agg: fix typo, add docs

Cargo.lock

@@ -1,6 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "estring"
-version = "0.1.2"
-
+version = "0.2.1"

src/agg.rs

@@ -1,2 +1,6 @@
 //! This module will contain aggregate functions (Sum, Product, etc)
 //!
+
+mod sum;
+
+pub use sum::*;

src/agg/sum.rs

@@ -0,0 +1,87 @@
+use std::marker::PhantomData;
+
+use crate::{Aggregatable, Aggregate, EString, ParseFragment};
+
+#[derive(Debug, PartialEq, Eq)]
+struct Sum<R, T>(T, PhantomData<R>);
+
+impl<R, T> Sum<R, T> {
+    fn new(inner: T) -> Self {
+        Self(inner, PhantomData::default())
+    }
+}
+
+impl<R, T> ParseFragment for Sum<R, T>
+where
+    T: ParseFragment,
+{
+    fn parse_frag(es: EString) -> crate::Result<Self> {
+        T::parse_frag(es).map(Self::new)
+    }
+}
+
+impl<R, T> Aggregate for Sum<R, T>
+where
+    R: std::iter::Sum,
+    T: Aggregatable<Item = R>,
+{
+    type Target = R;
+
+    fn agg(self) -> Self::Target {
+        self.0.items().into_iter().sum()
+    }
+}
+
+impl<R, T> Aggregatable for Sum<R, T>
+where
+    R: std::iter::Sum,
+    T: Aggregatable<Item = R>,
+{
+    type Item = R;
+
+    fn items(self) -> Vec<Self::Item> {
+        vec![self.agg()]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::SepVec;
+
+    use super::*;
+
+    type CommaVec<T> = SepVec<T, ','>;
+    type PlusVec<T> = SepVec<T, '+'>;
+
+    #[test]
+    fn should_parse_vec() {
+        let es = EString::from("1,2,3");
+        match es.parse::<Sum<i32, CommaVec<i32>>>() {
+            Ok(res) => assert_eq!(res, Sum::new(CommaVec::from(vec![1, 2, 3]))),
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn should_aggregate_vector() {
+        let es = EString::from("1,2,3");
+        let expr = es.parse::<Sum<i32, CommaVec<i32>>>().unwrap();
+        assert_eq!(expr.agg(), 6);
+    }
+
+    #[test]
+    fn should_aggregate_vector_with_inner_vector() {
+        let es = EString::from("1+2,2,3");
+        let expr = es.parse::<Sum<i32, CommaVec<PlusVec<i32>>>>().unwrap();
+        assert_eq!(expr.agg(), 8);
+    }
+
+    #[test]
+    fn should_aggregate_vector_with_inner_aggregation() {
+        let es = EString::from("1+2,2,3");
+        let expr = es
+            .parse::<Sum<_, CommaVec<Sum<_, PlusVec<i32>>>>>()
+            .unwrap();
+        assert_eq!(expr.agg(), 8);
+    }
+}

src/core.rs

@@ -110,6 +110,29 @@ pub trait ParseFragment: Sized {
     fn parse_frag(es: EString) -> crate::Result<Self>;
 }
 
+// TODO: add example
+/// Trait to represent structures that can act as aggregators.
+///
+/// The `agg` method works with data that has already been parsed. For this reason, **this trait
+/// should never fail**.
+pub trait Aggregate {
+    /// The resulting type after aggregation.
+    type Target: ?Sized;
+
+    /// Aggregates the value.
+    fn agg(self) -> Self::Target;
+}
+
+// TODO: add example
+/// Trait to represent structures that can iterate values for the aggregator.
+pub trait Aggregatable {
+    /// The type of the elements being iterated over.
+    type Item;
+
+    /// Returns Vec of aggregatable values
+    fn items(self) -> Vec<Self::Item>;
+}
+
 /// Wrapper under ``String`` type.
 ///
 /// # Examples
@@ -217,6 +240,15 @@ impl ParseFragment for EString {
     }
 }
 
+impl Aggregatable for EString {
+    type Item = Self;
+
+    #[inline]
+    fn items(self) -> Vec<Self::Item> {
+        vec![self]
+    }
+}
+
 impl ParseFragment for String {
     #[inline]
     fn parse_frag(es: EString) -> crate::Result<Self> {
@@ -231,6 +263,15 @@ impl ToEString for String {
     }
 }
 
+impl Aggregatable for String {
+    type Item = Self;
+
+    #[inline]
+    fn items(self) -> Vec<Self::Item> {
+        vec![self]
+    }
+}
+
 impl ParseFragment for &'static str {
     #[inline]
     fn parse_frag(es: EString) -> crate::Result<Self> {
@@ -245,6 +286,15 @@ impl<'a> ToEString for &'a str {
     }
 }
 
+impl<'a> Aggregatable for &'a str {
+    type Item = Self;
+
+    #[inline]
+    fn items(self) -> Vec<Self::Item> {
+        vec![self]
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/std/bool.rs

@@ -1,4 +1,4 @@
-use crate::core::{EString, ParseFragment, ToEString};
+use crate::core::{Aggregatable, EString, ParseFragment, ToEString};
 use crate::error::{Error, Reason};
 
 impl ParseFragment for bool {
@@ -19,6 +19,15 @@ impl ToEString for bool {
     }
 }
 
+impl Aggregatable for bool {
+    type Item = Self;
+
+    #[inline]
+    fn items(self) -> Vec<Self::Item> {
+        vec![self]
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/std/number.rs

@@ -1,4 +1,4 @@
-use crate::core::{EString, ParseFragment, ToEString};
+use crate::core::{Aggregatable, EString, ParseFragment, ToEString};
 use crate::error::{Error, Reason};
 
 #[doc(hidden)]
@@ -18,6 +18,15 @@ macro_rules! from_env_string_numbers_impl {
                     EString(self.to_string())
                 }
             }
+
+            impl Aggregatable for $ty {
+                type Item = Self;
+
+                #[inline]
+                fn items(self) -> Vec<Self::Item> {
+                    vec![self]
+                }
+            }
         )+
     };
 }

src/std/option.rs

@@ -1,4 +1,4 @@
-use crate::core::{EString, ParseFragment, ToEString};
+use crate::core::{Aggregatable, EString, ParseFragment, ToEString};
 
 impl<T> ToEString for Option<T>
 where
@@ -25,6 +25,17 @@ where
     }
 }
 
+impl<T> Aggregatable for Option<T>
+where
+    T: Aggregatable,
+{
+    type Item = T::Item;
+
+    fn items(self) -> Vec<Self::Item> {
+        self.map(T::items).unwrap_or_default()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/structs/sep_vec.rs

@@ -1,7 +1,7 @@
 //! Contains the implementations to vec type
 //!
 
-use crate::core::{EString, ParseFragment, ToEString};
+use crate::core::{Aggregatable, EString, ParseFragment, ToEString};
 use std::fmt::Write;
 
 /// Wrapper for ``Vec`` to split string by a separator (`SEP`).
@@ -92,17 +92,25 @@ where
     }
 }
 
+impl<T, const SEP: char> Aggregatable for SepVec<T, SEP>
+where
+    T: Aggregatable,
+{
+    type Item = T::Item;
+
+    fn items(self) -> Vec<Self::Item> {
+        self.0.into_iter().flat_map(T::items).collect()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::Pair;
     use crate::{Error, Reason};
 
-    const COMMA: char = ',';
-    const SEMI: char = ';';
-
-    type CommaVec<T> = SepVec<T, COMMA>;
-    type SemiVec<T> = SepVec<T, SEMI>;
+    type CommaVec<T> = SepVec<T, ','>;
+    type SemiVec<T> = SepVec<T, ';'>;
 
     #[test]
     fn should_parse_into_vec() {
@@ -171,4 +179,18 @@ d,e";
         let vec = SepVec::<_, ','>::from(vec![PlusPair::from((1, 2)), PlusPair::from((3, 4))]);
         assert_eq!(vec.to_estring(), EString(String::from("1+2,3+4")));
     }
+
+    #[test]
+    fn should_returns_aggregatable_items() {
+        let estr = EString::from("1,2,3,4,5");
+        let res = estr.parse::<CommaVec<i32>>().unwrap();
+        assert_eq!(res.items(), vec![1, 2, 3, 4, 5]);
+    }
+
+    #[test]
+    fn should_returns_flatten_aggregatable_items() {
+        let estr = EString::from("1,2; 3,4,5; 6,7");
+        let res = estr.parse::<SemiVec<CommaVec<i32>>>().unwrap();
+        assert_eq!(res.items(), vec![1, 2, 3, 4, 5, 6, 7]);
+    }
 }