var P = Parsimmon = require("parsimmon@1.8.0")
var assert = require('assert')
var except = function (allowed, forbidden) {
return Parsimmon.Parser(function (stream, i) {
var forbiddenResult = forbidden._(stream, i)
if (forbiddenResult.status) {
return Parsimmon.makeFailure(i, "something that is not '" +
forbiddenResult.value + "'")
} else {
var allowedResult = allowed._(stream, i)
if (allowedResult.status) {
return allowedResult
} else {
return Parsimmon.makeFailure(i, allowedResult.expected.join(',') +
' (except ' + forbiddenResult.expected.join(',') + ')')
}
}
})
}
var nonBLetter = except(P.letter, P.string('b'))
console.log( nonBLetter.parse('a').status ) // => true
console.log( nonBLetter.parse('c').status ) // => true
console.log( nonBLetter.parse('b').status ) // => false
console.log( nonBLetter.parse('b').expected ) // => [ 'something that is not \'b\'' ]
console.log( nonBLetter.parse('/').expected ) // => [ 'a letter (except \'b\')' ]
Created from: https://runkit.com/npm/parsimmon
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