@scalar/code-highlight/dist/rehype-highlight/rehype-highlight.js

Central methods and themes for code highlighting in Scalar projects

import { toText } from "hast-util-to-text";
import { createLowlight } from "lowlight";
import { visit } from "unist-util-visit";
import { lowlightLanguageMappings } from "../constants.js";
const emptyOptions = {};
function rehypeHighlight(options) {
  const settings = options || emptyOptions;
  const aliases = settings.aliases;
  const detect = options?.detect ?? false;
  const languages = settings.languages;
  const plainText = settings.plainText;
  const prefix = settings.prefix;
  const subset = settings.subset;
  let name = "hljs";
  const lowlight = options?.lowlight ?? createLowlight(languages);
  if (aliases) {
    lowlight.registerAlias(aliases);
  }
  if (prefix) {
    const pos = prefix.indexOf("-");
    name = pos > -1 ? prefix.slice(0, pos) : prefix;
  }
  return (tree, file) => {
    visit(tree, "element", (node, _, parent) => {
      if (node.tagName !== "code" || !parent || parent.type !== "element" || parent.tagName !== "pre") {
        return;
      }
      const lang = language(node);
      if (lang === "no-highlight" || !lang && !detect || lang && plainText?.includes(lang)) {
        return;
      }
      if (!Array.isArray(node.properties.className)) {
        node.properties.className = [];
      }
      if (!node.properties.className.includes(name)) {
        node.properties.className.unshift(name);
      }
      let result;
      try {
        result = lang ? lowlight.highlight(lang, toText(parent), { prefix }) : lowlight.highlightAuto(toText(parent), { prefix, subset });
      } catch (error) {
        const cause = error;
        if (lang && /Unknown language/.test(cause.message)) {
          file.message(`Cannot highlight as \`${lang}\`, it's not registered`, {
            ancestors: [parent, node],
            cause,
            place: node.position,
            ruleId: "missing-language",
            source: "rehype-highlight"
          });
          return;
        }
        throw cause;
      }
      if (!lang && result.data?.language) {
        node.properties.className.push("language-" + result.data.language);
      }
      if (result.children.length > 0) {
        node.children = result.children;
      }
    });
  };
}
function language(node) {
  const list = node.properties.className;
  if (!Array.isArray(list)) {
    return "";
  }
  const name = list.reduce((result, _item) => {
    if (result) {
      return result;
    }
    const item = String(_item);
    if (item === "no-highlight" || item === "nohighlight") {
      return "no-highlight";
    }
    if (item.slice(0, 5) === "lang-") {
      return item.slice(5);
    }
    if (item.slice(0, 9) === "language-") {
      return item.slice(9);
    }
    return result;
  }, "");
  return lowlightLanguageMappings[name || ""] || name;
}
export {
  rehypeHighlight
};
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