1 files changed, 90 insertions, 0 deletions

diff --git a/rust/libnewsboat/src/utils.rs b/rust/libnewsboat/src/utils.rs
index 91ee9cfe..d1ccca80 100644
--- a/rust/libnewsboat/src/utils.rs
+++ b/rust/libnewsboat/src/utils.rs
@@ -545,6 +545,44 @@ pub fn newsboat_major_version() -> u32 {
     env!("CARGO_PKG_VERSION_MAJOR").parse::<u32>().unwrap()
 }
 
+/// Returns the part of the string before first # character (or the whole input string if there are
+/// no # character in it). Pound characters inside double quotes and backticks are ignored.
+pub fn strip_comments(line: &str) -> &str {
+    let mut prev_was_backslash = false;
+    let mut inside_quotes = false;
+    let mut inside_backticks = false;
+
+    let mut first_pound_chr_idx = line.len();
+
+    for (idx, chr) in line.char_indices() {
+        if chr == '\\' {
+            prev_was_backslash = true;
+            continue;
+        } else if chr == '"' {
+            // If the quote is escaped or we're inside backticks, do nothing
+            if !prev_was_backslash && !inside_backticks {
+                inside_quotes = !inside_quotes;
+            }
+        } else if chr == '`' {
+            // If the backtick is escaped, do nothing
+            if !prev_was_backslash {
+                inside_backticks = !inside_backticks;
+            }
+        } else if chr == '#' {
+            if !prev_was_backslash && !inside_quotes && !inside_backticks {
+                first_pound_chr_idx = idx;
+                break;
+            }
+        }
+
+        // We call `continue` when we run into a backslash; here, we handle all the other
+        // characters, which clearly *aren't* a backslash
+        prev_was_backslash = false;
+    }
+
+    &line[0..first_pound_chr_idx]
+}
+
 #[cfg(test)]
 mod tests {
     extern crate tempfile;
@@ -827,6 +865,7 @@ mod tests {
             get_command_output("a-program-that-is-guaranteed-to-not-exists"),
             "".to_string()
         );
+        assert_eq!(get_command_output("echo c\" d e"), "".to_string());
     }
 
     #[test]
@@ -1042,4 +1081,55 @@ mod tests {
 
         assert_eq!(strnaturalcmp("aa10", "aa2"), Ordering::Greater);
     }
+
+    #[test]
+    fn t_strip_comments() {
+        // no comments in line
+        assert_eq!(strip_comments(""), "");
+        assert_eq!(strip_comments("\t\n"), "\t\n");
+        assert_eq!(strip_comments("some directive "), "some directive ");
+
+        // fully commented line
+        assert_eq!(strip_comments("#"), "");
+        assert_eq!(strip_comments("# #"), "");
+        assert_eq!(strip_comments("# comment"), "");
+
+        // partially commented line
+        assert_eq!(strip_comments("directive # comment"), "directive ");
+        assert_eq!(
+            strip_comments("directive # comment # another"),
+            "directive "
+        );
+        assert_eq!(strip_comments("directive#comment"), "directive");
+
+        // ignores # characters inside double quotes (#652)
+        let expected = r#"highlight article "[-=+#_*~]{3,}.*" green default"#;
+        let input = expected.to_owned() + "# this is a comment";
+        assert_eq!(strip_comments(&input), expected);
+
+        let expected =
+            r#"highlight all "(https?|ftp)://[\-\.,/%~_:?&=\#a-zA-Z0-9]+" blue default bold"#;
+        let input = expected.to_owned() + "#heresacomment";
+        assert_eq!(strip_comments(&input), expected);
+
+        // Escaped double quote inside double quotes is not treated as closing quote
+        let expected = r#"test "here \"goes # nothing\" etc" hehe"#;
+        let input = expected.to_owned() + "# and here is a comment";
+        assert_eq!(strip_comments(&input), expected);
+
+        // Ignores # characters inside backticks
+        let expected = r#"one `two # three` four"#;
+        let input = expected.to_owned() + "# and a comment, of course";
+        assert_eq!(strip_comments(&input), expected);
+
+        // Escaped backtick inside backticks is not treated as closing
+        let expected = r#"some `other \` tricky # test` hehe"#;
+        let input = expected.to_owned() + "#here goescomment";
+        assert_eq!(strip_comments(&input), expected);
+
+        // Ignores escaped # characters (\\#)
+        let expected = r#"one two \# three four"#;
+        let input = expected.to_owned() + "# and a comment";
+        assert_eq!(strip_comments(&input), expected);
+    }
 }