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//! Null-behavior declarations (SPEC Chapters 8 and 18).
use serde::{Deserialize, Serialize};
/// Declared null-propagation behavior for expressions and functions.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, Default)]
#[serde(rename_all = "camelCase")]
pub enum NullBehavior {
/// Null / missing inputs propagate as null.
#[default]
Propagate,
/// Null inputs are rejected (diagnostics / invalid).
Reject,
/// Null inputs are coalesced to a default / empty value.
Coalesce,
/// Behavior is function-specific and documented in the registry definition.
Defined,
}
impl NullBehavior {
/// Serialized name.
#[must_use]
pub fn as_str(self) -> &'static str {
match self {
Self::Propagate => "propagate",
Self::Reject => "reject",
Self::Coalesce => "coalesce",
Self::Defined => "defined",
}
}
/// Parse from registry / document string.
#[must_use]
pub fn parse(value: &str) -> Option<Self> {
match value.trim().to_ascii_lowercase().as_str() {
"propagate" => Some(Self::Propagate),
"reject" => Some(Self::Reject),
"coalesce" => Some(Self::Coalesce),
"defined" => Some(Self::Defined),
_ => None,
}
}
}