Enum zvariant::Value

pub enum Value<'a> {
    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),
}

A generic container, in the form of an enum that holds exactly one value of any of the other types.

Note that this type correponds 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

impl<'a> Value<'a>

pub fn new<T>(value: T) -> Self where
    T: Into<Self> + Type, 

Make a Value for a given value.

In general, you can use Into trait on basic types, except when you explicitely need to wrap Value itself, in which case this constructor comes handy.

Examples

use zvariant::Value;

let s = Value::new("hello");
let u: Value = 51.into();
assert_ne!(s, u);

pub fn value_signature(&self) -> Signature<'_>

Get the signature of the enclosed value.

pub fn downcast<T: ?Sized>(self) -> Option<T> where
    T: TryFrom<Value<'a>>, 

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));

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

impl<'a> Clone for Value<'a>

fn clone(&self) -> Value<'a>

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for Value<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de: 'a, 'a> Deserialize<'de> for Value<'a>

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where
    D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl<'a> From<&'_ Value<'a>> for OwnedValue

fn from(v: &Value<'a>) -> Self

Performs the conversion.

impl<'a> From<&'a &'a str> for Value<'a>

fn from(v: &'a &'a str) -> Self

Performs the conversion.

impl<'a> From<&'a Array<'a>> for Value<'a>

fn from(v: &'a Array<'a>) -> Self

Performs the conversion.

impl<'a> From<&'a Dict<'a, 'a>> for Value<'a>

fn from(v: &'a Dict<'a, 'a>) -> Self

Performs the conversion.

impl<'a> From<&'a Fd> for Value<'a>

fn from(v: &'a Fd) -> Self

Performs the conversion.

impl<'a> From<&'a Maybe<'a>> for Value<'a>

fn from(v: &'a Maybe<'a>) -> Self

Performs the conversion.

impl<'a> From<&'a ObjectPath<'a>> for Value<'a>

fn from(v: &'a ObjectPath<'a>) -> Self

Performs the conversion.

impl<'a> From<&'a Signature<'a>> for Value<'a>

fn from(v: &'a Signature<'a>) -> Self

Performs the conversion.

impl<'a> From<&'a bool> for Value<'a>

fn from(v: &'a bool) -> Self

Performs the conversion.

impl<'a> From<&'a f32> for Value<'a>

fn from(v: &'a f32) -> Self

Performs the conversion.

impl<'a> From<&'a f64> for Value<'a>

fn from(v: &'a f64) -> Self

Performs the conversion.

impl<'a> From<&'a i16> for Value<'a>

fn from(v: &'a i16) -> Self

Performs the conversion.

impl<'a> From<&'a i32> for Value<'a>

fn from(v: &'a i32) -> Self

Performs the conversion.

impl<'a> From<&'a i64> for Value<'a>

fn from(v: &'a i64) -> Self

Performs the conversion.

impl<'a> From<&'a i8> for Value<'a>

fn from(v: &'a i8) -> Self

Performs the conversion.

impl<'a> From<&'a str> for Value<'a>

fn from(v: &'a str) -> Self

Performs the conversion.

impl<'a> From<&'a u16> for Value<'a>

fn from(v: &'a u16) -> Self

Performs the conversion.

impl<'a> From<&'a u32> for Value<'a>

fn from(v: &'a u32) -> Self

Performs the conversion.

impl<'a> From<&'a u64> for Value<'a>

fn from(v: &'a u64) -> Self

Performs the conversion.

impl<'a> From<&'a u8> for Value<'a>

fn from(v: &'a u8) -> Self

Performs the conversion.

impl<'v, V> From<&'v [V]> for Value<'v> where
    &'v [V]: Into<Array<'v>>, 

fn from(v: &'v [V]) -> Value<'v>

Performs the conversion.

impl<'v> From<&'v String> for Value<'v>

fn from(v: &'v String) -> Value<'v>

Performs the conversion.

impl<'v, V> From<&'v Vec<V, Global>> for Value<'v> where
    &'v Vec<V>: Into<Array<'v>>, 

fn from(v: &'v Vec<V>) -> Value<'v>

Performs the conversion.

impl<'a> From<Array<'a>> for Value<'a>

fn from(v: Array<'a>) -> Self

Performs the conversion.

impl<'a> From<Dict<'a, 'a>> for Value<'a>

fn from(v: Dict<'a, 'a>) -> Self

Performs the conversion.

impl<'a> From<Fd> for Value<'a>

fn from(v: Fd) -> Self

Performs the conversion.

impl<'a, 'k, 'v, K, V> From<HashMap<K, V, RandomState>> for Value<'a> where
    'k: 'a,
    'v: 'a,
    K: Type + Into<Value<'k>> + Hash + Eq,
    V: Type + Into<Value<'k>>, 

fn from(value: HashMap<K, V>) -> Self

Performs the conversion.

impl<'a> From<Maybe<'a>> for Value<'a>

fn from(v: Maybe<'a>) -> Self

Performs the conversion.

impl<'a> From<ObjectPath<'a>> for Value<'a>

fn from(v: ObjectPath<'a>) -> Self

Performs the conversion.

impl<'v, V> From<Option<V>> for Value<'v> where
    Option<V>: Into<Maybe<'v>>, 

fn from(v: Option<V>) -> Value<'v>

Performs the conversion.

impl<'a> From<Signature<'a>> for Value<'a>

fn from(v: Signature<'a>) -> Self

Performs the conversion.

impl<'s> From<String> for Value<'s>

fn from(v: String) -> Self

Performs the conversion.

impl<'v, 's: 'v, T> From<T> for Value<'v> where
    T: Into<Structure<'s>>, 

fn from(v: T) -> Value<'v>

Performs the conversion.

impl<'a> From<Value<'a>> for OwnedValue

fn from(v: Value<'a>) -> Self

Performs the conversion.

impl<'v, V> From<Vec<V, Global>> for Value<'v> where
    Vec<V>: Into<Array<'v>>, 

fn from(v: Vec<V>) -> Value<'v>

Performs the conversion.

impl<'a> From<bool> for Value<'a>

fn from(v: bool) -> Self

Performs the conversion.

impl<'a> From<f32> for Value<'a>

fn from(v: f32) -> Self

Performs the conversion.

impl<'a> From<f64> for Value<'a>

fn from(v: f64) -> Self

Performs the conversion.

impl<'a> From<i16> for Value<'a>

fn from(v: i16) -> Self

Performs the conversion.

impl<'a> From<i32> for Value<'a>

fn from(v: i32) -> Self

Performs the conversion.

impl<'a> From<i64> for Value<'a>

fn from(v: i64) -> Self

Performs the conversion.

impl<'a> From<i8> for Value<'a>

fn from(v: i8) -> Self

Performs the conversion.

impl<'a> From<u16> for Value<'a>

fn from(v: u16) -> Self

Performs the conversion.

impl<'a> From<u32> for Value<'a>

fn from(v: u32) -> Self

Performs the conversion.

impl<'a> From<u64> for Value<'a>

fn from(v: u64) -> Self

Performs the conversion.

impl<'a> From<u8> for Value<'a>

fn from(v: u8) -> Self

Performs the conversion.

impl<'a> PartialEq<Value<'a>> for Value<'a>

fn eq(&self, other: &Value<'a>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Value<'a>) -> bool

This method tests for !=.

impl<'a> Serialize for Value<'a>

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where
    S: Serializer, 

Serialize this value into the given Serde serializer.

impl<'a> StructuralPartialEq for Value<'a>

impl<'a> TryFrom<&'a Value<'a>> for &'a Fd

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Fd

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Dict<'a, 'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Dict<'a, 'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Array<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Array<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Maybe<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Maybe<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a str

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Str<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Str<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Signature<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Signature<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a ObjectPath<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for ObjectPath<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for &'a Structure<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<&'a Value<'a>> for Structure<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: &'a Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<Value<'_>> for OwnedObjectPath

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<Value<'_>> for OwnedSignature

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Fd

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Str<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Signature<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for ObjectPath<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Structure<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Dict<'a, 'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Array<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<Value<'a>> for Maybe<'a>

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Value<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> Type for Value<'a>

fn signature() -> Signature<'static>

Get the signature for the implementing type.