srcrefs in swank:compile-string-for-emacs

Wow, this was hard.  parse() constructs a vector with mode
"expression", consisting of multiple, possibly nested calls.
Scattered throughout this structure are srcrefs with absolute
locations.  This means that we need to walk the parsed data structure
and adjust every srcref that we can find, giving it an offset based on
the location information passed to compile-string-for-emacs (which
requires bleeding-edge 2010-10-08 slime, because earlier versions
don't pass line/column information in the position argument).

But we can't simply adjust the "srcref" attribute on our parsed data
structure, because R tries very hard to be pure.  Instead we need to
return a copy with the right modifications (but preserving everything
else of importance).  It's straightforward once you know how, but
there were many painful missteps to get to this point.  Still, now
M-. works on function names assigned with C-c C-c in source buffers.

diff --git a/BUGS.org b/BUGS.org
index 6ce7ba0fed5851670a57c6d4a3e473c3f8b25cf3..7ebda446147d6afe6ceaab4b10efa9ad54bba97f 100644 (file)
--- a/BUGS.org
+++ b/BUGS.org
@@ -10,7 +10,7 @@
 * OPEN #2 popping beyond inspector history crashes                   :NORMAL:
   Inspecting something and hitting =l= causes the R debugger to pop
   up from trying to send =NULL= in a sexp to Emacs.
-* OPEN #3 source reference in compile-string-for-emacs             :WISHLIST:
+* RESOLVED #3 source reference in compile-string-for-emacs   :WISHLIST:FIXED:
   It would be good if we could associate the expressions in the string
   with a reference to the corresponding source.  Unfortunately, emacs
   only passes the buffer position in bytes (or maybe characters),

diff --git a/swank.R b/swank.R
index 747696acdee909c21279cc53c190b2c7919c63ed..fa22d64a89fbb81c7cbce794e5360a48870ad859 100644 (file)
--- a/swank.R
+++ b/swank.R
@@ -401,11 +401,42 @@ computeRestartsForEmacs <- function (sldbState) {
 }
 
 `swank:compile-string-for-emacs` <- function(slimeConnection, sldbState, string, buffer, position, filename, policy) {
-  # FIXME: I think in parse() here we can use srcref to associate
-  # buffer/filename/position to the objects.  Or something.
-  withRestarts({ times <- system.time(eval(parse(text=string), envir = globalenv())) },
+  lineOffset <- charOffset <- colOffset <- NULL
+  for(pos in position) {
+    switch(as.character(pos[[1]]),
+           `:position` = {charOffset <- pos[[2]]},
+           `:line` = {lineOffset <- pos[[2]]; colOffset <- pos[[3]]},
+           warning("unknown content in pos", pos))
+  }
+  frob <- function(refs) {
+    lapply(refs,
+           function(x)
+           srcref(attr(x,"srcfile"),
+                  c(x[1]+lineOffset-1, ifelse(x[1]==1, x[2]+colOffset-1, x[2]),
+                    x[3]+lineOffset-1, ifelse(x[3]==1, x[4]+colOffset-1, x[4]),
+                    ifelse(x[1]==1, x[5]+colOffset-1, x[5]),
+                    ifelse(x[3]==1, x[6]+colOffset-1, x[6]))))
+  }
+  transformSrcrefs <- function(s) {
+    srcrefs <- attr(s, "srcref")
+    attribs <- attributes(s)
+    new <- 
+      switch(mode(s),
+             "call"=as.call(lapply(s, transformSrcrefs)),
+             "expression"=as.expression(lapply(s, transformSrcrefs)),
+             s)
+    attributes(new) <- attribs
+    if(!is.null(attr(s, "srcref"))) {
+      attr(new, "srcref") <- frob(srcrefs)
+    }
+    new
+  }
+  withRestarts({
+    times <- system.time({
+      exprs <- parse(text=string, srcfile=srcfile(filename))
+      eval(transformSrcrefs(exprs), envir = globalenv()) })},
                abort="abort compilation")
-  list(quote(`:compilation-result`), list(), TRUE, times[3])
+  list(quote(`:compilation-result`), list(), TRUE, times[3], FALSE, FALSE)
 }
 
 withRetryRestart <- function(description, expr) {