Add builtin header check: Field is empty

libimagentryfilter/src/builtin/header/field_isempty.rs

@@ -0,0 +1,45 @@
+use libimagstore::store::Entry;
+
+use builtin::header::field_path::FieldPath;
+use filter::Filter;
+
+use toml::Value;
+
+pub struct FieldIsEmpty {
+    header_field_path: FieldPath,
+}
+
+impl FieldIsEmpty {
+
+    pub fn new(path: FieldPath) -> FieldIsEmpty {
+        FieldIsEmpty {
+            header_field_path: path,
+        }
+    }
+
+}
+
+impl Filter for FieldIsEmpty {
+
+    fn filter(&self, e: &Entry) -> bool {
+        let header = e.get_header();
+        self.header_field_path
+            .walk(header)
+            .map(|v| {
+                match v {
+                    Value::Array(a)   => a.is_empty(),
+                    Value::Boolean(_) => false,
+                    Value::Float(_)   => false,
+                    Value::Integer(_) => false,
+                    Value::String(_)  => false,
+                    Value::Table(t)   => t.is_empty(),
+                    _                 => true,
+                }
+            })
+            .unwrap_or(false)
+    }
+
+}
+
+
+