fix: panic when skipping char at boundary in convert_to_with (closes …

…#7)

src/converter.rs

@@ -236,7 +236,12 @@ impl ZhConverter {
                     // not shadowed: pick a word in original automaton
                     if shadowed_source_words.contains(a.2) {
                         // source word is disabled: skip one char and re-search
-                        let first_char_len = text.chars().next().unwrap().len_utf8();
+                        //
+                        // NOTE: In case there are two rules like `{abcd -> foo, abc -> bar}`,
+                        // even if the former is disabled, the latter won't take effect, since `a`
+                        // will be skipped and the next search start at `bc`.
+                        // It is inevitable if we do not re-build a new automaton every time.
+                        let first_char_len = text[a.0..].chars().next().unwrap().len_utf8();
                         (
                             last,
                             a.0 + first_char_len,

src/lib.rs

@@ -40,6 +40,7 @@
 //! assert_eq!(zhconv_mw("-{zh-tw:鼠麴草;zh-cn:香茅}-是菊科草本植物。", Variant::ZhCN), "香茅是菊科草本植物。");
 //! assert_eq!(zhconv_mw("菊科草本植物包括-{zh-tw:鼠麴草;zh-cn:香茅;}-等。", Variant::ZhTW), "菊科草本植物包括鼠麴草等。");
 //! assert_eq!(zhconv_mw("-{H|zh:馬;zh-cn:鹿;}-馬克思主義", Variant::ZhCN), "鹿克思主义"); // global rule
+//! assert_eq!(zhconv_mw("&二極體\n-{-|zh-hans:二极管; zh-hant:二極體}-\n", Variant::ZhCN), "&二极体\n\n")
 //! ```
 //!
 //! To load or add additional conversion rules such as CGroups or `(FROM, TO)` pairs,

src/rule.rs

@@ -102,7 +102,10 @@ impl FromStr for ConvRule {
             match flag {
                 // FIX: 'A'
                 '+' => action = Some(Action::Add),
-                '-' => action = Some(Action::Remove),
+                '-' => action = {
+                    output = None;
+                    Some(Action::Remove)
+                },
                 // no conv, just display the inner as-is
                 'R' => {
                     return Ok(ConvRule {