Conditional compilation

Author: alamb

datafusion/functions/Cargo.toml

@@ -12,8 +12,8 @@ authors = { workspace = true }
 rust-version = { workspace = true }
 
 [features]
-default = ["encoding_expressions"]
-# enable the encoding expressions
+default= []
+# enable the encode/decode functions
 encoding_expressions = ["base64", "hex"]
 
 

datafusion/functions/src/encoding/inner.rs

@@ -37,7 +37,6 @@ enum Encoding {
     Base64,
     Hex,
 }
-
 fn encode_process(value: &ColumnarValue, encoding: Encoding) -> Result<ColumnarValue> {
     match value {
         ColumnarValue::Array(a) => match a.data_type() {

datafusion/functions/src/encoding/meta.rs

@@ -0,0 +1,108 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Metadata information for "encode" and "decode" functions
+use datafusion_common::arrow::datatypes::DataType;
+use datafusion_common::{plan_err, DataFusionError, Result};
+use datafusion_expr::TypeSignature::*;
+use datafusion_expr::{ColumnarValue, FunctionImplementation, Signature, Volatility};
+use std::sync::OnceLock;
+use DataType::*;
+
+pub(super) struct EncodeFunc {}
+
+static ENCODE_SIGNATURE: OnceLock<Signature> = OnceLock::new();
+
+impl FunctionImplementation for EncodeFunc {
+    fn name(&self) -> &str {
+        "encode"
+    }
+
+    fn signature(&self) -> &Signature {
+        ENCODE_SIGNATURE.get_or_init(|| {
+            Signature::one_of(
+                vec![
+                    Exact(vec![Utf8, Utf8]),
+                    Exact(vec![LargeUtf8, Utf8]),
+                    Exact(vec![Binary, Utf8]),
+                    Exact(vec![LargeBinary, Utf8]),
+                ],
+                Volatility::Immutable,
+            )
+        })
+    }
+
+    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+        Ok(match arg_types[0] {
+            Utf8 => Utf8,
+            LargeUtf8 => LargeUtf8,
+            Binary => Utf8,
+            LargeBinary => LargeUtf8,
+            Null => Null,
+            _ => {
+                return plan_err!("The encode function can only accept utf8 or binary.");
+            }
+        })
+    }
+
+    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        // Put a feature flag here to make sure this is only compiled when the feature is activated
+        super::inner::encode(args)
+    }
+}
+
+pub(super) struct DecodeFunc {}
+
+static DECODE_SIGNATURE: OnceLock<Signature> = OnceLock::new();
+
+impl FunctionImplementation for DecodeFunc {
+    fn name(&self) -> &str {
+        "decode"
+    }
+
+    fn signature(&self) -> &Signature {
+        DECODE_SIGNATURE.get_or_init(|| {
+            Signature::one_of(
+                vec![
+                    Exact(vec![Utf8, Utf8]),
+                    Exact(vec![LargeUtf8, Utf8]),
+                    Exact(vec![Binary, Utf8]),
+                    Exact(vec![LargeBinary, Utf8]),
+                ],
+                Volatility::Immutable,
+            )
+        })
+    }
+
+    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+        Ok(match arg_types[0] {
+            Utf8 => Binary,
+            LargeUtf8 => LargeBinary,
+            Binary => Binary,
+            LargeBinary => LargeBinary,
+            Null => Null,
+            _ => {
+                return plan_err!("The decode function can only accept utf8 or binary.");
+            }
+        })
+    }
+
+    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        // Put a feature flag here to make sure this is only compiled when the feature is activated
+        super::inner::decode(args)
+    }
+}

datafusion/functions/src/encoding/mod.rs

@@ -15,120 +15,29 @@
 // specific language governing permissions and limitations
 // under the License.
 
+#[cfg(feature = "encoding_expressions")]
 mod inner;
+#[cfg(feature = "encoding_expressions")]
+mod meta;
 
-use datafusion_common::arrow::datatypes::DataType;
-use datafusion_common::{plan_err, DataFusionError, Result};
-use datafusion_expr::TypeSignature::*;
-use datafusion_expr::{
-    ColumnarValue, FunctionImplementation, ScalarUDF, Signature, Volatility,
-};
+use crate::utils::insert;
+use datafusion_expr::ScalarUDF;
 use std::collections::HashMap;
-use std::sync::{Arc, OnceLock};
-use DataType::*;
-
-// TODO make stub implementations when feature is not activated
-//#[cfg(feature = "encoding_expressions")]
-//pub mod encoding_expressions;
-
-pub fn encode_udf() -> ScalarUDF {
-    ScalarUDF::new_from_impl(Arc::new(EncodeFunc {}))
-}
-
-pub fn decode_udf() -> ScalarUDF {
-    ScalarUDF::new_from_impl(Arc::new(DecodeFunc {}))
-}
-
-fn insert(registry: &mut HashMap<String, Arc<ScalarUDF>>, udf: ScalarUDF) {
-    registry.insert(udf.name().to_string(), Arc::new(udf));
-}
+use std::sync::Arc;
 
 /// Registers the `encode` and `decode` functions with the function registry
+#[cfg(feature = "encoding_expressions")]
 pub fn register(registry: &mut HashMap<String, Arc<ScalarUDF>>) {
-    insert(registry, encode_udf());
-    insert(registry, decode_udf());
-}
-
-struct EncodeFunc {}
-
-static ENCODE_SIGNATURE: OnceLock<Signature> = OnceLock::new();
-
-impl FunctionImplementation for EncodeFunc {
-    fn name(&self) -> &str {
-        "encode"
-    }
-
-    fn signature(&self) -> &Signature {
-        ENCODE_SIGNATURE.get_or_init(|| {
-            Signature::one_of(
-                vec![
-                    Exact(vec![Utf8, Utf8]),
-                    Exact(vec![LargeUtf8, Utf8]),
-                    Exact(vec![Binary, Utf8]),
-                    Exact(vec![LargeBinary, Utf8]),
-                ],
-                Volatility::Immutable,
-            )
-        })
-    }
-
-    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
-        Ok(match arg_types[0] {
-            Utf8 => Utf8,
-            LargeUtf8 => LargeUtf8,
-            Binary => Utf8,
-            LargeBinary => LargeUtf8,
-            Null => Null,
-            _ => {
-                return plan_err!("The encode function can only accept utf8 or binary.");
-            }
-        })
-    }
-
-    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
-        // Put a feature flag here to make sure this is only compiled when the feature is activated
-        inner::encode(args)
-    }
+    insert(registry, meta::EncodeFunc {});
+    insert(registry, meta::DecodeFunc {});
 }
 
-struct DecodeFunc {}
-
-static DECODE_SIGNATURE: OnceLock<Signature> = OnceLock::new();
-
-impl FunctionImplementation for DecodeFunc {
-    fn name(&self) -> &str {
-        "decode"
-    }
-
-    fn signature(&self) -> &Signature {
-        DECODE_SIGNATURE.get_or_init(|| {
-            Signature::one_of(
-                vec![
-                    Exact(vec![Utf8, Utf8]),
-                    Exact(vec![LargeUtf8, Utf8]),
-                    Exact(vec![Binary, Utf8]),
-                    Exact(vec![LargeBinary, Utf8]),
-                ],
-                Volatility::Immutable,
-            )
-        })
-    }
-
-    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
-        Ok(match arg_types[0] {
-            Utf8 => Binary,
-            LargeUtf8 => LargeBinary,
-            Binary => Binary,
-            LargeBinary => LargeBinary,
-            Null => Null,
-            _ => {
-                return plan_err!("The decode function can only accept utf8 or binary.");
-            }
-        })
-    }
+/// Registers the `encode` and `decode` stubs with the function registry
+#[cfg(not(feature = "encoding_expressions"))]
+pub fn register(registry: &mut HashMap<String, Arc<ScalarUDF>>) {
+    let hint = "Requires compilation with feature flag: encoding_expressions.";
 
-    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
-        // Put a feature flag here to make sure this is only compiled when the feature is activated
-        inner::decode(args)
+    for function_name in ["encode", "decode"] {
+        insert(registry, crate::utils::StubFunc::new(function_name, hint));
     }
 }

datafusion/functions/src/lib.rs

@@ -22,6 +22,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 
 pub mod encoding;
+pub mod utils;
 
 /// Registers all "built in" functions from this crate with the provided registry
 pub fn register_all(registry: &mut HashMap<String, Arc<ScalarUDF>>) {

datafusion/functions/src/utils.rs

@@ -0,0 +1,66 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use arrow::datatypes::DataType;
+use datafusion_common::{exec_err, plan_err, DataFusionError, Result};
+use datafusion_expr::{
+    ColumnarValue, FunctionImplementation, ScalarUDF, Signature, Volatility,
+};
+use std::collections::HashMap;
+use std::sync::{Arc, OnceLock};
+
+/// Insert a function into the registry
+pub(crate) fn insert(
+    registry: &mut HashMap<String, Arc<ScalarUDF>>,
+    udf: impl FunctionImplementation + Send + Sync + 'static,
+) {
+    let udf = ScalarUDF::new_from_impl(Arc::new(udf));
+    registry.insert(udf.name().to_string(), Arc::new(udf));
+}
+
+/// A scalar function that always errors with a hint. This is used to stub out
+/// functions that are not enabled with the current set of crate features.
+pub struct StubFunc {
+    name: &'static str,
+    hint: &'static str,
+}
+
+impl StubFunc {
+    /// Create a new stub function
+    pub fn new(name: &'static str, hint: &'static str) -> Self {
+        Self { name, hint }
+    }
+}
+
+static STUB_SIGNATURE: OnceLock<Signature> = OnceLock::new();
+
+impl FunctionImplementation for StubFunc {
+    fn name(&self) -> &str {
+        self.name
+    }
+
+    fn signature(&self) -> &Signature {
+        STUB_SIGNATURE.get_or_init(|| Signature::variadic_any(Volatility::Volatile))
+    }
+
+    fn return_type(&self, _args: &[DataType]) -> Result<DataType> {
+        plan_err!("function {} not available. {}", self.name, self.hint)
+    }
+    fn invoke(&self, _args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        exec_err!("function {} not available. {}", self.name, self.hint)
+    }
+}