Add mul function

dsc_lib/src/functions/mod.rs

@@ -11,6 +11,7 @@ pub mod base64;
 pub mod concat;
 pub mod create_array;
 pub mod envvar;
+pub mod mul;
 pub mod parameters;
 pub mod resource_id;
 
@@ -58,6 +59,7 @@ impl FunctionDispatcher {
         functions.insert("concat".to_string(), Box::new(concat::Concat{}));
         functions.insert("createArray".to_string(), Box::new(create_array::CreateArray{}));
         functions.insert("envvar".to_string(), Box::new(envvar::Envvar{}));
+        functions.insert("mul".to_string(), Box::new(mul::Mul{}));
         functions.insert("parameters".to_string(), Box::new(parameters::Parameters{}));
         functions.insert("resourceId".to_string(), Box::new(resource_id::ResourceId{}));
         Self {

dsc_lib/src/functions/mul.rs

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use crate::DscError;
+use crate::configure::context::Context;
+use crate::functions::{AcceptedArgKind, Function};
+use serde_json::Value;
+use tracing::debug;
+
+#[derive(Debug, Default)]
+pub struct Mul {}
+
+impl Function for Mul {
+    fn min_args(&self) -> usize {
+        2
+    }
+
+    fn max_args(&self) -> usize {
+        2
+    }
+
+    fn accepted_arg_types(&self) -> Vec<AcceptedArgKind> {
+        vec![AcceptedArgKind::Number]
+    }
+
+    fn invoke(&self, args: &[Value], _context: &Context) -> Result<Value, DscError> {
+        debug!("mul function");
+        let value = args[0].as_i64().unwrap() * args[1].as_i64().unwrap();
+        Ok(Value::Number(value.into()))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::configure::context::Context;
+    use crate::parser::Statement;
+
+    #[test]
+    fn numbers() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[mul(2, 3)]", &Context::new()).unwrap();
+        assert_eq!(result, 6);
+    }
+
+    #[test]
+    fn nested() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[mul(2, mul(3, 4))]", &Context::new()).unwrap();
+        assert_eq!(result, 24);
+    }
+
+    #[test]
+    fn invalid_one_parameter() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[mul(5)]", &Context::new());
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn overflow_result() {
+        let mut parser = Statement::new().unwrap();
+        // max value for i64 is 2^63 -1 (or 9,223,372,036,854,775,807)
+        let result = parser.parse_and_execute("[mul(9223372036854775807, 2)]", &Context::new());
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn overflow_input() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[mul(9223372036854775808, 2)]", &Context::new());
+        assert!(result.is_err());
+    }
+}