| # File src/library/base/R/backquote.R |
| # Part of the R package, https://www.R-project.org |
| # |
| # Copyright (C) 1995-2017 The R Core Team |
| # |
| # This program is free software; you can redistribute it and/or modify |
| # it under the terms of the GNU General Public License as published by |
| # the Free Software Foundation; either version 2 of the License, or |
| # (at your option) any later version. |
| # |
| # This program is distributed in the hope that it will be useful, |
| # but WITHOUT ANY WARRANTY; without even the implied warranty of |
| # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| # GNU General Public License for more details. |
| # |
| # A copy of the GNU General Public License is available at |
| # https://www.R-project.org/Licenses/ |
| |
| ## quote() is .Primitive |
| |
| ### PR#15077: need to substitute in a length-one pairlist, so |
| ### handle pairlists first |
| bquote <- function(expr, where=parent.frame()) |
| { |
| unquote <- function(e) |
| if (is.pairlist(e)) as.pairlist(lapply(e, unquote)) |
| else if (length(e) <= 1L) e |
| else if (e[[1L]] == as.name(".")) eval(e[[2L]], where) |
| else as.call(lapply(e, unquote)) |
| |
| unquote(substitute(expr)) |
| } |
| |
| ## utility we've used ourselves |
| enquote <- function(cl) as.call(list(quote(base::quote), cl)) |