WIP. Test gen doc from macros

Cargo.toml

@@ -48,6 +48,8 @@ members = [
     "datafusion-examples",
     "test-utils",
     "benchmarks",
+    "datafusion/macros",
+    "datafusion/pre-macros"
 ]
 resolver = "2"
 
@@ -105,11 +107,13 @@ datafusion-functions-aggregate-common = { path = "datafusion/functions-aggregate
 datafusion-functions-nested = { path = "datafusion/functions-nested", version = "42.0.0" }
 datafusion-functions-window = { path = "datafusion/functions-window", version = "42.0.0" }
 datafusion-functions-window-common = { path = "datafusion/functions-window-common", version = "42.0.0" }
+datafusion-macros = { path = "datafusion/macros", version = "42.0.0" }
 datafusion-optimizer = { path = "datafusion/optimizer", version = "42.0.0", default-features = false }
 datafusion-physical-expr = { path = "datafusion/physical-expr", version = "42.0.0", default-features = false }
 datafusion-physical-expr-common = { path = "datafusion/physical-expr-common", version = "42.0.0", default-features = false }
 datafusion-physical-optimizer = { path = "datafusion/physical-optimizer", version = "42.0.0" }
 datafusion-physical-plan = { path = "datafusion/physical-plan", version = "42.0.0" }
+datafusion-pre-macros = { path = "datafusion/pre-macros", version = "42.0.0" }
 datafusion-proto = { path = "datafusion/proto", version = "42.0.0" }
 datafusion-proto-common = { path = "datafusion/proto-common", version = "42.0.0" }
 datafusion-sql = { path = "datafusion/sql", version = "42.0.0" }

datafusion/common/src/macros/mod.rs

@@ -0,0 +1,42 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, AttributeArgs, ItemFn, Lit, Meta};
+#[proc_macro_attribute]
+pub fn generate_fn_with_params(attr: TokenStream, item: TokenStream) -> TokenStream {
+    // Parse the input tokens into a syntax tree
+    let args = parse_macro_input!(attr as AttributeArgs);
+    let input_fn = parse_macro_input!(item as ItemFn);
+
+    // Extract parameters from the attribute
+    let mut param1 = String::new();
+    let mut param2 = String::new();
+
+    if let Some(syn::NestedMeta::Meta(Meta::NameValue(meta))) = args.get(0) {
+        if let Lit::Str(lit_str) = &meta.lit {
+            param1 = lit_str.value();
+        }
+    }
+
+    if let Some(syn::NestedMeta::Meta(Meta::NameValue(meta))) = args.get(1) {
+        if let Lit::Str(lit_str) = &meta.lit {
+            param2 = lit_str.value();
+        }
+    }
+
+    // Get the original function's name
+    let fn_name = &input_fn.sig.ident;
+
+    // Generate the new function that prints the two parameters
+    let expanded = quote! {
+        #input_fn
+
+        pub fn #fn_name() {
+            println!("Param1: {}", #param1);
+            println!("Param2: {}", #param2);
+        }
+    };
+
+    // Return the generated code as a TokenStream
+    TokenStream::from(expanded)
+}

datafusion/functions/Cargo.toml

@@ -72,6 +72,8 @@ blake2 = { version = "^0.10.2", optional = true }
 blake3 = { version = "1.0", optional = true }
 chrono = { workspace = true }
 datafusion-common = { workspace = true }
+datafusion-pre-macros = { workspace = true }
+datafusion-macros = { workspace = true }
 datafusion-execution = { workspace = true }
 datafusion-expr = { workspace = true }
 hashbrown = { workspace = true, optional = true }

datafusion/functions/src/math/log.rs

@@ -17,6 +17,7 @@
 
 //! Math function: `log()`.
 
+use datafusion_macros::udf_doc;
 use std::any::Any;
 use std::sync::{Arc, OnceLock};
 
@@ -37,6 +38,7 @@ use datafusion_expr::{
 };
 use datafusion_expr::{ScalarUDFImpl, Signature, Volatility};
 
+#[udf_doc(description="log_description", example="log_example")]
 #[derive(Debug)]
 pub struct LogFunc {
     signature: Signature,
@@ -183,10 +185,6 @@ impl ScalarUDFImpl for LogFunc {
         Ok(ColumnarValue::Array(arr))
     }
 
-    fn documentation(&self) -> Option<&Documentation> {
-        Some(get_log_doc())
-    }
-
     /// Simplify the `log` function by the relevant rules:
     /// 1. Log(a, 1) ===> 0
     /// 2. Log(a, Power(a, b)) ===> b
@@ -264,6 +262,7 @@ mod tests {
     use datafusion_common::DFSchema;
     use datafusion_expr::execution_props::ExecutionProps;
     use datafusion_expr::simplify::SimplifyContext;
+    use datafusion_pre_macros::DocumentationTest;
 
     #[test]
     fn test_log_f64() {
@@ -472,4 +471,13 @@ mod tests {
             SortProperties::Unordered
         );
     }
+
+    #[test]
+    fn test_doc() {
+        let log = LogFunc::new();
+        assert_eq!(log.documentation_test(), Some(DocumentationTest {
+            description: "log_description".to_string(),
+            syntax_example: "log_example".to_string(),
+        }));
+    }
 }

datafusion/macros/Cargo.toml

@@ -0,0 +1,43 @@
+# 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.
+
+[package]
+name = "datafusion-macros"
+description = "Proc macros for DataFusion query engine"
+keywords = ["datafusion", "query", "sql"]
+version = { workspace = true }
+edition = { workspace = true }
+homepage = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+authors = { workspace = true }
+rust-version = { workspace = true }
+
+[lints]
+workspace = true
+
+[lib]
+name = "datafusion_macros"
+path = "src/lib.rs"
+proc-macro = true
+
+[dependencies]
+quote = "1.0.37"
+syn = "2.0.79"
+proc-macro2 = "1.0"
+datafusion-pre-macros = { workspace = true }
+

datafusion/macros/src/lib.rs

@@ -0,0 +1,47 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput, Lit, LitStr, Meta, MetaNameValue};
+use datafusion_pre_macros::DocumentationTest;
+
+#[proc_macro_attribute]
+pub fn udf_doc(args: TokenStream, input: TokenStream) -> TokenStream {
+    let mut description: Option<LitStr> = None;
+    let mut example: Option<LitStr> = None;
+
+    let parser = syn::meta::parser(|meta| {
+        if meta.path.is_ident("description") {
+            description = Some(meta.value()?.parse()?);
+            Ok(())
+        } else if meta.path.is_ident("example") {
+            example = Some(meta.value()?.parse()?);
+            Ok(())
+        } else {
+            Err(meta.error("unsupported property"))
+        }
+    });
+    parse_macro_input!(args with parser);
+    eprintln!("description={description:?} example={example:?}");
+
+    // Parse the input struct
+    let input = parse_macro_input!(input as DeriveInput);
+    let name = input.clone().ident;
+
+    //eprintln!("input={input:?}");
+
+
+    let expanded = quote! {
+        #input
+
+        use datafusion_pre_macros::DocumentationTest;
+
+        impl #name {
+                fn documentation_test(&self) -> Option<DocumentationTest> {
+                    Some(DocumentationTest { description: #description.to_string(), syntax_example: #example.to_string() })
+            }
+        }
+    };
+
+    // Return the generated code
+    TokenStream::from(expanded)
+}

datafusion/pre-macros/Cargo.toml

@@ -0,0 +1,35 @@
+# 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.
+
+[package]
+name = "datafusion-pre-macros"
+description = "Proc pre macros for DataFusion query engine"
+keywords = ["datafusion", "query", "sql"]
+version = { workspace = true }
+edition = { workspace = true }
+homepage = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+authors = { workspace = true }
+rust-version = { workspace = true }
+
+[lints]
+workspace = true
+
+[lib]
+name = "datafusion_pre_macros"
+path = "src/lib.rs"

datafusion/pre-macros/src/lib.rs

@@ -0,0 +1,7 @@
+#[derive(Debug, Clone, PartialEq)]
+pub struct DocumentationTest {
+    /// the description for the UDF
+    pub description: String,
+    /// a brief example of the syntax. For example "ascii(str)"
+    pub syntax_example: String,
+}