r parser translating symbol_function_call as a symbol - r

Question

If I parse do.call(what=knitr::kable,args=args) the function kable in do.call is parsed to as a SYMBOL and not as a SYMBOL_FUNCTION_CALL.
Why shouldn't it be the later?
tf <- tempfile()
cat('do.call(knitr::kable,args=args)',file = tf)
parsed <- utils::getParseData(parse(tf))
knitr::kable(parsed)
| | line1| col1| line2| col2| id| parent|token |terminal |text |
|:--|-----:|----:|-----:|----:|--:|------:|:--------------------|:--------|:-------|
|18 | 1| 1| 1| 31| 18| 0|expr |FALSE | |
|1 | 1| 1| 1| 7| 1| 3|SYMBOL_FUNCTION_CALL |TRUE |do.call |
|3 | 1| 1| 1| 7| 3| 18|expr |FALSE | |
|2 | 1| 8| 1| 8| 2| 18|'(' |TRUE |( |
|7 | 1| 9| 1| 20| 7| 18|expr |FALSE | |
|4 | 1| 9| 1| 13| 4| 7|SYMBOL_PACKAGE |TRUE |knitr |
|5 | 1| 14| 1| 15| 5| 7|NS_GET |TRUE |:: |
|6 | 1| 16| 1| 20| 6| 7|SYMBOL |TRUE |kable |
|8 | 1| 21| 1| 21| 8| 18|',' |TRUE |, |
|11 | 1| 22| 1| 25| 11| 18|SYMBOL_SUB |TRUE |args |
|12 | 1| 26| 1| 26| 12| 18|EQ_SUB |TRUE |= |
|13 | 1| 27| 1| 30| 13| 15|SYMBOL |TRUE |args |
|15 | 1| 27| 1| 30| 15| 18|expr |FALSE | |
|14 | 1| 31| 1| 31| 14| 18|')' |TRUE |) |

Answer 1

If you just have ktable its a symbol. That symbol could point to a function or a value. It's not clear until you actually evaluate it what it is.
However if you have ktable(), it's clear that you expect ktable to be a function and that you are calling it.
The do.call obscures the parser's ability to recognize that you are trying to call a function and that intention isn't realized till run-time.
Things can get funny if you do something like
sum <- 5
sum
# [1] 5
sum(1:3)
# [1] 6
Here sum is behaving both like a regular variable and a function. We've actually created a shadow variable in our global environment that masks the sum function from base. But because the parse treats sum and sum() differently we can still get at both meanings.