> maybe there?s a reason for it, but the discrepancy between the > handling of `[` and `$` in deparsing seems odd to me: > > > substitute(a[1], list(a = quote(x * y))) > x * y[1] > > > substitute(a$b, list(a = quote(x * y))) > (x * y)$b > > The former is still executed in the right order (`*` first, then > `[`), which is not what you?d expect looking at the deparse result.
This is one of a large number of bugs in the deparser and parser that are fixed in the latest version of pqR (of 2015-09-14), as a result of a complete rewrite of the parser and extensive revisions to the deparser. As I communicated to this list, it would be reasonably easy to incorporate the rewritten parser and deparser into R Core versions of R. You can get more details from http://www.pqr-project.org/NEWS.txt The portion of the bugs section in that NEWS file relevant to parsing and deparsing is shown below: o The new parser fixes bugs arising from the old parser's kludge to handle semicolons, illustrated by the incorrect output seen below: > p<-parse() ?"abc;xyz" Error in parse() : <stdin>:1:1: unexpected INCOMPLETE_STRING 1: "abc; ^ > p<-parse() ?8 #abc;xyz Error in parse() : <stdin>:1:7: unexpected end of input 1: 8 #abc; ^ o Fixed deparsing of complex numbers, which were always deparsed as the sum of a real and an imaginary part, even though the parser can only produce complex numbers that are pure imaginary. For example, the following output was produced before: > deparse(quote(3*5i)) [1] "3 * (0+5i)" This is now deparsed to "3 * 5i". This bug exists in all R Core versions through at least R-3.2.2. o Fixed a number of bugs in the deparser that are illustrated by the following, which produce incorrect output as noted, in R Core versions through at least R-3.2.2: deparse(parse(text="`+`(a,b)[1]")[[1]])# Omits necessary parens deparse(quote(`[<-`(x,1)),control="S_compatible") # unmatched " and ' deparse(parse(text="a = b <- c")[[1]]) # Puts in unnecessary parens deparse(parse(text="a+!b")[[1]]) # Puts in unnecessary parens deparse(parse(text="?lm")[[1]]) # Doesn't know about ? operator deparse(parse(text="a:=b")[[1]]) # Doesn't know about := operator deparse(parse(text="a$'x'")[[1]]) # Conflates name and character deparse(parse(text="`*`(2)")[[1]]) # Result is syntactically invalid deparse(parse(text="`$`(a,b+2)")[[1]]) # Result is syntactically invalid e<-quote(if(x) X else Y); e[[3]]<-quote(if(T)3); deparse(e)# all here e <- quote(f(x)); e[[2]] <- quote((a=1))[[2]]; deparse(e) # and below e <- quote(f(Q=x)); e[[2]] <- quote((a=1))[[2]]; deparse(e)# need parens e <- quote(while(x) 1); e[[2]] <- quote((a=1))[[2]]; deparse(e) e <- quote(if(x) 1 else 2); e[[2]] <- quote((a=1))[[2]]; deparse(e) e <- quote(for(x in y) 1); e[[3]] <- quote((a=1))[[2]]; deparse(e) In addition, the bug illustrated below was fixed, which was fixed (differently) in R-3.0.0: a<-quote(f(1,2)); a[[1]]<-function(x,y)x+y; deparse(a) # Omits parens o Fixed the following bug (also in R Core versions to at least R-3.2.2): > parse() ?'\12a\x.' Error: '\x' used without hex digits in character string starting "'\1a\x" Note that the "2" has disappeared from the error message. This bug also affected the results of getParseData. o Fixed a memory leak that can be seen by running the code below: > long <- paste0 (c('"', rep("1234567890",820), '\x."'), collapse="") > for (i in 1:1000000) try (e <- parse(text=long), silent=TRUE) The leak will not occur if 820 is changed to 810 in the above. This bug also exists in R Core versions to at least R-3.2.2. o Entering a string constant containing Unicode escapes that was 9999 or 10000 characters long would produce an error message saying "String is too long (max 10000 chars)". This has been fixed so that the maximum now really is 10000 characters. (Also present in R Core versions, to at least R-3.2.2.) o Fixed a bug that caused the error caret in syntax error reports to be misplaced when more than one line of context was shown. This was supposedly fixed in R-3.0.2, but incorrectly, resulting in the error caret being misplaced when only one line of context is shown (in R Core versions to at least R-3.2.2). ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
