immutable-json-patch/lib/esm/revertJSONPatch.js

Immutable JSON patch with support for reverting operations

import { existsIn, getIn } from './immutabilityHelpers.js';
import { immutableJSONPatch, isArrayItem, parseFrom, parsePath } from './immutableJSONPatch.js';
import { compileJSONPointer } from './jsonPointer.js';
import { startsWith } from './utils.js';

/**
 * Create the inverse of a set of json patch operations
 * @param document
 * @param operations Array with JSON patch actions
 * @param [options]
 * @return Returns the operations to revert the changes
 */
export function revertJSONPatch(document, operations, options) {
  let allRevertOperations = [];
  const before = (document, operation) => {
    let revertOperations;
    const path = parsePath(document, operation.path);
    if (operation.op === 'add') {
      revertOperations = revertAdd(document, path);
    } else if (operation.op === 'remove') {
      revertOperations = revertRemove(document, path);
    } else if (operation.op === 'replace') {
      revertOperations = revertReplace(document, path);
    } else if (operation.op === 'copy') {
      revertOperations = revertCopy(document, path);
    } else if (operation.op === 'move') {
      revertOperations = revertMove(document, path, parseFrom(operation.from));
    } else if (operation.op === 'test') {
      revertOperations = [];
    } else {
      throw new Error(`Unknown JSONPatch operation ${JSON.stringify(operation)}`);
    }
    let updatedJson;
    if (options?.before) {
      const res = options.before(document, operation, revertOperations);
      if (res?.revertOperations) {
        revertOperations = res.revertOperations;
      }
      if (res?.document) {
        updatedJson = res.document;
      }

      // @ts-ignore
      if (res?.json) {
        // TODO: deprecated since v5.0.0. Cleanup this warning some day
        throw new Error('Deprecation warning: returned object property ".json" has been renamed to ".document"');
      }
    }
    allRevertOperations = revertOperations.concat(allRevertOperations);
    if (updatedJson !== undefined) {
      return {
        document: updatedJson
      };
    }
  };
  immutableJSONPatch(document, operations, {
    before
  });
  return allRevertOperations;
}
function revertReplace(document, path) {
  return existsIn(document, path) ? [{
    op: 'replace',
    path: compileJSONPointer(path),
    value: getIn(document, path)
  }] : [];
}
function revertRemove(document, path) {
  return [{
    op: 'add',
    path: compileJSONPointer(path),
    value: getIn(document, path)
  }];
}
function revertAdd(document, path) {
  if (isArrayItem(document, path) || !existsIn(document, path)) {
    return [{
      op: 'remove',
      path: compileJSONPointer(path)
    }];
  }
  return revertReplace(document, path);
}
function revertCopy(document, path) {
  return revertAdd(document, path);
}
function revertMove(document, path, from) {
  if (path.length < from.length && startsWith(from, path)) {
    // replacing the parent with the child
    return [{
      op: 'replace',
      path: compileJSONPointer(path),
      value: document
    }];
  }
  const move = {
    op: 'move',
    from: compileJSONPointer(path),
    path: compileJSONPointer(from)
  };
  if (!isArrayItem(document, path) && existsIn(document, path)) {
    // the move replaces an existing value in an object
    return [move, ...revertRemove(document, path)];
  }
  return [move];
}
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