LAL: add def local variable support with toJson/toJsonArray and type cast

[wu-sheng]

Add def local variable support in LAL DSL

• Update the documentation to include this new feature.
• Tests(including UT, IT, E2E) are added to verify the new feature.

Grammar: def varName = expression with optional as TypeName cast (built-in types or FQCN).

Built-in functions: toJson() converts String/Map/protobuf Struct to Gson JsonObject; toJsonArray() converts to JsonArray.

Type inference: Variable type inferred at compile time from initializer expression. Supports null-safe navigation (?.) and method chaining on the inferred type. Optional as cast narrows type when the inferred type is too general (e.g., Object from generic API).

Runtime helpers: LalRuntimeHelper.toJsonObject() overloads for String, Map, and protobuf Struct (recursive field conversion).

Test reorganization: Split monolithic LALClassGeneratorTest (641 lines) into 5 scoped test classes:

• LALClassGeneratorBasicTest (10 tests)
• LALClassGeneratorConditionTest (10 tests)
• LALClassGeneratorExtractorTest (10 tests)
• LALClassGeneratorDefTest (10 tests)
• LALClassGeneratorSinkTest (5 tests)

Plus shared LALClassGeneratorTestBase with .class file output to target/lal-generated-classes/ and {TestClass}_{testMethod} naming.

ALS-specific tests: EnvoyAlsLalTest in envoy receiver module — 3 tests for JWT extraction from proto filter_metadata via chained def variables.

• Update the CHANGES log.

[Copilot]

Pull request overview

Adds def local variables to the LAL DSL, including compile-time type inference and optional as TypeName casts, plus JSON helper functions (toJson/toJsonArray) and reorganized test coverage to validate parsing, codegen, and execution.

Changes:

• Extend LAL grammar/model/parser/codegen to support def var = expression with optional as casts (built-ins + qualified names).
• Introduce runtime JSON conversion helpers in LalRuntimeHelper and add Gson dependency.
• Add/reshape tests and script-based execution cases (including Envoy ALS-specific coverage) and update docs/changes log.

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
test/script-cases/scripts/lal/test-lal/feature-cases/execution-def.yaml	New script-case rules exercising def + toJson chains and safe navigation.
test/script-cases/scripts/lal/test-lal/feature-cases/execution-def.input.data	New script-case inputs/expected outputs for execution-def.yaml.
oap-server/server-receiver-plugin/envoy-metrics-receiver-plugin/src/test/java/org/apache/skywalking/oap/server/receiver/envoy/persistence/EnvoyAlsLalTest.java	New ALS-focused integration-style tests for chained def + toJson on proto Struct.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALScriptParserTest.java	Adds parser tests for def statements, toJson/toJsonArray, and qualified-name casts.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALExpressionExecutionTest.java	Updates assertions to consider output-builder stored standard fields.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorTestBase.java	New shared base for generator tests, with .class dump support and naming.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorTest.java	Removes the monolithic generator test class (split into scoped tests).
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorSinkTest.java	New scoped tests for sink/sampler/rateLimit/interpolation.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorExtractorTest.java	New scoped tests for extractor behaviors (ProcessRegistry, metrics, input/output types).
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorDefTest.java	New scoped tests for def type inference + toJson/toJsonArray codegen.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorConditionTest.java	New scoped tests for conditions/safe-nav/tag()/else-if generation.
oap-server/analyzer/log-analyzer/src/test/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGeneratorBasicTest.java	New scoped tests for basic compilation and error handling.
oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/rt/LalRuntimeHelper.java	Adds Gson-based JSON conversion helpers (toJsonObject/toJsonArray) + Struct conversion.
oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALScriptParser.java	Adds parsing for def and qualified-name casts.
oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALScriptModel.java	Introduces DefStatement in the AST model.
oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGenerator.java	Tracks def locals in codegen context and includes them in LVT + execute method generation.
oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALBlockCodegen.java	Implements def declaration/assignment codegen, typed chain resolution, and safe-nav updates.
oap-server/analyzer/log-analyzer/src/main/antlr4/org/apache/skywalking/lal/rt/grammar/LALParser.g4	Extends grammar with defStatement and qualified-name casts.
oap-server/analyzer/log-analyzer/src/main/antlr4/org/apache/skywalking/lal/rt/grammar/LALLexer.g4	Adds DEF keyword token.
oap-server/analyzer/log-analyzer/pom.xml	Adds Gson dependency for runtime JSON conversions.
oap-server/analyzer/log-analyzer/CLAUDE.md	Updates contributor guide with new test layout and def design notes.
docs/en/concepts-and-designs/lal.md	Documents def, type inference/casts, and toJson/toJsonArray functions; updates builder init signature docs.
docs/en/changes/changes.md	Records new def feature and LALOutputBuilder.init() signature breaking change.

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[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 3 comments.

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