From: Raymond Hettinger <python@rcn.com>
Date: Thu, 4 Mar 2004 08:00:54 +0000 (+0000)
Subject: Special case endpoint access for speed.
X-Git-Tag: v2.4a1~746
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6c79a518e70ea8e45e3287573d99c648ae3cb21b;p=python

Special case endpoint access for speed.
---

diff --git a/Modules/collectionsmodule.c b/Modules/collectionsmodule.c
index f7fb91ff78..ddc6f88461 100644
--- a/Modules/collectionsmodule.c
+++ b/Modules/collectionsmodule.c
@@ -326,18 +326,26 @@ deque_item(dequeobject *deque, int i)
 		return NULL;
 	}
 
-	i += deque->leftindex;
-	n = i / BLOCKLEN;
-	i %= BLOCKLEN;
-	if (i < (deque->len >> 1)) {
+	if (i == 0) {
+		i = deque->leftindex;
 		b = deque->leftblock;
-		while (n--)
-			b = b->rightlink;
-	} else {
-		n = (deque->leftindex + deque->len - 1) / BLOCKLEN - n;
+	} else if (i == deque->len - 1) {
+		i = deque->rightindex;
 		b = deque->rightblock;
-		while (n--)
-			b = b->leftlink;
+	} else {
+		i += deque->leftindex;
+		n = i / BLOCKLEN;
+		i %= BLOCKLEN;
+		if (i < (deque->len >> 1)) {
+			b = deque->leftblock;
+			while (n--)
+				b = b->rightlink;
+		} else {
+			n = (deque->leftindex + deque->len - 1) / BLOCKLEN - n;
+			b = deque->rightblock;
+			while (n--)
+				b = b->leftlink;
+		}
 	}
 	item = b->data[i];
 	Py_INCREF(item);