[gmpassos]

Faster createInstanceFromMap / JsonDecoder entity decoding, mostly for code compiled to JavaScript (the browser), and also on Wasm and the VM. The created instances are the same.

Changes

• Direct calls with a fieldValueResolver. A constructor that can be called directly (canInvokeFromResolvedMap) is now also called with the values revived by a fieldValueResolver, once per parameter, instead of through MethodInvocation (_revivedMapArguments). Unresolved values (a non-null value revived to null, or an entity list with a null) and resolvers that throw still take the MethodInvocation path, which resolves them again and reports them as before.
• Maps of the same shape. The fields-to-keys resolution, best constructors and fields to set are kept for the last map shape of each class (the same keys, in the same order, and the same FieldNameResolver), and reused for the next maps of that shape. FieldNameResolver now documents that its result must depend only on the field name and the map keys.
• createInstanceFromMap direct path: for a map of the last shape with a single constructor, the constructor is called without the intermediate calls. A constructor error is reported as before, without a second call. The helpers are static, because dart2js (without --omit-implicit-checks) checks the parameter types of instance methods on every call, and of static functions it doesn't.
• JsonDecoder: a decoded JSON object (Map<String, dynamic>) is no longer copied before decoding (is Map<String, Object> was false for it).
• JsonEntityCacheSimple.getEntityID: the ID field is found once per type.
• ClassReflection.getField(name, obj): no FieldReflection is allocated per call.

Benchmark

bones_api's benchmark/db_users/bin/json_decode_benchmark.dart decodes a JSON list of 1000 users (each with an address and 2 roles) as a module proxy does. µs per user:

Target	2.12.2	2.13.0
JavaScript (dart2js -O1 --minify, the webdev build --release default)	27.4	11.8 (−57%)
Wasm (dart2wasm -O2 --minify)	6.5	3.7 (−42%)
VM	7.5	3.9 (−48%)

These include the bones_api changes in its companion PR. The reflection_factory part is most of it, about −45% in JS.

Tests

581 pass (dart test). The instantiation and JSON tests also pass compiled to JS (-p node). New tests cover:

• revived values: called once per parameter, unresolved values, resolvers that throw, constructor errors
• maps of the same shape in sequence, compared with each map decoded alone, for both constructors and setters, with and without resolvers
• a resolver of another identity on the same shape
• getField of another object
• getEntityID

The existing equivalence helpers now also compare against the legacy MethodInvocation path with a reviver.

v2.13.0: version bumped, generated code regenerated (version lines only), CHANGELOG added.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.65%. Comparing base (eb94ee8) to head (d6d0d19).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #61      +/-   ##
==========================================
+ Coverage   93.55%   93.65%   +0.10%     
==========================================
  Files          14       14              
  Lines        6544     6652     +108     
==========================================
+ Hits         6122     6230     +108     
  Misses        422      422              

Flag	Coverage Δ
unittests	93.65% <100.00%> (+0.10%)	⬆️

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