parsetools (version 0.1.1)

calls: Call nodes

Description

Call nodes represent function calls.

Retrieves the ids of the arguments of a call as an integer vector.

Usage

pd_is_call(id, pd, calls = NULL, .check = TRUE)
pd_is_symbol_call(id, pd, .check = TRUE)
pd_get_call_symbol_id(id, pd, .check = TRUE)
pd_get_call_arg_ids(id, pd, .check = TRUE)

Arguments

id

id of the expression of interest

pd

The parse-data information

calls

an optional list of calls to restrict consideration to.

.check

Perform checks for input validation?

Value

a logical of the same length as id

a named list where each element is the id for the expr element of the argument.

Functions

• pd_is_call: Test if the node is a call expression.

• pd_is_symbol_call: Test if the node is specifically a symbol call expression.

• pd_get_call_symbol_id: Get the symbol, i.e. the name of the function, being called.

• pd_get_call_arg_ids: test Get the set of arguments to the function call.

Details

The traditional call of function_name(arguments) is a symbol call as function_name is the symbol directly referencing the function to call. Other calls may exists such as function_array[[1]]() which first indexes the function_array then calls the returned function. This qualifies as a call expression but not a symbol call expression. We are often only concerned with symbol calls and not the anonymous version.

Examples

# NOT RUN {
# load example file and get_parse data
ex.file <- system.file("examples", "example.R", package="parsetools")
exprs <- parse(ex.file, keep.source = TRUE)
pd <- get_parse_data(exprs)

# There are 3 expressions so there should be three roots.
sum(pd_is_root(pd$id, pd))
roots <- pd_all_root_ids(pd)

# which root is a call?
pd_is_call(roots, pd)
id <- roots[pd_is_call(roots, pd)]
# not all calls are symbole calls.
pd_is_symbol_call(id, pd)
# what is the symbol being called?
pd_text(pd_get_call_symbol_id(id, pd), pd)
# what are the arguments to the call
args <- pd_get_call_arg_ids(id, pd)
pd_token(pd_get_firstborn(args, pd), pd)
pd_text(pd_get_firstborn(args, pd), pd)
# }