Struct enso_flexer::group::Group

pub struct Group {
    pub id: Identifier,
    pub name: String,
    pub parent_index: Option<Identifier>,
    pub rules: Vec<Rule>,
    pub state_names: HashMap<usize, String>,
    pub state_callbacks: HashMap<usize, String>,
}

A group is a structure for associating multiple rules with each other, and is the basic building block of the flexer.

A group consists of the following:

• A set of Rules, each containing a regex pattern and associated callback.
• Inherited rules from a parent group, if such a group exists.

Internally, the flexer maintains a stack of groups, where only one group can be active at any given time. Rules are matched in order, and hence overlaps are handled by the order in which the rules are matched, with the first callback being triggered.

Whenever a rule.pattern from the active group is matched against part of the input, the associated rule.callback is executed. This callback may exit the current group or even enter a new one. As a result, groups allow us to elegantly model a situation where certain parts of a program (e.g. within a string literal) have very different lexing rules than other portions of a program (e.g. the body of a function).

Fields

id: Identifier

A unique identifier for the group.

name: String

A name for the group (useful in debugging).

parent_index: Option<Identifier>

The parent group from which rules are inherited.

It is ensured that the group is held mutably.

rules: Vec<Rule>

A set of flexer rules.

state_names: HashMap<usize, String>

The names for the user-defined states.

state_callbacks: HashMap<usize, String>

The callback functions for the user-defined states.

Implementations

impl Group

pub fn new(
    id: Identifier,
    name: impl Into<String>,
    parent_index: Option<Identifier>
) -> Self

Creates a new group.

pub fn add_rule(&mut self, rule: Rule)

Adds a new rule to the current group.

pub fn create_rule(&mut self, pattern: &Pattern, code: &str)

Creates a new rule.

pub fn callback_name(&self, rule_ix: usize) -> String

The canonical name for a given rule.

Trait Implementations

impl Clone for Group

fn clone(&self) -> Group

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Group

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

Formats the value using the given formatter.

impl Default for Group

fn default() -> Group

Returns the “default value” for a type.

impl Display for Group

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

Formats the value using the given formatter.

impl From<Group> for Registry

fn from(value: Group) -> Self

Performs the conversion.