syntactic: Syntactically Valid Names

#' Parameters
#'
#' @name params
#' @keywords internal
#'
#' @param names `logical(1)`.
#' Sanitize names.
#'
#' Only applies to string mode (`rename = FALSE`).
#'
#' @param object Object.
#'
#' @param prefix `logical(1)`.
#' Prepend "X" character if necessary, when string begins with a syntactically
#' invalid character, such as a number or non-alphanumeric. Note that names
#' are always made syntactically valid when applicable with "X" prefix.
#' See [`make.names()`][base::make.names] for details.
#'
#' Enabled by default for string mode, but disabled by default for rename
#' mode, when applicable.
#'
#' @param recursive `logical(1)`.
#' Should the function recurse into directories?
#' Only applicable when `rename = TRUE`.
#'
#' @param rename `logical(1)`.
#' File rename mode. Requires that input contains files and/or directories
#' that exist on disk. Both case-sensitive (e.g. Linux) and -insensitive (e.g.
#' macOS, Winddows) file systems are supported.
#'
#' The `prefix` and `smart` arguments are supported in this mode.
#'
#' @param smart `logical(1)`.
#' Handle complicated special cases, such as mixed case acronyms, plus/minus,
#' percentages, etc.
#'
#' @param strict `logical(1)`.
#' Enforce strict name sanitization. When `TRUE`, this does not allow the
#' return of any capitalized acronyms. "RNA" will become "Rna", for example.
#'
#' @param unique `logical(1)`.
#' If `TRUE`, the resulting elements are unique. Recommended by default, for
#' syntactically valid names (e.g. column, row names). Note that this is
#' disabled by default for [`make.names()`][base::make.names].
#'
#' @param ... Additional arguments.
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