Merge pull request #776 from SteveL-MSFT/if-function

Add `if()` function

Author: SteveL-MSFT

dsc_lib/locales/en-us.toml

@@ -197,6 +197,9 @@ divideByZero = "Cannot divide by zero"
 [functions.envvar]
 notFound = "Environment variable not found"
 
+[functions.if]
+conditionNotBoolean = "Condition is not a boolean"
+
 [functions.int]
 invalidInput = "invalid input string"
 parseStringError = "unable to parse string to int"

dsc_lib/src/functions/if.rs

@@ -0,0 +1,65 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use crate::DscError;
+use crate::configure::context::Context;
+use crate::functions::AcceptedArgKind;
+use super::Function;
+use rust_i18n::t;
+use serde_json::Value;
+
+#[derive(Debug, Default)]
+pub struct If {}
+
+impl Function for If {
+    fn accepted_arg_types(&self) -> Vec<AcceptedArgKind> {
+        vec![AcceptedArgKind::Boolean, AcceptedArgKind::String, AcceptedArgKind::Number, AcceptedArgKind::Array, AcceptedArgKind::Object]
+    }
+
+    fn min_args(&self) -> usize {
+        3
+    }
+
+    fn max_args(&self) -> usize {
+        3
+    }
+
+    fn invoke(&self, args: &[Value], _context: &Context) -> Result<Value, DscError> {
+        let Some(condition) = args[0].as_bool() else {
+            return Err(DscError::Function("if".to_string(), t!("functions.if.conditionNotBoolean").to_string()));
+        };
+
+        if condition {
+            Ok(args[1].clone())
+        } else {
+            Ok(args[2].clone())
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::configure::context::Context;
+    use crate::parser::Statement;
+
+    #[test]
+    fn invalid_condition() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[if('PATH', 1 , 2)]", &Context::new());
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn condition_true() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[if(true, 'left', 'right')]", &Context::new()).unwrap();
+        assert_eq!(result, "left");
+    }
+
+    #[test]
+    fn condition_false() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[if(false, 'left', 'right')]", &Context::new()).unwrap();
+        assert_eq!(result, "right");
+    }
+}

dsc_lib/src/functions/mod.rs

@@ -15,6 +15,7 @@ pub mod create_array;
 pub mod div;
 pub mod envvar;
 pub mod equals;
+pub mod r#if;
 pub mod int;
 pub mod max;
 pub mod min;
@@ -75,6 +76,7 @@ impl FunctionDispatcher {
         functions.insert("div".to_string(), Box::new(div::Div{}));
         functions.insert("envvar".to_string(), Box::new(envvar::Envvar{}));
         functions.insert("equals".to_string(), Box::new(equals::Equals{}));
+        functions.insert("if".to_string(), Box::new(r#if::If{}));
         functions.insert("int".to_string(), Box::new(int::Int{}));
         functions.insert("max".to_string(), Box::new(max::Max{}));
         functions.insert("min".to_string(), Box::new(min::Min{}));