54 lines
1.9 KiB
TypeScript
54 lines
1.9 KiB
TypeScript
/*
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* Copyright 2025 coze-dev Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { Direction } from '../../types/selection';
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import { compareNodePosition } from './compare-node-position';
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export const getSelectionDirection = (selection: Selection): Direction => {
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// Make sure there are constituencies
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if (!selection || selection.isCollapsed) {
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return Direction.Unknown; // No constituencies or constituencies not expanded
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}
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const { anchorNode } = selection;
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const { focusNode } = selection;
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// Make sure that neither anchorNode nor focusNode is null
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if (!anchorNode || !focusNode) {
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return Direction.Unknown; // Unable to determine direction
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}
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const { anchorOffset } = selection;
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const { focusOffset } = selection;
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// Compare anchor and focus positions
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if (anchorNode === focusNode) {
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// If the anchor and focus are on the same node, determine the direction by the offset
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return anchorOffset <= focusOffset ? Direction.Forward : Direction.Backward;
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} else {
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// If not in the same node, use Document Position to determine
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const position = compareNodePosition(anchorNode, focusNode);
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if (position === 'before') {
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return Direction.Forward;
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} else if (position === 'after') {
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return Direction.Backward;
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}
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}
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// If the direction cannot be determined, return'unknown'
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return Direction.Unknown;
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};
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