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use std::env;
use std::error::Error;
use std::io::{self, Read};
use std::fs;
use std::path::PathBuf;
use source::{Source, SourceBuilder};
mod nil;
#[cfg(feature = "toml")]
mod toml;
#[cfg(feature = "json")]
mod json;
pub enum FileFormat {
/// TOML (parsed with toml)
#[cfg(feature = "toml")]
Toml,
/// JSON (parsed with serde_json)
#[cfg(feature = "json")]
Json,
}
impl FileFormat {
fn extensions(&self) -> Vec<&'static str> {
match *self {
#[cfg(feature = "toml")]
FileFormat::Toml => vec!["toml"],
#[cfg(feature = "json")]
FileFormat::Json => vec!["json"],
}
}
#[allow(unused_variables)]
fn parse(&self, text: &str) -> Result<Box<Source>, Box<Error>> {
match *self {
#[cfg(feature = "toml")]
FileFormat::Toml => toml::Content::parse(text),
#[cfg(feature = "json")]
FileFormat::Json => json::Content::parse(text),
}
}
}
pub struct File {
/// Basename of configuration file
name: String,
/// Directory where configuration file is found
/// When not specified, the current working directory (CWD) is considered
path: Option<String>,
/// Namespace to restrict configuration from the file
namespace: Option<String>,
/// Format of file (which dictates what driver to use); Defauts to TOML.
format: FileFormat,
/// A required File will error if it cannot be found
required: bool,
}
impl File {
pub fn new(name: &str, format: FileFormat) -> File {
File {
name: name.into(),
format: format,
required: true,
path: None,
namespace: None,
}
}
pub fn path(self, path: &str) -> File {
File { path: Some(path.into()), ..self }
}
pub fn namespace(self, namespace: &str) -> File {
File { namespace: Some(namespace.into()), ..self }
}
pub fn required(self, required: bool) -> File {
File { required: required, ..self }
}
// Find configuration file
// Use algorithm similar to .git detection by git
fn find_file(&self) -> Result<PathBuf, Box<Error>> {
// Build expected configuration file
let mut basename = PathBuf::new();
let extensions = self.format.extensions();
if let Some(ref path) = self.path {
basename.push(path.clone());
}
basename.push(self.name.clone());
// Find configuration file (algorithm similar to .git detection by git)
let mut dir = env::current_dir()?;
loop {
let mut filename = dir.as_path().join(basename.clone());
for ext in &extensions {
filename.set_extension(ext);
if filename.is_file() {
// File exists and is a file
return Ok(filename);
}
}
// Not found.. travse up via the dir
if !dir.pop() {
// Failed to find the configuration file
return Err(io::Error::new(io::ErrorKind::NotFound,
format!("configuration file \"{}\" not found",
basename.to_string_lossy()))
.into());
}
}
}
// Build normally and return error on failure
fn try_build(&self) -> Result<Box<Source>, Box<Error>> {
// Find file
let filename = self.find_file()?;
// Read contents from file
let mut file = fs::File::open(filename)?;
let mut text = String::new();
file.read_to_string(&mut text)?;
// Parse the file
self.format.parse(&text)
}
}
impl SourceBuilder for File {
// Use try_build but only pass an error through if this source
// is required
fn build(&self) -> Result<Box<Source>, Box<Error>> {
if self.required {
self.try_build()
} else {
self.try_build().or_else(|_| Ok(Box::new(nil::Nil {})))
}
}
}
|
