Struct Matcher 

pub struct Matcher { /* private fields */ }

The automaton a rule set compiles into.

Implementations

impl Matcher

pub fn build(path: &str, rules: &[Rule]) -> Result<Matcher, Vec<Error>>

Compile a rule set.

Errors

A rule whose pattern is one an earlier rule already has can never fire, and that is reported rather than silently dropped. It is always a mistake: either the second rule was meant to say something else, or one of the two should not be there.

pub fn find<'t>(&self, term: &'t Term) -> Option<Match<'t>>

Match one term against the whole rule set, returning the rule that fires.

The term is matched as a whole. Finding the subterms of a function worth matching is the selector’s job and not this one’s.

pub fn len(&self) -> usize

How many nodes the trie has, which is what a rule set costs to match against.

pub fn is_empty(&self) -> bool

Whether the rule set was empty.

pub fn shape(&self) -> Shape

What this rule set costs to match against.

The widest node is the measurement that matters, because it is the one the shape of the tree was changed for: it is what a scan would read to the end of and what a search reads eight of. It goes in the header of the generated table, where somebody reviewing a rule they added can see what adding it did.

Trait Implementations

impl Debug for Matcher

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Matcher

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Prints the trie, one branch to a line, indented by depth. This is what makes a rule set’s shape reviewable: two rules that share a prefix share a line, and a rule that can only be reached through a wildcard is visibly the last thing tried.