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extern crate proc_macro;
use ::std::ffi::{OsStr, OsString};
use ::std::path::{Path, PathBuf};
use directories::ProjectDirs;
use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use syn::{parse_macro_input, DeriveInput, Error, Ident, Lit, Meta, MetaNameValue, Result};
#[derive(Debug, Default)]
struct ConfigPath {
parent: Option<PathBuf>,
filename: Option<OsString>,
extension: Option<OsString>,
}
#[proc_macro_derive(Configure, attributes(config_file))]
pub fn config_attribute(item: TokenStream) -> TokenStream {
let ast: DeriveInput = parse_macro_input!(item as DeriveInput);
let cfg_path = extract_attributes(&ast);
gen_impl(&ast, cfg_path)
}
fn extract_attributes(ast: &DeriveInput) -> ConfigPath {
for option in ast.attrs.iter() {
let option = option.parse_meta().unwrap();
match option {
Meta::NameValue(MetaNameValue {
ref path, ref lit, ..
}) if path.is_ident("config_file") => {
if let Lit::Str(f) = lit {
let f = f.value();
let fp = Path::new(&f);
let blank = Path::new("");
let parent = match fp.parent() {
Some(blank) => None,
other => other,
};
return ConfigPath {
parent: parent.map(Path::to_path_buf),
filename: fp.file_stem().map(OsStr::to_os_string),
extension: fp.extension().map(OsStr::to_os_string),
};
}
}
_ => {}
}
}
return Default::default();
}
fn pick_serializer(ext: &str) -> (Ident, Ident) {
/* returns serializer and a corresponding function to
* stringify with based on file extension
* toml::to_string_pretty
* serde_yaml::to_string
* serde_json::to_string_pretty
*/
match ext.as_ref() {
"toml" => (
Ident::new("toml", Span::call_site()),
Ident::new("to_string_pretty", Span::call_site()),
),
"yaml" => (
Ident::new("serde_yaml", Span::call_site()),
Ident::new("to_string", Span::call_site()),
),
"json" => (
Ident::new("serde_json", Span::call_site()),
Ident::new("to_string_pretty", Span::call_site()),
),
_ => panic!("Invalid extension!"),
}
}
fn gen_impl(ast: &DeriveInput, cfg_path: ConfigPath) -> TokenStream {
let struct_ident = &ast.ident;
let filename = cfg_path
.filename
.unwrap_or(OsStr::new("config").to_os_string());
let filetype = cfg_path
.extension
.unwrap_or(OsStr::new("toml").to_os_string());
let filename = filename.into_string().unwrap();
let filetype = filetype.into_string().unwrap();
let pkg_name = env!("CARGO_PKG_NAME");
let project = ProjectDirs::from("rs", "", pkg_name).unwrap();
let default_dir = project.config_dir();
let config_dir = cfg_path.parent.as_deref().unwrap_or(default_dir);
let tip = Path::new(&filename).with_extension(&filetype);
let config_file = [config_dir, tip.as_ref()]
.iter()
.collect::<PathBuf>()
.into_os_string()
.into_string()
.unwrap();
let parent: String = config_dir.to_str().unwrap().into();
let (ser, ser_fn) = pick_serializer(&filetype);
let gen = quote! {
use ::fondant::{Configure, ProjectDirs, toml, serde_json, serde_yaml, FondantError};
use ::std::option::Option;
use ::std::fs::{self, File, OpenOptions};
use ::std::io::prelude::*;
use ::std::io::{ ErrorKind::NotFound, Write };
use ::std::ffi::{OsStr, OsString};
use ::std::path::{Path, PathBuf};
impl Configure for #struct_ident {
fn load() -> Result<#struct_ident, FondantError> {
match File::open(&#config_file) {
Ok(mut cfg) => {
let mut cfg_data = String::new();
cfg.read_to_string(&mut cfg_data);
let config: #struct_ident = #ser::from_str(&cfg_data[..])
.map_err(|_| FondantError::ConfigParseError)?;
return Ok(config);
},
Err(ref e) if e.kind() == NotFound => {
fs::create_dir_all(#parent).map_err(FondantError::DirCreateErr)?;
let default_impl = #struct_ident::default();
Configure::store(&default_impl)?;
return Ok(default_impl);
},
Err(e) => return Err(FondantError::LoadError),
};
}
fn store(&self) -> Result<(), FondantError> {
let mut f = OpenOptions::new()
.write(true)
.create(true)
.truncate(true)
.open(#config_file)
.map_err(|_| FondantError::FileOpenError)?;
let s = #ser::#ser_fn(self).map_err(|_| FondantError::ConfigParseError)?;
f.write_all(s.as_bytes()).map_err(|_| FondantError::FileWriteError);
Ok(())
}
}
};
gen.into()
}
|
