Enum GrammarError 

pub enum GrammarError {
    Syntax {
        expected: String,
        offset: usize,
        rest: String,
    },
    UndefinedRule {
        name: String,
        rule_id: u32,
    },
    MissingRoot {
        name: String,
    },
    LeftRecursion {
        rule_id: u32,
        name: Option<String>,
    },
    RepetitionTooLarge {
        requested: u64,
        limit: u64,
        offset: usize,
    },
    TokenNeedsVocabulary {
        token: String,
        offset: usize,
    },
    TokenNotSingle {
        token: String,
        n_tokens: usize,
    },
    NoViableStack {
        piece: String,
    },
    TriggerPatternInvalid {
        pattern: String,
        reason: String,
    },
    TriggerPatternFailed {
        pattern: String,
        reason: String,
    },
    LazyWithoutTriggers,
    AwaitingTrigger,
    Internal(&'static str),
}

What the grammar engine refused, and why.

Variants

Syntax

A syntax error in the GBNF source. offset is the byte offset into the grammar text where llama.cpp’s parser would have thrown, and rest is the (truncated) input from there on, matching the "expecting X at " + src shape of the upstream messages.

Fields

expected: String

offset: usize

rest: String

UndefinedRule

A rule was referenced but never given a ::= definition.

Fields

name: String

rule_id: u32

MissingRoot

The grammar parsed but has no rule with the requested root name.

Fields

name: String

LeftRecursion

A rule can reach itself without consuming input. llama.cpp logs “unsupported grammar, left recursion detected” and returns null.

Fields

rule_id: u32

name: Option<String>

RepetitionTooLarge

A repetition operator would expand to more rules than the engine is willing to build. llama.cpp’s MAX_REPETITION_THRESHOLD.

Fields

requested: u64

limit: u64

offset: usize

TokenNeedsVocabulary

<name> token syntax was used but no vocabulary was supplied to resolve it. <[42]> needs no vocabulary and always works.

Fields

token: String

offset: usize

TokenNotSingle

A <name> token did not tokenize to exactly one token.

Fields

token: String

n_tokens: usize

NoViableStack

The generated text left no viable parse: every stack died. Carries the piece that killed it, as llama.cpp’s thrown message does.

Fields

piece: String

TriggerPatternInvalid

A lazy grammar’s trigger pattern does not compile. llama.cpp builds a std::regex in the constructor, which throws.

Fields

pattern: String

reason: String

TriggerPatternFailed

A trigger pattern compiled but failed while matching – the backtracking limit, in practice. Upstream’s std::regex has the same failure mode and does not report it.

Fields

pattern: String

reason: String

LazyWithoutTriggers

A grammar was made lazy with nothing that could ever switch it on, which is an unconstrained generation wearing a grammar. llama.cpp permits it; this engine will not pretend to constrain.

AwaitingTrigger

A not-yet-triggered lazy grammar was asked which tokens it forbids. It forbids nothing, and answering “nothing” would be indistinguishable from a grammar that allows everything – so the question is refused. Callers test Grammar::is_awaiting_trigger first, as llama_grammar_apply_impl does.

Internal(&'static str)

An invariant llama.cpp asserts with GGML_ABORT. Reaching one is a bug in this engine, not in the caller’s grammar.

Trait Implementations

impl Clone for GrammarError

fn clone(&self) -> GrammarError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GrammarError

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

Formats the value using the given formatter.

impl Display for GrammarError

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

Formats the value using the given formatter.

impl Eq for GrammarError

impl Error for GrammarError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<GrammarError> for SchemaError

fn from(e: GrammarError) -> Self

Converts to this type from the input type.

impl From<GrammarError> for ConstraintError

fn from(source: GrammarError) -> Self

Converts to this type from the input type.

impl PartialEq for GrammarError

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for GrammarError