Split out arrow-schema (apache#2594)

Cargo.toml

@@ -18,6 +18,7 @@
 [workspace]
 members = [
         "arrow",
+        "arrow-schema",
         "parquet",
         "parquet_derive",
         "parquet_derive_test",

arrow-schema/Cargo.toml

@@ -0,0 +1,52 @@
+# 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 = "arrow-schema"
+version = "22.0.0"
+description = "Defines the logical types for arrow arrays"
+homepage = "https://github.com/apache/arrow-rs"
+repository = "https://github.com/apache/arrow-rs"
+authors = ["Apache Arrow <dev@arrow.apache.org>"]
+license = "Apache-2.0"
+keywords = ["arrow"]
+include = [
+    "benches/*.rs",
+    "src/**/*.rs",
+    "Cargo.toml",
+]
+edition = "2021"
+rust-version = "1.62"
+
+[lib]
+name = "arrow_schema"
+path = "src/lib.rs"
+bench = false
+
+[dependencies]
+serde = { version = "1.0", default-features = false, features = ["derive"], optional = true }
+serde_json = { version = "1.0", default-features = false, features = ["std"], optional = true }
+
+[package.metadata.docs.rs]
+features = ["json"]
+
+[features]
+default = []
+json = ["serde", "serde_json"]
+
+[dev-dependencies]
+

arrow-schema/src/error.rs

@@ -0,0 +1,45 @@
+// 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.
+
+//! Defines `ArrowSchemaError` for representing failures in arrow schema
+
+use std::error::Error;
+
+#[derive(Debug)]
+pub enum ArrowSchemaError {
+    Parse(String),
+    Merge(String),
+    Field(String),
+}
+
+impl std::fmt::Display for ArrowSchemaError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ArrowSchemaError::Parse(message) => {
+                write!(f, "Error parsing schema: {}", message)
+            }
+            ArrowSchemaError::Merge(message) => {
+                write!(f, "Error merging schema: {}", message)
+            }
+            ArrowSchemaError::Field(message) => {
+                write!(f, "Error indexing field: {}", message)
+            }
+        }
+    }
+}
+
+impl Error for ArrowSchemaError {}