Cheaper xsi:nil checks and value reads on decode

[veewee]

Q	A
Type	improvement
BC Break	no
Fixed issues

Stacked on #80.

Summary

Decoding called Xmlns::xsi() for every element it checked for xsi:nil, which builds a new object on every call, and read every element value through Locator\Node\value($element, string()). That function reads substitutedNodeValue and coerces it with Psl, but on a Dom\Element that property is already a non-nullable string.

OptionalElementEncoder::iso() now resolves the xsi namespace once per iso, and ElementValueReader reads substitutedNodeValue directly. Each change is its own commit.

Same output

The namespace string and the value read are the same as before, so decoded values and exceptions cannot change. The removed coercion could not fail, because the property is typed string. The decoded results of the 3MB workloads have the same sha1 before and after.

Stacked on #80

This branch is based on #80, which deletes DocumentToLookupArrayReader, so the diff only touches OptionalElementEncoder and ElementValueReader. I left ElementLookup::text() alone because it only runs for the _ text value. I left XsiTypeDetector alone because #82 rewrites that line.

Speed

Median of 3 interleaved rounds on the same machine, with ext-soap as the noise reference.

workload	main	this PR
3MB decode sparse, stdClass	0.491 s	0.469 s (-4.6%)
3MB decode sparse, classmap	0.911 s	0.901 s (-1.1%)
3MB decode dense, stdClass	0.271 s	0.259 s (-4.3%)
3MB decode dense, classmap	0.327 s	0.317 s (-3.3%)
DecodeBench literal x500	31.75 ms	29.56 ms (-6.9%)
DecodeBench encoded x500	47.51 ms	48.12 ms (+1.3%)
ext-soap decode literal x500	5.37 ms	5.41 ms (+0.7%)

The gain is small and only on decode. Encode stays within 3% either way.

Summary by CodeRabbit

• Refactor
  • Updated XML decoding internals while preserving existing handling of nil elements and text values.
  • XML elements continue to produce the same decoded results, with no changes to the public interface.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 0506687b-414f-411b-af7d-cb38f2fe576c

📥 Commits

Reviewing files that changed from the base of the PR and between 403a479 and 353a61c.

📒 Files selected for processing: 3

• src/Encoder/OptionalElementEncoder.php
• src/Xml/Reader/DocumentToLookupArrayReader.php
• src/Xml/Reader/ElementValueReader.php

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

📝 Walkthrough

The changes update XSI namespace lookups for nil attributes and pass substituted XML node values directly to encoder and ISO conversion methods.

Changes: XML decoding

Layer / File(s)	Summary
XSI nil-attribute lookups src/Encoder/OptionalElementEncoder.php, src/Xml/Reader/DocumentToLookupArrayReader.php	The optional-element decoder captures the XSI namespace for its nil check. The document reader uses a private namespace constant for its nil check. Both retain the existing nil="true" behavior.
Element value conversion src/Xml/Reader/ElementValueReader.php	forEncoder and forIso pass Element::substitutedNodeValue directly to their conversion methods.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Merge Risk: ⚪ Minimal · up to 353a6

XML decoding retains its prior nil handling and entity-substituted values for supported DOM elements. No concrete behavior regression is indicated, so the change appears ready to merge under normal checks.

Pre-merge checks: 5

Check name	Status	Explanation
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 3 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main changes: reducing the cost of xsi:nil checks and element value reads during decoding.

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