alleviate wrangling label expressions

Author: teunbrand

R/guide-.R

@@ -225,13 +225,8 @@ Guide <- ggproto(
 
     mapped <- scale$map(breaks)
     labels <- scale$get_labels(breaks)
-    # {vctrs} doesn't play nice with expressions, convert to list.
-    # see also https://github.com/r-lib/vctrs/issues/559
-    if (is.expression(labels)) {
-      labels <- as.list(labels)
-    }
 
-    key <- data_frame(mapped, .name_repair = ~ aesthetic)
+    key <- data_frame(!!aesthetic := mapped)
     key$.value <- breaks
     key$.label <- labels
 

R/guide-axis-theta.R

@@ -110,7 +110,7 @@ GuideAxisTheta <- ggproto(
       # labels of these positions
       ends_apart <- (key$theta[n] - key$theta[1]) %% (2 * pi)
       if (n > 0 && ends_apart < 0.05 && !is.null(key$.label)) {
-        if (is.expression(key$.label)) {
+        if (is.expression(key$.label[[1]])) {
           combined <- substitute(
             paste(a, "/", b),
             list(a = key$.label[[1]], b = key$.label[[n]])

R/guide-bins.R

@@ -176,9 +176,6 @@ GuideBins <- ggproto(
     } else {
       key$.show[nrow(key)] <- TRUE
     }
-    if (is.expression(labels)) {
-      labels <- as.list(labels)
-    }
 
     key$.label <- labels
     key <- vec_slice(key, !is.na(oob_censor_any(key$.value)))

R/guide-colorsteps.R

@@ -111,16 +111,9 @@ GuideColoursteps <- ggproto(
     breaks <- parsed$breaks
 
     key <- data_frame0(!!aesthetic := scale$map(breaks))
-    if (even.steps) {
-      key$.value <- seq_along(breaks)
-    } else {
-      key$.value <- breaks
-    }
-    labels <- scale$get_labels(breaks)
-    if (is.expression(labels)) {
-      labels <- as.list(labels)
-    }
-    key$.label <- labels
+    fmt <- if (even.steps) seq_along else identity
+    key$.value <- fmt(breaks)
+    key$.label <- scale$get_labels(breaks)
 
     if (breaks[1] %in% limits) {
       key$.value  <- key$.value - 1L