Refactored to use itertools

Found an itertools mechanism that works for iterating
through the current and next row in the cursor.

sqlite_utils/cli.py

@@ -1,6 +1,6 @@
 import click
 import sqlite_utils
-from sqlite_utils.utils import iter_pairs
+import itertools
 import json as json_std
 import sys
 import csv as csv_std
@@ -140,11 +140,12 @@ def json(path, sql, nl, arrays):
     # We have to iterate two-at-a-time so we can know if we
     # should output a trailing comma or if we have reached
     # the last row.
-    row = None
+    current_iter, next_iter = itertools.tee(cursor, 2)
+    next(next_iter, None)
     first = True
     headers = [c[0] for c in cursor.description]
-    for row, next_row, is_last in iter_pairs(cursor):
-        # We now reliably have row and next_row
+    for row, next_row in itertools.zip_longest(current_iter, next_iter):
+        is_last = next_row is None
         data = row
         if not arrays:
             data = dict(zip(headers, row))

sqlite_utils/utils.py

@@ -1,28 +0,0 @@
-def iter_pairs(iterator):
-    # Yields (item, next_item, is_last) pairs
-    # Last row is (item, None, True)
-    first = True
-    next_item = None
-    while True:
-        next_done = False
-        if first:
-            item, done = next_with_done(iterator)
-            if done:
-                break
-            next_item, next_done = next_with_done(iterator)
-            first = False
-        else:
-            item = next_item
-            next_item, next_done = next_with_done(iterator)
-
-        yield item, next_item, next_done
-
-        if next_done:
-            break
-
-
-def next_with_done(iterator):
-    try:
-        return next(iterator), False
-    except StopIteration:
-        return None, True