From 563f18a04b44f707423ad4397272f30d7ba047e9 Mon Sep 17 00:00:00 2001
From: quake <quake.wang@gmail.com>
Date: Tue, 6 Sep 2022 14:16:15 +0900
Subject: [PATCH] pref: use `ExactSizeIterator`

---
 src/func/hashing.rs | 32 ++++++++++++++------------------
 src/module/mod.rs   |  2 +-
 2 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/src/func/hashing.rs b/src/func/hashing.rs
index 75331f66..1a79a684 100644
--- a/src/func/hashing.rs
+++ b/src/func/hashing.rs
@@ -96,18 +96,15 @@ pub fn get_hasher() -> ahash::AHasher {
 #[inline]
 #[must_use]
 pub fn calc_qualified_var_hash<'a>(
-    modules: impl IntoIterator<Item = &'a str>,
+    modules: impl IntoIterator<Item = &'a str, IntoIter = impl ExactSizeIterator<Item = &'a str>>,
     var_name: &str,
 ) -> u64 {
     let s = &mut get_hasher();
 
     // We always skip the first module
-    let mut len = 0;
-    modules
-        .into_iter()
-        .inspect(|_| len += 1)
-        .skip(1)
-        .for_each(|m| m.hash(s));
+    let iter = modules.into_iter();
+    let len = iter.len();
+    iter.skip(1).for_each(|m| m.hash(s));
     len.hash(s);
     var_name.hash(s);
 
@@ -133,19 +130,16 @@ pub fn calc_qualified_var_hash<'a>(
 #[inline]
 #[must_use]
 pub fn calc_qualified_fn_hash<'a>(
-    modules: impl IntoIterator<Item = &'a str>,
+    modules: impl IntoIterator<Item = &'a str, IntoIter = impl ExactSizeIterator<Item = &'a str>>,
     fn_name: &str,
     num: usize,
 ) -> u64 {
     let s = &mut get_hasher();
 
     // We always skip the first module
-    let mut len = 0;
-    modules
-        .into_iter()
-        .inspect(|_| len += 1)
-        .skip(1)
-        .for_each(|m| m.hash(s));
+    let iter = modules.into_iter();
+    let len = iter.len();
+    iter.skip(1).for_each(|m| m.hash(s));
     len.hash(s);
     fn_name.hash(s);
     num.hash(s);
@@ -179,11 +173,13 @@ pub fn calc_fn_hash(fn_name: &str, num: usize) -> u64 {
 /// If the hash happens to be zero, it is mapped to `DEFAULT_HASH`.
 #[inline]
 #[must_use]
-pub fn calc_fn_params_hash(params: impl IntoIterator<Item = TypeId>) -> u64 {
+pub fn calc_fn_params_hash(
+    params: impl IntoIterator<Item = TypeId, IntoIter = impl ExactSizeIterator<Item = TypeId>>,
+) -> u64 {
     let s = &mut get_hasher();
-    let mut len = 0;
-    params.into_iter().for_each(|t| {
-        len += 1;
+    let iter = params.into_iter();
+    let len = iter.len();
+    iter.for_each(|t| {
         t.hash(s);
     });
     len.hash(s);
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 51e1d0ea..0aa77a94 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -239,7 +239,7 @@ impl FuncInfo {
 /// The first module name is skipped.  Hashing starts from the _second_ module in the chain.
 #[inline]
 pub fn calc_native_fn_hash<'a>(
-    modules: impl IntoIterator<Item = &'a str>,
+    modules: impl IntoIterator<Item = &'a str, IntoIter = impl ExactSizeIterator<Item = &'a str>>,
     fn_name: &str,
     params: &[TypeId],
 ) -> u64 {