98 lines
2.5 KiB
Rust
98 lines
2.5 KiB
Rust
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use crate::{registry, InputValueResult, InputValueType, Type, Value};
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use std::borrow::Cow;
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/// Similar to `Option`, but it has three states, `undefined`, `null` and `x`.
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///
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/// Spec: https://spec.graphql.org/June2018/#sec-Null-Value
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#[allow(missing_docs)]
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pub enum MaybeUndefined<T> {
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Undefined,
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Null,
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Value(T),
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}
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impl<T> MaybeUndefined<T> {
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/// Returns true if the MaybeUndefined<T> is undefined.
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#[inline]
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pub fn is_undefined(&self) -> bool {
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if let MaybeUndefined::Undefined = self {
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true
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} else {
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false
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}
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}
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/// Returns true if the MaybeUndefined<T> is null.
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#[inline]
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pub fn is_null(&self) -> bool {
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if let MaybeUndefined::Null = self {
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true
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} else {
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false
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}
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}
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/// Borrow the value, returns `None` if the value is `undefined` or `null`, otherwise returns `Some(T)`.
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#[inline]
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pub fn value(&self) -> Option<&T> {
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match self {
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MaybeUndefined::Value(value) => Some(value),
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_ => None,
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}
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}
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/// Convert MaybeUndefined<T> to Option<T>.
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#[inline]
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pub fn take(self) -> Option<T> {
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match self {
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MaybeUndefined::Value(value) => Some(value),
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_ => None,
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}
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}
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}
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impl<T: Type> Type for MaybeUndefined<T> {
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fn type_name() -> Cow<'static, str> {
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T::type_name()
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}
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fn qualified_type_name() -> String {
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T::type_name().to_string()
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}
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fn create_type_info(registry: &mut registry::Registry) -> String {
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T::create_type_info(registry);
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T::type_name().to_string()
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}
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}
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impl<T: InputValueType> InputValueType for MaybeUndefined<T> {
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fn parse(value: Option<Value>) -> InputValueResult<Self> {
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match value {
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None => Ok(MaybeUndefined::Undefined),
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Some(Value::Null) => Ok(MaybeUndefined::Null),
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Some(value) => Ok(MaybeUndefined::Value(T::parse(Some(value))?)),
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}
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}
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fn to_value(&self) -> Value {
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match self {
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MaybeUndefined::Value(value) => value.to_value(),
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_ => Value::Null,
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::*;
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#[test]
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fn test_optional_type() {
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assert_eq!(MaybeUndefined::<i32>::type_name(), "Int");
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assert_eq!(MaybeUndefined::<i32>::qualified_type_name(), "Int");
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assert_eq!(&MaybeUndefined::<i32>::type_name(), "Int");
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assert_eq!(&MaybeUndefined::<i32>::qualified_type_name(), "Int");
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}
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}
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