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if (typeof ot === 'undefined') {
// Export for browsers
var ot = {};
}
ot.SimpleTextOperation = (function (global) {
var TextOperation = global.ot ? global.ot.TextOperation : require('./text-operation');
function SimpleTextOperation () {}
// Insert the string `str` at the zero-based `position` in the document.
function Insert (str, position) {
if (!this || this.constructor !== SimpleTextOperation) {
// => function was called without 'new'
return new Insert(str, position);
}
this.str = str;
this.position = position;
}
Insert.prototype = new SimpleTextOperation();
SimpleTextOperation.Insert = Insert;
Insert.prototype.toString = function () {
return 'Insert(' + JSON.stringify(this.str) + ', ' + this.position + ')';
};
Insert.prototype.equals = function (other) {
return other instanceof Insert &&
this.str === other.str &&
this.position === other.position;
};
Insert.prototype.apply = function (doc) {
return doc.slice(0, this.position) + this.str + doc.slice(this.position);
};
// Delete `count` many characters at the zero-based `position` in the document.
function Delete (count, position) {
if (!this || this.constructor !== SimpleTextOperation) {
return new Delete(count, position);
}
this.count = count;
this.position = position;
}
Delete.prototype = new SimpleTextOperation();
SimpleTextOperation.Delete = Delete;
Delete.prototype.toString = function () {
return 'Delete(' + this.count + ', ' + this.position + ')';
};
Delete.prototype.equals = function (other) {
return other instanceof Delete &&
this.count === other.count &&
this.position === other.position;
};
Delete.prototype.apply = function (doc) {
return doc.slice(0, this.position) + doc.slice(this.position + this.count);
};
// An operation that does nothing. This is needed for the result of the
// transformation of two deletions of the same character.
function Noop () {
if (!this || this.constructor !== SimpleTextOperation) { return new Noop(); }
}
Noop.prototype = new SimpleTextOperation();
SimpleTextOperation.Noop = Noop;
Noop.prototype.toString = function () {
return 'Noop()';
};
Noop.prototype.equals = function (other) { return other instanceof Noop; };
Noop.prototype.apply = function (doc) { return doc; };
var noop = new Noop();
SimpleTextOperation.transform = function (a, b) {
if (a instanceof Noop || b instanceof Noop) { return [a, b]; }
if (a instanceof Insert && b instanceof Insert) {
if (a.position < b.position || (a.position === b.position && a.str < b.str)) {
return [a, new Insert(b.str, b.position + a.str.length)];
}
if (a.position > b.position || (a.position === b.position && a.str > b.str)) {
return [new Insert(a.str, a.position + b.str.length), b];
}
return [noop, noop];
}
if (a instanceof Insert && b instanceof Delete) {
if (a.position <= b.position) {
return [a, new Delete(b.count, b.position + a.str.length)];
}
if (a.position >= b.position + b.count) {
return [new Insert(a.str, a.position - b.count), b];
}
// Here, we have to delete the inserted string of operation a.
// That doesn't preserve the intention of operation a, but it's the only
// thing we can do to get a valid transform function.
return [noop, new Delete(b.count + a.str.length, b.position)];
}
if (a instanceof Delete && b instanceof Insert) {
if (a.position >= b.position) {
return [new Delete(a.count, a.position + b.str.length), b];
}
if (a.position + a.count <= b.position) {
return [a, new Insert(b.str, b.position - a.count)];
}
// Same problem as above. We have to delete the string that was inserted
// in operation b.
return [new Delete(a.count + b.str.length, a.position), noop];
}
if (a instanceof Delete && b instanceof Delete) {
if (a.position === b.position) {
if (a.count === b.count) {
return [noop, noop];
} else if (a.count < b.count) {
return [noop, new Delete(b.count - a.count, b.position)];
}
return [new Delete(a.count - b.count, a.position), noop];
}
if (a.position < b.position) {
if (a.position + a.count <= b.position) {
return [a, new Delete(b.count, b.position - a.count)];
}
if (a.position + a.count >= b.position + b.count) {
return [new Delete(a.count - b.count, a.position), noop];
}
return [
new Delete(b.position - a.position, a.position),
new Delete(b.position + b.count - (a.position + a.count), a.position)
];
}
if (a.position > b.position) {
if (a.position >= b.position + b.count) {
return [new Delete(a.count, a.position - b.count), b];
}
if (a.position + a.count <= b.position + b.count) {
return [noop, new Delete(b.count - a.count, b.position)];
}
return [
new Delete(a.position + a.count - (b.position + b.count), b.position),
new Delete(a.position - b.position, b.position)
];
}
}
};
// Convert a normal, composable `TextOperation` into an array of
// `SimpleTextOperation`s.
SimpleTextOperation.fromTextOperation = function (operation) {
var simpleOperations = [];
var index = 0;
for (var i = 0; i < operation.ops.length; i++) {
var op = operation.ops[i];
if (TextOperation.isRetain(op)) {
index += op;
} else if (TextOperation.isInsert(op)) {
simpleOperations.push(new Insert(op, index));
index += op.length;
} else {
simpleOperations.push(new Delete(Math.abs(op), index));
}
}
return simpleOperations;
};
return SimpleTextOperation;
})(this);
// Export for CommonJS
if (typeof module === 'object') {
module.exports = ot.SimpleTextOperation;
}
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