R devel - Dec 2007 - parse() does not complain for not finished strings?

Hello,
parse() is supposed to detect incomplete instructions, isn't it?
For instance:
> # Correct code
> msg <- 'log(10)'
> mc <- textConnection(msg)
> parse(mc)
expression(log(10))
> close(mc)
> # Now, an incomplete code
> msg <- 'log('
> mc <- textConnection(msg)
> parse(mc)
Error in parse(mc) : unexpected end of input at
2: log(
> close(mc)
> # Now, another incomplete code (character string not finished)
> msg <- 'text <- "some incomplete string'
> mc <- textConnection(msg)
> parse(mc)
expression(text <- "some incomplete
string\n")
> close(mc)
I don't understand why parse() does not complain in this third case, and
why it "finishes" my string and adds a '\n' at its end. Does
anybody
could explain me,... or is this a bug?
Many thanks.

Philippe Grosjean

Philippe Grosjean wrote:
> Hello,
> parse() is supposed to detect incomplete instructions, isn't it?
> For instance:
>
>   
>> # Correct code
>> msg <- 'log(10)'
>> mc <- textConnection(msg)
>> parse(mc)
>>     
> expression(log(10))
>   
>> close(mc)
>>     
>
>   
>> # Now, an incomplete code
>> msg <- 'log('
>> mc <- textConnection(msg)
>> parse(mc)
>>     
> Error in parse(mc) : unexpected end of input at
> 2: log(
>   
>> close(mc)
>>     
>
>   
>> # Now, another incomplete code (character string not finished)
>> msg <- 'text <- "some incomplete string'
>> mc <- textConnection(msg)
>> parse(mc)
>>     
> expression(text <- "some incomplete string\n")
>   
>> close(mc)
>>     
>
> I don't understand why parse() does not complain in this third case,
and
> why it "finishes" my string and adds a '\n' at its end.
Does anybody
> could explain me,... or is this a bug
A buglet at least. It is not parsing per se that does it:

 > parse(text=msg)
Error in parse(text = msg) :
  unexpected end of input in "text <- "some incomplete string"

but it happens whenever you parse from a file or connection e.g.

$ cat > xxx
"incom
$ R
[....]
 > source("xxx")
 > .Last.value
$value
[1] "incom\n"

$visible
[1] TRUE


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