R: capture the loop counter of for control structure

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

Units/parser-r.r/r-loop-counters.d/args.ctags

@@ -0,0 +1,2 @@
+--kinds-R=+vz
+--sort=no

Units/parser-r.r/r-loop-counters.d/expected.tags

@@ -0,0 +1,6 @@
+`%*%`	input.r	/^`%*%` <- function (v, p) {$/;"	f
+v	input.r	/^`%*%` <- function (v, p) {$/;"	z	function:`%*%`
+p	input.r	/^`%*%` <- function (v, p) {$/;"	z	function:`%*%`
+r	input.r	/^    r <- 1$/;"	v	function:`%*%`
+i	input.r	/^        for (i in 1:p) {$/;"	v	function:`%*%`
+j	input.r	/^for (j in 1:3) {$/;"	g

Units/parser-r.r/r-loop-counters.d/input.r

@@ -0,0 +1,20 @@
+# defining an operator
+`%*%` <- function (v, p) {
+    r <- 1
+    if (p == 1) {
+        r <- v
+    } else {
+        for (i in 1:p) {
+            r <- r * v
+        }
+    }
+    r
+}
+
+print (c(2 %*% 10, 2%*%2, 2%*%3)[1:2])
+
+# j introduced as a global var.
+for (j in 1:3) {
+    print (j)
+}
+print (j)

parsers/r.c

@@ -849,6 +849,26 @@ static bool preParseExternalEntitiy (tokenInfo *const token, tokenInfo *const fu
 	return r;
 }
 
+static bool preParseLoopCounter(tokenInfo *const token, int parent)
+{
+	bool r = true;
+	TRACE_ENTER();
+
+	tokenReadNoNewline (token);
+	if (tokenIsType (token, SYMBOL))
+		makeSimpleRTag (token, parent,
+						(parent == CORK_NIL) ? K_GLOBALVAR: K_FUNCVAR , NULL);
+
+	if (tokenIsEOF (token)
+		|| tokenIsTypeVal (token, ')'))
+		r = false;
+
+	TRACE_LEAVE_TEXT(r
+					 ? "unread tokens and request parsing again to the upper context"
+					 : "parse all arguments");
+	return r;
+}
+
 
 /* If funcall is non-NULL, this pair represents the argument list for the function
  * call for FUNCALL. */
@@ -867,6 +887,8 @@ static void parsePair (tokenInfo *const token, int parent, tokenInfo *const func
 		if 	(tokenIsKeyword (funcall, LIBRARY) ||
 			 tokenIsKeyword (funcall, SOURCE))
 			done = !preParseExternalEntitiy (token, funcall);
+		else if (tokenIsKeyword (funcall, FOR))
+			done = !preParseLoopCounter (token, parent);
 	}
 
 	if (done)