emulate POSIX defn of diff -b

git-svn-id: https://svn.r-project.org/R/trunk@62407 00db46b3-68df-0310-9c12-caf00c1e9a41

doc/NEWS.Rd

@@ -32,6 +32,10 @@
 
       \item \code{chooseCRANmirror()} and \code{chooseBioCmirror()} gain
       an \code{ind} argument (like \code{setRepositories()}).
+
+      \item \code{tools::Rdiff(useDiff = FALSE)} is closer to the POSIX
+      definition of \command{diff -b} (as distinct from the description
+      in the \command{man} pages of most systems).
     }
   }
 

src/library/tools/R/testing.R

@@ -156,8 +156,12 @@ Rdiff <- function(from, to, useDiff = FALSE, forEx = FALSE, nullPointers=TRUE, L
         right <- clean2(right)
     }
     if (!useDiff && (length(left) == length(right))) {
-        bleft <- gsub("[[:space:]]+", " ", left)
-        bright <- gsub("[[:space:]]+", " ", right)
+        ## The idea is to emulate diff -b, as documented by POSIX:
+        ## http://pubs.opengroup.org/onlinepubs/9699919799/utilities/diff.html
+        bleft <- gsub("[[:space:]]*$", "", left)
+        bright <- gsub("[[:space:]]*$", "", right)
+        bleft <- gsub("[[:space:]]+", " ", bleft)
+        bright <- gsub("[[:space:]]+", " ", bright)
         if(all(bleft == bright))
             return(if(Log) list(status = 0L, out = character()) else 0L)
         cat("\n")

src/library/tools/man/Rdiff.Rd

@@ -26,6 +26,7 @@ Rdiff(from, to, useDiff = FALSE, forEx = FALSE,
     differences found?}
 }
 \details{
+
   The \R startup banner and any timing information from \command{R CMD
     BATCH} are removed from both files, together with lines about
   loading packages.  UTF-8 fancy quotes (see \code{\link{sQuote}}) and
@@ -35,12 +36,12 @@ Rdiff(from, to, useDiff = FALSE, forEx = FALSE,
   (e.g. \code{<environment: 0x12345678>}) are mapped to
   \code{0x00000000}.  The files are then compared line-by-line.  If
   there are the same number of lines and \code{useDiff} is false, a
-  simple \command{diff}-like display of differences is printed (which
-  ignores differences in consecutive spaces), otherwise \command{diff
-    -bw} is called on the edited files.  (This tries to ignore all
-  differences in whitespace: note that flag \option{-w} is not
-  required by POSIX but is supported by GNU, Solaris and FreeBSD
-  versions.)
+  simple \command{diff -b} -like display of differences is printed
+  (which ignores trailing spaces and differences in numbers of
+  consecutive spaces), otherwise \command{diff -bw} is called on the
+  edited files.  (This tries to ignore all differences in whitespace:
+  note that flag \option{-w} is not required by POSIX but is supported
+  by GNU, Solaris and FreeBSD versions.)
 
   This can compare uncompressed PDF files, ignoring differences in
   creation and modification dates.