CBOR-LD 1.0

3.1 JSON-LD to CBOR-LD Algorithm

This algorithm takes a JSON-LD object jsonldDocument and options as input.

1. Let result be an empty CBOR-encoded byte array.
2. Initialize contextUrls to the return value of the "Get Context URLs Algorithm" passing jsonldDocument as input.
3. If the "Get Context URLs Algorithm" resulted in an error, set result to the return value of the "Generate Uncompressed CBOR-LD Algorithm".
4. Otherwise, set result to the return value of the "Generate Compressed CBOR-LD Algorithm" passing contextUrls as options.contextUrls.
5. Return result.

3.2 Uncompressed CBOR-LD Buffer Algorithm

This algorithm takes a JSON-LD object jsonldDocument and options as input.

1. Let result be an empty CBOR-encoded byte array.
2. Set the first two bytes (CBOR Tag) to 0x0500 (CBOR-LD - 0x05, Uncompressed - 0x00, Tag 1280))
3. For every key-value in the map, generate the Uncompressed CBOR-LD Buffer by converting it to the associated CBOR-LD header and value. For complex values (maps, arrays), recursively convert the value to something that will losslessly encode and decode back to JSON-LD.
4. Return the Uncompressed CBOR-LD Buffer.

3.3 Compressed CBOR-LD Buffer Algorithm

This algorithm takes a JSON-LD object jsonldDocument and options as input. The options MUST contain:

applicationContextMap

A map of application-specific JSON-LD context URL strings that are mapped to their encoded CBOR-LD values. The values MUST be values greater than 32767 (0x7FFF). Values from 0-32767 (0x0-0x7FFF) are reserved for globally recognized JSON-LD Context URL values.

applicationTermMap

A map of JSON-LD terms and their associated CBOR-LD term codecs.

1. Let result be an empty CBOR-encoded byte array.
2. Set the first three bytes of result to 0xd90501 (CBOR Tag - 0xd9, CBOR-LD - 0x05, Compressed - CBOR-LD compression algorithm version 1 - 0x01, Tag 1281)).
3. Initialize termCodecMap to the result of the § 3.4 Get Term Codec Map Algorithm, passing contextUrls as input.
4. Add to result by recursively processing every name-value pair in jsonldDocument
   1. Let termHint be the value associated with the JSON name in the termCodecMap.
   2. Set the CBOR key to the termHint.value value.
   3. Set the CBOR value to the result of the termHint.valueCompressor function.
5. Return result.

3.4 Get Term Codec Map Algorithm

This algorithm takes a list of URL strings contextUrls and returns a CBOR-LD term codec map that maps JSON-LD terms to their associated byte values and value compression functions.

1. Let result be an ordered map.
2. For each value in contextUrls, dereference the JSON-LD contexts and process every entry.
   1. Set the entry key to the JSON-LD term key.
   2. Set the entry value to an unordered map with two entries.
      1. The first entry should be set to value with an undefined value.
      2. Let compressor be a known global compressor function associated with the @type property, a known local compressor function that was provided to this function, or the generic CBOR compressor function, which returns the bytes associated with a typical CBOR compression of the given datatype.
3. Let sortedTerms be the value of sorting all of the keys in result.
4. For every value in the list of sortedTerms set the associated termHint.value value to the associated index of sortedTerms.
5. Return result.

3.5 Get Context URLs Algorithm

1. Let result be a ordered map.
2. Walk the JSON tree, for each JSON name-value pair:
   1. If the name is @context
      1. Add all values that are referenced by a URL to result where the key in the map is set to the JSON value associated with @id.
   2. If a non-URL value is detected, throw an ERR_NON_URL_JSONLD_CONTEXT_DETECTED error.
3. Return result.