Add ignorable glob support (#1256)

src/glob.rs

@@ -48,3 +48,61 @@ impl<'de> Deserialize<'de> for Glob {
         Glob::new(&glob).map_err(D::Error::custom)
     }
 }
+
+/// A glob with optional gitignore-style negation. A leading `!` marks the
+/// pattern as a negation (re-includes paths that an earlier rule excluded).
+/// To match a literal `!` at the start of a pattern, escape it with `\!`.
+#[derive(Debug, Clone)]
+pub struct IgnorableGlob {
+    glob: Glob,
+    negated: bool,
+    raw: String,
+}
+
+impl IgnorableGlob {
+    pub fn new(pattern: &str) -> Result<Self, Error> {
+        let (negated, body) = if let Some(rest) = pattern.strip_prefix('!') {
+            (true, rest)
+        } else if pattern.starts_with(r"\!") {
+            (false, &pattern[1..])
+        } else {
+            (false, pattern)
+        };
+
+        Ok(IgnorableGlob {
+            glob: Glob::new(body)?,
+            negated,
+            raw: pattern.to_owned(),
+        })
+    }
+
+    pub fn is_match<P: AsRef<Path>>(&self, path: P) -> bool {
+        self.glob.is_match(path)
+    }
+
+    pub fn is_negation(&self) -> bool {
+        self.negated
+    }
+}
+
+impl PartialEq for IgnorableGlob {
+    fn eq(&self, other: &Self) -> bool {
+        self.negated == other.negated && self.glob == other.glob
+    }
+}
+
+impl Eq for IgnorableGlob {}
+
+impl Serialize for IgnorableGlob {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        serializer.serialize_str(&self.raw)
+    }
+}
+
+impl<'de> Deserialize<'de> for IgnorableGlob {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        let pattern = String::deserialize(deserializer)?;
+
+        IgnorableGlob::new(&pattern).map_err(D::Error::custom)
+    }
+}