rs: allow str literal date/time parts

Author: donhcd

src/ast/value.rs

@@ -127,6 +127,7 @@ pub enum DateTimeField {
     Minute,
     Second,
     Epoch,
+    Literal(String),
 }
 
 impl fmt::Display for DateTimeField {
@@ -147,6 +148,7 @@ impl fmt::Display for DateTimeField {
             DateTimeField::Minute => "MINUTE",
             DateTimeField::Second => "SECOND",
             DateTimeField::Epoch => "EPOCH",
+            DateTimeField::Literal(ref s) => return write!(f, "'{}'", s),
         })
     }
 }

src/parser.rs

@@ -666,6 +666,7 @@ impl<'a> Parser<'a> {
                 Keyword::EPOCH => Ok(DateTimeField::Epoch),
                 _ => self.expected("date/time field", Token::Word(w))?,
             },
+            Token::SingleQuotedString(w) => Ok(DateTimeField::Literal(w.clone())),
             unexpected => self.expected("date/time field", unexpected),
         }
     }