Enum GrammarRule 

pub enum GrammarRule<K: TokenKind, R: RuleId> {
    Sequence(Vec<GrammarRule<K, R>>),
    Choice(Vec<GrammarRule<K, R>>),
    Optional(Box<GrammarRule<K, R>>),
    ZeroOrMore(Box<GrammarRule<K, R>>),
    OneOrMore(Box<GrammarRule<K, R>>),
    Range {
        rule: Box<GrammarRule<K, R>>,
        min: usize,
        max: usize,
    },
    PrattExpr(Precedence),
    Token(K),
    Rule(R),
    Conditional {
        rule: Box<GrammarRule<K, R>>,
        condition: fn(usize) -> bool,
    },
    NegativeLookahead(Box<GrammarRule<K, R>>),
    PositiveLookahead(Box<GrammarRule<K, R>>),
}

High-level grammar building block.

Serialization

When the serde feature is enabled, this type implements Serialize and Deserialize. Note that K and R must also implement these traits for serialization to work.

Variants

Sequence(Vec<GrammarRule<K, R>>)

Sequence: a b c.

Choice(Vec<GrammarRule<K, R>>)

Choice: a | b | c.

Optional(Box<GrammarRule<K, R>>)

Optional: a?.

ZeroOrMore(Box<GrammarRule<K, R>>)

Zero or more: a*.

OneOrMore(Box<GrammarRule<K, R>>)

One or more: a+.

Range

Range repetition: a{min,max}.

Fields

rule: Box<GrammarRule<K, R>>

Rule that must repeat.

min: usize

Minimum number of occurrences (inclusive).

max: usize

Maximum number of occurrences (inclusive).

PrattExpr(Precedence)

Delegate to the Pratt parser for expression parsing.

Token(K)

Terminal token literal.

Rule(R)

Rule reference.

Conditional

Conditional rule that depends on the parser position.

Fields

rule: Box<GrammarRule<K, R>>

Nested rule to evaluate when the condition succeeds.

condition: fn(usize) -> bool

Condition receives the parser position and returns whether the rule should run.

NegativeLookahead(Box<GrammarRule<K, R>>)

Negative lookahead: succeeds if the rule does NOT match.

PositiveLookahead(Box<GrammarRule<K, R>>)

Positive lookahead: succeeds if the rule matches, but doesn’t consume input.

Trait Implementations

impl<K: Clone + TokenKind, R: Clone + RuleId> Clone for GrammarRule<K, R>

fn clone(&self) -> GrammarRule<K, R>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K: Debug + TokenKind, R: Debug + RuleId> Debug for GrammarRule<K, R>

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

Formats the value using the given formatter.