46 lines
1.4 KiB
Rust
46 lines
1.4 KiB
Rust
use crate::{InputType, InputValueError, InputValueResult, Name, Type, Value};
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/// A variant of an enum.
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pub struct EnumItem<T> {
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/// The name of the variant.
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pub name: &'static str,
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/// The value of the variant.
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pub value: T,
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}
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/// A GraphQL enum.
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pub trait EnumType: Type + Sized + Eq + Send + Copy + Sized + 'static {
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/// Get a list of possible variants of the enum and their values.
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fn items() -> &'static [EnumItem<Self>];
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}
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/// Parse a value as an enum value.
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///
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/// This can be used to implement `InputType::parse`.
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pub fn parse_enum<T: EnumType + InputType>(value: Value) -> InputValueResult<T> {
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let value = match &value {
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Value::Enum(s) => s,
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Value::String(s) => s.as_str(),
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_ => return Err(InputValueError::expected_type(value)),
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};
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T::items()
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.iter()
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.find(|item| item.name == value)
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.map(|item| item.value)
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.ok_or_else(|| {
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InputValueError::custom(format_args!(
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r#"Enumeration type does not contain value "{}"."#,
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value,
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))
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})
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}
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/// Convert the enum value into a GraphQL value.
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///
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/// This can be used to implement `InputType::to_value` or `OutputType::resolve`.
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pub fn enum_value<T: EnumType>(value: T) -> Value {
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let item = T::items().iter().find(|item| item.value == value).unwrap();
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Value::Enum(Name::new(item.name))
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}
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