Make Expr::Interval its own struct (#872)

* Make Expr::Interval its own struct

* Add test interval display

* Fix cargo fmt

src/ast/mod.rs

@@ -194,6 +194,70 @@ impl fmt::Display for Array {
     }
 }
 
+/// Represents an INTERVAL expression, roughly in the following format:
+/// `INTERVAL '<value>' [ <leading_field> [ (<leading_precision>) ] ]
+/// [ TO <last_field> [ (<fractional_seconds_precision>) ] ]`,
+/// e.g. `INTERVAL '123:45.67' MINUTE(3) TO SECOND(2)`.
+///
+/// The parser does not validate the `<value>`, nor does it ensure
+/// that the `<leading_field>` units >= the units in `<last_field>`,
+/// so the user will have to reject intervals like `HOUR TO YEAR`.
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
+pub struct Interval {
+    pub value: Box<Expr>,
+    pub leading_field: Option<DateTimeField>,
+    pub leading_precision: Option<u64>,
+    pub last_field: Option<DateTimeField>,
+    /// The seconds precision can be specified in SQL source as
+    /// `INTERVAL '__' SECOND(_, x)` (in which case the `leading_field`
+    /// will be `Second` and the `last_field` will be `None`),
+    /// or as `__ TO SECOND(x)`.
+    pub fractional_seconds_precision: Option<u64>,
+}
+
+impl fmt::Display for Interval {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let value = self.value.as_ref();
+        match (
+            self.leading_field,
+            self.leading_precision,
+            self.fractional_seconds_precision,
+        ) {
+            (
+                Some(DateTimeField::Second),
+                Some(leading_precision),
+                Some(fractional_seconds_precision),
+            ) => {
+                // When the leading field is SECOND, the parser guarantees that
+                // the last field is None.
+                assert!(self.last_field.is_none());
+                write!(
+                    f,
+                    "INTERVAL {value} SECOND ({leading_precision}, {fractional_seconds_precision})"
+                )
+            }
+            _ => {
+                write!(f, "INTERVAL {value}")?;
+                if let Some(leading_field) = self.leading_field {
+                    write!(f, " {leading_field}")?;
+                }
+                if let Some(leading_precision) = self.leading_precision {
+                    write!(f, " ({leading_precision})")?;
+                }
+                if let Some(last_field) = self.last_field {
+                    write!(f, " TO {last_field}")?;
+                }
+                if let Some(fractional_seconds_precision) = self.fractional_seconds_precision {
+                    write!(f, " ({fractional_seconds_precision})")?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
+
 /// JsonOperator
 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@@ -491,25 +555,8 @@ pub enum Expr {
     ArrayIndex { obj: Box<Expr>, indexes: Vec<Expr> },
     /// An array expression e.g. `ARRAY[1, 2]`
     Array(Array),
-    /// INTERVAL literals, roughly in the following format:
-    /// `INTERVAL '<value>' [ <leading_field> [ (<leading_precision>) ] ]
-    /// [ TO <last_field> [ (<fractional_seconds_precision>) ] ]`,
-    /// e.g. `INTERVAL '123:45.67' MINUTE(3) TO SECOND(2)`.
-    ///
-    /// The parser does not validate the `<value>`, nor does it ensure
-    /// that the `<leading_field>` units >= the units in `<last_field>`,
-    /// so the user will have to reject intervals like `HOUR TO YEAR`.
-    Interval {
-        value: Box<Expr>,
-        leading_field: Option<DateTimeField>,
-        leading_precision: Option<u64>,
-        last_field: Option<DateTimeField>,
-        /// The seconds precision can be specified in SQL source as
-        /// `INTERVAL '__' SECOND(_, x)` (in which case the `leading_field`
-        /// will be `Second` and the `last_field` will be `None`),
-        /// or as `__ TO SECOND(x)`.
-        fractional_seconds_precision: Option<u64>,
-    },
+    /// An interval expression e.g. `INTERVAL '1' YEAR`
+    Interval(Interval),
     /// `MySQL` specific text search function [(1)].
     ///
     /// Syntax:
@@ -861,42 +908,8 @@ impl fmt::Display for Expr {
             } => {
                 write!(f, "{timestamp} AT TIME ZONE '{time_zone}'")
             }
-            Expr::Interval {
-                value,
-                leading_field: Some(DateTimeField::Second),
-                leading_precision: Some(leading_precision),
-                last_field,
-                fractional_seconds_precision: Some(fractional_seconds_precision),
-            } => {
-                // When the leading field is SECOND, the parser guarantees that
-                // the last field is None.
-                assert!(last_field.is_none());
-                write!(
-                    f,
-                    "INTERVAL {value} SECOND ({leading_precision}, {fractional_seconds_precision})"
-                )
-            }
-            Expr::Interval {
-                value,
-                leading_field,
-                leading_precision,
-                last_field,
-                fractional_seconds_precision,
-            } => {
-                write!(f, "INTERVAL {value}")?;
-                if let Some(leading_field) = leading_field {
-                    write!(f, " {leading_field}")?;
-                }
-                if let Some(leading_precision) = leading_precision {
-                    write!(f, " ({leading_precision})")?;
-                }
-                if let Some(last_field) = last_field {
-                    write!(f, " TO {last_field}")?;
-                }
-                if let Some(fractional_seconds_precision) = fractional_seconds_precision {
-                    write!(f, " ({fractional_seconds_precision})")?;
-                }
-                Ok(())
+            Expr::Interval(interval) => {
+                write!(f, "{interval}")
             }
             Expr::MatchAgainst {
                 columns,
@@ -4410,4 +4423,30 @@ mod tests {
         ]);
         assert_eq!("CUBE (a, (b, c), d)", format!("{cube}"));
     }
+
+    #[test]
+    fn test_interval_display() {
+        let interval = Expr::Interval(Interval {
+            value: Box::new(Expr::Value(Value::SingleQuotedString(String::from(
+                "123:45.67",
+            )))),
+            leading_field: Some(DateTimeField::Minute),
+            leading_precision: Some(10),
+            last_field: Some(DateTimeField::Second),
+            fractional_seconds_precision: Some(9),
+        });
+        assert_eq!(
+            "INTERVAL '123:45.67' MINUTE (10) TO SECOND (9)",
+            format!("{interval}"),
+        );
+
+        let interval = Expr::Interval(Interval {
+            value: Box::new(Expr::Value(Value::SingleQuotedString(String::from("5")))),
+            leading_field: Some(DateTimeField::Second),
+            leading_precision: Some(1),
+            last_field: None,
+            fractional_seconds_precision: Some(3),
+        });
+        assert_eq!("INTERVAL '5' SECOND (1, 3)", format!("{interval}"));
+    }
 }

src/parser.rs

@@ -1615,13 +1615,13 @@ impl<'a> Parser<'a> {
                 }
             };
 
-        Ok(Expr::Interval {
+        Ok(Expr::Interval(Interval {
             value: Box::new(value),
             leading_field,
             leading_precision,
             last_field,
             fractional_seconds_precision: fsec_precision,
-        })
+        }))
     }
 
     /// Parse an operator following an expression

tests/sqlparser_common.rs

@@ -3395,20 +3395,20 @@ fn parse_interval() {
     let sql = "SELECT INTERVAL '1-1' YEAR TO MONTH";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from("1-1")))),
             leading_field: Some(DateTimeField::Year),
             leading_precision: None,
             last_field: Some(DateTimeField::Month),
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL '01:01.01' MINUTE (5) TO SECOND (5)";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from(
                 "01:01.01"
             )))),
@@ -3416,53 +3416,53 @@ fn parse_interval() {
             leading_precision: Some(5),
             last_field: Some(DateTimeField::Second),
             fractional_seconds_precision: Some(5),
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL '1' SECOND (5, 4)";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from("1")))),
             leading_field: Some(DateTimeField::Second),
             leading_precision: Some(5),
             last_field: None,
             fractional_seconds_precision: Some(4),
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL '10' HOUR";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from("10")))),
             leading_field: Some(DateTimeField::Hour),
             leading_precision: None,
             last_field: None,
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL 5 DAY";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(number("5"))),
             leading_field: Some(DateTimeField::Day),
             leading_precision: None,
             last_field: None,
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL 1 + 1 DAY";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::BinaryOp {
                 left: Box::new(Expr::Value(number("1"))),
                 op: BinaryOperator::Plus,
@@ -3472,27 +3472,27 @@ fn parse_interval() {
             leading_precision: None,
             last_field: None,
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL '10' HOUR (1)";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from("10")))),
             leading_field: Some(DateTimeField::Hour),
             leading_precision: Some(1),
             last_field: None,
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
     let sql = "SELECT INTERVAL '1 DAY'";
     let select = verified_only_select(sql);
     assert_eq!(
-        &Expr::Interval {
+        &Expr::Interval(Interval {
             value: Box::new(Expr::Value(Value::SingleQuotedString(String::from(
                 "1 DAY"
             )))),
@@ -3500,7 +3500,7 @@ fn parse_interval() {
             leading_precision: None,
             last_field: None,
             fractional_seconds_precision: None,
-        },
+        }),
         expr_from_projection(only(&select.projection)),
     );
 
@@ -3581,7 +3581,7 @@ fn parse_interval_and_or_xor() {
                             quote_style: None,
                         })),
                         op: BinaryOperator::Plus,
-                        right: Box::new(Expr::Interval {
+                        right: Box::new(Expr::Interval(Interval {
                             value: Box::new(Expr::Value(Value::SingleQuotedString(
                                 "5 days".to_string(),
                             ))),
@@ -3589,7 +3589,7 @@ fn parse_interval_and_or_xor() {
                             leading_precision: None,
                             last_field: None,
                             fractional_seconds_precision: None,
-                        }),
+                        })),
                     }),
                 }),
                 op: BinaryOperator::And,
@@ -3605,7 +3605,7 @@ fn parse_interval_and_or_xor() {
                             quote_style: None,
                         })),
                         op: BinaryOperator::Plus,
-                        right: Box::new(Expr::Interval {
+                        right: Box::new(Expr::Interval(Interval {
                             value: Box::new(Expr::Value(Value::SingleQuotedString(
                                 "3 days".to_string(),
                             ))),
@@ -3613,7 +3613,7 @@ fn parse_interval_and_or_xor() {
                             leading_precision: None,
                             last_field: None,
                             fractional_seconds_precision: None,
-                        }),
+                        })),
                     }),
                 }),
             }),