json-joy
Version:
Collection of libraries for building collaborative editing apps.
81 lines (80 loc) • 2.98 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.compose = void 0;
const util_1 = require("./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.
*/
const compose = (op1, op2) => {
const op3 = [];
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];
if (typeof comp2 === '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 isDelete = (0, util_1.isDeleteComponent)(comp);
const length1 = (0, util_1.componentLength)(comp1 || comp);
(0, util_1.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 : (0, util_1.chunk)(comp1, off1, remaining);
const compLength = (0, util_1.componentLength)(comp);
const isDelete = (0, util_1.isDeleteComponent)(comp);
const length1 = (0, util_1.componentLength)(comp1 || comp);
if (isDelete)
(0, util_1.append)(op3, comp);
else if (typeof comp === 'number')
(0, util_1.append)(op3, -compLength);
off1 += compLength;
if (off1 >= length1) {
i1++;
off1 = 0;
}
if (!isDelete)
off2 += compLength;
}
}
}
else if (comp2 instanceof Uint8Array) {
(0, util_1.append)(op3, comp2);
}
}
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.compose = compose;