Method highlightCode

core/codeRenderer/CodeRenderer.ts:169–223

(
    code: string,
    language: string = "javascript",
    currLineOffsetFromTop: number,
    newDiffLines: DiffLine[],
  )

  }

  async highlightCode(
    code: string,
    language: string = "javascript",
    currLineOffsetFromTop: number,
    newDiffLines: DiffLine[],
  ): Promise<string> {
    const lines = code.split("\n");
    const newDiffLineMap = new Set();

    if (newDiffLines) {
      newDiffLines.forEach((diffLine) => {
        if (diffLine.type === "new") {
          newDiffLineMap.add(diffLine.line);
        }
      });
    }

    const annotatedLines = [];

    // NOTE: Shiki's preprocessor deletes transformer annotations when applied to an empty line.
    // If you are transforming an empty line, make sure that
    // the transformation is applied to a non-empty line first.
    for (let i = 0; i < lines.length; i++) {
      const line = lines[i];

      // Add highlight comment before target line.
      if (i + 1 === currLineOffsetFromTop && currLineOffsetFromTop >= 0) {
        annotatedLines.push("// [!code highlight:1]");
      }

      // Handle diff lines
      if (newDiffLineMap.has(line)) {
        if (line.trim() === "") {
          // For empty lines, add the magic comment on a separate line before.
          annotatedLines.push("// [!code ++]");
          annotatedLines.push(line); // The empty line itself.
        } else {
          // For non-empty lines, append the magic comment.
          annotatedLines.push(line + "// [!code ++]");
        }
        newDiffLineMap.delete(line);
      } else {
        annotatedLines.push(line);
      }
    }

    const annotatedCode = annotatedLines.join("\n");

    await this.highlighter!.loadLanguage(language as BundledLanguage);
    return this.highlighter!.codeToHtml(annotatedCode, {
      lang: language,
      theme: this.currentTheme,
      transformers: [transformerNotationHighlight(), transformerNotationDiff()],
    });
  }

  async convertToSVG(
    code: string,