func maybeUpdatePostProcessor()

in Sources/Tokenizers/Tokenizer.swift [655:693]
32 lines of code
7 McCabe index (conditional complexity)

func maybeUpdatePostProcessor(tokenizerConfig: Config, processorConfig: Config?) throws -> Config? {
    // If it's already a Template processor (instead of a ByteLevel one), assume it's correct
    let postProcessor = PostProcessorFactory.fromConfig(config: processorConfig)
    guard !(postProcessor is TemplateProcessing) else { return nil }

    let addBosToken = tokenizerConfig.addBosToken.boolean(or: false)
    let bosToken = addedTokenAsString(tokenizerConfig.bosToken)
    if addBosToken, bosToken == nil {
        throw TokenizerError.mismatchedConfig("add_bos_token is True but bos_token is nil")
    }

    let addEosToken = tokenizerConfig.addEosToken.boolean(or: false)
    let eosToken = addedTokenAsString(tokenizerConfig.eosToken)
    if addEosToken, eosToken == nil {
        throw TokenizerError.mismatchedConfig("add_eos_token is True but eos_token is nil")
    }

    // alt implementation
    var single: [[String: Any]] = []
    if addBosToken {
        single = single + [["SpecialToken": ["id": bosToken!, "type_id": 0]]]
    }
    single = single + [["Sequence": ["id": "A", "type_id": 0]]]
    if addEosToken {
        single = single + [["SpecialToken": ["id": eosToken!, "type_id": 0]]]
    }

    var pair: [[String: Any]] = single
    if addBosToken {
        pair = pair + [["SpecialToken": ["id": bosToken!, "type_id": 1]]]
    }
    pair = pair + [["Sequence": ["id": "B", "type_id": 1]]]
    if addEosToken {
        pair = pair + [["SpecialToken": ["id": eosToken!, "type_id": 1]]]
    }

    let postProcessorConfig = Config(["type": PostProcessorType.TemplateProcessing.rawValue, "single": single, "pair": pair])
    return postProcessorConfig
}