fix: bug found with new CTS

serde_json_path/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # Unreleased
 
+- **fixed**: bug preventing registered functions from being used as arguments to other functions ([#84])
+
+[#84]: https://github.com/hiltontj/serde_json_path/pull/84
+
 # 0.6.6 (23 February 2024)
 
 - **docs**: update links to refer to RFC 9535 ([#81])

serde_json_path/src/parser/selector/function/registry.rs

@@ -9,6 +9,13 @@ use serde_json_path_core::spec::functions::{Function, LogicalType, NodesType, Va
 ///
 /// These come directly from the JSONPath specification, which includes a registry of standardized
 /// functions.
+///
+/// # Note
+///
+/// There is a function in `serde_json_path_core/src/spec/functions.rs` that gives
+/// the return type for each function registered here. When adding new functions to
+/// the register, i.e., when new functions are standardized, the function there needs
+/// to be updated too.
 pub(crate) static REGISTRY: Lazy<HashMap<&'static str, &'static Function>> = Lazy::new(|| {
     let mut m = HashMap::new();
     m.insert("length", &LENGTH_FUNC);

serde_json_path_core/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # Unreleased
 
+- **fixed**: bug preventing registered functions from being used as arguments to other functions ([#84])
+
+[#84]: https://github.com/hiltontj/serde_json_path/pull/84
+
 # 0.1.5 (23 February 2024)
 
 - **docs**: update links to refer to RFC 9535 ([#81])

serde_json_path_core/src/spec/functions.rs

@@ -618,14 +618,36 @@ impl FunctionExprArg {
                         return Ok(f.result_type);
                     }
                 }
-                Err(FunctionValidationError::Undefined {
-                    name: func.name.to_owned(),
+                registered_function_result_type(&func.name).ok_or_else(|| {
+                    FunctionValidationError::Undefined {
+                        name: func.name.to_owned(),
+                    }
                 })
             }
         }
     }
 }
 
+/// Get the result type of a registered function
+///
+/// This is a hack, but must be done, because the REGISTRY defined in `serde_json_path`
+/// is not accessible here. Therefore, this must also be maintained when new functions
+/// are added to the registry in the standard.
+///
+/// An alternative would be to define the registry of functions in core, we would then
+/// just not have the convenience macro for defining them, along with their validators
+/// and evaluators.
+fn registered_function_result_type(name: &str) -> Option<FunctionArgType> {
+    match name {
+        "length" => Some(FunctionArgType::Value),
+        "count" => Some(FunctionArgType::Value),
+        "match" => Some(FunctionArgType::Logical),
+        "search" => Some(FunctionArgType::Logical),
+        "value" => Some(FunctionArgType::Value),
+        _ => None,
+    }
+}
+
 /// Function argument types
 ///
 /// This is used to describe the type of a function argument to determine if it will be valid as a

serde_json_path_macros/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # Unreleased
 
+- **fixed**: bug preventing registered functions from being used as arguments to other functions ([#84])
+
+[#84]: https://github.com/hiltontj/serde_json_path/pull/84
+
 # 0.1.3 (23 February 2024)
 
 - **internal**: update serde_json_path_core dependency