| % File src/library/methods/man/languageEl.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2019 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{languageEl} |
| \alias{languageEl} |
| \alias{languageEl<-} |
| \alias{isGrammarSymbol} |
| \title{Elements of Language Objects} |
| \description{ |
| Internal routines to support some operations on language objects. |
| } |
| \usage{ |
| languageEl(object, which) |
| languageEl(object, which) <- value |
| |
| isGrammarSymbol(symbol) |
| } |
| \section{Summary of Functions}{ |
| \describe{ |
| \item{\code{languageEl}:}{ |
| extract an element of a language object, consistently for |
| different kinds of objects. |
| |
| The 1st., etc. elements of a function are the corresponding formal |
| arguments, with the default expression if any as value. |
| |
| The first element of a call is the name or the function object |
| being called. |
| |
| The 2nd, 3rd, etc. elements are the 1st, 2nd, etc. arguments |
| expressions. Note that the form of the extracted name is |
| different for R and S-Plus. When the name (the first element) of |
| a call is replaced, the languageEl replacement function coerces a |
| character string to the internal form for each system. |
| |
| The 1st, 2nd, 3rd elements of an \code{if} expression are the |
| test, first, and second branch. |
| |
| The 1st element of a \code{for} object is the name (symbol) being |
| used in the loop, the second is the expression for the range of |
| the loop, the third is the body of the loop. |
| |
| The first element of a \code{while} object is the loop test, and |
| the second the body of the loop. |
| } |
| |
| \item{\code{isGrammarSymbol}:}{ |
| Checks whether the symbol is part of the grammar. |
| Don't use this function directly. |
| } |
| } |
| } |
| \keyword{internal} |