77 lines
2.6 KiB
JavaScript
77 lines
2.6 KiB
JavaScript
import { visit } from 'unist-util-visit';
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/**
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* rehype 插件：将段落等文本节点拆分为逐词 <span>，并添加淡入动画 class。
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* 仅在流式渲染阶段使用，避免已渲染文字重复动画。
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*/
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export function rehypeSplitWordsIntoSpans(options = {}) {
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const { previousContentLength = 0 } = options;
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return (tree) => {
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let currentCharCount = 0; // 当前已处理的字符数
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visit(tree, 'element', (node) => {
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if (
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['p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'li', 'strong'].includes(node.tagName) &&
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node.children
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) {
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const newChildren = [];
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node.children.forEach((child) => {
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if (child.type === 'text') {
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try {
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// 使用 Intl.Segmenter 精准拆分中英文及标点
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const segmenter = new Intl.Segmenter('zh', { granularity: 'word' });
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const segments = segmenter.segment(child.value);
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Array.from(segments)
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.map((seg) => seg.segment)
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.filter(Boolean)
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.forEach((word) => {
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const wordStartPos = currentCharCount;
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const wordEndPos = currentCharCount + word.length;
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// 判断这个词是否是新增的（在 previousContentLength 之后）
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const isNewContent = wordStartPos >= previousContentLength;
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newChildren.push({
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type: 'element',
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tagName: 'span',
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properties: {
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className: isNewContent ? ['animate-fade-in'] : [],
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},
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children: [{ type: 'text', value: word }],
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});
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currentCharCount = wordEndPos;
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});
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} catch (_) {
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// Fallback：如果浏览器不支持 Segmenter
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const textStartPos = currentCharCount;
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const isNewContent = textStartPos >= previousContentLength;
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if (isNewContent) {
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// 新内容，添加动画
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newChildren.push({
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type: 'element',
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tagName: 'span',
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properties: {
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className: ['animate-fade-in'],
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},
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children: [{ type: 'text', value: child.value }],
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});
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} else {
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// 旧内容，不添加动画
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newChildren.push(child);
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}
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currentCharCount += child.value.length;
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}
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} else {
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newChildren.push(child);
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}
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});
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node.children = newChildren;
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}
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});
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};
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}
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