[query-engine] Static scalar expressions (open-telemetry#584)

## Changes

* Refactor static scalar expressions into their own enum

Author: CodeBlanch

rust/experimental/query_engine/expressions/src/lib.rs

@@ -1,6 +1,7 @@
 pub(crate) mod expression;
 pub(crate) mod logical_expressions;
 pub(crate) mod scalar_expressions;
+pub(crate) mod static_scalar_expressions;
 pub(crate) mod value_accessor;
 
 pub use expression::Expression;
@@ -11,3 +12,4 @@ pub use value_accessor::ValueSelector;
 
 pub use logical_expressions::*;
 pub use scalar_expressions::*;
+pub use static_scalar_expressions::*;

rust/experimental/query_engine/expressions/src/scalar_expressions.rs

@@ -1,6 +1,7 @@
-use chrono::{DateTime, FixedOffset};
-
-use crate::{Expression, LogicalExpression, QueryLocation, ValueAccessor, ValueSelector};
+use crate::{
+    Expression, LogicalExpression, QueryLocation, StaticScalarExpression, ValueAccessor,
+    ValueSelector,
+};
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum ScalarExpression {
@@ -26,20 +27,8 @@ pub enum ScalarExpression {
     /// executions.
     Variable(VariableScalarExpression),
 
-    /// Resolve a static bool value provided directly in a query.
-    Boolean(BooleanScalarExpression),
-
-    /// Resolve a static DateTime value provided directly in a query.
-    DateTime(DateTimeScalarExpression),
-
-    /// Resolve a static double value provided directly in a query.
-    Double(DoubleScalarExpression),
-
-    /// Resolve a static integer value provided directly in a query.
-    Integer(IntegerScalarExpression),
-
-    /// Resolve a static string value provided directly in a query.
-    String(StringScalarExpression),
+    /// Resolve a static value provided directly in a query.
+    Static(StaticScalarExpression),
 
     /// Negate the value returned by the inner scalar expression.
     Negate(NegateScalarExpression),
@@ -170,131 +159,3 @@ impl Expression for NegateScalarExpression {
         &self.query_location
     }
 }
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct BooleanScalarExpression {
-    query_location: QueryLocation,
-    value: bool,
-}
-
-impl BooleanScalarExpression {
-    pub fn new(query_location: QueryLocation, value: bool) -> BooleanScalarExpression {
-        Self {
-            query_location,
-            value,
-        }
-    }
-
-    pub fn get_value(&self) -> bool {
-        self.value
-    }
-}
-
-impl Expression for BooleanScalarExpression {
-    fn get_query_location(&self) -> &QueryLocation {
-        &self.query_location
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct DateTimeScalarExpression {
-    query_location: QueryLocation,
-    value: DateTime<FixedOffset>,
-}
-
-impl DateTimeScalarExpression {
-    pub fn new(
-        query_location: QueryLocation,
-        value: DateTime<FixedOffset>,
-    ) -> DateTimeScalarExpression {
-        Self {
-            query_location,
-            value,
-        }
-    }
-
-    pub fn get_value(&self) -> DateTime<FixedOffset> {
-        self.value
-    }
-}
-
-impl Expression for DateTimeScalarExpression {
-    fn get_query_location(&self) -> &QueryLocation {
-        &self.query_location
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct DoubleScalarExpression {
-    query_location: QueryLocation,
-    value: f64,
-}
-
-impl DoubleScalarExpression {
-    pub fn new(query_location: QueryLocation, value: f64) -> DoubleScalarExpression {
-        Self {
-            query_location,
-            value,
-        }
-    }
-
-    pub fn get_value(&self) -> f64 {
-        self.value
-    }
-}
-
-impl Expression for DoubleScalarExpression {
-    fn get_query_location(&self) -> &QueryLocation {
-        &self.query_location
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct IntegerScalarExpression {
-    query_location: QueryLocation,
-    value: i64,
-}
-
-impl IntegerScalarExpression {
-    pub fn new(query_location: QueryLocation, value: i64) -> IntegerScalarExpression {
-        Self {
-            query_location,
-            value,
-        }
-    }
-
-    pub fn get_value(&self) -> i64 {
-        self.value
-    }
-}
-
-impl Expression for IntegerScalarExpression {
-    fn get_query_location(&self) -> &QueryLocation {
-        &self.query_location
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct StringScalarExpression {
-    query_location: QueryLocation,
-    value: Box<str>,
-}
-
-impl StringScalarExpression {
-    pub fn new(query_location: QueryLocation, value: &str) -> StringScalarExpression {
-        Self {
-            query_location,
-            value: value.into(),
-        }
-    }
-
-    pub fn get_value(&self) -> &str {
-        &self.value
-    }
-}
-
-impl Expression for StringScalarExpression {
-    fn get_query_location(&self) -> &QueryLocation {
-        &self.query_location
-    }
-}

rust/experimental/query_engine/expressions/src/static_scalar_expressions.rs

@@ -0,0 +1,149 @@
+use chrono::{DateTime, FixedOffset};
+
+use crate::{Expression, QueryLocation};
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum StaticScalarExpression {
+    /// Resolve a static bool value provided directly in a query.
+    Boolean(BooleanScalarExpression),
+
+    /// Resolve a static DateTime value provided directly in a query.
+    DateTime(DateTimeScalarExpression),
+
+    /// Resolve a static double value provided directly in a query.
+    Double(DoubleScalarExpression),
+
+    /// Resolve a static integer value provided directly in a query.
+    Integer(IntegerScalarExpression),
+
+    /// Resolve a static string value provided directly in a query.
+    String(StringScalarExpression),
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct BooleanScalarExpression {
+    query_location: QueryLocation,
+    value: bool,
+}
+
+impl BooleanScalarExpression {
+    pub fn new(query_location: QueryLocation, value: bool) -> BooleanScalarExpression {
+        Self {
+            query_location,
+            value,
+        }
+    }
+
+    pub fn get_value(&self) -> bool {
+        self.value
+    }
+}
+
+impl Expression for BooleanScalarExpression {
+    fn get_query_location(&self) -> &QueryLocation {
+        &self.query_location
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct DateTimeScalarExpression {
+    query_location: QueryLocation,
+    value: DateTime<FixedOffset>,
+}
+
+impl DateTimeScalarExpression {
+    pub fn new(
+        query_location: QueryLocation,
+        value: DateTime<FixedOffset>,
+    ) -> DateTimeScalarExpression {
+        Self {
+            query_location,
+            value,
+        }
+    }
+
+    pub fn get_value(&self) -> DateTime<FixedOffset> {
+        self.value
+    }
+}
+
+impl Expression for DateTimeScalarExpression {
+    fn get_query_location(&self) -> &QueryLocation {
+        &self.query_location
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct DoubleScalarExpression {
+    query_location: QueryLocation,
+    value: f64,
+}
+
+impl DoubleScalarExpression {
+    pub fn new(query_location: QueryLocation, value: f64) -> DoubleScalarExpression {
+        Self {
+            query_location,
+            value,
+        }
+    }
+
+    pub fn get_value(&self) -> f64 {
+        self.value
+    }
+}
+
+impl Expression for DoubleScalarExpression {
+    fn get_query_location(&self) -> &QueryLocation {
+        &self.query_location
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct IntegerScalarExpression {
+    query_location: QueryLocation,
+    value: i64,
+}
+
+impl IntegerScalarExpression {
+    pub fn new(query_location: QueryLocation, value: i64) -> IntegerScalarExpression {
+        Self {
+            query_location,
+            value,
+        }
+    }
+
+    pub fn get_value(&self) -> i64 {
+        self.value
+    }
+}
+
+impl Expression for IntegerScalarExpression {
+    fn get_query_location(&self) -> &QueryLocation {
+        &self.query_location
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct StringScalarExpression {
+    query_location: QueryLocation,
+    value: Box<str>,
+}
+
+impl StringScalarExpression {
+    pub fn new(query_location: QueryLocation, value: &str) -> StringScalarExpression {
+        Self {
+            query_location,
+            value: value.into(),
+        }
+    }
+
+    pub fn get_value(&self) -> &str {
+        &self.value
+    }
+}
+
+impl Expression for StringScalarExpression {
+    fn get_query_location(&self) -> &QueryLocation {
+        &self.query_location
+    }
+}