Struct log::kv::value::Value

pub struct Value<'v> { /* private fields */ }

A value in a structured key-value pair.

Capturing values

There are a few ways to capture a value:

• Using the Value::capture_* methods.
• Using the Value::from_* methods.
• Using the ToValue trait.
• Using the standard From trait.

Using the Value::capture_* methods

Value offers a few constructor methods that capture values of different kinds. These methods require a T: 'static to support downcasting.

use log::kv::Value;

let value = Value::capture_debug(&42i32);

assert_eq!(Some(42), value.to_i64());

Using the Value::from_* methods

Value offers a few constructor methods that capture values of different kinds. These methods don’t require T: 'static, but can’t support downcasting.

use log::kv::Value;

let value = Value::from_debug(&42i32);

assert_eq!(None, value.to_i64());

Using the ToValue trait

The ToValue trait can be used to capture values generically. It’s the bound used by Source.

let value = 42i32.to_value();

assert_eq!(Some(42), value.to_i64());

use log::kv::ToValue;

let value = (&42i32 as &dyn Debug).to_value();

assert_eq!(None, value.to_i64());

Using the standard From trait

Standard types that implement ToValue also implement From.

use log::kv::Value;

let value = Value::from(42i32);

assert_eq!(Some(42), value.to_i64());

Implementations

impl<'v> Value<'v>

pub fn to_str(&self) -> Option<Cow<'_, str>>

Try convert this value into a string.

impl<'v> Value<'v>

pub fn from_any<T>(value: &'v T) -> Selfwhere T: ToValue,

Get a value from a type implementing ToValue.

pub fn capture_debug<T>(value: &'v T) -> Selfwhere T: Debug + 'static,

Get a value from a type implementing std::fmt::Debug.

pub fn capture_display<T>(value: &'v T) -> Selfwhere T: Display + 'static,

Get a value from a type implementing std::fmt::Display.

pub fn capture_error<T>(err: &'v T) -> Selfwhere T: Error + 'static,

Get a value from an error.

pub fn capture_serde<T>(value: &'v T) -> Selfwhere T: Serialize + 'static,

Get a value from a type implementing serde::Serialize.

pub fn capture_sval<T>(value: &'v T) -> Selfwhere T: Value + 'static,

Get a value from a type implementing sval::Value.

pub fn from_debug<T>(value: &'v T) -> Selfwhere T: Debug,

Get a value from a type implementing std::fmt::Debug.

pub fn from_display<T>(value: &'v T) -> Selfwhere T: Display,

Get a value from a type implementing std::fmt::Display.

pub fn from_serde<T>(value: &'v T) -> Selfwhere T: Serialize,

Get a value from a type implementing serde::Serialize.

pub fn from_sval<T>(value: &'v T) -> Selfwhere T: Value,

Get a value from a type implementing sval::Value.

pub fn from_dyn_debug(value: &'v dyn Debug) -> Self

Get a value from a dynamic std::fmt::Debug.

pub fn from_dyn_display(value: &'v dyn Display) -> Self

Get a value from a dynamic std::fmt::Display.

pub fn from_dyn_error(err: &'v (dyn Error + 'static)) -> Self

Get a value from a dynamic error.

pub fn is<T: 'static>(&self) -> bool

Check whether this value can be downcast to T.

pub fn downcast_ref<T: 'static>(&self) -> Option<&T>

Try downcast this value to T.

pub fn visit(&self, visitor: impl Visit<'v>) -> Result<(), Error>

Inspect this value using a simple visitor.

impl<'v> Value<'v>

pub fn to_u64(&self) -> Option<u64>

Try convert this value into a u64.

pub fn to_i64(&self) -> Option<i64>

Try convert this value into a i64.

pub fn to_u128(&self) -> Option<u128>

Try convert this value into a u128.

pub fn to_i128(&self) -> Option<i128>

Try convert this value into a i128.

pub fn to_f64(&self) -> Option<f64>

Try convert this value into a f64.

pub fn to_char(&self) -> Option<char>

Try convert this value into a char.

pub fn to_bool(&self) -> Option<bool>

Try convert this value into a bool.

impl<'v> Value<'v>

pub fn to_borrowed_error(&self) -> Option<&(dyn Error + 'static)>

Try convert this value into an error.

pub fn to_borrowed_str(&self) -> Option<&str>

Try convert this value into a borrowed string.

Trait Implementations

impl<'v> Debug for Value<'v>

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

Formats the value using the given formatter.

impl<'v> Display for Value<'v>

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

Formats the value using the given formatter.

impl<'v> From<&'v NonZeroI128> for Value<'v>

fn from(v: &'v NonZeroI128) -> Value<'v>

Converts to this type from the input type.

impl<'v> From<&'v NonZeroU128> for Value<'v>

fn from(v: &'v NonZeroU128) -> Value<'v>

Converts to this type from the input type.

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

fn from(v: &'v String) -> Self

Converts to this type from the input type.

impl<'v> From<&'v i128> for Value<'v>

fn from(value: &'v i128) -> Self

Converts to this type from the input type.

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

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

Converts to this type from the input type.

impl<'v> From<&'v u128> for Value<'v>

fn from(value: &'v u128) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroI16> for Value<'v>

fn from(value: NonZeroI16) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroI32> for Value<'v>

fn from(value: NonZeroI32) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroI64> for Value<'v>

fn from(value: NonZeroI64) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroI8> for Value<'v>

fn from(value: NonZeroI8) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroIsize> for Value<'v>

fn from(value: NonZeroIsize) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroU16> for Value<'v>

fn from(value: NonZeroU16) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroU32> for Value<'v>

fn from(value: NonZeroU32) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroU64> for Value<'v>

fn from(value: NonZeroU64) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroU8> for Value<'v>

fn from(value: NonZeroU8) -> Self

Converts to this type from the input type.

impl<'v> From<NonZeroUsize> for Value<'v>

fn from(value: NonZeroUsize) -> Self

Converts to this type from the input type.

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

fn from(value: bool) -> Self

Converts to this type from the input type.

impl<'v> From<char> for Value<'v>

fn from(value: char) -> Self

Converts to this type from the input type.

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

fn from(value: f32) -> Self

Converts to this type from the input type.

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

fn from(value: f64) -> Self

Converts to this type from the input type.

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

fn from(value: i16) -> Self

Converts to this type from the input type.

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

fn from(value: i32) -> Self

Converts to this type from the input type.

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

fn from(value: i64) -> Self

Converts to this type from the input type.

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

fn from(value: i8) -> Self

Converts to this type from the input type.

impl<'v> From<isize> for Value<'v>

fn from(value: isize) -> Self

Converts to this type from the input type.

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

fn from(value: u16) -> Self

Converts to this type from the input type.

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

fn from(value: u32) -> Self

Converts to this type from the input type.

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

fn from(value: u64) -> Self

Converts to this type from the input type.

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

fn from(value: u8) -> Self

Converts to this type from the input type.

impl<'v> From<usize> for Value<'v>

fn from(value: usize) -> Self

Converts to this type from the input type.

impl<'v> Serialize for Value<'v>

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

Serialize this value into the given Serde serializer.

impl<'v> ToValue for Value<'v>

fn to_value(&self) -> Value<'_>

Perform the conversion.

impl<'v> Value for Value<'v>

fn stream<'sval, S: Stream<'sval> + ?Sized>( &'sval self, stream: &mut S ) -> Result

Stream this value through a Stream.

fn to_bool(&self) -> Option<bool>

Try convert this value into a boolean.

fn to_f32(&self) -> Option<f32>

Try convert this value into a 32bit binary floating point number.

fn to_f64(&self) -> Option<f64>

Try convert this value into a 64bit binary floating point number.

fn to_i8(&self) -> Option<i8>

Try convert this value into a signed 8bit integer.

fn to_i16(&self) -> Option<i16>

Try convert this value into a signed 16bit integer.

fn to_i32(&self) -> Option<i32>

Try convert this value into a signed 32bit integer.

fn to_i64(&self) -> Option<i64>

Try convert this value into a signed 64bit integer.

fn to_i128(&self) -> Option<i128>

Try convert this value into a signed 128bit integer.

fn to_u8(&self) -> Option<u8>

Try convert this value into an unsigned 8bit integer.

fn to_u16(&self) -> Option<u16>

Try convert this value into an unsigned 16bit integer.

fn to_u32(&self) -> Option<u32>

Try convert this value into an unsigned 32bit integer.

fn to_u64(&self) -> Option<u64>

Try convert this value into an unsigned 64bit integer.

fn to_u128(&self) -> Option<u128>

Try convert this value into an unsigned 128bit integer.

fn to_text(&self) -> Option<&str>

Try convert this value into a text string.

fn to_binary(&self) -> Option<&[u8]>

Try convert this value into a bitstring.

impl<'v> ValueRef<'v> for Value<'v>

fn stream_ref<S: Stream<'v> + ?Sized>(&self, stream: &mut S) -> Result

Stream this value through a Stream.