Struct TokenRule 

pub struct TokenRule { /* private fields */ }

Spacing rules for one token kind (or for every token), on either side.

A token rule lives either at the top level of Rules (a default that applies wherever the token appears) or inside a NodeRule (applies only to tokens that are direct children of that node, and wins over the top-level default). On each side the most specific rule wins: a node’s rule for this exact kind, then the node’s rule for any token, then the top-level rule for this kind, then the top-level rule for any token.

Examples

use fmt_lang::{Space, TokenRule};

let plus = TokenRule::new("+").around(Space::Single);
let open_paren = TokenRule::new("(").after(Space::None);
// Every direct child token of a node (used inside a `NodeRule`).
let tight = TokenRule::any().before(Space::None).after(Space::None);

Implementations

impl TokenRule

pub fn new(kind: impl Into<String>) -> Self

A rule for tokens of the kind named kind, with no spacing set yet.

Examples

use fmt_lang::{Space, TokenRule};

let semi = TokenRule::new(";").before(Space::None);

pub fn any() -> Self

A rule for every token, whatever its kind. Inside a NodeRule it covers every direct child token of that node.

Examples

use fmt_lang::{NodeRule, Space, TokenRule};

// A prefix operator hugs its operand: `-x`, not `- x`.
let prefix = NodeRule::new("prefix").token(TokenRule::any().before(Space::None).after(Space::None));

pub fn before(self, space: Space) -> Self

Spacing in the gap before the token.

Examples

use fmt_lang::{Space, TokenRule};

let close = TokenRule::new(")").before(Space::None);

pub fn after(self, space: Space) -> Self

Spacing in the gap after the token.

Examples

use fmt_lang::{Space, TokenRule};

let comma = TokenRule::new(",").after(Space::Single);

pub fn around(self, space: Space) -> Self

The same spacing on both sides.

Examples

use fmt_lang::{Space, TokenRule};

let assign = TokenRule::new("=").around(Space::Single);

pub fn optional(self) -> Self

Marks the rule optional: if the language has no kind by this name, Rules::compile drops the rule instead of reporting RuleError::UnknownKind. Meant for presets shared across languages, such as Rules::conventional.

Examples

use fmt_lang::{Rules, Space, TokenRule};

let rules = Rules::new().token(TokenRule::new("=>").around(Space::Single).optional());
// The language below has no `=>`; the rule is dropped, not an error.
let style = rules.compile(|name| (name == "+").then_some(1u8))?;

Trait Implementations

impl Clone for TokenRule

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TokenRule

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

Formats the value using the given formatter.

impl Eq for TokenRule

impl Hash for TokenRule

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for TokenRule

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for TokenRule