All files / json-ot/types/ot-string-irreversible compose.ts

100% Statements 55/55
100% Branches 22/22
100% Functions 1/1
100% Lines 47/47

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76  3x                             3x 1006x 1006x 1006x 1006x 1006x 1006x 3151x 3151x   2004x 756x 756x 2035x 2035x 2035x 2035x 2035x 2035x 2035x 2035x 954x 954x   2035x     1248x 1248x 1248x 3751x 3751x 3751x 3751x 3751x 3751x 3751x 1946x 3751x 3751x 1912x 1912x   3751x     2004x     1147x 1147x       1006x 1006x 1006x 1006x    
import type {StringOp} from './types';
import {append, chunk, componentLength, isDeleteComponent, trim} from './util';
 
/**
 * Combine two operations into one, such that the changes produced by the
 * by the single operation are the same as if the two operations were applied
 * in sequence.
 *
 * ```
 * apply(str, combine(op1, op2)) === apply(apply(str, op1), op2)
 * ```
 *
 * @param op1 First operation.
 * @param op2 Second operation.
 * @returns A combined operation.
 */
export const compose = (op1: StringOp, op2: StringOp): StringOp => {
  const op3: StringOp = [];
  const len1 = op1.length;
  const len2 = op2.length;
  let off1 = 0;
  let i1 = 0;
  for (let i2 = 0; i2 < len2; i2++) {
    const comp2 = op2[i2];
    switch (typeof comp2) {
      case 'number': {
        if (comp2 > 0) {
          let length2 = comp2;
          while (length2 > 0) {
            const comp1 = op1[i1];
            const comp = i1 >= len1 ? length2 : chunk(comp1, off1, length2);
            const compLength = componentLength(comp);
            const isDelete = isDeleteComponent(comp);
            const length1 = componentLength(comp1 || comp);
            append(op3, comp);
            off1 += compLength;
            if (off1 >= length1) {
              i1++;
              off1 = 0;
            }
            if (!isDelete) length2 -= compLength;
          }
        } else {
          const length2 = -comp2;
          let off2 = 0;
          while (off2 < length2) {
            const remaining = length2 - off2;
            const comp1 = op1[i1];
            const comp = i1 >= len1 ? remaining : chunk(comp1, off1, remaining);
            const compLength = componentLength(comp);
            const isDelete = isDeleteComponent(comp);
            const length1 = componentLength(comp1 || comp);
            if (isDelete) append(op3, comp);
            else if (typeof comp === 'number') append(op3, -compLength);
            off1 += compLength;
            if (off1 >= length1) {
              i1++;
              off1 = 0;
            }
            if (!isDelete) off2 += compLength;
          }
        }
        break;
      }
      case 'string': {
        append(op3, comp2);
        break;
      }
    }
  }
  if (i1 < len1 && off1) append(op3, chunk(op1[i1++], off1, Number.POSITIVE_INFINITY));
  for (; i1 < len1; i1++) append(op3, op1[i1]);
  trim(op3);
  return op3;
};