Trait CBORTaggedEncodable

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pub trait CBORTaggedEncodable: CBORTagged {
    // Required method
    fn untagged_cbor(&self) -> CBOR;

    // Provided methods
    fn tagged_cbor(&self) -> CBOR { ... }
    fn tagged_cbor_data(&self) -> Vec<u8> ⓘ { ... }
}

Expand description

§Tagged CBOR Encoding Support

This module provides the CBORTaggedEncodable trait, which enables types to be encoded as tagged CBOR values.

CBOR tags provide semantic information about the encoded data. For example, tag 1 is used for dates, indicating that the value should be interpreted as a timestamp. The dCBOR library ensures these tags are encoded deterministically.

This trait enables seamless encoding of Rust types to properly tagged CBOR values. A trait for types that can be encoded to CBOR with a specific tag.

This trait extends CBORTagged to provide methods for encoding a value with its associated tag. Types that implement this trait define how they should be represented in CBOR format, both with and without their tag.

§Example

use dcbor::prelude::*;

// Define a Date type
#[derive(Debug, Clone, PartialEq)]
struct Date(f64); // Timestamp as seconds since epoch

// Implement CBORTagged
impl CBORTagged for Date {
    fn cbor_tags() -> Vec<Tag> {
        vec![Tag::with_value(1)] // Standard date tag
    }
}

// Implement encoding to tagged CBOR
impl CBORTaggedEncodable for Date {
    fn untagged_cbor(&self) -> CBOR {
        // Date content is represented as a number
        self.0.into()
    }
}

// Create a date and encode it
let date = Date(1609459200.0); // 2021-01-01 00:00:00 UTC

// Get the untagged CBOR (just the timestamp)
let untagged = date.untagged_cbor();
// Timestamp is converted to an integer when it has no fractional part
assert_eq!(untagged.diagnostic(), "1609459200");

// Get the tagged CBOR (with tag 1)
let tagged = date.tagged_cbor();
assert_eq!(tagged.diagnostic(), "1(1609459200)");

// Get binary representation
let data = date.tagged_cbor_data();

Required Methods§

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fn untagged_cbor(&self) -> CBOR

Returns the untagged CBOR encoding of this instance.

This method defines how the value itself (without its tag) should be represented in CBOR format.

Provided Methods§

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fn tagged_cbor(&self) -> CBOR

Returns the tagged CBOR encoding of this instance.

This method wraps the result of untagged_cbor() with the first tag from cbor_tags(), which is considered the “preferred” tag for the type.

Even if a type supports multiple tags for backward-compatible decoding via cbor_tags(), only the first (preferred) tag is used for encoding. This ensures consistency in newly created data while maintaining the ability to read older formats.

In most cases, you don’t need to override this method.

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