json-joy
Version:
Collection of libraries for building collaborative editing apps.
96 lines (95 loc) • 3.47 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.transform = void 0;
const util_1 = require("./util");
/**
* Transforms an operation such that the transformed operations can be
* applied to a string in reverse order.
*
* ```
* apply(apply(doc, op1), transform(op2, op1)) === apply(apply(doc, op2), transform(op1, op2))
* ```
*
* @param op1 The operation to transform.
* @param op2 The operation to transform against.
* @returns A new operation with user intentions preserved.
*/
const transform = (op1, op2, leftInsertFirst) => {
const op3 = [];
const len1 = op1.length;
const len2 = op2.length;
let i1 = 0;
let i2 = 0;
let off1 = 0;
for (; i2 < len2; i2++) {
const comp2 = op2[i2];
let doDelete = false;
switch (typeof comp2) {
case 'number': {
if (comp2 > 0) {
let length2 = comp2;
while (length2 > 0) {
const comp1 = op1[i1];
const comp = i1 >= len1 ? length2 : (0, util_1.chunk)(comp1, off1, length2);
const compLength = (0, util_1.componentLength)(comp);
const length1 = (0, util_1.componentLength)(comp1 || comp);
(0, util_1.append)(op3, comp);
off1 += compLength;
if (off1 >= length1) {
i1++;
off1 = 0;
}
if (typeof comp !== 'string')
length2 -= compLength;
}
}
else
doDelete = true;
break;
}
case 'string': {
if (leftInsertFirst) {
if (typeof op1[i1] === 'string') {
const comp = (0, util_1.chunk)(op1[i1++], off1, Number.POSITIVE_INFINITY);
off1 = 0;
(0, util_1.append)(op3, comp);
}
}
(0, util_1.append)(op3, comp2.length);
break;
}
case 'object': {
doDelete = true;
break;
}
}
if (doDelete) {
const isReversible = comp2 instanceof Array;
const length2 = isReversible ? comp2[0].length : -comp2;
let off2 = 0;
while (off2 < length2) {
const remaining = length2 - off2;
const comp1 = op1[i1];
const comp = i1 >= len1 ? remaining : (0, util_1.chunk)(comp1, off1, remaining);
const compLength = (0, util_1.componentLength)(comp);
const length1 = (0, util_1.componentLength)(comp1 || comp);
if (typeof comp === 'string')
(0, util_1.append)(op3, comp);
else
off2 += compLength;
off1 += compLength;
if (off1 >= length1) {
i1++;
off1 = 0;
}
}
}
}
if (i1 < len1 && off1)
(0, util_1.append)(op3, (0, util_1.chunk)(op1[i1++], off1, Number.POSITIVE_INFINITY));
for (; i1 < len1; i1++)
(0, util_1.append)(op3, op1[i1]);
(0, util_1.trim)(op3);
return op3;
};
exports.transform = transform;