Function processWithIndex

packages/react/src/core/component.tsx:247–283

(nodeList: ReactNode[])

  let expressionIndex = 0;

  function processWithIndex(nodeList: ReactNode[]): ReactNode[] {
    return nodeList
      .map((node) => {
        if (typeof node === "string") {
          const segments: ReactNode[] = [];
          let lastIndex = 0;
          const expressionRegex = /<expression\/>/g;
          let match;

          while ((match = expressionRegex.exec(node)) !== null) {
            if (match.index > lastIndex) {
              segments.push(node.slice(lastIndex, match.index));
            }

            const value = expressions[expressionIndex++];
            segments.push(value ?? match[0]);

            lastIndex = match.index + match[0].length;
          }

          if (lastIndex < node.length) {
            segments.push(node.slice(lastIndex));
          }

          return segments;
        } else if (isReactElement(node)) {
          const props = node.props as { children?: ReactNode };
          return createElement(
            node.type,
            { ...props },
            ...processWithIndex(_.castArray(props.children || [])),
          );
        }
        return node;
      })
      .flat();
  }

  return processWithIndex(nodes);
}