MFMをテキストに戻す (#6131)

* Disable Nyaize in quote

* mfmを文字列に戻す、nyaizeにmfmを使用

* Revert "Disable Nyaize in quote"

This reverts commit 1b238905a5535267d32d7e1aec8afd8bb07b0619.

* refactor

* use return type as string

src/mfm/toString.ts

@@ -0,0 +1,112 @@
+import { MfmForest, MfmTree } from './prelude';
+import { nyaize } from '../misc/nyaize';
+
+export type RestoreOptions = {
+	doNyaize?: boolean;
+};
+
+export function toString(tokens: MfmForest | null, opts?: RestoreOptions): string {
+
+	if (tokens === null) return '';
+
+	function appendChildren(children: MfmForest, opts?: RestoreOptions): string {
+		return children.map(t => handlers[t.node.type](t, opts)).join('');
+	}
+
+	const handlers: { [key: string]: (token: MfmTree, opts?: RestoreOptions) => string } = {
+		bold(token, opts) {
+			return `**${appendChildren(token.children, opts)}**`;
+		},
+
+		big(token, opts) {
+			return `***${appendChildren(token.children, opts)}***`;
+		},
+
+		small(token, opts) {
+			return `<small>${appendChildren(token.children, opts)}</small>`;
+		},
+
+		strike(token, opts) {
+			return `~~${appendChildren(token.children, opts)}~~`;
+		},
+
+		italic(token, opts) {
+			return `<i>${appendChildren(token.children, opts)}</i>`;
+		},
+
+		motion(token, opts) {
+			return `<motion>${appendChildren(token.children, opts)}</motion>`;
+		},
+
+		spin(token, opts) {
+			return `<spin>${appendChildren(token.children, opts)}</spin>`;
+		},
+
+		jump(token, opts) {
+			return `<jump>${appendChildren(token.children, opts)}</jump>`;
+		},
+
+		flip(token, opts) {
+			return `<flip>${appendChildren(token.children, opts)}</flip>`;
+		},
+
+		blockCode(token) {
+			return `\`\`\`${token.node.props.lang || ''}\n${token.node.props.code}\n\`\`\`\n`;
+		},
+
+		center(token, opts) {
+			return `<center>${appendChildren(token.children, opts)}</center>`;
+		},
+
+		emoji(token) {
+			return (token.node.props.emoji ? token.node.props.emoji : `:${token.node.props.name}:`);
+		},
+
+		hashtag(token) {
+			return `#${token.node.props.hashtag}`;
+		},
+
+		inlineCode(token) {
+			return `\`${token.node.props.code}\``;
+		},
+
+		mathInline(token) {
+			return `\\(${token.node.props.formula}\\)`;
+		},
+
+		mathBlock(token) {
+			return `\\[${token.node.props.formula}\\]`;
+		},
+
+		link(token, opts) {
+			return `[${appendChildren(token.children, opts)}](${token.node.props.url})`;
+		},
+
+		mention(token) {
+			return token.node.props.canonical;
+		},
+
+		quote(token) {
+			return `${appendChildren(token.children, {doNyaize: false}).replace(/^/gm,'>').trim()}\n`;
+		},
+
+		title(token, opts) {
+			return `[${appendChildren(token.children, opts)}]\n`;
+		},
+
+		text(token, opts) {
+			return (opts && opts.doNyaize) ? nyaize(token.node.props.text) : token.node.props.text;
+		},
+
+		url(token) {
+			return `<${token.node.props.url}>`;
+		},
+
+		search(token, opts) {
+			const query = token.node.props.query;
+			return `${(opts && opts.doNyaize ? nyaize(query) : query)} [search]\n`;
+		}
+	};
+
+	return appendChildren(tokens, { doNyaize: (opts && opts.doNyaize) || false }).trim();
+}