Merge branch 'main' into main

giosiragusa · web-flow · commit 53ec6c1e353c · 2024-07-14T11:07:48.000+02:00
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
@@ -2316,8 +2316,8 @@ Loading and running tests
    (see :ref:`Warning control <using-on-warnings>`),
    otherwise it will be set to ``'default'``.
 
-   Calling ``main`` actually returns an instance of the ``TestProgram`` class.
-   This stores the result of the tests run as the ``result`` attribute.
+   Calling ``main`` returns an object with the ``result`` attribute that contains
+   the result of the tests run as a :class:`unittest.TestResult`.
 
    .. versionchanged:: 3.1
       The *exit* parameter was added.
diff --git a/Misc/NEWS.d/next/Core and Builtins/2024-07-10-02-02-32.gh-issue-121562.8beIMi.rst b/Misc/NEWS.d/next/Core and Builtins/2024-07-10-02-02-32.gh-issue-121562.8beIMi.rst
@@ -0,0 +1,2 @@
+Optimized performance of hex_from_char by replacing switch-case with a
+lookup table
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
@@ -1142,69 +1142,39 @@ char_from_hex(int x)
     return Py_hexdigits[x];
 }
 
+/* This table maps characters to their hexadecimal values, only
+ * works with encodings whose lower half is ASCII (like UTF-8).
+ * '0' maps to 0, ..., '9' maps to 9.
+ * 'a' and 'A' map to 10, ..., 'f' and 'F' map to 15.
+ * All other indices map to -1.
+ */
+static const int
+_CHAR_TO_HEX[256] = {
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  -1, -1, -1, -1, -1, -1,
+    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+};
+
+/* Convert a character to its hexadecimal value, or -1 if it's not a
+ * valid hexadecimal character, only works with encodings whose lower
+ * half is ASCII (like UTF-8).
+ */
 static int
-hex_from_char(char c) {
-    int x;
-    switch(c) {
-    case '0':
-        x = 0;
-        break;
-    case '1':
-        x = 1;
-        break;
-    case '2':
-        x = 2;
-        break;
-    case '3':
-        x = 3;
-        break;
-    case '4':
-        x = 4;
-        break;
-    case '5':
-        x = 5;
-        break;
-    case '6':
-        x = 6;
-        break;
-    case '7':
-        x = 7;
-        break;
-    case '8':
-        x = 8;
-        break;
-    case '9':
-        x = 9;
-        break;
-    case 'a':
-    case 'A':
-        x = 10;
-        break;
-    case 'b':
-    case 'B':
-        x = 11;
-        break;
-    case 'c':
-    case 'C':
-        x = 12;
-        break;
-    case 'd':
-    case 'D':
-        x = 13;
-        break;
-    case 'e':
-    case 'E':
-        x = 14;
-        break;
-    case 'f':
-    case 'F':
-        x = 15;
-        break;
-    default:
-        x = -1;
-        break;
-    }
-    return x;
+hex_from_char(unsigned char c) {
+    return _CHAR_TO_HEX[c];
 }
 
 /* convert a float to a hexadecimal string */

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Optimized performance of hex_from_char by replacing switch-case with a`
	`2`	`+lookup table`