Disallow escaping of meta characters except for spaces

https://github.com/junegunn/fzf/issues/444#issuecomment-321719604

src/pattern.go

@@ -54,15 +54,13 @@ type Pattern struct {
 }
 
 var (
-	_patternCache       map[string]*Pattern
-	_splitRegex         *regexp.Regexp
-	_escapedPrefixRegex *regexp.Regexp
-	_cache              ChunkCache
+	_patternCache map[string]*Pattern
+	_splitRegex   *regexp.Regexp
+	_cache        ChunkCache
 )
 
 func init() {
 	_splitRegex = regexp.MustCompile(" +")
-	_escapedPrefixRegex = regexp.MustCompile("^\\\\['!^|]")
 	clearPatternCache()
 	clearChunkCache()
 }
@@ -179,17 +177,11 @@ func parseTerms(fuzzy bool, caseMode Case, normalize bool, str string) []termSet
 		}
 
 		if text != "$" && strings.HasSuffix(text, "$") {
-			if strings.HasSuffix(text, "\\$") {
-				text = text[:len(text)-2] + "$"
-			} else {
-				typ = termSuffix
-				text = text[:len(text)-1]
-			}
+			typ = termSuffix
+			text = text[:len(text)-1]
 		}
 
-		if _escapedPrefixRegex.MatchString(text) {
-			text = text[1:]
-		} else if strings.HasPrefix(text, "'") {
+		if strings.HasPrefix(text, "'") {
 			// Flip exactness
 			if fuzzy && !inv {
 				typ = termExact

test/test_go.rb

@@ -1391,24 +1391,10 @@ class TestGoFZF < TestBase
     writelines tempname, input.lines.map(&:chomp)
 
     assert_equal input.lines.count, `#{FZF} -f'foo bar' < #{tempname}`.lines.count
+    assert_equal input.lines.count - 1, `#{FZF} -f'^foo bar$' < #{tempname}`.lines.count
     assert_equal ['foo bar'], `#{FZF} -f'foo\\ bar' < #{tempname}`.lines.map(&:chomp)
-    assert_equal ['bar foo'], `#{FZF} -f'foo$' < #{tempname}`.lines.map(&:chomp)
-    assert_equal ['foo$bar'], `#{FZF} -f'foo\\$' < #{tempname}`.lines.map(&:chomp)
-    assert_equal [], `#{FZF} -f'!bar' < #{tempname}`.lines.map(&:chomp)
-    assert_equal ['foo!bar'], `#{FZF} -f'\\!bar' < #{tempname}`.lines.map(&:chomp)
     assert_equal ['foo bar'], `#{FZF} -f'^foo\\ bar$' < #{tempname}`.lines.map(&:chomp)
-    assert_equal [], `#{FZF} -f"'br" < #{tempname}`.lines.map(&:chomp)
-    assert_equal ["foo'bar"], `#{FZF} -f"\\'br" < #{tempname}`.lines.map(&:chomp)
-  end
-
-  def test_escaped_meta_characters_only_on_relevant_positions
-    input = <<~EOF
-      \\^
-      ^
-    EOF
-    writelines tempname, input.lines.map(&:chomp)
-    assert_equal %w[^ \\^], `#{FZF} -f"\\^" < #{tempname}`.lines.map(&:chomp)
-    assert_equal %w[\\^], `#{FZF} -f"'\\^" < #{tempname}`.lines.map(&:chomp)
+    assert_equal input.lines.count - 1, `#{FZF} -f'!^foo\\ bar$' < #{tempname}`.lines.count
   end
 end