[wp-trac] [WordPress Trac] #65129: Improve maintainability of DOCTYPE quirks mode detection in `WP_HTML_Doctype_Info` class

[WordPress Trac]

#65129: Improve maintainability of DOCTYPE quirks mode detection in
`WP_HTML_Doctype_Info` class
-------------------------------------------+-------------------------------
 Reporter:  baikare.sandeep007             |      Owner:  (none)
     Type:  enhancement                    |     Status:  new
 Priority:  normal                         |  Milestone:  Awaiting Review
Component:  HTML API                       |    Version:  trunk
 Severity:  normal                         |   Keywords:  has-patch needs-
  Focuses:  performance, coding-standards  |  testing
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 = Improve maintainability of DOCTYPE quirks mode detection in
 `WP_HTML_Doctype_Info` class =

 == Description

 This patch refactors the DOCTYPE quirks mode detection logic in
 `WP_HTML_Doctype_Info` by extracting the large list of legacy public
 identifier prefixes into a separate array and using a `foreach` loop
 instead of a monolithic `if` condition with multiple `str_starts_with()`
 calls chained with `||` operators.

 == Current Behavior

 The `determine_quirks_mode_from_public_identifier()` method currently
 contains a single `if` statement with over **70** conditions chained
 together using logical OR operators:

 {{{#!php
 <?php
 if (
     str_starts_with( $public_identifier, '+//silmaril//dtd html pro v0r11
 19970101//' ) ||
     str_starts_with( $public_identifier, '-//as//dtd html 3.0 aswedit +
 extensions//' ) ||
     // ... 70+ more conditions
 ) {
     $this->indicated_compatibility_mode = 'quirks';
     return;
 }
 }}}


 == Issues with Current Approach

 * Poor maintainability – Adding, removing, or modifying prefixes requires
 editing a long, sprawling conditional statement
 * Reduced readability – The logic flow is obscured by the sheer number of
 conditions
 * Difficult to test – Individual prefixes cannot be easily referenced or
 validated in isolation
 * Code duplication – The same pattern of str_starts_with() calls is
 repeated for each prefix

 == Proposed Changes

 This patch replaces the large conditional block with:

 * A single source of truth – All legacy quirks mode prefixes are now
 stored in a dedicated array $quirks_prefixes
 * Clean iteration – A foreach loop checks each prefix using
 str_starts_with()
 * Early return – When a match is found, the compatibility mode is set and
 the method exits immediately

 == Impact
 * No functional changes – The exact same set of public identifiers
 triggers quirks mode
 * Backward compatible – Behavior remains identical for all DOCTYPE
 declarations
 * Performance neutral – The loop iterates through the same number of
 checks as before
 * Improves code quality – Makes the HTML API more maintainable for future
 contributors

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Ticket URL: <https://core.trac.wordpress.org/ticket/65129>
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