Escape regex metacharacters in str_like()/str_ilike()

NEWS.md

@@ -1,5 +1,7 @@
 # stringr (development version)
 
+* `str_like()` and `str_ilike()` now match regular expression metacharacters such as `.` and `*` literally (@taekop, #617).
+
 # stringr 1.6.0
 
 ## Breaking changes

R/detect.R

@@ -241,11 +241,29 @@ str_ilike <- function(string, pattern) {
 }
 
 like_to_regex <- function(pattern) {
+  converted <- escape_like_metachars(pattern)
   converted <- stri_replace_all_regex(
-    pattern,
+    converted,
     "(?<!\\\\|\\[)%(?!\\])",
     "\\.\\*"
   )
   converted <- stri_replace_all_regex(converted, "(?<!\\\\|\\[)_(?!\\])", "\\.")
   paste0("^", converted, "$")
 }
+
+# Escapes regex metacharacters, except inside `[...]` groups or after `\`
+escape_like_metachars <- function(pattern) {
+  out <- rep(NA_character_, length(pattern))
+  tokens <- stri_extract_all_regex(
+    pattern,
+    "(?s)\\[[^\\]]*\\]|\\\\.|.",
+    omit_no_match = TRUE
+  )
+  for (i in which(!is.na(pattern))) {
+    token <- tokens[[i]]
+    meta <- stri_detect_regex(token, "^[.^$*+?(){}|]$")
+    token[meta] <- paste0("\\", token[meta])
+    out[[i]] <- paste0(token, collapse = "")
+  }
+  out
+}

tests/testthat/test-detect.R

@@ -102,6 +102,25 @@ test_that("str_ilike works", {
   expect_snapshot(str_ilike("abc", regex("x")), error = TRUE)
 })
 
+test_that("str_like and str_ilike treat regex metacharacters literally", {
+  expect_equal(str_like(c("a.c", "abc"), "a.c%"), c(TRUE, FALSE))
+  expect_equal(str_ilike(c("A.C", "ABC"), "a.c%"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a*c", "aac"), "a*c"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a(b)c", "abc"), "a(b)c"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a|b", "a"), "a|b"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a+b", "aab"), "a+b"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a?", "a"), "a?"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a^b$", "ab"), "a^b$"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a{2}", "aa"), "a{2}"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a.b]", "axb]"), "a.b]"), c(TRUE, FALSE))
+  expect_equal(str_like(c("a(b)]", "abb]"), "a(b)]"), c(TRUE, FALSE))
+  expect_equal(str_like(c("f(x]", "fx]"), "f(x]"), c(TRUE, FALSE))
+  expect_equal(
+    str_like(c("a.b9", "axb9", "a.bz"), "a.b[0-9]"),
+    c(TRUE, FALSE, FALSE)
+  )
+})
+
 test_that("like_to_regex generates expected regexps", {
   expect_equal(like_to_regex("ab%"), "^ab.*$")
   expect_equal(like_to_regex("ab_"), "^ab.$")