Dear R Users,
I wrote a minimal parser to extract strings and comments from the
function definitions.
The string extraction works fine. But there are no comments:
a.) Are the comments stripped from the compiled packages?
b.) Alternatively: Is the deparse() not suited for this task?
b.2.) Is deparse() parsing the function/expression itself?
[see code for extract.str.fun() function below]
### All strings in "base"
extract.str.pkg("base")
# type = 2 for Comments:
extract.str.pkg("base", type=2)
extract.str.pkg("sp", type=2)
extract.str.pkg("NetLogoR", type=2)
The code for the 2 functions (extract.str.pkg & extract.str.fun) and the
code for the parse.simple() parser are below.
Sincerely,
Leonard
=======
The latest code is on GitHub:
https://github.com/discoleo/R/blob/master/Stat/Tools.Formulas.R
### Code to process functions in packages:
extract.str.fun = function(fn, pkg, type=1, strip=TRUE) {
fn = as.symbol(fn); pkg = as.symbol(pkg);
fn = list(substitute(pkg ::: fn));
# deparse
s = paste0(do.call(deparse, fn), collapse="");
npos = parse.simple(s);
extract.str(s, npos[[type]], strip=strip)
}
extract.str.pkg = function(pkg, type=1, exclude.z = TRUE, strip=TRUE) {
nms = ls(getNamespace(pkg));
l = lapply(nms, function(fn) extract.str.fun(fn, pkg, type=type,
strip=strip));
if(exclude.z) {
hasStr = sapply(l, function(s) length(s) >= 1);
nms = nms[hasStr];
l = l[hasStr];
}
names(l) = nms;
return(l);
}
### minimal Parser:
# - proof of concept;
# - may be useful to process non-conformant R "code", e.g.:
# "{\"abc\" + \"bcd\"} {FUN}"; (still TODO)
# Warning:
# - not thoroughly checked &
# may be a little buggy!
parse.simple = function(x, eol="\n") {
len = nchar(x);
n.comm = list(integer(0), integer(0));
n.str = list(integer(0), integer(0));
is.hex = function(ch) {
# Note: only for 1 character!
return((ch >= "0" && ch <= "9") ||
(ch >= "A" && ch <= "F") ||
(ch >= "a" && ch <= "f"));
}
npos = 1;
while(npos <= len) {
s = substr(x, npos, npos);
# State: COMMENT
if(s == "#") {
n.comm[[1]] = c(n.comm[[1]], npos);
while(npos < len) {
npos = npos + 1;
if(substr(x, npos, npos) == eol) break;
}
n.comm[[2]] = c(n.comm[[2]], npos);
npos = npos + 1; next;
}
# State: STRING
if(s == "\"" || s == "'") {
n.str[[1]] = c(n.str[[1]], npos);
while(npos < len) {
npos = npos + 1;
se = substr(x, npos, npos);
if(se == "\\") {
npos = npos + 1;
# simple escape vs Unicode:
if(substr(x, npos, npos) != "u") next;
len.end = min(len, npos + 4);
npos = npos + 1;
isAllHex = TRUE;
while(npos <= len.end) {
se = substr(x, npos, npos);
if( ! is.hex(se)) { isAllHex = FALSE; break; }
npos = npos + 1;
}
if(isAllHex) next;
}
if(se == s) break;
}
n.str[[2]] = c(n.str[[2]], npos);
npos = npos + 1; next;
}
npos = npos + 1;
}
return(list(str = n.str, comm = n.comm));
}
extract.str = function(s, npos, strip=FALSE) {
if(length(npos[[1]]) == 0) return(character(0));
strip.FUN = if(strip) {
function(id) {
if(npos[[1]][[id]] + 1 < npos[[2]][[id]]) {
nStart = npos[[1]][[id]] + 1;
nEnd = npos[[2]][[id]] - 1; # TODO: Error with
malformed string
return(substr(s, nStart, nEnd));
} else {
return("");
}
}
} else function(id) substr(s, npos[[1]][[id]], npos[[2]][[id]]);
sapply(seq(length(npos[[1]])), strip.FUN);
}
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