/**
 * Cold/shape-stable helpers shared by the mdast and hast visitors. The
 * per-node hot decoders stay duplicated in each visitor on purpose: sharing
 * them would feed differently-shaped arguments through one call site and turn
 * it polymorphic.
 */
const EMPTY_BYTES = new Uint8Array(0);
export function asArray(value) {
    return Array.isArray(value) ? value : [value];
}
/** Thrown when declarative replacement content can't be compiled to the
 *  structural op-stream — an unsupported node type (e.g. a bare `root`/`doctype`
 *  handed in as content) or an out-of-range numeric field. The op-stream is the
 *  only structural encoding, so this is a hard error rather than a fallback. */
export function unencodableContentError(content) {
    const type = content?.type;
    return new Error(`satteri: cannot encode replacement content${typeof type === "string" ? ` of type "${type}"` : ""} ` +
        "into the structural op-stream — unsupported node type or out-of-range numeric field.");
}
/**
 * Arena id for a node passed to a context method, via a per-kind `nid` lookup
 * (closure keeps each kind's call site monomorphic). Plugin-built nodes have
 * no id; without this check the id would coerce to 0 in the command buffer
 * and the mutation would silently target the document root.
 */
export function makeRequireNid(nid) {
    return (node, method) => {
        const id = nid(node);
        if (id === undefined) {
            throw new Error(`${method}: node has no arena id — it was built in JS, not read from this tree. ` +
                `Pass plugin-built nodes as new content (e.g. the second argument of insertAfter).`);
        }
        return id;
    };
}
/** Concatenate the return-value and context command buffers for one pass,
 *  resetting both for reuse. */
export function mergeAndReset(returnBuffer, ctx) {
    const ctxCmdBuf = ctx.getCommandBuffer();
    // The common case — no mutations this pass — allocates nothing.
    if (returnBuffer.length === 0 && ctxCmdBuf.length === 0) {
        return { merged: EMPTY_BYTES, hasMutations: false };
    }
    const ctxBuf = ctxCmdBuf.getBuffer();
    const retBuf = returnBuffer.getBuffer();
    const merged = new Uint8Array(retBuf.length + ctxBuf.length);
    merged.set(retBuf, 0);
    merged.set(ctxBuf, retBuf.length);
    returnBuffer.reset();
    ctxCmdBuf.reset();
    return { merged, hasMutations: true };
}