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Merged
merged 4 commits into from
May 28, 2025
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gh-134580: Modernizing difflib.HtmlDiff for HTML Output #134581

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c022435
Improved the styling of HTML diff pages generated by the `difflib.Htm…
Wulian233 May 23, 2025
1288aa1
vertical padding removed
Wulian233 May 23, 2025
66cdcb5
Casing
hugovk May 27, 2025
102a544
casting
Wulian233 May 27, 2025
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7 changes: 7 additions & 0 deletions Doc/whatsnew/3.15.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,13 @@ New modules
Improved modules
================

difflib
-------

* Improved the styling of HTML diff pages generated by the :class:`difflib.HtmlDiff`
class, and migrated the output to the HTML5 standard.
(Contributed by Jiahao Li in :gh:`134580`.)

ssl
---

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50 changes: 36 additions & 14 deletions Lib/difflib.py
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Expand Up @@ -1615,16 +1615,13 @@ def _line_pair_iterator():


_file_template = """
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>

<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=%(charset)s" />
<title></title>
<style type="text/css">%(styles)s
<meta charset="%(charset)s">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Diff comparison</title>
<style>%(styles)s
</style>
</head>

Expand All @@ -1636,20 +1633,45 @@ def _line_pair_iterator():

_styles = """
:root {color-scheme: light dark}
table.diff {font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace; border:medium}
.diff_header {background-color:#e0e0e0}
td.diff_header {text-align:right}
.diff_next {background-color:#c0c0c0}
table.diff {
font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
border: medium;
}
.diff_header {
background-color: #e0e0e0;
font-weight: bold;
}
td.diff_header {
text-align: right;
padding: 0 8px;
}
.diff_next {
background-color: #c0c0c0;
padding: 4px 0;
}
.diff_add {background-color:palegreen}
.diff_chg {background-color:#ffff77}
.diff_sub {background-color:#ffaaaa}
table.diff[summary="Legends"] {
margin-top: 20px;
border: 1px solid #ccc;
}
table.diff[summary="Legends"] th {
background-color: #e0e0e0;
padding: 4px 8px;
}
table.diff[summary="Legends"] td {
padding: 4px 8px;
}

@media (prefers-color-scheme: dark) {
.diff_header {background-color:#666}
.diff_next {background-color:#393939}
.diff_add {background-color:darkgreen}
.diff_chg {background-color:#847415}
.diff_sub {background-color:darkred}
table.diff[summary="Legends"] {border-color:#555}
table.diff[summary="Legends"] th{background-color:#666}
}"""

_table_template = """
Expand Down Expand Up @@ -1692,7 +1714,7 @@ class HtmlDiff(object):
make_table -- generates HTML for a single side by side table
make_file -- generates complete HTML file with a single side by side table

See tools/scripts/diff.py for an example usage of this class.
See Doc/includes/diff.py for an example usage of this class.
"""

_file_template = _file_template
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6 changes: 3 additions & 3 deletions Lib/test/test_difflib.py
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Expand Up @@ -255,21 +255,21 @@ def test_make_file_default_charset(self):
html_diff = difflib.HtmlDiff()
output = html_diff.make_file(patch914575_from1.splitlines(),
patch914575_to1.splitlines())
self.assertIn('content="text/html; charset=utf-8"', output)
self.assertIn('charset="utf-8"', output)

def test_make_file_iso88591_charset(self):
html_diff = difflib.HtmlDiff()
output = html_diff.make_file(patch914575_from1.splitlines(),
patch914575_to1.splitlines(),
charset='iso-8859-1')
self.assertIn('content="text/html; charset=iso-8859-1"', output)
self.assertIn('charset="iso-8859-1"', output)

def test_make_file_usascii_charset_with_nonascii_input(self):
html_diff = difflib.HtmlDiff()
output = html_diff.make_file(patch914575_nonascii_from1.splitlines(),
patch914575_nonascii_to1.splitlines(),
charset='us-ascii')
self.assertIn('content="text/html; charset=us-ascii"', output)
self.assertIn('charset="us-ascii"', output)
self.assertIn('&#305;mpl&#305;c&#305;t', output)

class TestDiffer(unittest.TestCase):
Expand Down
48 changes: 35 additions & 13 deletions Lib/test/test_difflib_expect.html
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Original file line number Diff line number Diff line change
@@ -1,29 +1,51 @@

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>

<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=utf-8" />
<title></title>
<style type="text/css">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Diff comparison</title>
<style>
:root {color-scheme: light dark}
table.diff {font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace; border:medium}
.diff_header {background-color:#e0e0e0}
td.diff_header {text-align:right}
.diff_next {background-color:#c0c0c0}
table.diff {
font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
border: medium;
}
.diff_header {
background-color: #e0e0e0;
font-weight: bold;
}
td.diff_header {
text-align: right;
padding: 0 8px;
}
.diff_next {
background-color: #c0c0c0;
padding: 4px 0;
}
.diff_add {background-color:palegreen}
.diff_chg {background-color:#ffff77}
.diff_sub {background-color:#ffaaaa}
table.diff[summary="Legends"] {
margin-top: 20px;
border: 1px solid #ccc;
}
table.diff[summary="Legends"] th {
background-color: #e0e0e0;
padding: 4px 8px;
}
table.diff[summary="Legends"] td {
padding: 4px 8px;
}

@media (prefers-color-scheme: dark) {
.diff_header {background-color:#666}
.diff_next {background-color:#393939}
.diff_add {background-color:darkgreen}
.diff_chg {background-color:#847415}
.diff_sub {background-color:darkred}
table.diff[summary="Legends"] {border-color:#555}
table.diff[summary="Legends"] th{background-color:#666}
}
</style>
</head>
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2025-05-23-20-01-52.gh-issue-134580.xnaJ70.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Improved the styling of HTML diff pages generated by the
:class:`difflib.HtmlDiff` class, and migrated the output to the HTML5
standard.
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