Validation
You can validate grammar and inputs.
Validating Grammars
gbnf accepts GBNF grammars as defined in llama.cpp.
Validate a grammar by providing it to gbnf. If the provided grammar is invalid, gbnf will throw an error containing information about that error:
import GBNF from 'gbnf'
try {
GBNF('root ::= "foo"') // if grammar is valid, no errors
console.log('this passes fine')
GBNF('root := "foo"') // if grammar is invalid, errors
} catch(err) {
console.error(err.message)
}
Once you have a valid grammar, you can test it against incoming input. If passed invalid input, GBNF will throw an error indicating where the input is bad:
import GBNF from 'gbnf'
try {
let grammar = GBNF('root ::= "foo"')
grammar.add('foo') // if input is valid, no errors
console.log('this passes fine')
grammar.add('bar') // if input is invalid, errors
} catch(err) {
console.error(err.message)
}You can also pass input during grammar instantiation:
import GBNF from 'gbnf'
try {
const grammar = GBNF(`root ::= "foo" | "bar"`, 'baz')
} catch(err) {
console.error(err.message)
}You can iteratively pass input to grammar state objects:
import GBNF from 'gbnf'
try {
let grammar = GBNF(`root ::= "foo" | "bar"`)
grammar = grammar.add('b')
grammar = grammar.add('a')
grammar = grammar.add('z') // this input is invalid
} catch(err) {
console.error(err.message)
}By default the error message will only contain the most recent string provided; alternatively, you can view the full input so far:
import GBNF from 'gbnf'
try {
let grammar = GBNF(`root ::= "foo" | "bar"`)
grammar = grammar.add('b')
grammar = grammar.add('a')
grammar = grammar.add('z') // this input is invalid
} catch(err) {
console.error(err.messageExpanded)
}