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/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @format
* @typechecks
*/
'use strict';
const mixInEventEmitter = require('mixInEventEmitter');
/**
* DocumentSelectionState is responsible for maintaining selection information
* for a document.
*
* It is intended for use by AbstractTextEditor-based components for
* identifying the appropriate start/end positions to modify the
* DocumentContent, and for programmatically setting browser selection when
* components re-render.
*/
class DocumentSelectionState {
/**
* @param {number} anchor
* @param {number} focus
*/
constructor(anchor, focus) {
this._anchorOffset = anchor;
this._focusOffset = focus;
this._hasFocus = false;
}
/**
* Apply an update to the state. If either offset value has changed,
* set the values and emit the `change` event. Otherwise no-op.
*
* @param {number} anchor
* @param {number} focus
*/
update(anchor, focus) {
if (this._anchorOffset !== anchor || this._focusOffset !== focus) {
this._anchorOffset = anchor;
this._focusOffset = focus;
this.emit('update');
}
}
/**
* Given a max text length, constrain our selection offsets to ensure
* that the selection remains strictly within the text range.
*
* @param {number} maxLength
*/
constrainLength(maxLength) {
this.update(
Math.min(this._anchorOffset, maxLength),
Math.min(this._focusOffset, maxLength),
);
}
focus() {
if (!this._hasFocus) {
this._hasFocus = true;
this.emit('focus');
}
}
blur() {
if (this._hasFocus) {
this._hasFocus = false;
this.emit('blur');
}
}
/**
* @return {boolean}
*/
hasFocus() {
return this._hasFocus;
}
/**
* @return {boolean}
*/
isCollapsed() {
return this._anchorOffset === this._focusOffset;
}
/**
* @return {boolean}
*/
isBackward() {
return this._anchorOffset > this._focusOffset;
}
/**
* @return {?number}
*/
getAnchorOffset() {
return this._hasFocus ? this._anchorOffset : null;
}
/**
* @return {?number}
*/
getFocusOffset() {
return this._hasFocus ? this._focusOffset : null;
}
/**
* @return {?number}
*/
getStartOffset() {
return this._hasFocus
? Math.min(this._anchorOffset, this._focusOffset)
: null;
}
/**
* @return {?number}
*/
getEndOffset() {
return this._hasFocus
? Math.max(this._anchorOffset, this._focusOffset)
: null;
}
/**
* @param {number} start
* @param {number} end
* @return {boolean}
*/
overlaps(start, end) {
return (
this.hasFocus() &&
this.getStartOffset() <= end &&
start <= this.getEndOffset()
);
}
}
mixInEventEmitter(DocumentSelectionState, {
blur: true,
focus: true,
update: true,
});
module.exports = DocumentSelectionState;
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