Support parameter amount errors for functions with varying parameter amounts

CHANGELOG.md

@@ -10,9 +10,12 @@
 
 ### Changed
 
+ * The error type `WrongFunctionArgumentAmount` now expects a range of argument amounts instead of a single one (#159)
+
 ### Fixed
 
  * Minor error in README.
+ * Regex functions do not silently ignore superfluous arguments anymore.
 
 ### Deprecated
 

src/error/display.rs

@@ -11,11 +11,18 @@ impl fmt::Display for EvalexprError {
                 "An operator expected {} arguments, but got {}.",
                 expected, actual
             ),
-            WrongFunctionArgumentAmount { expected, actual } => write!(
-                f,
-                "A function expected {} arguments, but got {}.",
-                expected, actual
-            ),
+            WrongFunctionArgumentAmount { expected, actual } => {
+                let expected_arguments = if expected.start() == expected.end() {
+                    format!("{}", expected.start())
+                } else {
+                    format!("{} to {}", expected.start(), expected.end())
+                };
+                write!(
+                    f,
+                    "A function expected {} arguments, but got {}.",
+                    expected_arguments, actual
+                )
+            },
             ExpectedString { actual } => {
                 write!(f, "Expected a Value::String, but got {:?}.", actual)
             },

src/error/mod.rs

@@ -5,6 +5,8 @@
 //! The module also contains some helper functions starting with `expect_` that check for a condition and return `Err(_)` if the condition is not fulfilled.
 //! They are meant as shortcuts to not write the same error checking code everywhere.
 
+use std::ops::RangeInclusive;
+
 use crate::{token::PartialToken, value::value_type::ValueType};
 
 use crate::{operator::Operator, value::Value};
@@ -28,7 +30,7 @@ pub enum EvalexprError {
     /// A function was called with a wrong amount of arguments.
     WrongFunctionArgumentAmount {
         /// The expected amount of arguments.
-        expected: usize,
+        expected: RangeInclusive<usize>,
         /// The actual amount of arguments.
         actual: usize,
     },
@@ -217,11 +219,24 @@ pub enum EvalexprError {
 }
 
 impl EvalexprError {
-    pub(crate) fn wrong_operator_argument_amount(actual: usize, expected: usize) -> Self {
+    /// Construct a `WrongOperatorArgumentAmount` error.
+    pub fn wrong_operator_argument_amount(actual: usize, expected: usize) -> Self {
         EvalexprError::WrongOperatorArgumentAmount { actual, expected }
     }
 
-    pub(crate) fn wrong_function_argument_amount(actual: usize, expected: usize) -> Self {
+    /// Construct a `WrongFunctionArgumentAmount` error for a function with a fixed amount of arguments.
+    pub fn wrong_function_argument_amount(actual: usize, expected: usize) -> Self {
+        EvalexprError::WrongFunctionArgumentAmount {
+            actual,
+            expected: expected..=expected,
+        }
+    }
+
+    /// Construct a `WrongFunctionArgumentAmount` error for a function with a range of possible amounts of arguments.
+    pub fn wrong_function_argument_amount_range(
+        actual: usize,
+        expected: RangeInclusive<usize>,
+    ) -> Self {
         EvalexprError::WrongFunctionArgumentAmount { actual, expected }
     }
 

src/function/builtin.rs

@@ -223,7 +223,7 @@ pub fn builtin_function(identifier: &str) -> Option<Function> {
         // String functions
         #[cfg(feature = "regex_support")]
         "str::regex_matches" => Some(Function::new(|argument| {
-            let arguments = argument.as_tuple()?;
+            let arguments = argument.as_fixed_len_tuple(2)?;
 
             let subject = arguments[0].as_string()?;
             let re_str = arguments[1].as_string()?;
@@ -237,7 +237,7 @@ pub fn builtin_function(identifier: &str) -> Option<Function> {
         })),
         #[cfg(feature = "regex_support")]
         "str::regex_replace" => Some(Function::new(|argument| {
-            let arguments = argument.as_tuple()?;
+            let arguments = argument.as_fixed_len_tuple(3)?;
 
             let subject = arguments[0].as_string()?;
             let re_str = arguments[1].as_string()?;

tests/integration.rs

@@ -1737,7 +1737,7 @@ fn test_error_constructors() {
     assert_eq!(
         expect_function_argument_amount(2, 3),
         Err(EvalexprError::WrongFunctionArgumentAmount {
-            expected: 3,
+            expected: 3..=3,
             actual: 2
         })
     );