perspective-client 5.9.0

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// ┃ Copyright (c) 2017, the Perspective Authors.                              ┃
// ┃ ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ ┃
// ┃ This file is part of the Perspective library, distributed under the terms ┃
// ┃ of the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0). ┃
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use serde::{Deserialize, Deserializer};

/// A trailing `#[serde(flatten)]` field which fails deserialization when its
/// struct is given a key it does not define.
#[derive(Clone, Debug, Default, PartialEq)]
pub struct UnknownKeys;

impl<'de> Deserialize<'de> for UnknownKeys {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        let keys =
            std::collections::BTreeMap::<String, serde::de::IgnoredAny>::deserialize(deserializer)?;

        if keys.is_empty() {
            Ok(Self)
        } else {
            let keys = keys
                .keys()
                .map(|key| format!("`{key}`"))
                .collect::<Vec<_>>()
                .join(", ");

            Err(serde::de::Error::custom(format!(
                "Unknown config keys {keys}"
            )))
        }
    }
}