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## Formula #1:
## expression: ~ rhs
## AST: (~ rhs)
## tweaked expression: rhs; ~ rhs
##
## Formula #2:
## expression: lhs ~ rhs
## AST: (~ lhs rhs)
## tweaked expression: rhs; lhs ~ rhs
tweakFormulaCall <- function(expr) {
if (!is.call(expr)) return(expr)
op <- expr[[1]]
if (!is.symbol(op)) return(expr)
op <- as.character(op)
if (op != "~") return(expr)
n <- length(expr)
if (n != 2 && n != 3) return(expr)
if (n == 2) {
lhs <- NULL
rhs <- expr[[2]]
} else if (n == 3) {
lhs <- expr[[2]]
rhs <- expr[[3]]
}
substitute(
{ lhs; rhs; e },
list(lhs = lhs, rhs = rhs, e = expr)
)
} ## tweakFormulaCall()
## Subassignment #1:
## expression: x$a <- value
## AST: (<- ($ x a) value)
## tweaked expression: x; x$a <- value
##
## expression: value -> x$a
## AST: (<- ($ x a) value)
## tweaked expression: x; value -> x$a
##
## Subassignment #2:
## expression: x[["a"]] <- value
## AST: (<- ($ [[ a) value)
## tweaked expression: x; x[["a"]] <- value
##
## expression: value -> x[["a"]]
## AST: (<- ([[ x a) value)
## tweaked expression: x; value -> x[["a"]]
##
## Subassignment #3:
## expression: x["a"] <- value
## AST: (<- ([ x a) value)
## tweaked expression: x; x["a"] <- value
##
## expression: x[1, 2, 3] <- value
## AST: (<- ([ x 1 2 3) value)
## tweaked expression: x; x[1, 2, 3] <- value
tweakSubassignmentCall <- function(expr) {
if (!is.call(expr)) return(expr)
op <- expr[[1]]
if (!is.symbol(op)) return(expr)
op <- as.character(op)
if (op != "<-") return(expr)
n <- length(expr)
if (n != 3) return(expr)
## expression #2: x$a, x[["a"]], or x[...]
## AST #2: ($ x a), ([[ x a), or ([ x ...)
expr2 <- expr[[2]]
if (!is.call(expr2)) return(expr)
op2 <- expr2[[1]]
if (!is.symbol(op2)) return(expr)
op2 <- as.character(op2)
if (!op2 %in% c("$", "[[", "[")) return(expr)
n2 <- length(expr2)
if (n2 < 3) return(expr)
target <- expr2[[2]]
substitute(
{ target; e },
list(target = target, e = expr)
)
} ## tweakSubassignmentCall()
## Future assignment #1:
## expression: lhs %<-% rhs
## AST: (%<-% lhs rhs)
## tweaked expression: lhs <- rhs; lhs %<-% rhs
tweakFutureAssignmentCall <- function(expr) {
if (!is.call(expr)) return(expr)
op <- expr[[1]]
if (!is.symbol(op)) return(expr)
n <- length(expr)
if (n != 3) return(expr)
op <- as.character(op)
if (op %in% c("<<-", "%<-%")) {
lhs <- expr[[2]]
rhs <- expr[[3]]
expr <- substitute(
{a <- b; e},
list(a = lhs, b = rhs, e = expr)
)
} else if (op %in% c("->>", "%->%")) {
lhs <- expr[[3]]
rhs <- expr[[2]]
expr <- substitute(
{a <- b; e},
list(a = lhs, b = rhs, e = expr)
)
}
expr
} ## tweakFutureAssignmentCall()
# Tweaks a future expression prior to searching for globals
#
# @param expr An \R expression
#
# @return An \R expression
#
# @keywords internal
#
#' @importFrom globals walkAST
tweakExpression <- function(expr) {
if (!is.language(expr)) return(expr)
expr <- walkAST(expr, call = tweakFutureAssignmentCall)
expr <- walkAST(expr, call = tweakFormulaCall)
expr <- walkAST(expr, call = tweakSubassignmentCall)
expr
}
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