eliminate maybe macro

Author: maxcountryman

src/parser.rs

@@ -34,14 +34,6 @@ macro_rules! parser_err {
     };
 }
 
-macro_rules! maybe {
-    ($e:expr) => {{
-        if let Some(v) = $e {
-            return Ok(v);
-        }
-    }};
-}
-
 #[derive(PartialEq)]
 pub enum IsOptional {
     Optional,
@@ -198,19 +190,19 @@ impl Parser {
         //      INTERVAL '7' DAY
         //
         // Note also that naively `SELECT date` looks like a syntax error because the `date` type
-        // name is not followed by a string literal, but in fact in PostgreSQL it is a valid 
+        // name is not followed by a string literal, but in fact in PostgreSQL it is a valid
         // expression that should parse as the column name "date".
-        maybe!(self.maybe_parse(|parser| {
-            match parser.parse_data_type()? {
-                DataType::Interval => parser.parse_literal_interval(),
-                data_type => Ok(Expr::Cast {
-                    expr: Box::new(Expr::Value(Value::SingleQuotedString(
-                        parser.parse_literal_string()?,
-                    ))),
-                    data_type,
-                }),
-            }
-        }));
+        if let Some(parsed) = self.maybe_parse(|parser| match parser.parse_data_type()? {
+            DataType::Interval => parser.parse_literal_interval(),
+            data_type => Ok(Expr::Cast {
+                expr: Box::new(Expr::Value(Value::SingleQuotedString(
+                    parser.parse_literal_string()?,
+                ))),
+                data_type,
+            }),
+        }) {
+            return Ok(parsed);
+        }
 
         let tok = self
             .next_token()
@@ -1975,7 +1967,11 @@ impl Parser {
             // Check if the recently consumed '(' started a derived table, in which case we've
             // parsed the subquery, followed by the closing ')', and the alias of the derived
             // table. In the example above this is case (3), or another nested join (2).
-            maybe!(self.maybe_parse(|parser| parser.parse_derived_table_factor(NotLateral)));
+            if let Some(parsed) =
+                self.maybe_parse(|parser| parser.parse_derived_table_factor(NotLateral))
+            {
+                return Ok(parsed);
+            }
 
             // Inside the parentheses we expect to find a table factor
             // followed by some joins or another level of nesting.