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import type { Properties } from 'hast';
import {
type BundledLanguage,
createCssVariablesTheme,
getHighlighter,
isSpecialLang,
} from 'shiki';
import { visit } from 'unist-util-visit';
import type { ShikiConfig } from './types.js';
export interface ShikiHighlighter {
highlight(
code: string,
lang?: string,
options?: {
inline?: boolean;
attributes?: Record<string, string>;
/**
* Raw `meta` information to be used by Shiki transformers
*/
meta?: string;
},
): Promise<string>;
}
// TODO: Remove this special replacement in Astro 5
const ASTRO_COLOR_REPLACEMENTS: Record<string, string> = {
'--astro-code-foreground': '--astro-code-color-text',
'--astro-code-background': '--astro-code-color-background',
};
const COLOR_REPLACEMENT_REGEX = new RegExp(
`${Object.keys(ASTRO_COLOR_REPLACEMENTS).join('|')}`,
'g',
);
let _cssVariablesTheme: ReturnType<typeof createCssVariablesTheme>;
const cssVariablesTheme = () =>
_cssVariablesTheme ??
(_cssVariablesTheme = createCssVariablesTheme({ variablePrefix: '--astro-code-' }));
export async function createShikiHighlighter({
langs = [],
theme = 'github-dark',
themes = {},
defaultColor,
wrap = false,
transformers = [],
langAlias = {},
}: ShikiConfig = {}): Promise<ShikiHighlighter> {
theme = theme === 'css-variables' ? cssVariablesTheme() : theme;
const highlighter = await getHighlighter({
langs: ['plaintext', ...langs],
langAlias,
themes: Object.values(themes).length ? Object.values(themes) : [theme],
});
return {
async highlight(code, lang = 'plaintext', options) {
const resolvedLang = langAlias[lang] ?? lang;
const loadedLanguages = highlighter.getLoadedLanguages();
if (!isSpecialLang(lang) && !loadedLanguages.includes(resolvedLang)) {
try {
await highlighter.loadLanguage(resolvedLang as BundledLanguage);
} catch (_err) {
const langStr =
lang === resolvedLang ? `"${lang}"` : `"${lang}" (aliased to "${resolvedLang}")`;
console.warn(
`[Shiki] The language ${langStr} doesn't exist, falling back to "plaintext".`,
);
lang = 'plaintext';
}
}
const themeOptions = Object.values(themes).length ? { themes } : { theme };
const inline = options?.inline ?? false;
return highlighter.codeToHtml(code, {
...themeOptions,
defaultColor,
lang,
// NOTE: while we can spread `options.attributes` here so that Shiki can auto-serialize this as rendered
// attributes on the top-level tag, it's not clear whether it is fine to pass all attributes as meta, as
// they're technically not meta, nor parsed from Shiki's `parseMetaString` API.
meta: options?.meta ? { __raw: options?.meta } : undefined,
transformers: [
{
pre(node) {
// Swap to `code` tag if inline
if (inline) {
node.tagName = 'code';
}
const {
class: attributesClass,
style: attributesStyle,
...rest
} = options?.attributes ?? {};
Object.assign(node.properties, rest);
const classValue =
(normalizePropAsString(node.properties.class) ?? '') +
(attributesClass ? ` ${attributesClass}` : '');
const styleValue =
(normalizePropAsString(node.properties.style) ?? '') +
(attributesStyle ? `; ${attributesStyle}` : '');
// Replace "shiki" class naming with "astro-code"
node.properties.class = classValue.replace(/shiki/g, 'astro-code');
// Add data-language attribute
node.properties.dataLanguage = lang;
// Handle code wrapping
// if wrap=null, do nothing.
if (wrap === false) {
node.properties.style = styleValue + '; overflow-x: auto;';
} else if (wrap === true) {
node.properties.style =
styleValue + '; overflow-x: auto; white-space: pre-wrap; word-wrap: break-word;';
}
},
line(node) {
// Add "user-select: none;" for "+"/"-" diff symbols.
// Transform `<span class="line"><span style="...">+ something</span></span>
// into `<span class="line"><span style="..."><span style="user-select: none;">+</span> something</span></span>`
if (resolvedLang === 'diff') {
const innerSpanNode = node.children[0];
const innerSpanTextNode =
innerSpanNode?.type === 'element' && innerSpanNode.children?.[0];
if (innerSpanTextNode && innerSpanTextNode.type === 'text') {
const start = innerSpanTextNode.value[0];
if (start === '+' || start === '-') {
innerSpanTextNode.value = innerSpanTextNode.value.slice(1);
innerSpanNode.children.unshift({
type: 'element',
tagName: 'span',
properties: { style: 'user-select: none;' },
children: [{ type: 'text', value: start }],
});
}
}
}
},
code(node) {
if (inline) {
return node.children[0] as typeof node;
}
},
root(node) {
if (Object.values(themes).length) {
return;
}
const themeName = typeof theme === 'string' ? theme : theme.name;
if (themeName === 'css-variables') {
// Replace special color tokens to CSS variables
visit(node as any, 'element', (child) => {
if (child.properties?.style) {
child.properties.style = replaceCssVariables(child.properties.style);
}
});
}
},
},
...transformers,
],
});
},
};
}
function normalizePropAsString(value: Properties[string]): string | null {
return Array.isArray(value) ? value.join(' ') : (value as string | null);
}
function replaceCssVariables(str: string) {
return str.replace(COLOR_REPLACEMENT_REGEX, (match) => ASTRO_COLOR_REPLACEMENTS[match] || match);
}
|
