Optimize visiting code

Author: krlmlr

R/visit.R

@@ -20,9 +20,19 @@ pre_visit <- function(pd_nested, funs) {
   if (is.null(pd_nested)) {
     return()
   }
+  if (length(funs) == 0) {
+    return(pd_nested)
+  }
   pd_nested <- visit_one(pd_nested, funs)
 
-  pd_nested$child <- map(pd_nested$child, pre_visit, funs = funs)
+  children <- pd_nested$child
+  for (i in seq_along(children)) {
+    child <- children[[i]]
+    if (!is.null(child)) {
+      children[[i]] <- pre_visit(child, funs)
+    }
+  }
+  pd_nested$child <- children
   pd_nested
 }
 
@@ -32,8 +42,19 @@ post_visit <- function(pd_nested, funs) {
   if (is.null(pd_nested)) {
     return()
   }
+  if (length(funs) == 0) {
+    return(pd_nested)
+  }
+
+  children <- pd_nested$child
+  for (i in seq_along(children)) {
+    child <- children[[i]]
+    if (!is.null(child)) {
+      children[[i]] <- post_visit(child, funs)
+    }
+  }
+  pd_nested$child <- children
 
-  pd_nested$child <- map(pd_nested$child, post_visit, funs = funs)
   visit_one(pd_nested, funs)
 }
 
@@ -46,7 +67,10 @@ post_visit <- function(pd_nested, funs) {
 #' @family visitors
 #' @keywords internal
 visit_one <- function(pd_flat, funs) {
-  Reduce(function(x, fun) fun(x), funs, init = pd_flat)
+  for (f in funs) {
+    pd_flat <- f(pd_flat)
+  }
+  pd_flat
 }
 
 #' Propagate context to terminals