All files / json-patch-diff JsonPatchDiff.ts

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import {deepEqual} from '@jsonjoy.com/util/lib/json-equal/deepEqual';
import * as str from '../util/diff/str';
import * as line from '../util/diff/line';
import {structHash} from '../json-hash';
import type {Operation} from '../json-patch/codec/json/types';
 
export class JsonPatchDiff {
  protected patch: Operation[] = [];
 
  protected diffVal(path: string, src: unknown, dst: unknown): void {
    if (deepEqual(src, dst)) return;
    this.patch.push({op: 'replace', path, value: dst});
  }
 
  protected diffStr(path: string, src: string, dst: string): void {
    if (src === dst) return;
    const patch = this.patch;
    str.apply(
      str.diff(src, dst),
      src.length,
      (pos, str) => patch.push({op: 'str_ins', path, pos, str}),
      (pos, len, str) => patch.push({op: 'str_del', path, pos, len, str}),
    );
  }
 
  protected diffBin(path: string, src: Uint8Array, dst: Uint8Array): void {
    throw new Error('Not implemented');
  }
 
  protected diffObj(path: string, src: Record<string, unknown>, dst: Record<string, unknown>): void {
    const patch = this.patch;
    for (const key in src) {
      if (key in dst) {
        const val1 = src[key];
        const val2 = dst[key];
        if (val1 === val2) continue;
        this.diffAny(path + '/' + key, val1, val2);
      } else {
        patch.push({op: 'remove', path: path + '/' + key});
      }
    }
    for (const key in dst) {
      if (key in src) continue;
      patch.push({op: 'add', path: path + '/' + key, value: dst[key]});
    }
  }
 
  protected diffArr(path: string, src: unknown[], dst: unknown[]): void {
    const srcLines: string[] = [];
    const dstLines: string[] = [];
    const srcLen = src.length;
    const dstLen = dst.length;
    for (let i = 0; i < srcLen; i++) srcLines.push(structHash(src[i]));
    for (let i = 0; i < dstLen; i++) dstLines.push(structHash(dst[i]));
    const pfx = path + '/';
    const patch = this.patch;
    const linePatch = line.diff(srcLines, dstLines);
    const length = linePatch.length;
    for (let i = length - 1; i >= 0; i--) {
      const [type, srcIdx, dstIdx] = linePatch[i];
      switch (type) {
        case line.LINE_PATCH_OP_TYPE.EQL:
          break;
        case line.LINE_PATCH_OP_TYPE.MIX: {
          const srcValue = src[srcIdx];
          const dstValue = dst[dstIdx];
          this.diff(pfx + srcIdx, srcValue, dstValue);
          break;
        }
        case line.LINE_PATCH_OP_TYPE.INS:
          patch.push({op: 'add', path: pfx + (srcIdx + 1), value: dst[dstIdx]});
          break;
        case line.LINE_PATCH_OP_TYPE.DEL:
          patch.push({op: 'remove', path: pfx + srcIdx});
          break;
      }
    }
  }
 
  public diffAny(path: string, src: unknown, dst: unknown): void {
    switch (typeof src) {
      case 'string': {
        if (typeof dst === 'string') this.diffStr(path, src, dst);
        else this.diffVal(path, src, dst);
        break;
      }
      case 'number':
      case 'boolean':
      case 'bigint': {
        this.diffVal(path, src, dst);
        break;
      }
      case 'object': {
        if (!src || !dst || typeof dst !== 'object') {
          this.diffVal(path, src, dst);
          return;
        }
        if (Array.isArray(src)) {
          if (Array.isArray(dst)) this.diffArr(path, src, dst);
          else Ethis.diffVal(path, src, dst);
          return;
        }
        this.diffObj(path, src as Record<string, unknown>, dst as Record<string, unknown>);
        break;
      }
      default:
        this.diffVal(path, src, dst);
        break;
    }
  }
 
  public diff(path: string, src: unknown, dst: unknown): Operation[] {
    this.diffAny(path, src, dst);
    return this.patch;
  }
}