Auto merge of #23293 - tbu-:pr_additive_multiplicative, r=alexcrichton

Previously it could not be implemented for types outside `libcore/iter.rs` due
to coherence issues.

Author: bors

Diff for: src/libcollections/slice.rs

@@ -85,7 +85,6 @@ use core::clone::Clone;
 use core::cmp::Ordering::{self, Greater, Less};
 use core::cmp::{self, Ord, PartialEq};
 use core::iter::Iterator;
-use core::iter::MultiplicativeIterator;
 use core::marker::Sized;
 use core::mem::size_of;
 use core::mem;
@@ -1182,7 +1181,7 @@ impl Iterator for ElementSwaps {
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
         // For a vector of size n, there are exactly n! permutations.
-        let n = (2..self.sdir.len() + 1).product();
+        let n: usize = (2..self.sdir.len() + 1).product();
         (n - self.swaps_made, Some(n - self.swaps_made))
     }
 }

Diff for: src/libcollections/str.rs

@@ -53,7 +53,6 @@ use self::RecompositionState::*;
 use self::DecompositionType::*;
 
 use core::clone::Clone;
-use core::iter::AdditiveIterator;
 use core::iter::{Iterator, Extend};
 use core::option::Option::{self, Some, None};
 use core::result::Result;
@@ -116,7 +115,7 @@ impl<S: AsRef<str>> SliceConcatExt<str, String> for [S] {
         // this is wrong without the guarantee that `self` is non-empty
         // `len` calculation may overflow but push_str but will check boundaries
         let len = sep.len() * (self.len() - 1)
-            + self.iter().map(|s| s.as_ref().len()).sum();
+            + self.iter().map(|s| s.as_ref().len()).sum::<usize>();
         let mut result = String::with_capacity(len);
         let mut first = true;
 

Diff for: src/libcollectionstest/str.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use std::cmp::Ordering::{Equal, Greater, Less};
-use std::iter::AdditiveIterator;
 use std::str::{Utf8Error, from_utf8};
 
 #[test]

Diff for: src/libcore/iter.rs

@@ -65,7 +65,7 @@ use default::Default;
 use marker;
 use mem;
 use num::{Int, Zero, One};
-use ops::{self, Add, Sub, FnMut, RangeFrom};
+use ops::{self, Add, Sub, FnMut, Mul, RangeFrom};
 use option::Option::{self, Some, None};
 use marker::Sized;
 use usize;
@@ -489,15 +489,14 @@ pub trait Iterator {
     ///
     /// ```
     /// # #![feature(core)]
-    /// use std::iter::AdditiveIterator;
     ///
     /// let a = [1, 4, 2, 3, 8, 9, 6];
-    /// let sum = a.iter()
-    ///            .map(|x| *x)
-    ///            .inspect(|&x| println!("filtering {}", x))
-    ///            .filter(|&x| x % 2 == 0)
-    ///            .inspect(|&x| println!("{} made it through", x))
-    ///            .sum();
+    /// let sum: i32 = a.iter()
+    ///                 .map(|x| *x)
+    ///                 .inspect(|&x| println!("filtering {}", x))
+    ///                 .filter(|&x| x % 2 == 0)
+    ///                 .inspect(|&x| println!("{} made it through", x))
+    ///                 .sum();
     /// println!("{}", sum);
     /// ```
     #[inline]
@@ -1022,6 +1021,47 @@ pub trait Iterator {
             }
         }
     }
+
+    /// Iterates over the entire iterator, summing up all the elements
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(core)]
+    ///
+    /// let a = [1, 2, 3, 4, 5];
+    /// let mut it = a.iter().cloned();
+    /// assert!(it.sum::<i32>() == 15);
+    /// ```
+    #[unstable(feature="core")]
+    fn sum<S=<Self as Iterator>::Item>(self) -> S where
+        S: Add<Self::Item, Output=S> + Zero,
+        Self: Sized,
+    {
+        self.fold(Zero::zero(), |s, e| s + e)
+    }
+
+    /// Iterates over the entire iterator, multiplying all the elements
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(core)]
+    ///
+    /// fn factorial(n: u32) -> u32 {
+    ///     (1..).take_while(|&i| i <= n).product()
+    /// }
+    /// assert!(factorial(0) == 1);
+    /// assert!(factorial(1) == 1);
+    /// assert!(factorial(5) == 120);
+    /// ```
+    #[unstable(feature="core")]
+    fn product<P=<Self as Iterator>::Item>(self) -> P where
+        P: Mul<Self::Item, Output=P> + One,
+        Self: Sized,
+    {
+        self.fold(One::one(), |p, e| p * e)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1222,95 +1262,6 @@ impl<I> RandomAccessIterator for Rev<I>
     }
 }
 
-/// A trait for iterators over elements which can be added together
-#[unstable(feature = "core",
-           reason = "needs to be re-evaluated as part of numerics reform")]
-pub trait AdditiveIterator<A> {
-    /// Iterates over the entire iterator, summing up all the elements
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # #![feature(core)]
-    /// use std::iter::AdditiveIterator;
-    ///
-    /// let a = [1, 2, 3, 4, 5];
-    /// let mut it = a.iter().cloned();
-    /// assert!(it.sum() == 15);
-    /// ```
-    fn sum(self) -> A;
-}
-
-macro_rules! impl_additive {
-    ($A:ty, $init:expr) => {
-        #[unstable(feature = "core", reason = "trait is experimental")]
-        impl<T: Iterator<Item=$A>> AdditiveIterator<$A> for T {
-            #[inline]
-            fn sum(self) -> $A {
-                self.fold($init, |acc, x| acc + x)
-            }
-        }
-    };
-}
-impl_additive! { i8,   0 }
-impl_additive! { i16,  0 }
-impl_additive! { i32,  0 }
-impl_additive! { i64,  0 }
-impl_additive! { isize,  0 }
-impl_additive! { u8,   0 }
-impl_additive! { u16,  0 }
-impl_additive! { u32,  0 }
-impl_additive! { u64,  0 }
-impl_additive! { usize, 0 }
-impl_additive! { f32,  0.0 }
-impl_additive! { f64,  0.0 }
-
-/// A trait for iterators over elements which can be multiplied together.
-#[unstable(feature = "core",
-           reason = "needs to be re-evaluated as part of numerics reform")]
-pub trait MultiplicativeIterator<A> {
-    /// Iterates over the entire iterator, multiplying all the elements
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # #![feature(core)]
-    /// use std::iter::MultiplicativeIterator;
-    ///
-    /// fn factorial(n: usize) -> usize {
-    ///     (1..).take_while(|&i| i <= n).product()
-    /// }
-    /// assert!(factorial(0) == 1);
-    /// assert!(factorial(1) == 1);
-    /// assert!(factorial(5) == 120);
-    /// ```
-    fn product(self) -> A;
-}
-
-macro_rules! impl_multiplicative {
-    ($A:ty, $init:expr) => {
-        #[unstable(feature = "core", reason = "trait is experimental")]
-        impl<T: Iterator<Item=$A>> MultiplicativeIterator<$A> for T {
-            #[inline]
-            fn product(self) -> $A {
-                self.fold($init, |acc, x| acc * x)
-            }
-        }
-    };
-}
-impl_multiplicative! { i8,   1 }
-impl_multiplicative! { i16,  1 }
-impl_multiplicative! { i32,  1 }
-impl_multiplicative! { i64,  1 }
-impl_multiplicative! { isize,  1 }
-impl_multiplicative! { u8,   1 }
-impl_multiplicative! { u16,  1 }
-impl_multiplicative! { u32,  1 }
-impl_multiplicative! { u64,  1 }
-impl_multiplicative! { usize, 1 }
-impl_multiplicative! { f32,  1.0 }
-impl_multiplicative! { f64,  1.0 }
-
 /// `MinMaxResult` is an enum returned by `min_max`. See `Iterator::min_max` for
 /// more detail.
 #[derive(Clone, PartialEq, Debug)]

Diff for: src/libcore/num/mod.rs

@@ -86,6 +86,20 @@ macro_rules! zero_one_impl {
 }
 zero_one_impl! { u8 u16 u32 u64 usize i8 i16 i32 i64 isize }
 
+macro_rules! zero_one_impl_float {
+    ($($t:ty)*) => ($(
+        impl Zero for $t {
+            #[inline]
+            fn zero() -> $t { 0.0 }
+        }
+        impl One for $t {
+            #[inline]
+            fn one() -> $t { 1.0 }
+        }
+    )*)
+}
+zero_one_impl_float! { f32 f64 }
+
 /// A built-in signed or unsigned integer.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[deprecated(since = "1.0.0",

Diff for: src/libcoretest/iter.rs

@@ -329,17 +329,17 @@ fn test_iterator_len() {
 #[test]
 fn test_iterator_sum() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-    assert_eq!(v[..4].iter().cloned().sum(), 6);
-    assert_eq!(v.iter().cloned().sum(), 55);
-    assert_eq!(v[..0].iter().cloned().sum(), 0);
+    assert_eq!(v[..4].iter().cloned().sum::<i32>(), 6);
+    assert_eq!(v.iter().cloned().sum::<i32>(), 55);
+    assert_eq!(v[..0].iter().cloned().sum::<i32>(), 0);
 }
 
 #[test]
 fn test_iterator_product() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-    assert_eq!(v[..4].iter().cloned().product(), 0);
-    assert_eq!(v[1..5].iter().cloned().product(), 24);
-    assert_eq!(v[..0].iter().cloned().product(), 1);
+    assert_eq!(v[..4].iter().cloned().product::<i32>(), 0);
+    assert_eq!(v[1..5].iter().cloned().product::<i32>(), 24);
+    assert_eq!(v[..0].iter().cloned().product::<i32>(), 1);
 }
 
 #[test]

Diff for: src/librustc/middle/check_match.rs

@@ -26,7 +26,7 @@ use middle::ty::*;
 use middle::ty;
 use std::cmp::Ordering;
 use std::fmt;
-use std::iter::{range_inclusive, AdditiveIterator, FromIterator, IntoIterator, repeat};
+use std::iter::{range_inclusive, FromIterator, IntoIterator, repeat};
 use std::slice;
 use syntax::ast::{self, DUMMY_NODE_ID, NodeId, Pat};
 use syntax::ast_util;
@@ -76,7 +76,7 @@ impl<'a> fmt::Debug for Matrix<'a> {
             pretty_printed_matrix.iter().map(|row| row[col].len()).max().unwrap_or(0)
         }).collect();
 
-        let total_width = column_widths.iter().cloned().sum() + column_count * 3 + 1;
+        let total_width = column_widths.iter().cloned().sum::<usize>() + column_count * 3 + 1;
         let br = repeat('+').take(total_width).collect::<String>();
         try!(write!(f, "{}\n", br));
         for row in pretty_printed_matrix {

Diff for: src/librustc_trans/trans/_match.rs

@@ -220,7 +220,6 @@ use util::ppaux::{Repr, vec_map_to_string};
 
 use std;
 use std::cmp::Ordering;
-use std::iter::AdditiveIterator;
 use std::rc::Rc;
 use syntax::ast;
 use syntax::ast::{DUMMY_NODE_ID, NodeId};

Diff for: src/librustc_typeck/astconv.rs

@@ -61,7 +61,7 @@ use rscope::{self, UnelidableRscope, RegionScope, ElidableRscope,
 use util::common::{ErrorReported, FN_OUTPUT_NAME};
 use util::ppaux::{self, Repr, UserString};
 
-use std::iter::{repeat, AdditiveIterator};
+use std::iter::repeat;
 use std::rc::Rc;
 use std::slice;
 use syntax::{abi, ast, ast_util};
@@ -517,12 +517,13 @@ fn find_implied_output_region(input_tys: &[Ty], input_pats: Vec<String>)
         lifetimes_for_params.push((input_pat, accumulator.len()));
     }
 
-    let implied_output_region = if lifetimes_for_params.iter().map(|&(_, n)| n).sum() == 1 {
-        assert!(possible_implied_output_region.is_some());
-        possible_implied_output_region
-    } else {
-        None
-    };
+    let implied_output_region =
+        if lifetimes_for_params.iter().map(|&(_, n)| n).sum::<usize>() == 1 {
+            assert!(possible_implied_output_region.is_some());
+            possible_implied_output_region
+        } else {
+            None
+        };
     (implied_output_region, lifetimes_for_params)
 }
 

Diff for: src/libstd/old_path/posix.rs

@@ -15,8 +15,7 @@ use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
 use old_io::Writer;
-use iter::{AdditiveIterator, Extend};
-use iter::{Iterator, Map};
+use iter::{Extend, Iterator, Map};
 use marker::Sized;
 use option::Option::{self, Some, None};
 use result::Result::{self, Ok, Err};
@@ -351,7 +350,7 @@ impl Path {
                         Some(vec![SEP_BYTE])
                     } else {
                         let n = if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum();
+                                comps.iter().map(|v| v.len()).sum::<usize>();
                         let mut v = Vec::with_capacity(n);
                         let mut it = comps.into_iter();
                         if !is_abs {

Diff for: src/libstd/old_path/windows.rs

@@ -20,8 +20,7 @@ use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
 use old_io::Writer;
-use iter::{AdditiveIterator, Extend};
-use iter::{Iterator, Map, repeat};
+use iter::{Extend, Iterator, Map, repeat};
 use mem;
 use option::Option::{self, Some, None};
 use result::Result::{self, Ok, Err};
@@ -785,7 +784,7 @@ impl Path {
                         let prefix_ = &s[..prefix_len(prefix)];
                         let n = prefix_.len() +
                                 if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum();
+                                comps.iter().map(|v| v.len()).sum::<usize>();
                         let mut s = String::with_capacity(n);
                         match prefix {
                             Some(DiskPrefix) => {

Diff for: src/libunicode/u_str.rs

@@ -20,7 +20,7 @@ use core::prelude::*;
 
 use core::char;
 use core::cmp;
-use core::iter::{Filter, AdditiveIterator};
+use core::iter::Filter;
 use core::mem;
 use core::slice;
 use core::str::Split;

Diff for: src/rustbook/book.rs

@@ -13,7 +13,6 @@
 use std::io::prelude::*;
 use std::io::BufReader;
 use std::iter;
-use std::iter::AdditiveIterator;
 use std::path::{Path, PathBuf};
 
 pub struct BookItem {
@@ -151,7 +150,7 @@ pub fn parse_summary(input: &mut Read, src: &Path) -> Result<Book, Vec<String>>
                 '\t' => 4,
                 _ => unreachable!()
             }
-        }).sum() / 4 + 1;
+        }).sum::<usize>() / 4 + 1;
 
         if level > stack.len() + 1 {
             errors.push(format!("section '{}' is indented too deeply; \

Diff for: src/test/bench/shootout-spectralnorm.rs

@@ -43,7 +43,7 @@
 #![allow(non_snake_case)]
 #![feature(unboxed_closures, core, os)]
 
-use std::iter::{repeat, AdditiveIterator};
+use std::iter::repeat;
 use std::thread;
 use std::mem;
 use std::num::Float;

Diff for: src/test/run-pass/issue-15673.rs

@@ -12,8 +12,7 @@
 
 #![feature(core)]
 
-use std::iter::AdditiveIterator;
 fn main() {
     let x: [u64; 3] = [1, 2, 3];
-    assert_eq!(6, (0..3).map(|i| x[i]).sum());
+    assert_eq!(6, (0..3).map(|i| x[i]).sum::<u64>());
 }