pub enum Value<'a> {
}Expand description
A generic container, in the form of an enum that holds exactly one value of any of the other types.
Note that this type corresponds to the VARIANT data type defined by the D-Bus specification
and as such, its encoding is not the same as that of the enclosed value.
Examples
use std::convert::TryFrom;
use zvariant::{from_slice, to_bytes, EncodingContext, Value};
// Create a Value from an i16
let v = Value::new(i16::max_value());
// Encode it
let ctxt = EncodingContext::<byteorder::LE>::new_dbus(0);
let encoding = to_bytes(ctxt, &v).unwrap();
// Decode it back
let v: Value = from_slice(&encoding, ctxt).unwrap();
// Check everything is as expected
assert_eq!(i16::try_from(&v).unwrap(), i16::max_value());Now let’s try a more complicated example:
use std::convert::TryFrom;
use zvariant::{from_slice, to_bytes, EncodingContext};
use zvariant::{Structure, Value, Str};
// Create a Value from a tuple this time
let v = Value::new((i16::max_value(), "hello", true));
// Same drill as previous example
let ctxt = EncodingContext::<byteorder::LE>::new_dbus(0);
let encoding = to_bytes(ctxt, &v).unwrap();
let v: Value = from_slice(&encoding, ctxt).unwrap();
// Check everything is as expected
let s = Structure::try_from(v).unwrap();
assert_eq!(
<(i16, Str, bool)>::try_from(s).unwrap(),
(i16::max_value(), Str::from("hello"), true),
);Variants§
U8(u8)
Bool(bool)
I16(i16)
U16(u16)
I32(i32)
U32(u32)
I64(i64)
U64(u64)
F64(f64)
Str(Str<'a>)
Signature(Signature<'a>)
ObjectPath(ObjectPath<'a>)
Value(Box<Value<'a>>)
Array(Array<'a>)
Dict(Dict<'a, 'a>)
Structure(Structure<'a>)
Maybe(Maybe<'a>)
Fd(Fd)
Implementations§
source§impl<'a> Value<'a>
impl<'a> Value<'a>
sourcepub fn new<T>(value: T) -> Selfwhere
T: Into<Self> + DynamicType,
pub fn new<T>(value: T) -> Selfwhere
T: Into<Self> + DynamicType,
sourcepub fn to_owned(&self) -> OwnedValue
pub fn to_owned(&self) -> OwnedValue
Create an owned version of self.
Ideally, we should implement std::borrow::ToOwned trait for Value, but that’s
implemented generically for us through impl<T: Clone> ToOwned for T and it’s not what we
need/want.
sourcepub fn value_signature(&self) -> Signature<'_>
pub fn value_signature(&self) -> Signature<'_>
Get the signature of the enclosed value.
sourcepub fn downcast<T>(self) -> Option<T>where
T: TryFrom<Value<'a>> + ?Sized,
pub fn downcast<T>(self) -> Option<T>where
T: TryFrom<Value<'a>> + ?Sized,
Try to get the underlying type T.
Note that TryFrom<Value> is implemented for various types, and it’s usually best to use
that instead. However, in generic code where you also want to unwrap Value::Value,
you should use this function (because TryFrom<Value> can not be implemented for Value
itself as From<Value> is implicitly implemented for Value).
Examples
use std::convert::TryFrom;
use zvariant::{Result, Value};
fn value_vec_to_type_vec<'a, T>(values: Vec<Value<'a>>) -> Result<Vec<T>>
where
T: TryFrom<Value<'a>>,
{
let mut res = vec![];
for value in values.into_iter() {
res.push(value.downcast().unwrap());
}
Ok(res)
}
// Let's try u32 values first
let v = vec![Value::U32(42), Value::U32(43)];
let v = value_vec_to_type_vec::<u32>(v).unwrap();
assert_eq!(v[0], 42);
assert_eq!(v[1], 43);
// Now try Value values
let v = vec![Value::new(Value::U32(42)), Value::new(Value::U32(43))];
let v = value_vec_to_type_vec::<Value>(v).unwrap();
assert_eq!(v[0], Value::U32(42));
assert_eq!(v[1], Value::U32(43));sourcepub fn downcast_ref<T>(&'a self) -> Option<&'a T>where
T: ?Sized,
&'a T: TryFrom<&'a Value<'a>>,
pub fn downcast_ref<T>(&'a self) -> Option<&'a T>where
T: ?Sized,
&'a T: TryFrom<&'a Value<'a>>,
Try to get a reference to the underlying type T.
Same as downcast except it doesn’t consume self and get a reference to the underlying
value.
Examples
use std::convert::TryFrom;
use zvariant::{Result, Value};
fn value_vec_to_type_vec<'a, T>(values: &'a Vec<Value<'a>>) -> Result<Vec<&'a T>>
where
&'a T: TryFrom<&'a Value<'a>>,
{
let mut res = vec![];
for value in values.into_iter() {
res.push(value.downcast_ref().unwrap());
}
Ok(res)
}
// Let's try u32 values first
let v = vec![Value::U32(42), Value::U32(43)];
let v = value_vec_to_type_vec::<u32>(&v).unwrap();
assert_eq!(*v[0], 42);
assert_eq!(*v[1], 43);
// Now try Value values
let v = vec![Value::new(Value::U32(42)), Value::new(Value::U32(43))];
let v = value_vec_to_type_vec::<Value>(&v).unwrap();
assert_eq!(*v[0], Value::U32(42));
assert_eq!(*v[1], Value::U32(43));Trait Implementations§
source§impl<'de: 'a, 'a> Deserialize<'de> for Value<'a>
impl<'de: 'a, 'a> Deserialize<'de> for Value<'a>
source§fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>where
D: Deserializer<'de>,
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>where
D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. Read more
source§impl<'a> From<&'a ObjectPath<'a>> for Value<'a>
impl<'a> From<&'a ObjectPath<'a>> for Value<'a>
source§fn from(v: &'a ObjectPath<'a>) -> Self
fn from(v: &'a ObjectPath<'a>) -> Self
Converts to this type from the input type.
source§impl<'o> From<&'o OwnedValue> for Value<'o>
impl<'o> From<&'o OwnedValue> for Value<'o>
source§fn from(v: &'o OwnedValue) -> Value<'o>
fn from(v: &'o OwnedValue) -> Value<'o>
Converts to this type from the input type.
source§impl<'a> From<&Value<'a>> for OwnedValue
impl<'a> From<&Value<'a>> for OwnedValue
source§impl<'a, 'k, 'v, K, V, H> From<HashMap<K, V, H>> for Value<'a>where
K: Type + Into<Value<'k>> + Hash + Eq,
V: Type + Into<Value<'v>>,
H: BuildHasher + Default,
'k: 'a,
'v: 'a,
impl<'a, 'k, 'v, K, V, H> From<HashMap<K, V, H>> for Value<'a>where
K: Type + Into<Value<'k>> + Hash + Eq,
V: Type + Into<Value<'v>>,
H: BuildHasher + Default,
'k: 'a,
'v: 'a,
source§impl<'a> From<ObjectPath<'a>> for Value<'a>
impl<'a> From<ObjectPath<'a>> for Value<'a>
source§fn from(v: ObjectPath<'a>) -> Self
fn from(v: ObjectPath<'a>) -> Self
Converts to this type from the input type.
source§impl From<OwnedObjectPath> for Value<'static>
impl From<OwnedObjectPath> for Value<'static>
source§fn from(o: OwnedObjectPath) -> Self
fn from(o: OwnedObjectPath) -> Self
Converts to this type from the input type.
source§impl From<OwnedSignature> for Value<'static>
impl From<OwnedSignature> for Value<'static>
source§fn from(o: OwnedSignature) -> Self
fn from(o: OwnedSignature) -> Self
Converts to this type from the input type.
source§impl From<OwnedValue> for Value<'static>
impl From<OwnedValue> for Value<'static>
source§fn from(v: OwnedValue) -> Value<'static>
fn from(v: OwnedValue) -> Value<'static>
Converts to this type from the input type.