Add structopt dependency in version 0.3.7

This patch series replaces argparse with structopt in the argument
handling code. As a first step, we need structopt as a dependency.

Import subrepo structopt/:structopt at efbdda4753592e27bc430fb01f7b9650b2f3174d
Import subrepo bitflags/:bitflags at 30668016aca6bd3b02c766e8347e0b4080d4c296
Import subrepo clap/:clap at 784524f7eb193e35f81082cc69454c8c21b948f7
Import subrepo heck/:heck at 093d56fbf001e1506e56dbfa38631d99b1066df1
Import subrepo proc-macro-error/:proc-macro-error at 6c4cfe79a622c5de8ae68557993542be46eacae2
Import subrepo proc-macro2/:proc-macro2 at d5d48eddca4566e5438e8a2cbed4a74e049544de
Import subrepo quote/:quote at 727436c6c137b20f0f34dde5d8fda2679b9747ad
Import subrepo rustversion/:rustversion at 0c5663313516263059ce9059ef81fc7a1cf655ca
Import subrepo syn-mid/:syn-mid at 5d3d85414a9e6674e1857ec22a87b96e04a6851a
Import subrepo syn/:syn at e87c27e87f6f4ef8919d0372bdb056d53ef0d8f3
Import subrepo textwrap/:textwrap at abcd618beae3f74841032aa5b53c1086b0a57ca2
Import subrepo unicode-segmentation/:unicode-segmentation at 637c9874c4fe0c205ff27787faf150a40295c6c3
Import subrepo unicode-width/:unicode-width at 3033826f8bf05e82724140a981d5941e48fce393
Import subrepo unicode-xid/:unicode-xid at 4baae9fffb156ba229665b972a9cd5991787ceb7

25 files changed, 1520 insertions, 0 deletions

diff --git a/syn-mid/.editorconfig b/syn-mid/.editorconfig
new file mode 100644
index 0000000..920ea40
--- /dev/null
+++ b/syn-mid/.editorconfig
@@ -0,0 +1,22 @@
+# EditorConfig configuration
+# http://EditorConfig.org
+
+# Top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file, utf-8 charset
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8
+
+# Match rust/toml, set 4 space indentation
+[*.{rs,toml}]
+indent_style = space
+indent_size = 4
+
+# Match yaml/markdown, set 2 space indentation
+[*.{yml,md}]
+indent_style = space
+indent_size = 2
diff --git a/syn-mid/.gitignore b/syn-mid/.gitignore
new file mode 100644
index 0000000..2e6c307
--- /dev/null
+++ b/syn-mid/.gitignore
@@ -0,0 +1,6 @@
+.idea/
+.vscode/
+target/
+**/*.rs.bk
+Cargo.lock
+___*
diff --git a/syn-mid/.rustfmt.toml b/syn-mid/.rustfmt.toml
new file mode 100644
index 0000000..a27c0b7
--- /dev/null
+++ b/syn-mid/.rustfmt.toml
@@ -0,0 +1,4 @@
+# Set the default settings again to always apply the proper formatting without being affected by the editor settings.
+# https://github.com/rust-lang/rls/issues/501#issuecomment-333717736
+edition = "2018"
+tab_spaces = 4
diff --git a/syn-mid/CHANGELOG.md b/syn-mid/CHANGELOG.md
new file mode 100644
index 0000000..25c17c1
--- /dev/null
+++ b/syn-mid/CHANGELOG.md
@@ -0,0 +1,33 @@
+# Unreleased
+
+# 0.4.0 - 2019-08-15
+
+* Updated all data structures based on `syn` 1.0.
+
+* Updated `proc-macro2`, `syn`, and `quote` to 1.0.
+
+* Bumped the minimum required version from Rust 1.30 to Rust 1.31.
+
+# 0.3.0 - 2019-02-18
+
+* Removed support for unneeded syntax.
+
+* Removed unneeded types and fields.
+
+* Implemented `Parse` for `Block`.
+
+* Changed `clone-impls` feature to "disabled by default".
+
+* Removed `extra-traits` feature.
+
+* Bumped the minimum required version from Rust 1.15 to Rust 1.30.
+
+# 0.2.0 - 2019-02-15
+
+* Reduced features.
+
+* Fixed bugs.
+
+# 0.1.0 - 2019-02-14
+
+Initial release
diff --git a/syn-mid/Cargo.toml b/syn-mid/Cargo.toml
new file mode 100644
index 0000000..f92e7a0
--- /dev/null
+++ b/syn-mid/Cargo.toml
@@ -0,0 +1,23 @@
+[package]
+name = "syn-mid"
+version = "0.4.0"
+authors = ["Taiki Endo <te316e89@gmail.com>"]
+edition = "2018"
+license = "Apache-2.0/MIT"
+repository = "https://github.com/taiki-e/syn-mid"
+documentation = "https://docs.rs/syn-mid/"
+readme = "README.md"
+keywords = ["syn", "macros"]
+categories = ["development-tools::procedural-macro-helpers"]
+description = "Providing the features between \"full\" and \"derive\" of syn."
+
+[workspace]
+members = ["examples/const_fn", "examples/const_fn_test"]
+
+[features]
+clone-impls = ["syn/clone-impls"]
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "1.0", default-features = false, features = ["parsing", "printing", "derive"] }
diff --git a/syn-mid/LICENSE-APACHE b/syn-mid/LICENSE-APACHE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/syn-mid/LICENSE-APACHE
@@ -0,0 +1,202 @@
+
+                                 Apache License
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+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
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diff --git a/syn-mid/LICENSE-MIT b/syn-mid/LICENSE-MIT
new file mode 100644
index 0000000..31aa793
--- /dev/null
+++ b/syn-mid/LICENSE-MIT
@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/syn-mid/README.md b/syn-mid/README.md
new file mode 100644
index 0000000..b9b1c75
--- /dev/null
+++ b/syn-mid/README.md
@@ -0,0 +1,72 @@
+# syn-mid
+
+[![Build Status][azure-badge]][azure-url]
+[![Crates.io][crates-version-badge]][crates-url]
+[![Docs.rs][docs-badge]][docs-url]
+[![License][crates-license-badge]][crates-url]
+[![Minimum supported Rust version][rustc-badge]][rustc-url]
+
+[azure-badge]: https://dev.azure.com/taiki-e/taiki-e/_apis/build/status/taiki-e.syn-mid?branchName=master
+[azure-url]: https://dev.azure.com/taiki-e/taiki-e/_build/latest?definitionId=11&branchName=master
+[crates-version-badge]: https://img.shields.io/crates/v/syn-mid.svg
+[crates-license-badge]: https://img.shields.io/crates/l/syn-mid.svg
+[crates-badge]: https://img.shields.io/crates/v/syn-mid.svg
+[crates-url]: https://crates.io/crates/syn-mid/
+[docs-badge]: https://docs.rs/syn-mid/badge.svg
+[docs-url]: https://docs.rs/syn-mid/
+[rustc-badge]: https://img.shields.io/badge/rustc-1.31+-lightgray.svg
+[rustc-url]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html
+
+Providing the features between "full" and "derive" of syn.
+
+This crate provides the following two unique data structures.
+
+* `syn_mid::ItemFn` -- A function whose body is not parsed.
+
+  ```text
+  fn process(n: usize) -> Result<()> { ... }
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^     ^
+  ```
+
+* `syn_mid::Block` -- A block whose body is not parsed.
+
+  ```text
+  { ... }
+  ^     ^
+  ```
+
+Other data structures are the same as data structures of [syn]. These are defined in this crate because they cannot be used in [syn] without "full" feature.
+
+[syn]: https://github.com/dtolnay/syn
+
+## Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+syn-mid = "0.4"
+```
+
+The current syn-mid requires Rust 1.31 or later.
+
+[**Examples**](examples)
+
+[**Documentation**](https://docs.rs/syn-mid/)
+
+## Optional features
+
+* **`clone-impls`** — Clone impls for all syntax tree types.
+
+## License
+
+Licensed under either of
+
+* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
+* MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
diff --git a/syn-mid/azure-pipelines.yml b/syn-mid/azure-pipelines.yml
new file mode 100644
index 0000000..6f0c968
--- /dev/null
+++ b/syn-mid/azure-pipelines.yml
@@ -0,0 +1,49 @@
+trigger:
+- master
+- staging
+- trying
+
+variables:
+  RUSTFLAGS: -Dwarnings
+
+jobs:
+# This is the minimum Rust version supported by syn-mid.
+# When updating this, the reminder to update the minimum supported
+# Rust version in README.md.
+#
+# Tests are not run as tests may require newer versions of rust.
+- template: ci/azure-test.yml
+  parameters:
+    name: minrust
+    rust: 1.31.0
+
+- template: ci/azure-test.yml
+  parameters:
+    name: stable
+    rust: stable
+
+- template: ci/azure-test.yml
+  parameters:
+    name: beta
+    rust: beta
+
+- template: ci/azure-test.yml
+  parameters:
+    name: nightly
+    rust: nightly
+    cmd: test
+
+- template: ci/azure-clippy.yml
+  parameters:
+    name: clippy
+    rust: nightly
+
+- template: ci/azure-rustfmt.yml
+  parameters:
+    name: rustfmt
+    rust: stable
+
+- template: ci/azure-rustdoc.yml
+  parameters:
+    name: rustdoc
+    rust: nightly
diff --git a/syn-mid/bors.toml b/syn-mid/bors.toml
new file mode 100644
index 0000000..b477894
--- /dev/null
+++ b/syn-mid/bors.toml
@@ -0,0 +1 @@
+status = ["taiki-e.syn-mid"]
diff --git a/syn-mid/ci/azure-clippy.yml b/syn-mid/ci/azure-clippy.yml
new file mode 100644
index 0000000..22165c6
--- /dev/null
+++ b/syn-mid/ci/azure-clippy.yml
@@ -0,0 +1,31 @@
+jobs:
+- job: ${{ parameters.name }}
+  displayName: Clippy
+  pool:
+    vmImage: ubuntu-16.04
+
+  steps:
+    - template: azure-install-rust.yml
+      parameters:
+        rust: ${{ parameters.rust }}
+
+    - script: |
+        set +e
+        if rustup component add clippy; then
+          set -e
+        else
+          set -e
+          target=`curl https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-gnu/clippy`
+          echo "'clippy' is unavailable on the toolchain '${{ parameters.rust }}', use the toolchain 'nightly-$target' instead"
+          rustup toolchain install nightly-$target
+          rustup default nightly-$target
+          rustup component add clippy
+          rustup toolchain list
+          rustc -Vv
+          cargo -V
+        fi
+        cargo clippy --version
+      displayName: rustup component add clippy
+
+    - script: cargo clippy --all --all-features
+      displayName: cargo clippy --all-features
diff --git a/syn-mid/ci/azure-install-rust.yml b/syn-mid/ci/azure-install-rust.yml
new file mode 100644
index 0000000..6b008c6
--- /dev/null
+++ b/syn-mid/ci/azure-install-rust.yml
@@ -0,0 +1,33 @@
+steps:
+  # Linux and macOS.
+  - script: |
+      set -e
+      curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain none
+      export PATH=$PATH:$HOME/.cargo/bin
+      rustup toolchain install $RUSTUP_TOOLCHAIN
+      rustup default $RUSTUP_TOOLCHAIN
+      echo "##vso[task.setvariable variable=PATH;]$PATH:$HOME/.cargo/bin"
+    env:
+      RUSTUP_TOOLCHAIN: ${{ parameters.rust }}
+    displayName: Install rust (*nix)
+    condition: not(eq(variables['Agent.OS'], 'Windows_NT'))
+
+  # Windows.
+  - script: |
+      curl -sSf -o rustup-init.exe https://win.rustup.rs
+      rustup-init.exe -y --default-toolchain none
+      set PATH=%PATH%;%USERPROFILE%\.cargo\bin
+      rustup toolchain install %RUSTUP_TOOLCHAIN%
+      rustup default %RUSTUP_TOOLCHAIN%
+      echo "##vso[task.setvariable variable=PATH;]%PATH%;%USERPROFILE%\.cargo\bin"
+    env:
+      RUSTUP_TOOLCHAIN: ${{ parameters.rust }}
+    displayName: Install rust (windows)
+    condition: eq(variables['Agent.OS'], 'Windows_NT')
+
+  # All platforms.
+  - script: |
+        rustup toolchain list
+        rustc -Vv
+        cargo -V
+    displayName: Query rust and cargo versions
diff --git a/syn-mid/ci/azure-rustdoc.yml b/syn-mid/ci/azure-rustdoc.yml
new file mode 100644
index 0000000..99a43ff
--- /dev/null
+++ b/syn-mid/ci/azure-rustdoc.yml
@@ -0,0 +1,13 @@
+jobs:
+- job: ${{ parameters.name }}
+  displayName: Rustdoc
+  pool:
+    vmImage: ubuntu-16.04
+
+  steps:
+    - template: azure-install-rust.yml
+      parameters:
+        rust: ${{ parameters.rust }}
+
+    - script: RUSTDOCFLAGS=-Dwarnings cargo doc --no-deps --all --all-features
+      displayName: cargo doc --all-features
diff --git a/syn-mid/ci/azure-rustfmt.yml b/syn-mid/ci/azure-rustfmt.yml
new file mode 100644
index 0000000..0b20da3
--- /dev/null
+++ b/syn-mid/ci/azure-rustfmt.yml
@@ -0,0 +1,18 @@
+jobs:
+- job: ${{ parameters.name }}
+  displayName: Rustfmt
+  pool:
+    vmImage: ubuntu-16.04
+
+  steps:
+    - template: azure-install-rust.yml
+      parameters:
+        rust: ${{ parameters.rust }}
+
+    - script: |
+        rustup component add rustfmt
+        cargo fmt --version
+      displayName: rustup component add rustfmt
+
+    - script: cargo fmt --all -- --check
+      displayName: cargo fmt -- --check
diff --git a/syn-mid/ci/azure-test.yml b/syn-mid/ci/azure-test.yml
new file mode 100644
index 0000000..32a56ed
--- /dev/null
+++ b/syn-mid/ci/azure-test.yml
@@ -0,0 +1,34 @@
+parameters:
+  cmd: check
+
+jobs:
+- job: ${{ parameters.name }}
+  displayName: ${{ parameters.displayName }} ${{ parameters.rust }}
+  strategy:
+    matrix:
+      Linux:
+        vmImage: ubuntu-16.04
+
+      ${{ if parameters.cross }}:
+        MacOS:
+          vmImage: macOS-10.13
+        Windows:
+          vmImage: vs2017-win2016
+  pool:
+    vmImage: $(vmImage)
+
+  steps:
+    - template: azure-install-rust.yml
+      parameters:
+        rust: ${{ parameters.rust }}
+
+    - script: |
+        cargo ${{ parameters.cmd }}
+        cargo ${{ parameters.cmd }} --all-features
+      displayName: cargo ${{ parameters.cmd }}
+
+    - ${{ if eq(parameters.rust, 'nightly') }}:
+      - script: |
+          cargo update -Zminimal-versions
+          cargo check --all-features
+        displayName: cargo check -Zminimal-versions
diff --git a/syn-mid/examples/const_fn/Cargo.toml b/syn-mid/examples/const_fn/Cargo.toml
new file mode 100644
index 0000000..d823e76
--- /dev/null
+++ b/syn-mid/examples/const_fn/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "const_fn"
+version = "0.0.0"
+authors = ["Taiki Endo <te316e89@gmail.com>"]
+edition = "2018"
+publish = false
+
+[lib]
+proc-macro = true
+path = "lib.rs"
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = "1.0"
+syn-mid = { version = "0.4", path = "../..", features = ["clone-impls"] }
diff --git a/syn-mid/examples/const_fn/lib.rs b/syn-mid/examples/const_fn/lib.rs
new file mode 100644
index 0000000..29255f2
--- /dev/null
+++ b/syn-mid/examples/const_fn/lib.rs
@@ -0,0 +1,31 @@
+#![warn(rust_2018_idioms)]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use proc_macro2::TokenStream as TokenStream2;
+use quote::quote;
+use syn_mid::ItemFn;
+
+/// An attribute for easy generation of a const function with conditional compilations.
+#[proc_macro_attribute]
+pub fn const_fn(args: TokenStream, function: TokenStream) -> TokenStream {
+    assert!(!args.is_empty(), "requires an argument");
+
+    let mut function = syn::parse_macro_input!(function as ItemFn);
+    let mut const_function = function.clone();
+
+    if function.constness.is_some() {
+        function.constness = None;
+    } else {
+        const_function.constness = Some(Default::default());
+    }
+
+    let args = TokenStream2::from(args);
+    TokenStream::from(quote! {
+        #[cfg(not(#args))]
+        #function
+        #[cfg(#args)]
+        #const_function
+    })
+}
diff --git a/syn-mid/examples/const_fn_test/Cargo.toml b/syn-mid/examples/const_fn_test/Cargo.toml
new file mode 100644
index 0000000..b3e2807
--- /dev/null
+++ b/syn-mid/examples/const_fn_test/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "const_fn_test"
+version = "0.0.0"
+authors = ["Taiki Endo <te316e89@gmail.com>"]
+edition = "2018"
+publish = false
+
+[dependencies]
+const_fn = { path = "../const_fn" }
diff --git a/syn-mid/examples/const_fn_test/build.rs b/syn-mid/examples/const_fn_test/build.rs
new file mode 100644
index 0000000..bebf234
--- /dev/null
+++ b/syn-mid/examples/const_fn_test/build.rs
@@ -0,0 +1,16 @@
+use std::{env, process::Command};
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    if is_nightly() {
+        println!("cargo:rustc-cfg=nightly");
+    }
+}
+
+fn is_nightly() -> bool {
+    env::var_os("RUSTC")
+        .and_then(|rustc| Command::new(rustc).arg("--version").output().ok())
+        .and_then(|output| String::from_utf8(output.stdout).ok())
+        .map_or(false, |version| version.contains("nightly"))
+}
diff --git a/syn-mid/examples/const_fn_test/tests/test.rs b/syn-mid/examples/const_fn_test/tests/test.rs
new file mode 100644
index 0000000..1b2c742
--- /dev/null
+++ b/syn-mid/examples/const_fn_test/tests/test.rs
@@ -0,0 +1,25 @@
+#![cfg_attr(nightly, feature(const_fn, const_vec_new))]
+#![warn(rust_2018_idioms)]
+#![allow(dead_code)]
+
+use const_fn::const_fn;
+
+#[const_fn(nightly)]
+fn const_vec_new<T>() -> Vec<T> {
+    let vec = Vec::new();
+    vec
+}
+
+#[test]
+fn test_stable() {
+    assert_eq!(const_vec_new::<u8>(), Vec::new());
+}
+
+#[cfg(nightly)]
+const CONST_UNSTABLE: Vec<u8> = const_vec_new();
+
+#[cfg(nightly)]
+#[test]
+fn test_unstable() {
+    assert_eq!(CONST_UNSTABLE, Vec::new());
+}
diff --git a/syn-mid/src/arg.rs b/syn-mid/src/arg.rs
new file mode 100644
index 0000000..593a1ac
--- /dev/null
+++ b/syn-mid/src/arg.rs
@@ -0,0 +1,99 @@
+use syn::{Attribute, Lifetime, Token};
+
+use super::PatType;
+
+ast_enum_of_structs! {
+    /// An argument in a function signature: the `n: usize` in `fn f(n: usize)`.
+    pub enum FnArg {
+        /// The `self` argument of an associated method, whether taken by value
+        /// or by reference.
+        Receiver(Receiver),
+
+        /// A function argument accepted by pattern and type.
+        Typed(PatType),
+    }
+}
+
+ast_struct! {
+    /// The `self` argument of an associated method, whether taken by value
+    /// or by reference.
+    pub struct Receiver {
+        pub attrs: Vec<Attribute>,
+        pub reference: Option<(Token![&], Option<Lifetime>)>,
+        pub mutability: Option<Token![mut]>,
+        pub self_token: Token![self],
+    }
+}
+
+mod parsing {
+    use syn::{
+        parse::{discouraged::Speculative, Parse, ParseStream, Result},
+        Attribute, Token,
+    };
+
+    use super::{FnArg, PatType, Receiver};
+
+    impl Parse for FnArg {
+        fn parse(input: ParseStream<'_>) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let ahead = input.fork();
+            if let Ok(mut receiver) = ahead.parse::<Receiver>() {
+                if !ahead.peek(Token![:]) {
+                    input.advance_to(&ahead);
+                    receiver.attrs = attrs;
+                    return Ok(FnArg::Receiver(receiver));
+                }
+            }
+
+            let mut typed = input.call(fn_arg_typed)?;
+            typed.attrs = attrs;
+            Ok(FnArg::Typed(typed))
+        }
+    }
+
+    impl Parse for Receiver {
+        fn parse(input: ParseStream<'_>) -> Result<Self> {
+            Ok(Self {
+                attrs: Vec::new(),
+                reference: {
+                    if input.peek(Token![&]) {
+                        Some((input.parse()?, input.parse()?))
+                    } else {
+                        None
+                    }
+                },
+                mutability: input.parse()?,
+                self_token: input.parse()?,
+            })
+        }
+    }
+
+    fn fn_arg_typed(input: ParseStream<'_>) -> Result<PatType> {
+        Ok(PatType {
+            attrs: Vec::new(),
+            pat: input.parse()?,
+            colon_token: input.parse()?,
+            ty: Box::new(input.parse()?),
+        })
+    }
+}
+
+mod printing {
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    use super::Receiver;
+
+    impl ToTokens for Receiver {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            if let Some((ampersand, lifetime)) = &self.reference {
+                ampersand.to_tokens(tokens);
+                lifetime.to_tokens(tokens);
+            }
+            self.mutability.to_tokens(tokens);
+            self.self_token.to_tokens(tokens);
+        }
+    }
+}
diff --git a/syn-mid/src/lib.rs b/syn-mid/src/lib.rs
new file mode 100644
index 0000000..69bdec9
--- /dev/null
+++ b/syn-mid/src/lib.rs
@@ -0,0 +1,190 @@
+//! Providing the features between "full" and "derive" of syn.
+//!
+//! This crate provides the following two unique data structures.
+//!
+//! * [`syn_mid::ItemFn`] -- A function whose body is not parsed.
+//!
+//!   ```text
+//!   fn process(n: usize) -> Result<()> { ... }
+//!   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^     ^
+//!   ```
+//!
+//! * [`syn_mid::Block`] -- A block whose body is not parsed.
+//!
+//!   ```text
+//!   { ... }
+//!   ^     ^
+//!   ```
+//!
+//! Other data structures are the same as data structures of [syn]. These are defined in this crate
+//! because they cannot be used in [syn] without "full" feature.
+//!
+//! ## Optional features
+//!
+//! syn-mid in the default features aims to provide the features between "full"
+//! and "derive" of [syn].
+//!
+//! * **`clone-impls`** — Clone impls for all syntax tree types.
+//!
+//! [`syn_mid::ItemFn`]: struct.ItemFn.html
+//! [`syn_mid::Block`]: struct.Block.html
+//! [syn]: https://github.com/dtolnay/syn
+//!
+
+#![doc(html_root_url = "https://docs.rs/syn-mid/0.4.0")]
+#![doc(test(attr(deny(warnings), allow(dead_code, unused_assignments, unused_variables))))]
+#![warn(unsafe_code)]
+#![warn(rust_2018_idioms, unreachable_pub)]
+#![warn(single_use_lifetimes)]
+#![warn(clippy::all, clippy::pedantic)]
+#![allow(
+    clippy::eval_order_dependence,
+    clippy::large_enum_variant,
+    clippy::module_name_repetitions,
+    clippy::use_self
+)]
+
+// Many of the code contained in this crate are copies from https://github.com/dtolnay/syn.
+
+#[macro_use]
+mod macros;
+
+mod arg;
+mod pat;
+mod path;
+
+pub use self::arg::*;
+pub use self::pat::*;
+
+use proc_macro2::TokenStream;
+use syn::{
+    punctuated::Punctuated, token, Abi, Attribute, Generics, Ident, ReturnType, Token, Visibility,
+};
+
+ast_struct! {
+    /// A braced block containing Rust statements.
+    pub struct Block {
+        pub brace_token: token::Brace,
+        /// Statements in a block
+        pub stmts: TokenStream,
+    }
+}
+
+ast_struct! {
+    /// A free-standing function: `fn process(n: usize) -> Result<()> { ...
+    /// }`.
+    pub struct ItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub constness: Option<Token![const]>,
+        pub asyncness: Option<Token![async]>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub abi: Option<Abi>,
+        pub fn_token: Token![fn],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub paren_token: token::Paren,
+        pub inputs: Punctuated<FnArg, Token![,]>,
+        pub output: ReturnType,
+        pub block: Block,
+    }
+}
+
+mod parsing {
+    use syn::{
+        braced, parenthesized,
+        parse::{Parse, ParseStream, Result},
+        Abi, Attribute, Generics, Ident, ReturnType, Token, Visibility, WhereClause,
+    };
+
+    use super::{Block, FnArg, ItemFn};
+
+    impl Parse for Block {
+        fn parse(input: ParseStream<'_>) -> Result<Self> {
+            let content;
+            Ok(Self {
+                brace_token: braced!(content in input),
+                stmts: content.parse()?,
+            })
+        }
+    }
+
+    impl Parse for ItemFn {
+        fn parse(input: ParseStream<'_>) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let constness: Option<Token![const]> = input.parse()?;
+            let asyncness: Option<Token![async]> = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let abi: Option<Abi> = input.parse()?;
+            let fn_token: Token![fn] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let generics: Generics = input.parse()?;
+
+            let content;
+            let paren_token = parenthesized!(content in input);
+            let inputs = content.parse_terminated(FnArg::parse)?;
+
+            let output: ReturnType = input.parse()?;
+            let where_clause: Option<WhereClause> = input.parse()?;
+
+            let block = input.parse()?;
+
+            Ok(Self {
+                attrs,
+                vis,
+                constness,
+                asyncness,
+                unsafety,
+                abi,
+                fn_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                paren_token,
+                inputs,
+                output,
+                block,
+            })
+        }
+    }
+}
+
+mod printing {
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    use super::{Block, ItemFn};
+
+    impl ToTokens for Block {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.stmts.clone());
+            });
+        }
+    }
+
+    impl ToTokens for ItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            self.vis.to_tokens(tokens);
+            self.constness.to_tokens(tokens);
+            self.asyncness.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.abi.to_tokens(tokens);
+            self.fn_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.inputs.to_tokens(tokens);
+            });
+            self.output.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.block.stmts.clone());
+            });
+        }
+    }
+}
diff --git a/syn-mid/src/macros.rs b/syn-mid/src/macros.rs
new file mode 100644
index 0000000..87be7b4
--- /dev/null
+++ b/syn-mid/src/macros.rs
@@ -0,0 +1,107 @@
+macro_rules! ast_struct {
+    (
+        [$($attrs_pub:tt)*]
+        struct $name:ident $($rest:tt)*
+    ) => {
+        #[cfg_attr(feature = "clone-impls", derive(Clone))]
+        $($attrs_pub)* struct $name $($rest)*
+    };
+
+    ($($t:tt)*) => {
+        strip_attrs_pub!(ast_struct!($($t)*));
+    };
+}
+
+macro_rules! ast_enum {
+    (
+        [$($attrs_pub:tt)*]
+        enum $name:ident $($rest:tt)*
+    ) => (
+        #[cfg_attr(feature = "clone-impls", derive(Clone))]
+        $($attrs_pub)* enum $name $($rest)*
+    );
+
+    ($($t:tt)*) => {
+        strip_attrs_pub!(ast_enum!($($t)*));
+    };
+}
+
+macro_rules! ast_enum_of_structs {
+    (
+        $(#[$enum_attr:meta])*
+        $pub:ident $enum:ident $name:ident $body:tt
+    ) => {
+        ast_enum!($(#[$enum_attr])* $pub $enum $name $body);
+        ast_enum_of_structs_impl!($pub $enum $name $body);
+    };
+}
+
+macro_rules! ast_enum_of_structs_impl {
+    (
+        $pub:ident $enum:ident $name:ident {
+            $(
+                $(#[$variant_attr:meta])*
+                $variant:ident $( ($member:ident) )*,
+            )*
+        }
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(enum $enum);
+
+        $(
+            $(
+                impl From<$member> for $name {
+                    fn from(e: $member) -> $name {
+                        $name::$variant(e)
+                    }
+                }
+            )*
+        )*
+
+        generate_to_tokens! {
+            ()
+            tokens
+            $name { $($variant $($member)*,)* }
+        }
+    };
+}
+
+macro_rules! generate_to_tokens {
+    (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident, $($next:tt)*}) => {
+        generate_to_tokens!(
+            ($($arms)* $name::$variant => {})
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident $member:ident, $($next:tt)*}) => {
+        generate_to_tokens!(
+            ($($arms)* $name::$variant(_e) => quote::ToTokens::to_tokens(_e, $tokens),)
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (($($arms:tt)*) $tokens:ident $name:ident {}) => {
+        impl quote::ToTokens for $name {
+            fn to_tokens(&self, $tokens: &mut proc_macro2::TokenStream) {
+                match self {
+                    $($arms)*
+                }
+            }
+        }
+    };
+}
+
+macro_rules! strip_attrs_pub {
+    ($mac:ident!($(#[$m:meta])* $pub:ident $($t:tt)*)) => {
+        check_keyword_matches!(pub $pub);
+
+        $mac!([$(#[$m])* $pub] $($t)*);
+    };
+}
+
+macro_rules! check_keyword_matches {
+    (struct struct) => {};
+    (enum enum) => {};
+    (pub pub) => {};
+}
diff --git a/syn-mid/src/pat.rs b/syn-mid/src/pat.rs
new file mode 100644
index 0000000..8f95381
--- /dev/null
+++ b/syn-mid/src/pat.rs
@@ -0,0 +1,413 @@
+use syn::{punctuated::Punctuated, token, Attribute, Ident, Member, Path, Token, Type};
+
+ast_enum_of_structs! {
+    /// A pattern in a local binding, function signature, match expression, or
+    /// various other places.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
+    pub enum Pat {
+        /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+        Ident(PatIdent),
+
+        /// A path pattern like `Color::Red`.
+        Path(PatPath),
+
+        /// A reference pattern: `&mut var`.
+        Reference(PatReference),
+
+        /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+        Struct(PatStruct),
+
+        /// A tuple pattern: `(a, b)`.
+        Tuple(PatTuple),
+
+        /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+        TupleStruct(PatTupleStruct),
+
+        /// A type ascription pattern: `foo: f64`.
+        Type(PatType),
+
+        /// A pattern that matches any value: `_`.
+        Wild(PatWild),
+
+        #[doc(hidden)]
+        __Nonexhaustive,
+    }
+}
+
+ast_struct! {
+    /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+    pub struct PatIdent {
+        pub attrs: Vec<Attribute>,
+        pub by_ref: Option<Token![ref]>,
+        pub mutability: Option<Token![mut]>,
+        pub ident: Ident,
+    }
+}
+
+ast_struct! {
+    /// A path pattern like `Color::Red`.
+    pub struct PatPath {
+        pub attrs: Vec<Attribute>,
+        pub path: Path,
+    }
+}
+
+ast_struct! {
+    /// A reference pattern: `&mut var`.
+    pub struct PatReference {
+        pub attrs: Vec<Attribute>,
+        pub and_token: Token![&],
+        pub mutability: Option<Token![mut]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+ast_struct! {
+    /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+    pub struct PatStruct {
+        pub attrs: Vec<Attribute>,
+        pub path: Path,
+        pub brace_token: token::Brace,
+        pub fields: Punctuated<FieldPat, Token![,]>,
+        pub dot2_token: Option<Token![..]>,
+    }
+}
+
+ast_struct! {
+    /// A tuple pattern: `(a, b)`.
+    pub struct PatTuple {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+    pub struct PatTupleStruct {
+        pub attrs: Vec<Attribute>,
+        pub path: Path,
+        pub pat: PatTuple,
+    }
+}
+
+ast_struct! {
+    /// A type ascription pattern: `foo: f64`.
+    pub struct PatType {
+        pub attrs: Vec<Attribute>,
+        pub pat: Box<Pat>,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A pattern that matches any value: `_`.
+    pub struct PatWild {
+        pub attrs: Vec<Attribute>,
+        pub underscore_token: Token![_],
+    }
+}
+
+ast_struct! {
+    /// A single field in a struct pattern.
+    ///
+    /// Patterns like the fields of Foo `{ x, ref y, ref mut z }` are treated
+    /// the same as `x: x, y: ref y, z: ref mut z` but there is no colon token.
+    pub struct FieldPat {
+        pub attrs: Vec<Attribute>,
+        pub member: Member,
+        pub colon_token: Option<Token![:]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+mod parsing {
+    use syn::{
+        braced,
+        ext::IdentExt,
+        parenthesized,
+        parse::{Parse, ParseStream, Result},
+        punctuated::Punctuated,
+        token, Ident, Member, Path, Token,
+    };
+
+    use crate::path;
+
+    use super::{
+        FieldPat, Pat, PatIdent, PatPath, PatReference, PatStruct, PatTuple, PatTupleStruct,
+        PatWild,
+    };
+
+    impl Parse for Pat {
+        fn parse(input: ParseStream<'_>) -> Result<Self> {
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Ident)
+                && ({
+                    input.peek2(Token![::])
+                        || input.peek2(token::Brace)
+                        || input.peek2(token::Paren)
+                })
+                || input.peek(Token![self]) && input.peek2(Token![::])
+                || lookahead.peek(Token![::])
+                || lookahead.peek(Token![<])
+                || input.peek(Token![Self])
+                || input.peek(Token![super])
+                || input.peek(Token![extern])
+                || input.peek(Token![crate])
+            {
+                pat_path_or_struct(input)
+            } else if lookahead.peek(Token![_]) {
+                input.call(pat_wild).map(Pat::Wild)
+            } else if lookahead.peek(Token![ref])
+                || lookahead.peek(Token![mut])
+                || input.peek(Token![self])
+                || input.peek(Ident)
+            {
+                input.call(pat_ident).map(Pat::Ident)
+            } else if lookahead.peek(Token![&]) {
+                input.call(pat_reference).map(Pat::Reference)
+            } else if lookahead.peek(token::Paren) {
+                input.call(pat_tuple).map(Pat::Tuple)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    fn pat_path_or_struct(input: ParseStream<'_>) -> Result<Pat> {
+        let path = path::parse_path(input)?;
+
+        if input.peek(token::Brace) {
+            pat_struct(input, path).map(Pat::Struct)
+        } else if input.peek(token::Paren) {
+            pat_tuple_struct(input, path).map(Pat::TupleStruct)
+        } else {
+            Ok(Pat::Path(PatPath {
+                attrs: Vec::new(),
+                path,
+            }))
+        }
+    }
+
+    fn pat_wild(input: ParseStream<'_>) -> Result<PatWild> {
+        Ok(PatWild {
+            attrs: Vec::new(),
+            underscore_token: input.parse()?,
+        })
+    }
+
+    fn pat_ident(input: ParseStream<'_>) -> Result<PatIdent> {
+        Ok(PatIdent {
+            attrs: Vec::new(),
+            by_ref: input.parse()?,
+            mutability: input.parse()?,
+            ident: input.call(Ident::parse_any)?,
+        })
+    }
+
+    fn pat_tuple_struct(input: ParseStream<'_>, path: Path) -> Result<PatTupleStruct> {
+        Ok(PatTupleStruct {
+            attrs: Vec::new(),
+            path,
+            pat: input.call(pat_tuple)?,
+        })
+    }
+
+    fn pat_struct(input: ParseStream<'_>, path: Path) -> Result<PatStruct> {
+        let content;
+        let brace_token = braced!(content in input);
+
+        let mut fields = Punctuated::new();
+        while !content.is_empty() && !content.peek(Token![..]) {
+            let value = content.call(field_pat)?;
+            fields.push_value(value);
+            if !content.peek(Token![,]) {
+                break;
+            }
+            let punct: Token![,] = content.parse()?;
+            fields.push_punct(punct);
+        }
+
+        let dot2_token = if fields.empty_or_trailing() && content.peek(Token![..]) {
+            Some(content.parse()?)
+        } else {
+            None
+        };
+
+        Ok(PatStruct {
+            attrs: Vec::new(),
+            path,
+            brace_token,
+            fields,
+            dot2_token,
+        })
+    }
+
+    fn field_pat(input: ParseStream<'_>) -> Result<FieldPat> {
+        let boxed: Option<Token![box]> = input.parse()?;
+        let by_ref: Option<Token![ref]> = input.parse()?;
+        let mutability: Option<Token![mut]> = input.parse()?;
+        let member: Member = input.parse()?;
+
+        if boxed.is_none() && by_ref.is_none() && mutability.is_none() && input.peek(Token![:])
+            || is_unnamed(&member)
+        {
+            return Ok(FieldPat {
+                attrs: Vec::new(),
+                member,
+                colon_token: input.parse()?,
+                pat: input.parse()?,
+            });
+        }
+
+        let ident = match member {
+            Member::Named(ident) => ident,
+            Member::Unnamed(_) => unreachable!(),
+        };
+
+        let pat = Pat::Ident(PatIdent {
+            attrs: Vec::new(),
+            by_ref,
+            mutability,
+            ident: ident.clone(),
+        });
+
+        Ok(FieldPat {
+            member: Member::Named(ident),
+            pat: Box::new(pat),
+            attrs: Vec::new(),
+            colon_token: None,
+        })
+    }
+
+    fn pat_tuple(input: ParseStream<'_>) -> Result<PatTuple> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value: Pat = content.parse()?;
+            elems.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(PatTuple {
+            attrs: Vec::new(),
+            paren_token,
+            elems,
+        })
+    }
+
+    fn pat_reference(input: ParseStream<'_>) -> Result<PatReference> {
+        Ok(PatReference {
+            attrs: Vec::new(),
+            and_token: input.parse()?,
+            mutability: input.parse()?,
+            pat: input.parse()?,
+        })
+    }
+
+    fn is_unnamed(member: &Member) -> bool {
+        match member {
+            Member::Named(_) => false,
+            Member::Unnamed(_) => true,
+        }
+    }
+}
+
+mod printing {
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+    use syn::Token;
+
+    use super::{
+        FieldPat, PatIdent, PatPath, PatReference, PatStruct, PatTuple, PatTupleStruct, PatType,
+        PatWild,
+    };
+
+    impl ToTokens for PatWild {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.underscore_token.to_tokens(tokens);
+        }
+    }
+
+    impl ToTokens for PatIdent {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.by_ref.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+        }
+    }
+
+    impl ToTokens for PatStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                self.fields.to_tokens(tokens);
+                // NOTE: We need a comma before the dot2 token if it is present.
+                if !self.fields.empty_or_trailing() && self.dot2_token.is_some() {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+                self.dot2_token.to_tokens(tokens);
+            });
+        }
+    }
+
+    impl ToTokens for PatTupleStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+        }
+    }
+
+    impl ToTokens for PatType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            self.pat.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    impl ToTokens for PatPath {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens)
+        }
+    }
+
+    impl ToTokens for PatTuple {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    impl ToTokens for PatReference {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.and_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+        }
+    }
+
+    impl ToTokens for FieldPat {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if let Some(colon_token) = &self.colon_token {
+                self.member.to_tokens(tokens);
+                colon_token.to_tokens(tokens);
+            }
+            self.pat.to_tokens(tokens);
+        }
+    }
+}
diff --git a/syn-mid/src/path.rs b/syn-mid/src/path.rs
new file mode 100644
index 0000000..8093b53
--- /dev/null
+++ b/syn-mid/src/path.rs
@@ -0,0 +1,50 @@
+use syn::{
+    ext::IdentExt,
+    parse::{ParseStream, Result},
+    punctuated::Punctuated,
+    Ident, Path, PathArguments, PathSegment, Token,
+};
+
+fn parse_path_segment(input: ParseStream<'_>) -> Result<PathSegment> {
+    if input.peek(Token![super])
+        || input.peek(Token![self])
+        || input.peek(Token![crate])
+        || input.peek(Token![extern])
+    {
+        let ident = input.call(Ident::parse_any)?;
+        return Ok(PathSegment::from(ident));
+    }
+
+    let ident = if input.peek(Token![Self]) {
+        input.call(Ident::parse_any)?
+    } else {
+        input.parse()?
+    };
+
+    if input.peek(Token![::]) && input.peek3(Token![<]) {
+        Ok(PathSegment {
+            ident,
+            arguments: PathArguments::AngleBracketed(input.parse()?),
+        })
+    } else {
+        Ok(PathSegment::from(ident))
+    }
+}
+
+pub(crate) fn parse_path(input: ParseStream<'_>) -> Result<Path> {
+    Ok(Path {
+        leading_colon: input.parse()?,
+        segments: {
+            let mut segments = Punctuated::new();
+            let value = parse_path_segment(input)?;
+            segments.push_value(value);
+            while input.peek(Token![::]) {
+                let punct: Token![::] = input.parse()?;
+                segments.push_punct(punct);
+                let value = parse_path_segment(input)?;
+                segments.push_value(value);
+            }
+            segments
+        },
+    })
+}