Skip to content

Fix merge_styles for proper ordering of styles w.r.t. "constituent" styles #267

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Open
earshinov wants to merge 4 commits into
base: master
Choose a base branch
from
Open

Fix merge_styles for proper ordering of styles w.r.t. "constituent" styles #267

earshinov wants to merge 4 commits into from

Conversation

@earshinov
Copy link

@earshinov earshinov commented Oct 31, 2021

"Constituent" styles are, for example, margin-bottom for margin.

Rationale

To illustrate the problem, suppose you have this HTML:

<style>
	.c {
		display: inline-block;
		width: 50px;
		height: 50px;
		border: 5px solid red;
		border-bottom-width: 10px;
	}
</style>
<div class="c" style="border: 1px solid blue;"></div>
<!-- Effective style: border: 1px solid blue; -->

input

After "premailing" with the current version, this becomes

<html>
  <head></head>
  <body>
    <div class="c" style="display:inline-block; width:50px; height:50px; border:1px solid blue; border-bottom-width:10px" width="50" height="50"></div>
    <!-- Effective style: border: 1px solid blue; border-bottom-width: 10px; -->
  </body>
</html>

actual_output

what is obviously wrong. The desired output would be:

<html>
  <head></head>
  <body>
    <div class="c" style="display:inline-block; width:50px; height:50px; border-bottom-width:10px; border:1px solid blue" width="50" height="50"></div>
    <!-- Effective style: border: 1px solid blue; -->
  </body>
</html>

Note the ordering of border and border-bottom-width.

Suggested fix

The underlying reason for this error is that when you assign to an existing key in OrderedDict, it replaces the value in-place instead of appending it to the end. That is,

>>> import collections
>>> d = collections.OrderedDict((("a", 1), ("b", 2)))
>>> d["a"] = 3
>>> d
OrderedDict([('a', 3), ('b', 2)])

This way, the inline border style in the example takes place of the border style inherited from the .c class, and gets lesser priority than border-bottom-width.

The simplest fix to achieve the desired behavior would be to del the key from the OrderedDict first.

PR contents

PR contains a fix and a unit test failing without the fix.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

1 more reviewer

@samjack2233 samjack2233 samjack2233 approved these changes

Reviewers whose approvals may not affect merge requirements

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@earshinov @samjack2233