Convert function to accept only array

Author: Gijsreyn

docs/reference/schemas/config/functions/join.md

@@ -7,7 +7,7 @@ title:       join
 
 ## Synopsis
 
-Joins a string array into a single string, separated using a delimiter.
+Joins an array into a single string, separated using a delimiter.
 
 ## Syntax
 
@@ -17,14 +17,12 @@ join(inputArray, delimiter)
 
 ## Description
 
-The `join()` function takes either an array or a string and a delimiter.
+The `join()` function takes an array and a delimiter.
 
-- If `inputArray` is an array, each element is converted to a string and
-  concatenated with the delimiter between elements.
-- If `inputArray` is a string, its characters are joined with the delimiter
-  between each character.
+- Each array element is converted to a string and concatenated with the
+  delimiter between elements.
 
-The `delimiter` can be any value; it is converted to a string.
+The `delimiter` can be any value; it’s converted to a string.
 
 ## Examples
 
@@ -123,17 +121,17 @@ hadErrors: false
 
 ### inputArray
 
-An array or a string.
+The array whose elements will be concatenated.
 
 ```yaml
-Type:     array | string
+Type:     array
 Required: true
 Position: 1
 ```
 
 ### delimiter
 
-Any value used between elements/characters. Converted to a string.
+Any value used between elements. Converted to a string.
 
 ```yaml
 Type:     any

dsc/tests/dsc_functions.tests.ps1

@@ -411,9 +411,7 @@ Describe 'tests for function expressions' {
 
   It 'join function works for: <expression>' -TestCases @(
     @{ expression = "[join(createArray('a','b','c'), '-')]"; expected = 'a-b-c' }
-    @{ expression = "[join('abc', '-')]"; expected = 'a-b-c' }
     @{ expression = "[join(createArray(), '-')]"; expected = '' }
-    @{ expression = "[join('', '-')]"; expected = '' }
   ) {
     param($expression, $expected)
 

dsc_lib/locales/en-us.toml

@@ -324,9 +324,9 @@ invoked = "indexOf function"
 invalidArrayArg = "First argument must be an array"
 
 [functions.join]
-description = "Joins a string array into a single string, separated using a delimiter."
+description = "Joins the elements of an array into a single string, separated using a delimiter."
 invoked = "join function"
-invalidInputType = "The inputArray must be an array or a string."
+invalidArrayArg = "First argument must be an array"
 
 [functions.length]
 description = "Returns the length of a string, array, or object"

dsc_lib/src/functions/join.rs

@@ -29,7 +29,7 @@ impl Function for Join {
             min_args: 2,
             max_args: 2,
             accepted_arg_ordered_types: vec![
-                vec![FunctionArgKind::Array, FunctionArgKind::String],
+                vec![FunctionArgKind::Array],
                 // delimiter: accept any type (no validation), convert to string
                 vec![
                     FunctionArgKind::Array,
@@ -55,14 +55,7 @@ impl Function for Join {
             return Ok(Value::String(items.join(&delimiter)));
         }
 
-        if let Some(s) = args[0].as_str() {
-            // Edge case: empty string => empty string
-            if s.is_empty() { return Ok(Value::String(String::new())); }
-            let items: Vec<String> = s.chars().map(|c| c.to_string()).collect();
-            return Ok(Value::String(items.join(&delimiter)));
-        }
-
-        Err(DscError::Parser(t!("functions.join.invalidInputType").to_string()))
+        Err(DscError::Parser(t!("functions.join.invalidArrayArg").to_string()))
     }
 }
 
@@ -79,9 +72,9 @@ mod tests {
     }
 
     #[test]
-    fn join_string_chars() {
+    fn join_empty_array_returns_empty() {
         let mut parser = Statement::new().unwrap();
-        let result = parser.parse_and_execute("[join('abc', '-')]", &Context::new()).unwrap();
-        assert_eq!(result, "a-b-c");
+        let result = parser.parse_and_execute("[join(createArray(), '-')]", &Context::new()).unwrap();
+        assert_eq!(result, "");
     }
 }