48 lines
1.4 KiB
Rust
48 lines
1.4 KiB
Rust
use crate::parser::types::Name;
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use crate::{InputValueError, InputValueResult, 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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/// An enum value.
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pub trait EnumType: Type + Sized + Eq + Send + Copy + Sized + 'static {
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/// Get a list of the variants of the enum value.
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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 `InputValueType::parse`.
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pub fn parse_enum<T: EnumType>(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::ExpectedType(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!(
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r#"Enumeration type "{}" does not contain the value "{}""#,
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T::type_name(),
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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 `InputValueType::to_value` or `OutputValueType::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_unchecked(item.name.to_owned()))
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}
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