@wordpress/block-editor/src/utils/block-bindings.js

Generic block editor.

const DEFAULT_ATTRIBUTE = '__default';
const PATTERN_OVERRIDES_SOURCE = 'core/pattern-overrides';

/**
 * Checks if the block has the `__default` binding for pattern overrides.
 *
 * @param {?Record<string, object>} bindings A block's bindings from the metadata attribute.
 *
 * @return {boolean} Whether the block has the `__default` binding for pattern overrides.
 */
export function hasPatternOverridesDefaultBinding( bindings ) {
	return bindings?.[ DEFAULT_ATTRIBUTE ]?.source === PATTERN_OVERRIDES_SOURCE;
}

/**
 * Returns the bindings with the `__default` binding for pattern overrides
 * replaced with the full-set of supported attributes. e.g.:
 *
 * - bindings passed in: `{ __default: { source: 'core/pattern-overrides' } }`
 * - bindings returned: `{ content: { source: 'core/pattern-overrides' } }`
 *
 * @param {?Record<string, object>} bindings            A block's bindings from the metadata attribute.
 * @param {string[]}                supportedAttributes The block's attributes which are supported by block bindings.
 *
 * @return {Object} The bindings with default replaced for pattern overrides.
 */
export function replacePatternOverridesDefaultBinding(
	bindings,
	supportedAttributes
) {
	// The `__default` binding currently only works for pattern overrides.
	if ( hasPatternOverridesDefaultBinding( bindings ) ) {
		const bindingsWithDefaults = {};
		for ( const attributeName of supportedAttributes ) {
			// If the block has mixed binding sources, retain any non pattern override bindings.
			const bindingSource = bindings[ attributeName ]
				? bindings[ attributeName ]
				: { source: PATTERN_OVERRIDES_SOURCE };
			bindingsWithDefaults[ attributeName ] = bindingSource;
		}

		return bindingsWithDefaults;
	}

	return bindings;
}