fix(ellmer_prompt): Truncate lines and items individually

R/interpolate.R

@@ -106,6 +106,9 @@ print.ellmer_prompt <- function(
   max_items = 20,
   max_lines = max_items * 10
 ) {
+  check_number_whole(max_items, min = 1)
+  check_number_whole(max_lines, min = 1)
+
   n <- length(x)
   n_extra <- length(x) - max_items
   if (n_extra > 0) {
@@ -128,13 +131,18 @@ print.ellmer_prompt <- function(
   x <- gsub("\n", paste0("\n", exdent), x)
 
   lines <- strsplit(x, "\n")
-  ids <- rep(seq_along(x), length(lines))
+  ids <- rep(seq_along(x), lengths(lines))
+  first <- c(TRUE, ids[-length(ids)] != ids[-1])
   lines <- unlist(lines)
 
   if (length(lines) > max_lines) {
+    if (first[max_lines + 1]) {
+      max_lines <- if (ids[max_lines] > 1) max_lines - 1 else max(max_lines, 1)
+    }
+
     lines <- lines[seq_len(max_lines)]
     lines <- c(lines, paste0(exdent, "..."))
-    n_extra <- n - ids[max_lines - 1]
+    n_extra <- n - ids[max_lines]
   }
 
   cat(lines, sep = "\n")

tests/testthat/_snaps/interpolate.md

@@ -40,6 +40,13 @@
           | y
       [2] | a
           | ...
+    Code
+      print(ellmer_prompt("a\nb\nc\nd\ne"), max_lines = 3)
+    Output
+      [1] | a
+          | b
+          | c
+          | ...
 
 # errors if the path does not exist
 

tests/testthat/test-interpolate.R

@@ -22,6 +22,7 @@ test_that("print method truncates many elements", {
     print(prompt, max_items = 1)
     print(prompt, max_lines = 2)
     print(prompt, max_lines = 3)
+    print(ellmer_prompt("a\nb\nc\nd\ne"), max_lines = 3)
   })
 })