Struct hcl::ser::LabeledBlock

pub struct LabeledBlock<T>(_);

A transparent wrapper type which hints the Serializer to serialize T as a labeled HCL block.

When passed to a serializer other than the one from this crate, a LabeledBlock<T> serializes exactly like T, if T implements serde::Serialize.

A LabeledBlock<T> can only be used in the value position of a map-like structure. For example:

• It can be used to wrap the value type of a map, e.g. Map<K, LabeledBlock<T>>
• As the value of a struct field, e.g. struct S { field: LabeledBlock<T> }
• Or as the value of an enum variant, e.g. enum E { Variant(LabeledBlock<T>) }

The serialized block’s identifier will be the respective map key, struct field name or variant name.

The wrapped T must be shaped as follows to be serialized as a labeled HCL block:

• A map-like value (e.g. a map or struct) where the value may to be another LabeledBlock<T>, in which case a block with multiple labels is produced. Can be nested arbitrarily deep to allow for any number of block labels.
• A sequence-like value (e.g. a vector, slice or tuple) with map-like elements as described above. In this case, multiple blocks with the same identifier and labels are produced.

Wrapping a type T that does not fulfil one of the criteria above in a LabeledBlock<T> will result in serialization errors.

For more convenient usage, see the labeled_block and doubly_labeled_block functions.

Example

use hcl::ser::LabeledBlock;
use indexmap::{indexmap, IndexMap};
use serde::Serialize;

#[derive(Serialize)]
struct Config {
    user: LabeledBlock<IndexMap<String, User>>,
}

#[derive(Serialize)]
struct User {
    email: String,
}

let users = indexmap! {
    "john".into() => User {
        email: "johndoe@example.com".into(),
    },
    "jane".into() => User {
        email: "janedoe@example.com".into(),
    },
};

let config = Config {
    user: LabeledBlock::new(users),
};

let expected = r#"
user "john" {
  email = "johndoe@example.com"
}

user "jane" {
  email = "janedoe@example.com"
}
"#.trim_start();

assert_eq!(hcl::to_string(&config)?, expected);

Implementations

impl<T> LabeledBlock<T>

pub fn new(value: T) -> LabeledBlock<T>

Create a new LabeledBlock<T> from a T.

pub fn into_inner(self) -> T

Consume the LabeledBlock and return the wrapped T.

Trait Implementations

impl<T> Clone for LabeledBlock<T>where T: Clone,

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for LabeledBlock<T>where T: Debug,

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

Formats the value using the given formatter.

impl<T> Deref for LabeledBlock<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for LabeledBlock<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'de, T> Deserialize<'de> for LabeledBlock<T>where T: Deserialize<'de>,

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

Deserialize this value from the given Serde deserializer.

impl<T> Serialize for LabeledBlock<T>where T: Serialize,

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

Serialize this value into the given Serde serializer.