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Delta.ts
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Delta.ts
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import diff from 'fast-diff';
import cloneDeep from 'lodash.clonedeep';
import isEqual from 'lodash.isequal';
import AttributeMap from './AttributeMap';
import Op from './Op';
import OpIterator from './OpIterator';
const NULL_CHARACTER = String.fromCharCode(0); // Placeholder char for embed in diff()
class Delta {
static Op = Op;
static OpIterator = OpIterator;
static AttributeMap = AttributeMap;
ops: Op[];
constructor(ops?: Op[] | { ops: Op[] }) {
// Assume we are given a well formed ops
if (Array.isArray(ops)) {
this.ops = ops;
} else if (ops != null && Array.isArray(ops.ops)) {
this.ops = ops.ops;
} else {
this.ops = [];
}
}
insert(
arg: string | Record<string, unknown>,
attributes?: AttributeMap,
): this {
const newOp: Op = {};
if (typeof arg === 'string' && arg.length === 0) {
return this;
}
newOp.insert = arg;
if (
attributes != null &&
typeof attributes === 'object' &&
Object.keys(attributes).length > 0
) {
newOp.attributes = attributes;
}
return this.push(newOp);
}
delete(length: number): this {
if (length <= 0) {
return this;
}
return this.push({ delete: length });
}
retain(length: number, attributes?: AttributeMap): this {
if (length <= 0) {
return this;
}
const newOp: Op = { retain: length };
if (
attributes != null &&
typeof attributes === 'object' &&
Object.keys(attributes).length > 0
) {
newOp.attributes = attributes;
}
return this.push(newOp);
}
push(newOp: Op): this {
let index = this.ops.length;
let lastOp = this.ops[index - 1];
newOp = cloneDeep(newOp);
if (typeof lastOp === 'object') {
if (
typeof newOp.delete === 'number' &&
typeof lastOp.delete === 'number'
) {
this.ops[index - 1] = { delete: lastOp.delete + newOp.delete };
return this;
}
// Since it does not matter if we insert before or after deleting at the same index,
// always prefer to insert first
if (typeof lastOp.delete === 'number' && newOp.insert != null) {
index -= 1;
lastOp = this.ops[index - 1];
if (typeof lastOp !== 'object') {
this.ops.unshift(newOp);
return this;
}
}
if (isEqual(newOp.attributes, lastOp.attributes)) {
if (
typeof newOp.insert === 'string' &&
typeof lastOp.insert === 'string'
) {
this.ops[index - 1] = { insert: lastOp.insert + newOp.insert };
if (typeof newOp.attributes === 'object') {
this.ops[index - 1].attributes = newOp.attributes;
}
return this;
} else if (
typeof newOp.retain === 'number' &&
typeof lastOp.retain === 'number'
) {
this.ops[index - 1] = { retain: lastOp.retain + newOp.retain };
if (typeof newOp.attributes === 'object') {
this.ops[index - 1].attributes = newOp.attributes;
}
return this;
}
}
}
if (index === this.ops.length) {
this.ops.push(newOp);
} else {
this.ops.splice(index, 0, newOp);
}
return this;
}
chop(): this {
const lastOp = this.ops[this.ops.length - 1];
if (lastOp && lastOp.retain && !lastOp.attributes) {
this.ops.pop();
}
return this;
}
filter(predicate: (op: Op, index: number) => boolean): Op[] {
return this.ops.filter(predicate);
}
forEach(predicate: (op: Op, index: number) => void): void {
this.ops.forEach(predicate);
}
map<T>(predicate: (op: Op, index: number) => T): T[] {
return this.ops.map(predicate);
}
partition(predicate: (op: Op) => boolean): [Op[], Op[]] {
const passed: Op[] = [];
const failed: Op[] = [];
this.forEach((op) => {
const target = predicate(op) ? passed : failed;
target.push(op);
});
return [passed, failed];
}
reduce<T>(
predicate: (accum: T, curr: Op, index: number) => T,
initialValue: T,
): T {
return this.ops.reduce(predicate, initialValue);
}
changeLength(): number {
return this.reduce((length, elem) => {
if (elem.insert) {
return length + Op.length(elem);
} else if (elem.delete) {
return length - elem.delete;
}
return length;
}, 0);
}
length(): number {
return this.reduce((length, elem) => {
return length + Op.length(elem);
}, 0);
}
slice(start = 0, end = Infinity): Delta {
const ops = [];
const iter = new OpIterator(this.ops);
let index = 0;
while (index < end && iter.hasNext()) {
let nextOp;
if (index < start) {
nextOp = iter.next(start - index);
} else {
nextOp = iter.next(end - index);
ops.push(nextOp);
}
index += Op.length(nextOp);
}
return new Delta(ops);
}
compose(other: Delta): Delta {
const thisIter = new OpIterator(this.ops);
const otherIter = new OpIterator(other.ops);
const ops = [];
const firstOther = otherIter.peek();
if (
firstOther != null &&
typeof firstOther.retain === 'number' &&
firstOther.attributes == null
) {
let firstLeft = firstOther.retain;
while (
thisIter.peekType() === 'insert' &&
thisIter.peekLength() <= firstLeft
) {
firstLeft -= thisIter.peekLength();
ops.push(thisIter.next());
}
if (firstOther.retain - firstLeft > 0) {
otherIter.next(firstOther.retain - firstLeft);
}
}
const delta = new Delta(ops);
while (thisIter.hasNext() || otherIter.hasNext()) {
if (otherIter.peekType() === 'insert') {
delta.push(otherIter.next());
} else if (thisIter.peekType() === 'delete') {
delta.push(thisIter.next());
} else {
const length = Math.min(thisIter.peekLength(), otherIter.peekLength());
const thisOp = thisIter.next(length);
const otherOp = otherIter.next(length);
if (typeof otherOp.retain === 'number') {
const newOp: Op = {};
if (typeof thisOp.retain === 'number') {
newOp.retain = length;
} else {
newOp.insert = thisOp.insert;
}
// Preserve null when composing with a retain, otherwise remove it for inserts
const attributes = AttributeMap.compose(
thisOp.attributes,
otherOp.attributes,
typeof thisOp.retain === 'number',
);
if (attributes) {
newOp.attributes = attributes;
}
delta.push(newOp);
// Optimization if rest of other is just retain
if (
!otherIter.hasNext() &&
isEqual(delta.ops[delta.ops.length - 1], newOp)
) {
const rest = new Delta(thisIter.rest());
return delta.concat(rest).chop();
}
// Other op should be delete, we could be an insert or retain
// Insert + delete cancels out
} else if (
typeof otherOp.delete === 'number' &&
typeof thisOp.retain === 'number'
) {
delta.push(otherOp);
}
}
}
return delta.chop();
}
concat(other: Delta): Delta {
const delta = new Delta(this.ops.slice());
if (other.ops.length > 0) {
delta.push(other.ops[0]);
delta.ops = delta.ops.concat(other.ops.slice(1));
}
return delta;
}
diff(other: Delta, cursor?: number | diff.CursorInfo): Delta {
if (this.ops === other.ops) {
return new Delta();
}
const strings = [this, other].map((delta) => {
return delta
.map((op) => {
if (op.insert != null) {
return typeof op.insert === 'string' ? op.insert : NULL_CHARACTER;
}
const prep = delta === other ? 'on' : 'with';
throw new Error('diff() called ' + prep + ' non-document');
})
.join('');
});
const retDelta = new Delta();
const diffResult = diff(strings[0], strings[1], cursor);
const thisIter = new OpIterator(this.ops);
const otherIter = new OpIterator(other.ops);
diffResult.forEach((component: diff.Diff) => {
let length = component[1].length;
while (length > 0) {
let opLength = 0;
switch (component[0]) {
case diff.INSERT:
opLength = Math.min(otherIter.peekLength(), length);
retDelta.push(otherIter.next(opLength));
break;
case diff.DELETE:
opLength = Math.min(length, thisIter.peekLength());
thisIter.next(opLength);
retDelta.delete(opLength);
break;
case diff.EQUAL:
opLength = Math.min(
thisIter.peekLength(),
otherIter.peekLength(),
length,
);
const thisOp = thisIter.next(opLength);
const otherOp = otherIter.next(opLength);
if (isEqual(thisOp.insert, otherOp.insert)) {
retDelta.retain(
opLength,
AttributeMap.diff(thisOp.attributes, otherOp.attributes),
);
} else {
retDelta.push(otherOp).delete(opLength);
}
break;
}
length -= opLength;
}
});
return retDelta.chop();
}
eachLine(
predicate: (
line: Delta,
attributes: AttributeMap,
index: number,
) => boolean | void,
newline = '\n',
): void {
const iter = new OpIterator(this.ops);
let line = new Delta();
let i = 0;
while (iter.hasNext()) {
if (iter.peekType() !== 'insert') {
return;
}
const thisOp = iter.peek();
const start = Op.length(thisOp) - iter.peekLength();
const index =
typeof thisOp.insert === 'string'
? thisOp.insert.indexOf(newline, start) - start
: -1;
if (index < 0) {
line.push(iter.next());
} else if (index > 0) {
line.push(iter.next(index));
} else {
if (predicate(line, iter.next(1).attributes || {}, i) === false) {
return;
}
i += 1;
line = new Delta();
}
}
if (line.length() > 0) {
predicate(line, {}, i);
}
}
invert(base: Delta): Delta {
const inverted = new Delta();
this.reduce((baseIndex, op) => {
if (op.insert) {
inverted.delete(Op.length(op));
} else if (op.retain && op.attributes == null) {
inverted.retain(op.retain);
return baseIndex + op.retain;
} else if (op.delete || (op.retain && op.attributes)) {
const length = (op.delete || op.retain) as number;
const slice = base.slice(baseIndex, baseIndex + length);
slice.forEach((baseOp) => {
if (op.delete) {
inverted.push(baseOp);
} else if (op.retain && op.attributes) {
inverted.retain(
Op.length(baseOp),
AttributeMap.invert(op.attributes, baseOp.attributes),
);
}
});
return baseIndex + length;
}
return baseIndex;
}, 0);
return inverted.chop();
}
transform(index: number, priority?: boolean): number;
transform(other: Delta, priority?: boolean): Delta;
transform(arg: number | Delta, priority = false): typeof arg {
priority = !!priority;
if (typeof arg === 'number') {
return this.transformPosition(arg, priority);
}
const other: Delta = arg;
const thisIter = new OpIterator(this.ops);
const otherIter = new OpIterator(other.ops);
const delta = new Delta();
while (thisIter.hasNext() || otherIter.hasNext()) {
if (
thisIter.peekType() === 'insert' &&
(priority || otherIter.peekType() !== 'insert')
) {
delta.retain(Op.length(thisIter.next()));
} else if (otherIter.peekType() === 'insert') {
delta.push(otherIter.next());
} else {
const length = Math.min(thisIter.peekLength(), otherIter.peekLength());
const thisOp = thisIter.next(length);
const otherOp = otherIter.next(length);
if (thisOp.delete) {
// Our delete either makes their delete redundant or removes their retain
continue;
} else if (otherOp.delete) {
delta.push(otherOp);
} else {
// We retain either their retain or insert
delta.retain(
length,
AttributeMap.transform(
thisOp.attributes,
otherOp.attributes,
priority,
),
);
}
}
}
return delta.chop();
}
transformPosition(index: number, priority = false): number {
priority = !!priority;
const thisIter = new OpIterator(this.ops);
let offset = 0;
while (thisIter.hasNext() && offset <= index) {
const length = thisIter.peekLength();
const nextType = thisIter.peekType();
thisIter.next();
if (nextType === 'delete') {
index -= Math.min(length, index - offset);
continue;
} else if (nextType === 'insert' && (offset < index || !priority)) {
index += length;
}
offset += length;
}
return index;
}
}
export default Delta;
if (typeof module === 'object') {
module.exports = Delta;
module.exports.default = Delta;
}