evaluate.md
In downlit: Syntax Highlighting and Automatic Linking

handles parsing failures gracefully

Code
  test_evaluate("1 + ", highlight = TRUE)
Output
  <span class='r-in'>1 + </span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span> <span class='error'>Error:</span> &lt;text&gt;:2:0: unexpected end of input</span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span> 1: 1 + </span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span>    ^</span>

highlights when requested

Code
  test_evaluate("1 + \n 2 + 3", highlight = TRUE)
Output
  <span class='r-in'><span><span class='fl'>1</span> <span class='op'>+</span> </span></span>
  <span class='r-in'><span> <span class='fl'>2</span> <span class='op'>+</span> <span class='fl'>3</span></span></span>
  <span class='r-out co'><span class='r-pr'>#&gt;</span> [1] 6</span>

handles basic cases

Code
  test_evaluate("# comment")
Output
  <span class='r-in'># comment</span>
Code
  test_evaluate("message('x')")
Output
  <span class='r-in'>message('x')</span>
  <span class='r-msg co'><span class='r-pr'>#&gt;</span> x</span>
Code
  test_evaluate("warning('x')")
Output
  <span class='r-in'>warning('x')</span>
  <span class='r-wrn co'><span class='r-pr'>#&gt;</span> <span class='warning'>Warning: </span>x</span>
Code
  test_evaluate("stop('x', call. = FALSE)")
Output
  <span class='r-in'>stop('x', call. = FALSE)</span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span> <span class='error'>Error:</span> x</span>
Code
  test_evaluate("f <- function() stop('x'); f()")
Output
  <span class='r-in'>f &lt;- function() stop('x'); f()</span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span> <span class='error'>Error in f():</span> x</span>

each line of input gets span

Code
  test_evaluate("1 +\n 2 +\n 3 +\n 4 +\n 5")
Output
  <span class='r-in'>1 +</span>
  <span class='r-in'> 2 +</span>
  <span class='r-in'> 3 +</span>
  <span class='r-in'> 4 +</span>
  <span class='r-in'> 5</span>
  <span class='r-out co'><span class='r-pr'>#&gt;</span> [1] 15</span>

output always gets trailing nl

Code
  test_evaluate("cat(\"a\")\ncat(\"a\\n\")")
Output
  <span class='r-in'>cat("a")</span>
  <span class='r-out co'><span class='r-pr'>#&gt;</span> a</span>
  <span class='r-in'>cat("a\n")</span>
  <span class='r-out co'><span class='r-pr'>#&gt;</span> a</span>

combines plots as needed

Code
  f1 <- (function() plot(1))
  f2 <- (function() lines(0:2, 0:2))
  test_evaluate("f1()\nf2()\n")
Output
  <span class='r-in'>f1()</span>
  <span class='r-in'>f2()</span>
  <span class='r-plt img'><img src='1.png' alt='' width='10' height='10' /></span>

Code
  f3 <- (function() {
    plot(1)
    plot(2)
  })
  test_evaluate("f3()")
Output
  <span class='r-in'>f3()</span>
  <span class='r-plt img'><img src='1.png' alt='' width='10' height='10' /></span>
  <span class='r-plt img'><img src='2.png' alt='' width='10' height='10' /></span>

handles other plots

<span class='r-in'>f3()</span>
<span class='r-in'>f4()</span>
<HTML for plot 4>

ansi escapes are translated to html

Code
  blue <- (function(x) paste0("\033[34m", x, "\033[39m"))
  f <- (function(x) {
    cat("Output: ", blue("blue"), "\n", sep = "")
    message(paste0("Message: ", blue("blue")))
    warning(blue("blue"), call. = FALSE)
    stop(blue("blue"), call. = FALSE)
  })
  test_evaluate("f()\n")
Output
  <span class='r-in'>f()</span>
  <span class='r-out co'><span class='r-pr'>#&gt;</span> Output: <span style='color: #0000BB;'>blue</span></span>
  <span class='r-msg co'><span class='r-pr'>#&gt;</span> Message: <span style='color: #0000BB;'>blue</span></span>
  <span class='r-wrn co'><span class='r-pr'>#&gt;</span> <span class='warning'>Warning: </span><span style='color: #0000BB;'>blue</span></span>
  <span class='r-err co'><span class='r-pr'>#&gt;</span> <span class='error'>Error:</span> <span style='color: #0000BB;'>blue</span></span>