Merge pull request #148 from gaborcsardi/trailing-semicolon

trailing_semicolon_linter #147

NAMESPACE

@@ -31,6 +31,7 @@ export(snake_case_linter)
 export(spaces_inside_linter)
 export(spaces_left_parentheses_linter)
 export(trailing_blank_lines_linter)
+export(trailing_semicolons_linter)
 export(trailing_whitespace_linter)
 export(with_defaults)
 import(rex)

NEWS.md

@@ -1,4 +1,5 @@
 # lintr 1.0.0.9000 #
+* trailing_semicolon_linter (#147, @gaborcsardi)
 
 * Commas linter handles missing arguments calls properly (#145)
 

R/trailing_semicolons_linter.R

@@ -0,0 +1,39 @@
+#' @describeIn linters check there are no trailing semicolons.
+#' @export
+trailing_semicolons_linter <- function(source_file) {
+
+  allsc <- which(source_file$parsed_content$token == "';'")
+
+  if (!length(allsc)) return(list())
+
+  ## Check that it is the last token in the line
+  ## Note that we need to restrict the search to terminal
+  ## nodes, because parse is buggy and sometimes reports false,
+  ## too large end positions for non-terminal nodes.
+  badsc <- Filter(
+    x = allsc,
+    f = function(line) {
+      with(
+        source_file$parsed_content,
+        all(! terminal | line1 != line1[line] | col2 <= col2[line])
+      )
+    }
+  )
+
+  lapply(
+    badsc,
+    function(line) {
+      parsed <- source_file$parsed_content[line, ]
+      Lint(
+        filename = source_file$filename,
+        line_number = parsed$line1,
+        column_number = parsed$col1,
+        type = "style",
+        message = "Avoid trailing semicolons, they are not needed.",
+        line = source_file$lines[as.character(parsed$line1)],
+        ranges = list(c(parsed$col1, parsed$col2)),
+        linter = "trailing_semicolons_linter"
+      )
+    }
+  )
+}

tests/testthat/test-trailing_semicolons_linter.R

@@ -0,0 +1,23 @@
+context("trailing_semicolons_linter")
+
+test_that("finds trailing semicolons", {
+  expect_lint("function() { 42 }\n",
+    NULL,
+    trailing_semicolons_linter)
+
+  expect_lint("function() { \"But here\";\n\"  and here\"; }",
+    rex("trailing semicolons"),
+    trailing_semicolons_linter)
+})
+
+test_that("finds trailing semicolons even with trailing whitespace", {
+  expect_lint("function() { \"Here, too!\";  \n }\n",
+    rex("trailing semicolons"),
+    trailing_semicolons_linter)
+})
+
+test_that("ignores non-trailing semicolons", {
+  expect_lint("function() { 1 ; 2 ; \"is good\" }\n",
+    NULL,
+    trailing_semicolons_linter)
+})