Cleaner handling of var names

This commit separates the conversion of an expression (a name or call)
to a string, and the escaping of '.' for safe vega vars. This makes it
possible to use correct titles for axes legends when the data column
has a '.' in it.

R/flatten.R

@@ -29,7 +29,7 @@ combine_data_props <- function(mark) {
 
   # Remove duplicates, and props that don't appear in the data
   lapply(props_by_id, function(props) {
-    names <- vapply(props, prop_label, character(1))
+    names <- safe_vega_var(vapply(props, prop_label, character(1)))
     ok <- !duplicated(names) & names != ""
 
     setNames(props[ok], names[ok])
@@ -62,7 +62,7 @@ apply_props <- function(data, props) {
 #' @export
 apply_props.data.frame <- function(data, props) {
   cols <- lapply(props, prop_value, data = data)
-  names(cols) <- vapply(props, prop_label, character(1))
+  names(cols) <- safe_vega_var(vapply(props, prop_label, character(1)))
   quickdf(cols)
 }
 

R/ggvis.R

@@ -264,7 +264,7 @@ register_scales_from_props <- function(vis, props) {
   add_scale_from_prop <- function(vis, prop) {
     # Automatically add label, unless it's blank or has a trailing '_'
     label <- prop_label(prop)
-    if (label == "" || grepl("_$", prop_label(prop))) {
+    if (label == "" || grepl("_$", label)) {
       label <- NULL
     }
 

R/prop.R

@@ -224,9 +224,9 @@ prop_label <- function(x) UseMethod("prop_label")
 #' @export
 prop_label.prop_constant <- function(x) ""
 #' @export
-prop_label.prop_variable <- function(x) safe_vega_var(x$value)
+prop_label.prop_variable <- function(x) as_char(x$value)
 #' @export
-prop_label.prop_reactive <- function(x) safe_vega_var(reactive_id(x$value))
+prop_label.prop_reactive <- function(x) as_char(reactive_id(x$value))
 
 # Reports whether this is a scaled prop
 prop_is_scaled <- function(prop) !is.null(prop$scale)
@@ -246,7 +246,7 @@ prop_vega.prop_constant <- function(x, default_scale) {
 prop_vega.prop_variable <- function(x, default_scale) {
   compact(list(
     scale = if (prop_is_scaled(x)) x$scale,
-    field = paste0("data.", prop_label(x)),
+    field = paste0("data.", safe_vega_var(prop_label(x))),
     mult = x$mult,
     offset = x$offset
   ))
@@ -269,7 +269,7 @@ prop_domain.prop_constant <- function(x, data) {
 prop_domain.prop_variable <- function(x, data) {
   list(
     data = data,
-    field = paste0("data.", prop_label(x))
+    field = paste0("data.", safe_vega_var(prop_label(x)))
   )
 }
 #' @export

R/utils.R

@@ -132,15 +132,18 @@ param_string <- function(x, collapse = TRUE) {
   paste0("(", paste0(names(x), " = ", values, collapse = ", "), ")")
 }
 
+# Convert various objects to char strings.
+as_char <- function(x) UseMethod("as_char")
+#' @export
+as_char.name <- function(x) as.character(x)
+#' @export
+as_char.call <- function(x) deparse2(x)
+#' @export
+as_char.default <- function(x) stop("Don't know how to convert to string.")
+
 # Given a string, return a string that is safe as a vega variable.
 # Replaces . with \.
 safe_vega_var <- function(x) {
-  if (is.name(x)) {
-    x <- as.character(x)
-  } else if (is.quoted(x)) {
-    x <- deparse2(x)
-  }
-
   gsub(".", "\\.", x, fixed = TRUE)
 }
 

R/vega.R

@@ -147,7 +147,7 @@ as.vega.mark <- function(mark, in_group = FALSE) {
   }
 
   if (!is.null(key)) {
-    m$key <- paste0("data.", prop_label(key))
+    m$key <- paste0("data.", safe_vega_var(prop_label(key)))
   }
   m
 }