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-rw-r--r--2.27.1/src/singular.rs594
1 files changed, 594 insertions, 0 deletions
diff --git a/2.27.1/src/singular.rs b/2.27.1/src/singular.rs
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+use std::default::Default;
+use std::fmt;
+use std::hash::Hash;
+use std::hash::Hasher;
+use std::mem;
+use std::option;
+
+#[cfg(feature = "with-serde")]
+use serde;
+
+use crate::clear::Clear;
+
+/// Like `Option<T>`, but keeps the actual element on `clear`.
+pub struct SingularField<T> {
+ value: T,
+ set: bool,
+}
+
+/// Like `Option<Box<T>>`, but keeps the actual element on `clear`.
+pub struct SingularPtrField<T> {
+ value: Option<Box<T>>,
+ set: bool,
+}
+
+impl<T> SingularField<T> {
+ /// Construct this object from given value.
+ #[inline]
+ pub fn some(value: T) -> SingularField<T> {
+ SingularField {
+ value: value,
+ set: true,
+ }
+ }
+
+ /// True iff this object contains data.
+ #[inline]
+ pub fn is_some(&self) -> bool {
+ self.set
+ }
+
+ /// True iff this object contains no data.
+ #[inline]
+ pub fn is_none(&self) -> bool {
+ !self.is_some()
+ }
+
+ /// Convert this object into `Option`.
+ #[inline]
+ pub fn into_option(self) -> Option<T> {
+ if self.set {
+ Some(self.value)
+ } else {
+ None
+ }
+ }
+
+ /// View data as `Option`.
+ #[inline]
+ pub fn as_ref<'a>(&'a self) -> Option<&'a T> {
+ if self.set {
+ Some(&self.value)
+ } else {
+ None
+ }
+ }
+
+ /// View data as mutable `Option`.
+ #[inline]
+ pub fn as_mut<'a>(&'a mut self) -> Option<&'a mut T> {
+ if self.set {
+ Some(&mut self.value)
+ } else {
+ None
+ }
+ }
+
+ /// Unwrap data as reference.
+ #[inline]
+ pub fn unwrap_ref<'a>(&'a self) -> &'a T {
+ self.as_ref().unwrap()
+ }
+
+ /// Unwrap data as mutable reference.
+ #[inline]
+ pub fn unwrap_mut_ref<'a>(&'a mut self) -> &'a mut T {
+ self.as_mut().unwrap()
+ }
+
+ /// Unwrap data, panic if not set.
+ #[inline]
+ pub fn unwrap(self) -> T {
+ if self.set {
+ self.value
+ } else {
+ panic!();
+ }
+ }
+
+ /// Unwrap data or return given default value.
+ #[inline]
+ pub fn unwrap_or(self, def: T) -> T {
+ if self.set {
+ self.value
+ } else {
+ def
+ }
+ }
+
+ /// Unwrap data or return given default value.
+ #[inline]
+ pub fn unwrap_or_else<F>(self, f: F) -> T
+ where
+ F: FnOnce() -> T,
+ {
+ if self.set {
+ self.value
+ } else {
+ f()
+ }
+ }
+
+ /// Apply a function to contained element and store result in new `SingularPtrField`.
+ #[inline]
+ pub fn map<U, F>(self, f: F) -> SingularPtrField<U>
+ where
+ F: FnOnce(T) -> U,
+ {
+ SingularPtrField::from_option(self.into_option().map(f))
+ }
+
+ /// View as iterator over references.
+ #[inline]
+ pub fn iter<'a>(&'a self) -> option::IntoIter<&'a T> {
+ self.as_ref().into_iter()
+ }
+
+ /// View as iterator over mutable references.
+ #[inline]
+ pub fn mut_iter<'a>(&'a mut self) -> option::IntoIter<&'a mut T> {
+ self.as_mut().into_iter()
+ }
+
+ /// Clear this object.
+ /// Note, contained object destructor is not called, so allocated memory could be reused.
+ #[inline]
+ pub fn clear(&mut self) {
+ self.set = false;
+ }
+}
+
+impl<T: Default> SingularField<T> {
+ /// Construct a `SingularField` with no data.
+ #[inline]
+ pub fn none() -> SingularField<T> {
+ SingularField {
+ value: Default::default(),
+ set: false,
+ }
+ }
+
+ /// Construct `SingularField` from `Option`.
+ #[inline]
+ pub fn from_option(option: Option<T>) -> SingularField<T> {
+ match option {
+ Some(x) => SingularField::some(x),
+ None => SingularField::none(),
+ }
+ }
+
+ /// Return data as option, clear this object.
+ #[inline]
+ pub fn take(&mut self) -> Option<T> {
+ if self.set {
+ self.set = false;
+ Some(mem::replace(&mut self.value, Default::default()))
+ } else {
+ None
+ }
+ }
+}
+
+impl<T> SingularPtrField<T> {
+ /// Construct `SingularPtrField` from given object.
+ #[inline]
+ pub fn some(value: T) -> SingularPtrField<T> {
+ SingularPtrField {
+ value: Some(Box::new(value)),
+ set: true,
+ }
+ }
+
+ /// Construct an empty `SingularPtrField`.
+ #[inline]
+ pub fn none() -> SingularPtrField<T> {
+ SingularPtrField {
+ value: None,
+ set: false,
+ }
+ }
+
+ /// Construct `SingularPtrField` from optional.
+ #[inline]
+ pub fn from_option(option: Option<T>) -> SingularPtrField<T> {
+ match option {
+ Some(x) => SingularPtrField::some(x),
+ None => SingularPtrField::none(),
+ }
+ }
+
+ /// True iff this object contains data.
+ #[inline]
+ pub fn is_some(&self) -> bool {
+ self.set
+ }
+
+ /// True iff this object contains no data.
+ #[inline]
+ pub fn is_none(&self) -> bool {
+ !self.is_some()
+ }
+
+ /// Convert into `Option<T>`.
+ #[inline]
+ pub fn into_option(self) -> Option<T> {
+ if self.set {
+ Some(*self.value.unwrap())
+ } else {
+ None
+ }
+ }
+
+ /// View data as reference option.
+ #[inline]
+ pub fn as_ref<'a>(&'a self) -> Option<&'a T> {
+ if self.set {
+ Some(&**self.value.as_ref().unwrap())
+ } else {
+ None
+ }
+ }
+
+ /// View data as mutable reference option.
+ #[inline]
+ pub fn as_mut<'a>(&'a mut self) -> Option<&'a mut T> {
+ if self.set {
+ Some(&mut **self.value.as_mut().unwrap())
+ } else {
+ None
+ }
+ }
+
+ /// Get data as reference.
+ /// Panics if empty.
+ #[inline]
+ pub fn get_ref<'a>(&'a self) -> &'a T {
+ self.as_ref().unwrap()
+ }
+
+ /// Get data as mutable reference.
+ /// Panics if empty.
+ #[inline]
+ pub fn get_mut_ref<'a>(&'a mut self) -> &'a mut T {
+ self.as_mut().unwrap()
+ }
+
+ /// Take the data.
+ /// Panics if empty
+ #[inline]
+ pub fn unwrap(self) -> T {
+ if self.set {
+ *self.value.unwrap()
+ } else {
+ panic!();
+ }
+ }
+
+ /// Take the data or return supplied default element if empty.
+ #[inline]
+ pub fn unwrap_or(self, def: T) -> T {
+ if self.set {
+ *self.value.unwrap()
+ } else {
+ def
+ }
+ }
+
+ /// Take the data or return supplied default element if empty.
+ #[inline]
+ pub fn unwrap_or_else<F>(self, f: F) -> T
+ where
+ F: FnOnce() -> T,
+ {
+ if self.set {
+ *self.value.unwrap()
+ } else {
+ f()
+ }
+ }
+
+ /// Apply given function to contained data to construct another `SingularPtrField`.
+ /// Returns empty `SingularPtrField` if this object is empty.
+ #[inline]
+ pub fn map<U, F>(self, f: F) -> SingularPtrField<U>
+ where
+ F: FnOnce(T) -> U,
+ {
+ SingularPtrField::from_option(self.into_option().map(f))
+ }
+
+ /// View data as iterator.
+ #[inline]
+ pub fn iter<'a>(&'a self) -> option::IntoIter<&'a T> {
+ self.as_ref().into_iter()
+ }
+
+ /// View data as mutable iterator.
+ #[inline]
+ pub fn mut_iter<'a>(&'a mut self) -> option::IntoIter<&'a mut T> {
+ self.as_mut().into_iter()
+ }
+
+ /// Take data as option, leaving this object empty.
+ #[inline]
+ pub fn take(&mut self) -> Option<T> {
+ if self.set {
+ self.set = false;
+ Some(*self.value.take().unwrap())
+ } else {
+ None
+ }
+ }
+
+ /// Clear this object, but do not call destructor of underlying data.
+ #[inline]
+ pub fn clear(&mut self) {
+ self.set = false;
+ }
+}
+
+impl<T: Default + Clear> SingularField<T> {
+ /// Get contained data, consume self. Return default value for type if this is empty.
+ #[inline]
+ pub fn unwrap_or_default(mut self) -> T {
+ if !self.set {
+ self.value.clear();
+ }
+ self.value
+ }
+
+ /// Initialize this object with default value.
+ /// This operation can be more efficient then construction of clear element,
+ /// because it may reuse previously contained object.
+ #[inline]
+ pub fn set_default<'a>(&'a mut self) -> &'a mut T {
+ self.set = true;
+ self.value.clear();
+ &mut self.value
+ }
+}
+
+impl<T: Default + Clear> SingularPtrField<T> {
+ /// Get contained data, consume self. Return default value for type if this is empty.
+ #[inline]
+ pub fn unwrap_or_default(mut self) -> T {
+ if self.set {
+ self.unwrap()
+ } else if self.value.is_some() {
+ self.value.clear();
+ *self.value.unwrap()
+ } else {
+ Default::default()
+ }
+ }
+
+ /// Initialize this object with default value.
+ /// This operation can be more efficient then construction of clear element,
+ /// because it may reuse previously contained object.
+ #[inline]
+ pub fn set_default<'a>(&'a mut self) -> &'a mut T {
+ self.set = true;
+ if self.value.is_some() {
+ self.value.as_mut().unwrap().clear();
+ } else {
+ self.value = Some(Default::default());
+ }
+ self.as_mut().unwrap()
+ }
+}
+
+impl<T: Default> Default for SingularField<T> {
+ #[inline]
+ fn default() -> SingularField<T> {
+ SingularField::none()
+ }
+}
+
+impl<T> Default for SingularPtrField<T> {
+ #[inline]
+ fn default() -> SingularPtrField<T> {
+ SingularPtrField::none()
+ }
+}
+
+impl<T: Default> From<Option<T>> for SingularField<T> {
+ fn from(o: Option<T>) -> Self {
+ SingularField::from_option(o)
+ }
+}
+
+impl<T> From<Option<T>> for SingularPtrField<T> {
+ fn from(o: Option<T>) -> Self {
+ SingularPtrField::from_option(o)
+ }
+}
+
+impl<T: Clone + Default> Clone for SingularField<T> {
+ #[inline]
+ fn clone(&self) -> SingularField<T> {
+ if self.set {
+ SingularField::some(self.value.clone())
+ } else {
+ SingularField::none()
+ }
+ }
+}
+
+impl<T: Clone> Clone for SingularPtrField<T> {
+ #[inline]
+ fn clone(&self) -> SingularPtrField<T> {
+ if self.set {
+ SingularPtrField::some(self.as_ref().unwrap().clone())
+ } else {
+ SingularPtrField::none()
+ }
+ }
+}
+
+impl<T: fmt::Debug> fmt::Debug for SingularField<T> {
+ #[inline]
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ if self.is_some() {
+ write!(f, "Some({:?})", *self.as_ref().unwrap())
+ } else {
+ write!(f, "None")
+ }
+ }
+}
+
+impl<T: fmt::Debug> fmt::Debug for SingularPtrField<T> {
+ #[inline]
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ if self.is_some() {
+ write!(f, "Some({:?})", *self.as_ref().unwrap())
+ } else {
+ write!(f, "None")
+ }
+ }
+}
+
+impl<T: PartialEq> PartialEq for SingularField<T> {
+ #[inline]
+ fn eq(&self, other: &SingularField<T>) -> bool {
+ self.as_ref() == other.as_ref()
+ }
+}
+
+impl<T: Eq> Eq for SingularField<T> {}
+
+impl<T: PartialEq> PartialEq for SingularPtrField<T> {
+ #[inline]
+ fn eq(&self, other: &SingularPtrField<T>) -> bool {
+ self.as_ref() == other.as_ref()
+ }
+}
+
+impl<T: Eq> Eq for SingularPtrField<T> {}
+
+impl<T: Hash> Hash for SingularField<T> {
+ fn hash<H: Hasher>(&self, state: &mut H) {
+ self.as_ref().hash(state);
+ }
+}
+
+impl<T: Hash> Hash for SingularPtrField<T> {
+ fn hash<H: Hasher>(&self, state: &mut H) {
+ self.as_ref().hash(state);
+ }
+}
+
+impl<'a, T> IntoIterator for &'a SingularField<T> {
+ type Item = &'a T;
+ type IntoIter = option::IntoIter<&'a T>;
+
+ fn into_iter(self) -> option::IntoIter<&'a T> {
+ self.iter()
+ }
+}
+
+impl<'a, T> IntoIterator for &'a SingularPtrField<T> {
+ type Item = &'a T;
+ type IntoIter = option::IntoIter<&'a T>;
+
+ fn into_iter(self) -> option::IntoIter<&'a T> {
+ self.iter()
+ }
+}
+
+#[cfg(feature = "with-serde")]
+impl<T: serde::Serialize> serde::Serialize for SingularPtrField<T> {
+ fn serialize<S>(
+ &self,
+ serializer: S,
+ ) -> Result<<S as serde::Serializer>::Ok, <S as serde::Serializer>::Error>
+ where
+ S: serde::Serializer,
+ {
+ self.as_ref().serialize(serializer)
+ }
+}
+
+#[cfg(feature = "with-serde")]
+impl<T: serde::Serialize> serde::Serialize for SingularField<T> {
+ fn serialize<S>(
+ &self,
+ serializer: S,
+ ) -> Result<<S as serde::Serializer>::Ok, <S as serde::Serializer>::Error>
+ where
+ S: serde::Serializer,
+ {
+ self.as_ref().serialize(serializer)
+ }
+}
+
+#[cfg(feature = "with-serde")]
+impl<'de, T: serde::Deserialize<'de>> serde::Deserialize<'de> for SingularPtrField<T> {
+ fn deserialize<D>(deserializer: D) -> Result<Self, <D as serde::Deserializer<'de>>::Error>
+ where
+ D: serde::Deserializer<'de>,
+ {
+ Option::deserialize(deserializer).map(SingularPtrField::from_option)
+ }
+}
+
+#[cfg(feature = "with-serde")]
+impl<'de, T: serde::Deserialize<'de> + Default> serde::Deserialize<'de> for SingularField<T> {
+ fn deserialize<D>(deserializer: D) -> Result<Self, <D as serde::Deserializer<'de>>::Error>
+ where
+ D: serde::Deserializer<'de>,
+ {
+ Option::deserialize(deserializer).map(SingularField::from_option)
+ }
+}
+
+#[cfg(test)]
+mod test {
+ use super::SingularField;
+ use crate::clear::Clear;
+
+ #[test]
+ fn test_set_default_clears() {
+ #[derive(Default)]
+ struct Foo {
+ b: isize,
+ }
+
+ impl Clear for Foo {
+ fn clear(&mut self) {
+ self.b = 0;
+ }
+ }
+
+ let mut x = SingularField::some(Foo { b: 10 });
+ x.clear();
+ x.set_default();
+ assert_eq!(0, x.as_ref().unwrap().b);
+
+ x.as_mut().unwrap().b = 11;
+ // without clear
+ x.set_default();
+ assert_eq!(0, x.as_ref().unwrap().b);
+ }
+
+ #[test]
+ fn unwrap_or_default() {
+ assert_eq!(
+ "abc",
+ SingularField::some("abc".to_owned()).unwrap_or_default()
+ );
+ assert_eq!("", SingularField::<String>::none().unwrap_or_default());
+ let mut some = SingularField::some("abc".to_owned());
+ some.clear();
+ assert_eq!("", some.unwrap_or_default());
+ }
+}
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