Do not error with inline \\Sexpr.

Fixes #127

NEWS.md

@@ -1,4 +1,5 @@
 # lintr 1.0.0.9000 #
+* Do not error with inline \\Sexpr (#127).
 * Do not error with '<% %>' constructs (#185).
 * Allow closing parenthesis or comma after closing curly brace (#167, @Enchufa2)
 * Support checkstyle XML output (#156, @joshkgold)

R/extract.R

@@ -9,6 +9,11 @@ extract_r_source <- function(filename, lines) {
   starts <- grep(pattern$chunk.begin, lines, perl = TRUE)
   ends <- grep(pattern$chunk.end, lines, perl = TRUE)
 
+  # no chunks found, so just return the lines
+  if (length(starts) == 0 || length(ends) == 0) {
+    return(lines)
+  }
+
   if (length(starts) != length(ends)) {
     stop("Malformed file!", call. = FALSE)
   }

tests/testthat/test-knitr_formats.R

@@ -74,3 +74,11 @@ test_that("it does _not_ handle brew", {
     ),
     default_linters)
 })
+
+test_that("it does _not_ error with inline \\Sexpr", {
+  expect_lint("#' text \\Sexpr{1 + 1} more text\n",
+    checks = list(
+      rex("Trailing blank lines are superfluous.")
+    ),
+    default_linters)
+})