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//! Structures for representing configuration items and values. //! //! This basic `Item` structure is used to create the two fundamental types //! of just-config: //! //! - [`StringItem`] //! - [`TypedItem`] //! //! The configuration pipeline uses the two types of configuration items at //! different stages. The configuration pipeline looks like the following: //! //! ```text //! +--------+ +------------+ +------------+ +----------------+ //! | source +-->| processors +-->| validators |-->| ValueExtractor | //! +--------+ +------------+ +------------+ +----------------+ //! ``` //! //! To make this more transparent take the following example: //! //! ```rust //! # use justconfig::Config; //! # use justconfig::ConfPath; //! # use justconfig::item::ValueExtractor; //! # use justconfig::sources::defaults::Defaults; //! # use justconfig::processors::Trim; //! # use justconfig::validators::Range; //! # //! # let mut conf = Config::default(); //! # let mut defaults = Defaults::default(); //! # defaults.set(conf.root().push_all(&["myvalue"]), "3", "source info"); //! # conf.add_source(defaults); //! # //! let myvalue: u32 = conf.get(ConfPath::from(&["myvalue"])).trim().max(5).value().expect("myvalue not found"); //! ``` //! //! The first part `conf.get` searches all registered configuration sources and //! returns a `Result<StringItem, ConfigError>`. //! //! The following `trim()` method is a processor. Processors operate on the //! string value of the configuration item and manipulate the string without //! knowing anything about the meaning of the string. //! //! The next call is `max(5)`. This is a validator. Validators need to know more //! about the meaning of the string value. Therefore the first call of validator //! converts the `Result<StringItem, ConfigError>` into a //! `Result<TypedItem<T>, ConfigError>`. To make this conversion possible, T must //! implement the `FromStr` trait. //! //! This conversion is also responsible for the restriction, that all processors //! have to be placed before the validators within the pipeline. //! //! The last call `value()` is implemented via the //! [`ValueExtractor`] trait. //! The `ValueExtractor` can (like [`validators`](crate::validators)) be called on //! `Result<`[`StringItem`]`, `[`ConfigError`]`>` or `Result<`[`TypedItem<T>`]`, `[`ConfigError`]`>`. It //! extracts the value from the pipeline and returns it to the caller. There are //! multiple methods implemented for the [`ValueExtractor`] trait to be able to //! return different kinds of values: //! //! * Optional values //! * Multiple values //! * Single, mandatory values use crate::confpath::ConfPath; use crate::error::ConfigError; use std::str::FromStr; use std::rc::Rc; use std::convert::TryInto; use std::error::Error; use std::ops::RangeBounds; /// Trait implemented by source location structs provided by data sources. /// /// This trait is used to provide the source of a configuration entry, for /// example, for use in error messages. pub trait SourceLocation : std::fmt::Display + std::fmt::Debug {} /// Structure representing a configuration value. /// /// Any configuration item can have multiple configuration values. /// /// Every configuration value is linked to its source. Every configuration source /// implements a struct that implements the `SourceLocation` trait. The source /// location is used to supply information to the user where the configuration /// value is coming from. /// /// See [`Item`](crate::item) for more Information. pub struct Value<T> { value: T, source: Rc<dyn SourceLocation> } impl <T> Value<T> { /// Create a new configuration value. /// /// Configuration values are normally created to be included into configuration /// [`Item`](crate::item)s. pub fn new(value: T, source: Rc<dyn SourceLocation>) -> Rc<Self> { Rc::new(Self { value, source }) } /// Returns the source of this configuration value. pub fn source(&self) -> Rc<dyn SourceLocation>{ self.source.clone() } } #[derive(Clone)] struct Item<T> { key: ConfPath, values: Vec<Rc<Value<T>>> } /// Newtype for Items while they are passed though the processors of the config /// pipeline. /// /// `StringItem` implements some additional methods that are useful while a new /// `Item` is created within a config source. /// See [`Source`](crate::Source) for more information. /// /// For more information about processors and validators see /// [`Item`](crate::item). #[derive(Clone)] pub struct StringItem(Item<String>); impl StringItem { pub(crate) fn new(key: ConfPath) -> Self { Self { 0: Item { key, values: Vec::with_capacity(1) } } } pub(crate) fn from(key: ConfPath, values: &[Rc<Value<String>>]) -> Self { Self { 0: Item { key, values: Vec::from(values) } } } pub(crate) fn push(&mut self, new_value: Rc<Value<String>>) { self.0.values.push(new_value); } pub(crate) fn clear(&mut self) -> &mut Self { self.0.values.clear(); self } } /// Newtype for Items while they are passed though the validators of the config /// pipeline and to the [`ValueExtractor`]. /// /// See [`Item`](crate::item) for more Information. #[derive(Clone)] pub struct TypedItem<T: FromStr>(Item<T>); impl <T: FromStr> TypedItem<T> { pub(crate) fn new(key: ConfPath, values: Vec<Rc<Value<T>>>) -> Self { Self { 0: Item { key, values } } } } impl <T: FromStr> TypedItem<T> { pub fn filter(self, filter: impl Fn(&T) -> Result<(), Box<dyn Error>>) -> Result<Self, ConfigError> { for v in self.0.values.iter() { filter(&v.value).map_err(|e| ConfigError::ValueError(e, v.source.clone()))?; } Ok(self) } } pub enum MapAction { Keep, Replace(Vec<String>), Drop, Fail(Box<dyn Error>) } impl StringItem { pub fn map(self, mapper: impl Fn(&String) -> MapAction) -> Result<Self, ConfigError> { let mut mapped_item = StringItem::new(self.0.key); for v in self.0.values.into_iter() { match mapper(&v.value) { MapAction::Keep => mapped_item.push(v), MapAction::Replace(new_values_list) => for value in new_values_list.into_iter().map(|mapped_v| Value::new(mapped_v, v.source.clone())) { mapped_item.push(value); }, MapAction::Drop => (), MapAction::Fail(error) => return Err(ConfigError::ValueError(error, v.source.clone())) } } Ok(mapped_item) } } impl <T: FromStr> TryInto<TypedItem<T>> for Result<StringItem, ConfigError> where T::Err: Error + 'static { type Error = ConfigError; fn try_into(self) -> Result<TypedItem<T>, ConfigError> { let s = self?; // Iterate all String-Values... let typed_values: Result<Vec<Rc<Value<T>>>, ConfigError> = s.0.values.into_iter().map(|v| // ...and convert them to T... v.value.parse::<T>().map(|nv| Value::new(nv, v.source.clone()) ) // ...if an error occures while converting, map it to a ConfigError... .map_err(|e| ConfigError::from_error(e, v.source.clone())) ) //.. and collect everything. If there is one Result::Err this will lead to an err on the final collection .collect(); Ok(TypedItem::new(s.0.key, typed_values?)) } } /// Trait implemented for `TypedItem` and `StringItem` to allow retrieval of the /// stored config value. /// /// This Trait is implemented for `Result<TypedItem<T>, ConfigError>` and /// `Result<StringItem, ConfigError>`. This makes sure that the methods can be /// called on the raw `StringItems` and on the `TypedItems` returned by /// [validators](crate::validators). /// /// The Implementation for `StringItem` will do the same conversion that is /// normally done when calling a validator. pub trait ValueExtractor<T: FromStr> { /// Returns a configuration value if it exists or ´None´ otherwise. /// /// An error is only returned if one of the following occures: /// * The value of the configuration item could not be converted into the /// required data type. /// * A processor or validator returned an error. /// * There is more that one value available. /// /// This method should be used to return optional configuration values. /// A default value can be provided by using `unwrap_or`. /// /// ## Example /// /// ```rust /// # use justconfig::Config; /// # use justconfig::ConfPath; /// # use justconfig::item::ValueExtractor; /// # use justconfig::sources::defaults::Defaults; /// # /// # let mut conf = Config::default(); /// # let mut defaults = Defaults::default(); /// # defaults.set(conf.root().push_all(&["myvalue"]), "3", "source info"); /// # conf.add_source(defaults); /// # /// let myvalue: u32 = conf.get(ConfPath::from(&["myvalue"])).try_value().expect("Error").unwrap_or(0); /// ``` fn try_value(self) -> Result<Option<T>, ConfigError>; /// Returns a configuration value or raises an error if it does not exists. /// /// This method works like [`try_value()`](Self::try_value) but returns an error if the /// configuration item does not exist. /// /// This method should be used to return mandatory configuration values that /// should result in an error if they are not found. /// /// ## Example /// /// ```rust /// # use justconfig::Config; /// # use justconfig::ConfPath; /// # use justconfig::item::ValueExtractor; /// # use justconfig::sources::defaults::Defaults; /// # /// # let mut conf = Config::default(); /// # let mut defaults = Defaults::default(); /// # defaults.set(conf.root().push_all(&["myvalue"]), "3", "source info"); /// # conf.add_source(defaults); /// # /// let myvalue: u32 = conf.get(ConfPath::from(&["myvalue"])).value().expect("Error or not found"); /// ``` fn value(self) -> Result<T, ConfigError>; /// Returns all configuration values for a configuration item. /// /// This is the only method that allows more than one configuration value /// to exist. Use this method to read multi value items. If the /// configuration item does not exist, an empty array is returned. /// /// The method accepts a range to specify how many configuration values can /// be set for this item. If any number of configuration values are /// acceptible, just specify `..`. If the number of values should be /// limited, specify a range. /// /// ## Example /// /// ```rust /// # use justconfig::Config; /// # use justconfig::ConfPath; /// # use justconfig::item::ValueExtractor; /// # use justconfig::sources::defaults::Defaults; /// # /// # let mut conf = Config::default(); /// # let mut defaults = Defaults::default(); /// # defaults.set(conf.root().push_all(&["myvalue"]), "3", "source info"); /// # conf.add_source(defaults); /// # /// let myvalue: Vec<u32> = conf.get(ConfPath::from(&["myvalue"])).values(..).expect("Error"); /// ``` /// /// If there must be at least one instance of `myvalue` specify a range of /// `1..`: /// /// ```rust /// # use justconfig::Config; /// # use justconfig::ConfPath; /// # use justconfig::item::ValueExtractor; /// # use justconfig::sources::defaults::Defaults; /// # /// # let mut conf = Config::default(); /// # let mut defaults = Defaults::default(); /// # defaults.set(conf.root().push_all(&["myvalue"]), "3", "source info"); /// # conf.add_source(defaults); /// # /// let myvalue: Vec<u32> = conf.get(ConfPath::from(&["myvalue"])).values(1..).expect("Error"); /// ``` /// /// If the number of values should be limited to at most 3 values the range /// must be `..=3`. /// fn values<R: RangeBounds<usize>>(self, range: R) -> Result<Vec<T>, ConfigError>; } #[allow(clippy::unnecessary_unwrap)] // Until https://github.com/rust-lang/rfcs/pull/2497 gets implemented fn values_out_of_range<T: FromStr, R: RangeBounds<usize>>(mut item: TypedItem<T>, range: R) -> Result<Vec<T>, ConfigError> { let num_items = item.0.values.len(); if range.contains(&num_items) { item.0.values.drain(..).map(|r| Rc::try_unwrap(r).map(|v| v.value).map_err(|_| ConfigError::MultipleReferences)).collect() } else { // The number of items is not part of the range. Check if the upper or lower bound // was violated. // The lower limit is inclusive, the upper is exlusive. This is done to make sure // we do not underflow the unsigned value. let lower_limit_inc = match range.start_bound() { std::ops::Bound::Included(min) => Some(*min), std::ops::Bound::Excluded(min) => Some(*min + 1), std::ops::Bound::Unbounded => None }; let upper_limit_excl = match range.end_bound() { std::ops::Bound::Included(max) => Some(*max + 1), std::ops::Bound::Excluded(max) => Some(*max), std::ops::Bound::Unbounded => None }; if lower_limit_inc.is_some() && (num_items < lower_limit_inc.unwrap()) { // Lower bound violated Err(ConfigError::NotEnoughValues(lower_limit_inc.unwrap(), item.0.key)) } else if upper_limit_excl.is_some() && (num_items >= upper_limit_excl.unwrap()) { let first_surplus_index = upper_limit_excl.unwrap().saturating_sub(1); // Upper bound violated let surplus_sources = item.0.values.drain(first_surplus_index..).map(|r| Rc::try_unwrap(r).map(|v| v.source).map_err(|_| ConfigError::MultipleReferences)).collect::<Result<Vec<Rc<dyn SourceLocation>>, ConfigError>>()?; Err(ConfigError::TooManyValues(first_surplus_index, item.0.key, surplus_sources)) } else { unreachable!("This is not possible because we checked that num_items is not contained in range."); } } } impl <T: FromStr> ValueExtractor<T> for Result<TypedItem<T>, ConfigError> { fn try_value(self) -> Result<Option<T>, ConfigError> { match self.value() { Ok(value) => Ok(Some(value)), Err(ConfigError::ValueNotFound(_)) => Ok(None), Err(error) => Err(error) } } fn value(self) -> Result<T, ConfigError> { let mut ci = self?.0; match ci.values.len() { 0 => Err(ConfigError::ValueNotFound(ci.key)), 1 => Rc::try_unwrap(ci.values.pop().unwrap()).map(|v| v.value).map_err(|_| ConfigError::MultipleReferences), _ => Err(ConfigError::TooManyValues(1, ci.key, ci.values.iter().map(|v| v.source()).collect())) } } fn values<R: RangeBounds<usize>>(self, range: R) -> Result<Vec<T>, ConfigError> { // This match converts a ValueNotFound error into an empty vector. // This makes sure that an empty value-vectors is equvalent with an ValueNotFound error for all purposes. match self { Ok(item) => values_out_of_range(item, range), Err(ConfigError::ValueNotFound(_)) => Ok(Vec::default()), Err(error) => Err(error) } } } impl <T: FromStr> ValueExtractor<T> for Result<StringItem, ConfigError> where T::Err: Error + 'static { fn try_value(self) -> Result<Option<T>, ConfigError> { (self.try_into() as Result<TypedItem<T>, ConfigError>).try_value() } fn value(self) -> Result<T, ConfigError> { (self.try_into() as Result<TypedItem<T>, ConfigError>).value() } fn values<R: RangeBounds<usize>>(self, range: R) -> Result<Vec<T>, ConfigError> { (self.try_into() as Result<TypedItem<T>, ConfigError>).values(range) } } #[cfg(test)] mod tests { use super::*; use crate::Config; use crate::sources::defaults::{Defaults}; use crate::error::ConfigError; fn prepare_test_config() -> Config { let mut c = Config::default(); let mut defaults = Defaults::default(); defaults.empty(c.root().push_all(&["no_value"])); defaults.set(c.root().push_all(&["one_value"]), "one_value", "1.1"); defaults.put(c.root().push_all(&["two_values"]), "two_values", "2.1"); defaults.put(c.root().push_all(&["two_values"]), "two_values", "2.2"); c.add_source(defaults); c } #[test] fn value_no_value() { let c = prepare_test_config(); assert_eq!(format!("{}", (c.get(c.root().push_all(&["no_value"])).value() as Result<String, ConfigError>).unwrap_err()), "Missing value for config key 'no_value'."); } #[test] fn value_one_value() { let c = prepare_test_config(); assert_eq!((c.get(c.root().push_all(&["one_value"])).value() as Result<String, ConfigError>).unwrap(), "one_value"); } #[test] fn value_two_values() { let c = prepare_test_config(); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).value() as Result<String, ConfigError>).unwrap_err()), "More than 1 value found for key two_values@['default from 2.1', 'default from 2.2']"); } #[test] fn try_value_no_value() { let c = prepare_test_config(); assert!((c.get(c.root().push_all(&["no_value"])).try_value() as Result<Option<String>, ConfigError>).unwrap().is_none()); } #[test] fn try_value_one_value() { let c = prepare_test_config(); assert_eq!((c.get(c.root().push_all(&["one_value"])).try_value() as Result<Option<String>, ConfigError>).unwrap().unwrap(), "one_value"); } #[test] fn try_value_two_values() { let c = prepare_test_config(); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).try_value() as Result<Option<String>, ConfigError>).unwrap_err()), "More than 1 value found for key two_values@['default from 2.1', 'default from 2.2']"); } #[test] fn values_no_value() { let c = prepare_test_config(); let values: Vec<String> = c.get(c.root().push_all(&["no_value"])).values(..).unwrap(); assert_eq!(values.len(), 0); } #[test] fn values_one_value() { let c = prepare_test_config(); let mut values: Vec<String> = c.get(c.root().push_all(&["one_value"])).values(..).unwrap(); assert_eq!(values.len(), 1); assert_eq!(values.pop().unwrap(), "one_value"); } #[test] fn values_two_values() { let c = prepare_test_config(); let mut values: Vec<String> = c.get(c.root().push_all(&["two_values"])).values(..).unwrap(); assert_eq!(values.len(), 2); assert_eq!(values.pop().unwrap(), "two_values"); assert_eq!(values.pop().unwrap(), "two_values"); } #[test] fn range_lower_limit() { let c = prepare_test_config(); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).values(3..) as Result<Vec<String>, ConfigError>).unwrap_err()), "Key \'two_values\' must have at least 3 values."); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).values(4..5) as Result<Vec<String>, ConfigError>).unwrap_err()), "Key \'two_values\' must have at least 4 values."); } #[test] fn range_upper_limit() { let c = prepare_test_config(); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).values(..=1) as Result<Vec<String>, ConfigError>).unwrap_err()), "More than 1 value found for key two_values@['default from 2.2']"); assert_eq!(format!("{}", (c.get(c.root().push_all(&["two_values"])).values(1..=1) as Result<Vec<String>, ConfigError>).unwrap_err()), "More than 1 value found for key two_values@['default from 2.2']"); } #[test] fn range_ok() { let c = prepare_test_config(); let mut values: Vec<String> = c.get(c.root().push_all(&["two_values"])).values(1..=2).unwrap(); assert_eq!(values.len(), 2); assert_eq!(values.pop().unwrap(), "two_values"); assert_eq!(values.pop().unwrap(), "two_values"); let mut values: Vec<String> = c.get(c.root().push_all(&["two_values"])).values(2..3).unwrap(); assert_eq!(values.len(), 2); assert_eq!(values.pop().unwrap(), "two_values"); assert_eq!(values.pop().unwrap(), "two_values"); let mut values: Vec<String> = c.get(c.root().push_all(&["two_values"])).values(0..10).unwrap(); assert_eq!(values.len(), 2); assert_eq!(values.pop().unwrap(), "two_values"); assert_eq!(values.pop().unwrap(), "two_values"); let mut values: Vec<String> = c.get(c.root().push_all(&["one_value"])).values(..3).unwrap(); assert_eq!(values.len(), 1); assert_eq!(values.pop().unwrap(), "one_value"); let mut values: Vec<String> = c.get(c.root().push_all(&["one_value"])).values(1..).unwrap(); assert_eq!(values.len(), 1); assert_eq!(values.pop().unwrap(), "one_value"); } }