Cleanup BlockSplitIterator

* Use methods instead of fns
* delete unused `InitBlockSplitIterator`

Author: nyurik

src/enc/histogram.rs

@@ -333,44 +333,30 @@ pub struct BlockSplitIterator<'a, Alloc: alloc::Allocator<u8> + 'a + alloc::Allo
     pub length_: usize,
 }
 
-fn NewBlockSplitIterator<'a, Alloc: alloc::Allocator<u8> + alloc::Allocator<u32>>(
-    split: &'a BlockSplit<Alloc>,
-) -> BlockSplitIterator<'a, Alloc> {
-    return BlockSplitIterator::<'a> {
-        split_: split,
-        idx_: 0usize,
-        type_: 0usize,
-        length_: if !split.lengths.slice().is_empty() {
-            split.lengths.slice()[0] as usize
-        } else {
-            0usize
-        },
-    };
-}
-
-fn InitBlockSplitIterator<'a, Alloc: alloc::Allocator<u8> + alloc::Allocator<u32>>(
-    xself: &'a mut BlockSplitIterator<'a, Alloc>,
-    split: &'a BlockSplit<Alloc>,
-) {
-    xself.split_ = split;
-    xself.idx_ = 0usize;
-    xself.type_ = 0usize;
-    xself.length_ = if !split.lengths.slice().is_empty() {
-        split.lengths.slice()[0]
-    } else {
-        0u32
-    } as usize;
-}
-fn BlockSplitIteratorNext<'a, Alloc: alloc::Allocator<u8> + alloc::Allocator<u32>>(
-    xself: &mut BlockSplitIterator<Alloc>,
-) {
-    if xself.length_ == 0usize {
-        xself.idx_ = xself.idx_.wrapping_add(1);
-        xself.type_ = xself.split_.types.slice()[xself.idx_] as usize;
-        xself.length_ = xself.split_.lengths.slice()[xself.idx_] as usize;
+impl<'a, Alloc: alloc::Allocator<u8> + alloc::Allocator<u32> + 'a> BlockSplitIterator<'a, Alloc> {
+    fn new(split: &'a BlockSplit<Alloc>) -> Self {
+        Self {
+            split_: split,
+            idx_: 0,
+            type_: 0,
+            length_: if !split.lengths.slice().is_empty() {
+                split.lengths.slice()[0] as usize
+            } else {
+                0
+            },
+        }
+    }
+
+    fn next(&mut self) {
+        if self.length_ == 0 {
+            self.idx_ = self.idx_.wrapping_add(1);
+            self.type_ = self.split_.types.slice()[self.idx_] as usize;
+            self.length_ = self.split_.lengths.slice()[self.idx_] as usize;
+        }
+        self.length_ = self.length_.wrapping_sub(1);
     }
-    xself.length_ = xself.length_.wrapping_sub(1);
 }
+
 pub fn HistogramAddItem<HistogramType: SliceWrapper<u32> + SliceWrapperMut<u32> + CostAccessors>(
     xself: &mut HistogramType,
     val: usize,
@@ -499,21 +485,21 @@ pub fn BrotliBuildHistogramsWithContext<'a, Alloc: alloc::Allocator<u8> + alloc:
     let mut literal_it: BlockSplitIterator<Alloc>;
     let mut insert_and_copy_it: BlockSplitIterator<Alloc>;
     let mut dist_it: BlockSplitIterator<Alloc>;
-    literal_it = NewBlockSplitIterator(literal_split);
-    insert_and_copy_it = NewBlockSplitIterator(insert_and_copy_split);
-    dist_it = NewBlockSplitIterator(dist_split);
+    literal_it = BlockSplitIterator::new(literal_split);
+    insert_and_copy_it = BlockSplitIterator::new(insert_and_copy_split);
+    dist_it = BlockSplitIterator::new(dist_split);
     for i in 0usize..num_commands {
         let cmd = &cmds[i];
         let mut j: usize;
-        BlockSplitIteratorNext(&mut insert_and_copy_it);
+        insert_and_copy_it.next();
         HistogramAddItem(
             &mut insert_and_copy_histograms[insert_and_copy_it.type_],
             cmd.cmd_prefix_ as usize,
         );
         j = cmd.insert_len_ as usize;
         while j != 0usize {
             {
-                BlockSplitIteratorNext(&mut literal_it);
+                literal_it.next();
                 let context: usize = if !context_modes.is_empty() {
                     (literal_it.type_ << 6).wrapping_add(Context(
                         prev_byte,
@@ -538,7 +524,7 @@ pub fn BrotliBuildHistogramsWithContext<'a, Alloc: alloc::Allocator<u8> + alloc:
             prev_byte2 = ringbuffer[(pos.wrapping_sub(2) & mask)];
             prev_byte = ringbuffer[(pos.wrapping_sub(1) & mask)];
             if cmd.cmd_prefix_ as i32 >= 128i32 {
-                BlockSplitIteratorNext(&mut dist_it);
+                dist_it.next();
                 let context: usize =
                     (dist_it.type_ << 2).wrapping_add(cmd.distance_context() as usize);
                 HistogramAddItem(