	text	Subject text.
[in]	first_byte_skip	When true (default), fast-forward over bytes that cannot start any rule while the walk is in the start state (a pure optimization). Pass false to disable for equivalence tests.

Returns

One bool per rule, in construction order, true where that pattern matched.

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

• include/real/dfa.hpp