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<h1>N4JS Design Specification</h1>
<div class="details">
<span id="author" class="author">2019-08-08 13:15:33 CEST</span><br>
<span id="revnumber">version 0.9</span>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="introduction.html#_introduction">1. Introduction</a>
<ul class="sectlevel2">
<li><a href="introduction.html#notation">1.1. Notation</a></li>
<li><a href="introduction.html#sec:IDE_Overview">1.2. IDE Components</a>
<ul class="sectlevel3">
<li><a href="introduction.html#sec:Naming_Conventions">1.2.1. Naming Conventions</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="eclipse_setup.html#_eclipse-setup">2. Eclipse Setup</a>
<ul class="sectlevel2">
<li><a href="eclipse_setup.html#_system-requirements">2.1. System Requirements</a></li>
<li><a href="eclipse_setup.html#_contribute">2.2. Contribute</a>
<ul class="sectlevel3">
<li><a href="eclipse_setup.html#_eclipse-installer">2.2.1. Eclipse Installer</a>
<ul class="sectlevel4">
<li><a href="eclipse_setup.html#_changing-the-setup-script">2.2.1.1. Changing the Setup Script</a></li>
</ul>
</li>
<li><a href="eclipse_setup.html#_manual-ide-configuration">2.2.2. Manual IDE Configuration</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="release_engineering.html#_release-engineering">3. Release Engineering</a>
<ul class="sectlevel2">
<li><a href="release_engineering.html#_nightly-build-on-eclipse-infrastructure">3.1. Nightly build on Eclipse infrastructure</a></li>
<li><a href="release_engineering.html#_build-the-n4js-ide-from-command-line">3.2. Build the N4JS IDE from command line</a>
<ul class="sectlevel3">
<li><a href="release_engineering.html#_publish-maven-tooling-code-org-eclipse-n4js-releng-util-code">3.2.1. Publish maven-tooling <code>org.eclipse.n4js.releng.util</code></a></li>
<li><a href="release_engineering.html#sec:test-verdaccio">3.2.2. Test Verdaccio containing n4js-libs</a></li>
<li><a href="release_engineering.html#_generation-of-eclipse-help-for-spec-and-design-document">3.2.3. Generation of Eclipse help for spec and design document</a></li>
</ul>
</li>
<li><a href="release_engineering.html#_updating-frameworks-and-dependencies">3.3. Updating frameworks and dependencies</a>
<ul class="sectlevel3">
<li><a href="release_engineering.html#_update-of-eclipse-emf-xtext-etc">3.3.1. Update of Eclipse, EMF, Xtext, etc.</a></li>
<li><a href="release_engineering.html#_update-of-the-embedded-jre">3.3.2. Update of the embedded JRE</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="tips_and_tricks.html#_tips-and-tricks">4. Tips and Tricks</a>
<ul class="sectlevel2">
<li><a href="tips_and_tricks.html#_naming">4.1. Naming</a></li>
<li><a href="tips_and_tricks.html#_logging">4.2. Logging</a></li>
<li><a href="tips_and_tricks.html#_cancellation-handling">4.3. Cancellation Handling</a></li>
<li><a href="tips_and_tricks.html#_caching">4.4. Caching</a></li>
<li><a href="tips_and_tricks.html#_dependency-injection">4.5. Dependency Injection</a></li>
<li><a href="tips_and_tricks.html#_miscellaneous">4.6. Miscellaneous</a></li>
</ul>
</li>
<li><a href="#_parser">5. Parser</a>
<ul class="sectlevel2">
<li><a href="#sec:Parser_Overview">5.1. Overview</a></li>
<li><a href="#sec:N4JS_Parser">5.2. N4JS Parser</a></li>
<li><a href="#sec:Parser_Generation_Post_Processing">5.3. Parser Generation Post-Processing</a>
<ul class="sectlevel3">
<li><a href="#sec:Automatic_Semicolon_Insertion">5.3.1. Automatic Semicolon Insertion</a>
<ul class="sectlevel4">
<li><a href="#sec:Injected_code_in_the_Antlr_grammar_file">5.3.1.1. Injected code in the Antlr grammar file</a></li>
<li><a href="#sec:Customized_error_recovery">5.3.1.2. Customized error recovery</a></li>
</ul>
</li>
<li><a href="#sec:_No_line_terminator_allowed_here__handling">5.3.2. Async and <code>No line terminator allowed here</code> Handling</a></li>
<li><a href="#sec:Regular_Expression">5.3.3. Regular Expression</a></li>
<li><a href="#sec:Unicode">5.3.4. Unicode</a></li>
<li><a href="#sec:Literals">5.3.5. Literals</a></li>
</ul>
</li>
<li><a href="#sec:Modifiers">5.4. Modifiers</a></li>
<li><a href="#sec:Conflict_Resolutions">5.5. Conflict Resolutions</a>
<ul class="sectlevel3">
<li><a href="#sec:Reserved_Keywords_vs__Identifier_Names">5.5.1. Reserved Keywords vs. Identifier Names</a></li>
<li><a href="#sec:Operators_and_Generics">5.5.2. Operators and Generics</a></li>
</ul>
</li>
<li><a href="#sec:Content_Assist_Parser">5.6. Content-Assist Parser</a></li>
</ul>
</li>
<li><a href="type_system.html#_type-system">6. Type System</a>
<ul class="sectlevel2">
<li><a href="type_system.html#sec:Type_Model_and_Grammar">6.1. Type Model and Grammar</a>
<ul class="sectlevel3">
<li><a href="type_system.html#sec:Type_Model_Overview">6.1.1. Type Model Overview</a></li>
<li><a href="type_system.html#sec:Built_in_Types">6.1.2. Built-in and Primitive Types</a></li>
<li><a href="type_system.html#sec:Type_Model_DSL">6.1.3. Type Model DSL</a></li>
</ul>
</li>
<li><a href="type_system.html#sec:Type_System_Implementation">6.2. Type System Implementation</a></li>
<li><a href="type_system.html#sec:Type_Inference_combined_with_AST_Traversal">6.3. Type Inference of AST</a>
<ul class="sectlevel3">
<li><a href="type_system.html#sec:Type_Inference_combined_with_AST_Traversal__Background">6.3.1. Background</a></li>
<li><a href="type_system.html#sec:Triggering_Type_Inference_of_AST">6.3.2. Triggering</a></li>
<li><a href="type_system.html#sec:Traversal_Order_During_Type_Inference_of_AST">6.3.3. Traversal Order</a></li>
<li><a href="type_system.html#sec:Cross_References_During_Type_Inference_of_AST">6.3.4. Cross-References</a></li>
<li><a href="type_system.html#sec:Function_Accessor_Bodies_During_Type_Inference_of_AST">6.3.5. Function/Accessor Bodies</a></li>
<li><a href="type_system.html#sec:Poly_Expressions_During_Type_Inference_of_AST">6.3.6. Poly Expressions</a></li>
<li><a href="type_system.html#sec:Constraint_Solver_used_During_Type_Inference_of_AST">6.3.7. Constraint Solver</a></li>
<li><a href="type_system.html#sec:Type_Guards_During_Type_Inference_of_AST">6.3.8. Type Guards</a></li>
</ul>
</li>
<li><a href="type_system.html#sec:Structural_Typing">6.4. Structural Typing</a></li>
</ul>
</li>
<li><a href="type_index.html#_type-index">7. Type Index</a>
<ul class="sectlevel2">
<li><a href="type_index.html#sec:Type_Index_Design_Rationale">7.1. Design Rationale</a>
<ul class="sectlevel3">
<li><a href="type_index.html#sec:Getting_the_Xtext_Index_Content_IResourceDescriptions">7.1.1. Getting the Xtext Index (<code>IResourceDescriptions</code>) Content</a></li>
</ul>
</li>
<li><a href="type_index.html#sec:Design_Overview">7.2. Design Overview</a></li>
<li><a href="type_index.html#sec:N4JS_Resource_Load_States">7.3. N4JS Resource Load States</a></li>
<li><a href="type_index.html#sec:Type_Builder">7.4. Types Builder</a>
<ul class="sectlevel3">
<li><a href="type_index.html#sec:Type_Inference_not_allowed_in_Type_Builder">7.4.1. Type Inference not allowed in Types Builder</a></li>
<li><a href="type_index.html#sec:ComputedTypeReferences">7.4.2. Deferred Type References</a></li>
<li><a href="type_index.html#sec:Use_cases_of_ComputedTypeRef">7.4.3. Use cases of DeferredTypeRef</a></li>
</ul>
</li>
<li><a href="type_index.html#sec:Incremental_Builder_Overview">7.5. Incremental Builder (Overview)</a>
<ul class="sectlevel3">
<li><a href="type_index.html#sec:Incremental_Builder_Overview__XtextBuilder">7.5.1. XtextBuilder</a></li>
<li><a href="type_index.html#sec:Incremental_Builder_Overview__IBuilderState">7.5.2. IBuilderState</a>
<ul class="sectlevel4">
<li><a href="type_index.html#copy-and-update-xtext-index">7.5.2.1. Copy and Update Xtext Index</a></li>
<li><a href="type_index.html#build-state-setup-phase">7.5.2.2. Build State Setup Phase</a></li>
<li><a href="type_index.html#process-queued-uris">7.5.2.3. Process Queued URIs</a></li>
<li><a href="type_index.html#queueing-affected-resources">7.5.2.4. Queueing Affected Resources</a></li>
</ul>
</li>
<li><a href="type_index.html#sec:Incremental_Builder_Overview__Example">7.5.3. Example</a></li>
</ul>
</li>
<li><a href="type_index.html#dirty-state-handling">7.6. Dirty state handling</a>
<ul class="sectlevel3">
<li><a href="type_index.html#use-case-restoring-types-from-user-data">7.6.1. Use case: Restoring types from user data</a></li>
<li><a href="type_index.html#use-case-updating-the-xtext-index">7.6.2. Use case: Updating the Xtext index</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="project_model.html#_project-model">8. Project Model</a>
<ul class="sectlevel2">
<li><a href="project_model.html#sec:Package_json">8.1. Package.json File</a></li>
<li><a href="project_model.html#_accessing-project-information">8.2. Accessing Project Information</a>
<ul class="sectlevel3">
<li><a href="project_model.html#sec:IN4JSCore">8.2.1. IN4JSCore</a></li>
<li><a href="project_model.html#sec:N4JSModel">8.2.2. N4JSModel</a></li>
<li><a href="project_model.html#sec:N4JSWorkspace">8.2.3. N4JSWorkspace</a></li>
<li><a href="project_model.html#sec:N4JSProject">8.2.4. N4JSProject</a></li>
<li><a href="project_model.html#sec:SourceContainer">8.2.5. SourceContainer</a></li>
<li><a href="project_model.html#sec:N4JSProjectsStateHelper">8.2.6. N4JSProjectsStateHelper</a></li>
</ul>
</li>
<li><a href="project_model.html#sec:Caching">8.3. Caching</a>
<ul class="sectlevel3">
<li><a href="project_model.html#_caching-of-externallibraryworkspace">8.3.1. Caching of ExternalLibraryWorkspace</a></li>
<li><a href="project_model.html#_caching-of-n4jsprojectsstatehelper">8.3.2. Caching of N4JSProjectsStateHelper</a></li>
</ul>
</li>
<li><a href="project_model.html#sec:WildcardPathFilter">8.4. WildcardPathFilter</a></li>
<li><a href="project_model.html#sec:ProjectUtils">8.5. ProjectUtils</a></li>
</ul>
</li>
<li><a href="binding.html#_binding">9. Binding</a>
<ul class="sectlevel2">
<li><a href="binding.html#sec:Binding_Design_Rationale">9.1. Design Rationale</a></li>
<li><a href="binding.html#sec:Binding_to_Members">9.2. Binding to Members</a></li>
<li><a href="binding.html#sec:Binding_Getter_Setter">9.3. Getter / Setter Binding</a></li>
<li><a href="binding.html#chap:Statics">9.4. Static Member Binding</a></li>
<li><a href="binding.html#sec:Binding_Enumeration">9.5. Enumeration Literals Binding</a></li>
<li><a href="binding.html#sec:Accessibility_of_types_and_members">9.6. Accessibility of types and members</a></li>
<li><a href="binding.html#sec:Member_Scope_Example">9.7. Member Scope Example</a></li>
<li><a href="binding.html#sec:Scoping_for_Members_of_Composed_Type_Explained">9.8. Scoping for Members of Composed Type (Union/Intersection) Example</a></li>
<li><a href="binding.html#sec:Binding_of_Structurally_References_Types">9.9. Structurally References Types</a></li>
<li><a href="binding.html#sec:Building">9.10. Building</a>
<ul class="sectlevel3">
<li><a href="binding.html#sec:Build_Phases">9.10.1. Build Phases</a></li>
<li><a href="binding.html#sec:Build_Scenarios">9.10.2. Build Scenarios</a></li>
<li><a href="binding.html#sec:Lazy_linking_problem">9.10.3. Lazy linking problem</a></li>
</ul>
</li>
<li><a href="binding.html#sec:Proxies_and_Proxy_Resolution">9.11. Proxies and Proxy Resolution (Overview)</a>
<ul class="sectlevel3">
<li><a href="binding.html#xtexts-lazy-linking-proxies">9.11.1. Xtext’s Lazy Linking Proxies</a></li>
<li><a href="binding.html#standard-emf-proxies">9.11.2. Standard EMF Proxies</a></li>
<li><a href="binding.html#_how-is-proxy-resolution-triggered">9.11.3. How is Proxy Resolution Triggered?</a></li>
<li><a href="binding.html#_when-is-proxy-resolution-allowed">9.11.4. When is Proxy Resolution Allowed?</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="validation.html#_validation">10. Validation</a>
<ul class="sectlevel2">
<li><a href="validation.html#sec:validation_overview">10.1. Validation overview</a></li>
<li><a href="validation.html#sec:validation_control_flow">10.2. Validation control flow</a></li>
<li><a href="validation.html#sec:validation_issue_ids">10.3. Issue IDs and Messages</a></li>
<li><a href="validation.html#sec:validation_usage_patterns">10.4. Usage Pattern</a></li>
<li><a href="validation.html#sec:validation_links">10.5. Links</a></li>
</ul>
</li>
<li><a href="references.html#_references">11. References</a>
<ul class="sectlevel2">
<li><a href="references.html#sec:usecases">11.1. Use cases</a></li>
<li><a href="references.html#sec:calculation_algorithm">11.2. Calculation algorithm</a>
<ul class="sectlevel3">
<li><a href="references.html#sec:Xtext_default_implementation">11.2.1. Xtext default implementation</a></li>
<li><a href="references.html#sec:N4_implementation">11.2.2. N4JS implementation</a></li>
</ul>
</li>
<li><a href="references.html#sec:PerformanceOfDependencyCalculation">11.3. Performance Of Dependency Calculation</a></li>
<li><a href="references.html#sec:kinds_of_references">11.4. Kinds of references</a>
<ul class="sectlevel3">
<li><a href="references.html#sec:Cross_References_to_be_ignored">11.4.1. Cross References to be ignored</a></li>
<li><a href="references.html#sec:Cross_References_to_be_handled">11.4.2. Cross References to be handled</a></li>
</ul>
</li>
<li><a href="references.html#sec:transitive_dependencies">11.5. Transitive dependencies</a></li>
<li><a href="references.html#sec:find-references">11.6. Find references</a>
<ul class="sectlevel3">
<li><a href="references.html#_background">11.6.1. Background</a></li>
<li><a href="references.html#_how-find-references-work">11.6.2. How Find References Work</a>
<ul class="sectlevel4">
<li><a href="references.html#_step-1-convert-cursor-position-to-declared-element">11.6.2.1. Step 1: Convert Cursor Position to Declared Element</a></li>
<li><a href="references.html#_step-2-convert-declared-element-to-target-uris">11.6.2.2. Step 2: Convert Declared Element to Target URIs</a></li>
<li><a href="references.html#_step-3-filter-potential-resources">11.6.2.3. Step 3: Filter Potential Resources</a></li>
<li><a href="references.html#_step-4-search-references-in-resource">11.6.2.4. Step 4: Search References in Resource</a></li>
<li><a href="references.html#_limitations-and-possible-enhancements">11.6.2.5. Limitations and Possible Enhancements</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><a href="compilation.html#_compilation">12. Compilation</a>
<ul class="sectlevel2">
<li><a href="compilation.html#chap:compilation">12.1. Introduction</a>
<ul class="sectlevel3">
<li><a href="compilation.html#sec:general_design_rationals">12.1.1. General design rationals</a>
<ul class="sectlevel4">
<li><a href="compilation.html#sec:logging_and_error_reporting">12.1.1.1. Logging and error reporting</a></li>
<li><a href="compilation.html#sec:progress_monitor">12.1.1.2. Progress monitor</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:Xtext_Integration">12.1.2. Xtext Integration</a>
<ul class="sectlevel4">
<li><a href="compilation.html#sec:xtext_default_behaviour">12.1.2.1. Xtext default behaviour</a></li>
<li><a href="compilation.html#sec:n4js_requirements">12.1.2.2. N4JS requirements</a></li>
<li><a href="compilation.html#sec:compiler_discovery_in_ui">12.1.2.3. Compiler discovery in UI</a></li>
<li><a href="compilation.html#sec:compiler_discovery_in_headless">12.1.2.4. Compiler discovery in headless</a></li>
<li><a href="compilation.html#sec:general_generator_implementation">12.1.2.5. General generator implementation</a></li>
<li><a href="compilation.html#sec:general_generator_activation">12.1.2.6. General generator activation</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:Overview_of_Input_Models">12.1.3. Overview of the Input Models</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:Core_Generator">12.2. Generators</a>
<ul class="sectlevel3">
<li><a href="compilation.html#sec:Compiler_Components">12.2.1. Generator Components</a></li>
<li><a href="compilation.html#sec:Generator_architecture">12.2.2. Generator architecture</a></li>
<li><a href="compilation.html#sec:Unified_Compiler_Configuration">12.2.3. Unified Compiler Configuration</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:Transpilers">12.3. Transpilers</a>
<ul class="sectlevel3">
<li><a href="compilation.html#sec:Phases">12.3.1. Overview</a></li>
<li><a href="compilation.html#relation-between-ast-and-im">12.3.2. Relation between AST and IM</a></li>
<li><a href="compilation.html#implementation-overview">12.3.3. Implementation Overview</a></li>
<li><a href="compilation.html#sec:Guidelines_for_Implementing_Transformations">12.3.4. Guidelines for Implementing Transformations</a></li>
<li><a href="compilation.html#symbol-table-in-the-im">12.3.5. Symbol Table in the IM</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:N4JS_to_EcmaScript_Transpiler">12.4. N4JS-to-EcmaScript Transpiler</a>
<ul class="sectlevel3">
<li><a href="compilation.html#sec:Overview_of_Transformations">12.4.1. Overview of Transformations</a></li>
<li><a href="compilation.html#sec:Transpiling_members">12.4.2. Transpiling members</a>
<ul class="sectlevel4">
<li><a href="compilation.html#sec:Transpiling_members__Delegating_members">12.4.2.1. Techniques for special member handling</a></li>
<li><a href="compilation.html#sec:Transpiling_members__Partial_shadowing_of_getter_setter_pairs">12.4.2.2. Partial shadowing</a></li>
<li><a href="compilation.html#sec:Transpiling_members__Consuming_or_inheriting_members_of_an_interface">12.4.2.3. Consuming or inheriting members of an interface</a></li>
<li><a href="compilation.html#sec:Transpiling_members__Static_polyfill">12.4.2.4. Static polyfill</a></li>
<li><a href="compilation.html#sec:Transpiling_members__API_implementation_stubs">12.4.2.5. API / implementation stubs</a></li>
</ul>
</li>
<li><a href="compilation.html#sec:Support_for_incomplete_API_implementation_testing_in_the_N4JS_to_EcmaScript_5_Transpiler">12.4.3. Support for incomplete API implementation testing</a>
<ul class="sectlevel4">
<li><a href="compilation.html#sec:Modifications_in_Impl_projects">12.4.3.1. Modifications in Impl projects</a></li>
<li><a href="compilation.html#sec:Implementation_of_stub_generation">12.4.3.2. Implementation of stub-generation</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="compilation.html#sec:n4jsc_Headless_Compiler_Interface">12.5. n4jsc Headless Compiler Interface</a>
<ul class="sectlevel3">
<li><a href="compilation.html#sec:building_the_headless_compiler">12.5.1. building the headless compiler</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="execution.html#_execution">13. Execution</a>
<ul class="sectlevel2">
<li><a href="execution.html#sec:N4JS_Project_Execution_And_Linking_Model">13.1. N4JS Project Execution And Linking Model</a>
<ul class="sectlevel3">
<li><a href="execution.html#subsec:N4JS_Execution_With_NodeJS">13.1.1. N4JS Execution With NodeJS</a></li>
</ul>
</li>
<li><a href="execution.html#sec:N4JS_Execution_And_Linking_File">13.2. N4JS Execution And Linking File</a>
<ul class="sectlevel3">
<li><a href="execution.html#subsec:NodeJS_Specific_ELF">13.2.1. NodeJS Specific ELF</a></li>
</ul>
</li>
<li><a href="execution.html#sec:Runners-execution">13.3. Runners</a>
<ul class="sectlevel3">
<li><a href="execution.html#subsec:N4_Runtime_Environments_Convention">13.3.1. N4 Runtime Environments Convention</a></li>
<li><a href="execution.html#subsec:Passing_Information_from_IDE_to_Execution_Code_in_Runtime_Environment">13.3.2. Passing Information from IDE to Execution Code in Runtime Environment</a></li>
<li><a href="execution.html#subsec:Runners_Design">13.3.3. Runners Design</a></li>
</ul>
</li>
<li><a href="execution.html#sec:Legacy_Execution_Engine">13.4. Legacy Execution Engine</a></li>
<li><a href="execution.html#sec:Design">13.5. Design</a>
<ul class="sectlevel3">
<li><a href="execution.html#sec:Usage_Outside_N4JSIDE">13.5.1. Usage Outside N4JSIDE</a>
<ul class="sectlevel4">
<li><a href="execution.html#sec:Use_Node_with_Maven">13.5.1.1. Use Node with Maven</a></li>
</ul>
</li>
<li><a href="execution.html#sec:Usage_Inside_N4JSIDE">13.5.2. Usage Inside N4JSIDE</a></li>
</ul>
</li>
<li><a href="execution.html#sec:Runtime_Injection">13.6. Runtime Injection</a>
<ul class="sectlevel3">
<li><a href="execution.html#sec:Running_String_Code">13.6.1. Running String Code</a></li>
<li><a href="execution.html#sec:Running_File_Code">13.6.2. Running File Code</a></li>
<li><a href="execution.html#sec:Injection_Code_Example">13.6.3. Injection Code Example</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="tests.html#_tests">14. Tests</a>
<ul class="sectlevel2">
<li><a href="tests.html#sec:Performance_Tests">14.1. Performance Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Synthetic_Performance_Tests">14.1.1. Synthetic Performance Tests</a>
<ul class="sectlevel4">
<li><a href="tests.html#sec:Design_of_Generator">14.1.1.1. Design of Generator</a></li>
<li><a href="tests.html#sec:Design_of_Performance_Test_Execution">14.1.1.2. Design of Performance Test Configuration and Execution</a></li>
<li><a href="tests.html#sec:JUnit_Configuration">14.1.1.3. JUnit Configuration</a></li>
<li><a href="tests.html#sec:JUnitBenchmark_Test_Configuration">14.1.1.4. JUnitBenchmark Test Configuration</a></li>
<li><a href="tests.html#sec:JUnitBenchmark_Report_Configuration">14.1.1.5. JUnitBenchmark Report Configuration</a></li>
<li><a href="tests.html#sec:JUnitBenchmark_Run_Configuration">14.1.1.6. JUnitBenchmark Run Configuration</a></li>
<li><a href="tests.html#sec:JUnitBenchmark_Example">14.1.1.7. JUnitBenchmark Example</a></li>
<li><a href="tests.html#sec:Note_on_Jenkins_Job">14.1.1.8. Note on Jenkins Job</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="tests.html#sec:ECMA_Tests">14.2. ECMA Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Grammar_Tests">14.2.1. Grammar Tests</a>
<ul class="sectlevel4">
<li><a href="tests.html#sec:Negative_Tests">14.2.1.1. Negative Tests</a></li>
<li><a href="tests.html#sec:Test_Exclusion">14.2.1.2. Test Exclusion</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="tests.html#sec:Integration_Tests">14.3. Integration Tests</a></li>
<li><a href="tests.html#sec:Test_Helpers">14.4. Test Helpers</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Parameterized_N4JS_Tests">14.4.1. Parameterized N4JS tests</a>
<ul class="sectlevel4">
<li><a href="tests.html#sec:ParameterizedXtextRunner">14.4.1.1. ParameterizedXtextRunner</a></li>
<li><a href="tests.html#sec:TestCodeProvider">14.4.1.2. TestCodeProvider</a></li>
<li><a href="tests.html#sec:Example_Of_Parameterized_Parser_Test">14.4.1.3. Example of parameterized parser test</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="tests.html#sec:Issue_Suppression">14.5. Issue Suppression</a></li>
<li><a href="tests.html#sec:Xpect_Tests">14.6. Xpect Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Xpect_Test_Setup">14.6.1. Xpect Test Setup</a></li>
<li><a href="tests.html#sec:Xpect_Issue_Suppression">14.6.2. Xpect Issue Suppression</a></li>
<li><a href="tests.html#sec:Xpect_Provided_Test_Methods">14.6.3. Xpect Provided Test Methods</a>
<ul class="sectlevel4">
<li><a href="tests.html#errors">14.6.3.1. errors</a></li>
<li><a href="tests.html#warnings">14.6.3.2. warnings</a></li>
</ul>
</li>
<li><a href="tests.html#sec:N4JS_Specific_Xpect_Test_Methods">14.6.4. N4JS Specific Xpect Test Methods</a>
<ul class="sectlevel4">
<li><a href="tests.html#sec:XPECT_noerrors">14.6.4.1. noerrors and nowarnings</a></li>
<li><a href="tests.html#sec:XPECT_scope">14.6.4.2. scope</a></li>
<li><a href="tests.html#sec:XPECT_scopeWithPosition">14.6.4.3. scopeWithPosition</a></li>
<li><a href="tests.html#sec:XPECT_scopeWithResource">14.6.4.4. scopeWithResource</a></li>
<li><a href="tests.html#sec:XPECT_binding">14.6.4.5. binding</a></li>
<li><a href="tests.html#sec:XPECT_linkedPathname">14.6.4.6. linkedPathname</a></li>
<li><a href="tests.html#sec:XPECT_type_of">14.6.4.7. type of</a></li>
<li><a href="tests.html#sec:XPECT_expectedType">14.6.4.8. expectedType</a></li>
<li><a href="tests.html#sec:XPECT_elementKeyword">14.6.4.9. elementKeyword</a></li>
<li><a href="tests.html#sec:XPECT_accessModifier">14.6.4.10. accessModifier</a></li>
<li><a href="tests.html#sec:XPECT_compileResult">14.6.4.11. compileResult</a></li>
<li><a href="tests.html#sec:XPECT_output">14.6.4.12. output</a></li>
<li><a href="tests.html#sec:XPECT_outputRegEx">14.6.4.13. outputRegEx</a></li>
<li><a href="tests.html#sec:XPECT_calculatedAccessModifier">14.6.4.14. calculatedAccessModifier</a></li>
<li><a href="tests.html#sec:XPECT_spec">14.6.4.15. spec</a></li>
<li><a href="tests.html#sec:XPECT_deadCode">14.6.4.16. deadCode</a></li>
<li><a href="tests.html#sec:XPECT_returnOrThrows">14.6.4.17. returnOrThrows</a></li>
<li><a href="tests.html#sec:XPECT_lint">14.6.4.18. lint</a></li>
<li><a href="tests.html#sec:XPECT_lintFails">14.6.4.19. lintFails</a></li>
</ul>
</li>
<li><a href="tests.html#sec:FIXME_Xpect_modifier">14.6.5. FIXME Xpect modifier</a></li>
<li><a href="tests.html#sec:Expectmatrix_Xpect_Test_Methods">14.6.6. Expectmatrix Xpect tests</a></li>
<li><a href="tests.html#xpect-lint-tests">14.6.7. Xpect Lint Tests</a></li>
</ul>
</li>
<li><a href="tests.html#xpect-proposal-tests">14.7. Xpect Proposal Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Validation_vs__Non_Validation">14.7.1. Validation vs. Non-Validation</a></li>
<li><a href="tests.html#sec:General_Proposal_Test_Features">14.7.2. General Proposal Test Features</a>
<ul class="sectlevel4">
<li><a href="tests.html#sec:Test_Variables">14.7.2.1. Test Variables</a></li>
<li><a href="tests.html#sec:Location_and_Selection">14.7.2.2. at – Location and Selection</a></li>
<li><a href="tests.html#sec:Multi_Line_Expectations_in_Proposal_Tests">14.7.2.3. Multi Line Expectations in Proposal Tests</a></li>
<li><a href="tests.html#sec:Timeout">14.7.2.4. Timeout and Performance</a></li>
</ul>
</li>
<li><a href="tests.html#proposals-verify-existence-of-proposals">14.7.3. proposals – Verify Existence of Proposals</a></li>
<li><a href="tests.html#sec:Verify_displayed_string">14.7.4. display – Verify displayed string</a></li>
<li><a href="tests.html#sec:Apply_Proposal">14.7.5. apply – Apply Proposal</a>
<ul class="sectlevel4">
<li><a href="tests.html#resource-application-in-other-files">14.7.5.1. resource – application in other files</a></li>
</ul>
</li>
<li><a href="tests.html#sec:Content_Assist_Cycling">14.7.6. kind – Content Assist Cycling</a></li>
<li><a href="tests.html#fileValidVerify-validation-status">14.7.7. fileValid – Verify validation status</a></li>
</ul>
</li>
<li><a href="tests.html#sec:Apply_Proposal_And_Execute_Tests">14.8. Apply Proposal And Execute Tests</a></li>
<li><a href="tests.html#sec:Organize_Imports_Test">14.9. Organize Imports Test</a>
<ul class="sectlevel3">
<li><a href="tests.html#organizeimports">14.9.1. organizeImports</a></li>
</ul>
</li>
<li><a href="tests.html#sec:Access_Control_Test">14.10. Access Control Test</a>
<ul class="sectlevel3">
<li><a href="tests.html#test-scenarios">14.10.1. Test Scenarios</a></li>
<li><a href="tests.html#n4js-code-generator">14.10.2. N4JS Code Generator</a></li>
<li><a href="tests.html#xtext-issue-matcher">14.10.3. Xtext Issue Matcher</a></li>
</ul>
</li>
<li><a href="tests.html#sec:Smoke_Tests">14.11. Smoke Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#how-to-handle-smoke-test-errors">14.11.1. How to handle smoke test errors?</a></li>
<li><a href="tests.html#smoketester-and-exceptionanalyzer">14.11.2. SmokeTester and ExceptionAnalyzer</a></li>
</ul>
</li>
<li><a href="tests.html#sec:UI_Tests_with_SWTBot">14.12. UI Tests with SWTBot</a>
<ul class="sectlevel3">
<li><a href="tests.html#writing-swtbot-tests">14.12.1. Writing SWTBot Tests</a></li>
<li><a href="tests.html#running-swtbot-tests">14.12.2. Running SWTBot Tests</a></li>
</ul>
</li>
<li><a href="tests.html#sec:Debugging_UI_Tests">14.13. Debugging UI Tests</a>
<ul class="sectlevel3">
<li><a href="tests.html#sec:Connecting_to_the_X_server_on_the_build_node">14.13.1. Connecting to the X-server on the build-node</a></li>
<li><a href="tests.html#sec:Tools_to_investigate_the_java_stack">14.13.2. Tools to investigate the java-stack</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="ui_concepts.html#_ui-concepts">15. UI Concepts</a>
<ul class="sectlevel2">
<li><a href="ui_concepts.html#sec:User_Interface_Concepts">15.1. User Interface Concepts</a>
<ul class="sectlevel3">
<li><a href="ui_concepts.html#sec:Eclipse_UI_Concepts">15.1.1. Eclipse UI Concepts</a>
<ul class="sectlevel4">
<li><a href="ui_concepts.html#sec:Label_Provider">15.1.1.1. Label Provider</a></li>
<li><a href="ui_concepts.html#sec:Markers">15.1.1.2. Markers</a></li>
<li><a href="ui_concepts.html#sec:Commands__Toolbar_and_Menus">15.1.1.3. Commands, Toolbar and Menus</a></li>
<li><a href="ui_concepts.html#sec:Content_Assist">15.1.1.4. Content Assist</a></li>
<li><a href="ui_concepts.html#sec:Quick_Fixes">15.1.1.5. Quick Fixes</a></li>
<li><a href="ui_concepts.html#sec:Quick_Assist">15.1.1.6. Quick Assist</a></li>
<li><a href="ui_concepts.html#sec:Clean_Up_Actions">15.1.1.7. Clean Up Actions</a></li>
<li><a href="ui_concepts.html#sec:Save_Actions">15.1.1.8. Save Actions</a></li>
<li><a href="ui_concepts.html#sec:Auto_Edit">15.1.1.9. Auto Edit</a></li>
<li><a href="ui_concepts.html#sec:Template_Proposals">15.1.1.10. Template Proposals</a></li>
<li><a href="ui_concepts.html#sec:Outline_View___Quick_Outline">15.1.1.11. Outline View / Quick Outline</a></li>
<li><a href="ui_concepts.html#sec:Navigator__Package_Explorer__Project_Explorer">15.1.1.12. Navigator, Package Explorer, Project Explorer</a></li>
<li><a href="ui_concepts.html#sec:Hyperlinking_and_Navigation">15.1.1.13. Hyperlinking and Navigation</a></li>
<li><a href="ui_concepts.html#sec:Syntax_and_Semantic_Coloring">15.1.1.14. Syntax and Semantic Coloring</a></li>
<li><a href="ui_concepts.html#sec:Code_Formatter">15.1.1.15. Code Formatter</a></li>
<li><a href="ui_concepts.html#sec:Wizards">15.1.1.16. Wizards</a></li>
<li><a href="ui_concepts.html#sec:Cheat_Sheets">15.1.1.17. Cheat Sheets</a></li>
<li><a href="ui_concepts.html#sec:Context_sensitive_Help">15.1.1.18. Context-sensitive Help</a></li>
<li><a href="ui_concepts.html#sec:Hovers">15.1.1.19. Hovers</a></li>
<li><a href="ui_concepts.html#sec:Folding">15.1.1.20. Folding</a></li>
<li><a href="ui_concepts.html#sec:Customizable_validation___severity">15.1.1.21. Customizable validation / severity</a></li>
<li><a href="ui_concepts.html#sec:Proposals">15.1.1.22. Proposals</a></li>
</ul>
</li>
<li><a href="ui_concepts.html#sec:Non_Eclipse_UI_Concepts">15.1.2. Non-Eclipse UI Concepts</a>
<ul class="sectlevel4">
<li><a href="ui_concepts.html#sec:Overlays">15.1.2.1. Overlays</a></li>
<li><a href="ui_concepts.html#sec:Goto__Inferred__Type">15.1.2.2. Goto (Inferred) Type</a></li>
<li><a href="ui_concepts.html#sec:Postfix_Completion">15.1.2.3. Postfix Completion</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="ui_concepts.html#_user-interface-resources">15.2. User Interface Resources</a>
<ul class="sectlevel3">
<li><a href="ui_concepts.html#_icons">15.2.1. Icons</a>
<ul class="sectlevel4">
<li><a href="ui_concepts.html#_eclipse-platform-icons">15.2.1.1. Eclipse Platform Icons</a></li>
<li><a href="ui_concepts.html#_n4js-specific-icons">15.2.1.2. N4JS Specific Icons</a></li>
<li><a href="ui_concepts.html#_high-resolution-icons">15.2.1.3. High Resolution Icons</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><a href="formatting.html#_formatting">16. Formatting</a>
<ul class="sectlevel2">
<li><a href="formatting.html#sec:FmtObjective">16.1. Objective</a>
<ul class="sectlevel3">
<li><a href="formatting.html#sec:FmtFormatting_Comments">16.1.1. Formatting Comments</a></li>
</ul>
</li>
<li><a href="formatting.html#sec:FmtArchitecture">16.2. Architecture</a>
<ul class="sectlevel3">
<li><a href="formatting.html#sec:Implementation_example">16.2.1. Implementation example</a></li>
</ul>
</li>
<li><a href="formatting.html#sec:FmtFormatter_Implementation_Guidelines">16.3. Formatter Implementation Guidelines</a></li>
<li><a href="formatting.html#sec:FmtConfiguration">16.4. Configuration</a></li>
<li><a href="formatting.html#sec:FmtUI_Integration">16.5. UI Integration</a></li>
<li><a href="formatting.html#sec:FmtUnit_Testing_with_Xpect">16.6. Unit Testing with Xpect</a></li>
</ul>
</li>
<li><a href="external_libraries.html#_external-libraries">17. External Libraries</a>
<ul class="sectlevel2">
<li><a href="external_libraries.html#sec:Major_Components">17.1. Major Components</a>
<ul class="sectlevel3">
<li><a href="external_libraries.html#subsec:External_Resources">17.1.1. External Resources</a></li>
<li><a href="external_libraries.html#subsec:External_Library_Workspace">17.1.2. External Library Workspace</a></li>
<li><a href="external_libraries.html#subsec:External_Library_Preference_Store">17.1.3. External Library Preference Store</a></li>
<li><a href="external_libraries.html#subsec:npm_Manager">17.1.4. Library Manager</a></li>
<li><a href="external_libraries.html#subsec:External_Library_Builder_Helper">17.1.5. External Library Builder</a></li>
<li><a href="external_libraries.html#subsec:External_Library_Xtext_Index_Persister">17.1.6. External Library Xtext Index Persister</a></li>
<li><a href="external_libraries.html#subsec:External_Library_Preference_Page">17.1.7. External Library Preference Page</a></li>
</ul>
</li>
<li><a href="external_libraries.html#sec:Headless_External_Library_Support">17.2. Headless External Library Support</a>
<ul class="sectlevel3">
<li><a href="external_libraries.html#_custom-npm-settings">17.2.1. Custom npm settings</a></li>
</ul>
</li>
<li><a href="external_libraries.html#sec:lmFutureWork">17.3. Future Work</a>
<ul class="sectlevel3">
<li><a href="external_libraries.html#subsec:lmMultipleDependencyScope">17.3.1. Multiple Dependency Scope</a></li>
<li><a href="external_libraries.html#subsec:lmRunTestsFromLibrary">17.3.2. Run Tests from TestLibrary</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="json_support.html#sec:JSON_Support">18. JSON Support</a>
<ul class="sectlevel2">
<li><a href="json_support.html#sec:JSON_Parser">18.1. JSON Parser</a>
<ul class="sectlevel3">
<li><a href="json_support.html#sec:JSON_Parser_Unicode_Escaping">18.1.1. Escaping Unicode Control Characters in String Literals</a></li>
<li><a href="json_support.html#sec:JSON_Parser_Empty_Text">18.1.2. Empty Text</a></li>
<li><a href="json_support.html#sec:JSON_Parser_Nested_Structures">18.1.3. Nested Structures</a></li>
<li><a href="json_support.html#sec:JSON_Parser_Whitespace">18.1.4. Whitespace</a></li>
<li><a href="json_support.html#sec:JSON_Parser_Comments">18.1.5. Comments</a></li>
</ul>
</li>
<li><a href="json_support.html#sec:JSON_Language_Extensions">18.2. JSON Language Extensions</a>
<ul class="sectlevel3">
<li><a href="json_support.html#sec:JSON_Validator_Extensions">18.2.1. JSON Validator Extensions</a>
<ul class="sectlevel4">
<li><a href="json_support.html#sec:File_Specitic_Validator_Extensions">18.2.1.1. File-Specific Validator Extensions</a></li>
<li><a href="json_support.html#sec:JSON_Declarative_JSON_Validator_Extensions">18.2.1.2. Declarative JSON Validator Extensions</a></li>
</ul>
</li>
<li><a href="json_support.html#_json-resource-description-strategy">18.2.2. JSON Resource Description Strategy</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="jsdoc.html#_jsdoc">19. JSDoc</a>
<ul class="sectlevel2">
<li><a href="jsdoc.html#sec:Design_Rationale">19.1. Design Rationale</a>
<ul class="sectlevel3">
<li><a href="jsdoc.html#_general-design">19.1.1. General Design</a></li>
<li><a href="jsdoc.html#sec:Type_Expressions">19.1.2. Type Expressions</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="docexporter.html#_docexporter">20. DocExporter</a>
<ul class="sectlevel2">
<li><a href="docexporter.html#sec:Specification_Exporter">20.1. Specification Exporter</a></li>
</ul>
</li>
<li><a href="rename_refactoring.html#_rename-refactoring">21. Rename Refactoring</a>
<ul class="sectlevel2">
<li><a href="rename_refactoring.html#_rename-refactoring-ui-interaction">21.1. Rename Refactoring UI interaction</a></li>
<li><a href="rename_refactoring.html#_renameelementprocessor-interaction">21.2. RenameElementProcessor interaction</a></li>
</ul>
</li>
<li><a href="flow_graphs.html#chap:flowgraphs">22. Flow Graphs</a>
<ul class="sectlevel2">
<li><a href="flow_graphs.html#sec:flowgraphs_overview">22.1. Flow graphs overview</a>
<ul class="sectlevel3">
<li><a href="flow_graphs.html#_internal-graph">22.1.1. Internal graph</a></li>
<li><a href="flow_graphs.html#_optimizations">22.1.2. Optimizations</a></li>
<li><a href="flow_graphs.html#_api-for-client-analyses">22.1.3. API for client analyses</a>
<ul class="sectlevel4">
<li><a href="flow_graphs.html#_mapping-from-internal-to-ast-elements">22.1.3.1. Mapping from internal to AST elements</a></li>
<li><a href="flow_graphs.html#_graph-visitor">22.1.3.2. Graph visitor</a></li>
<li><a href="flow_graphs.html#_graph-explorer">22.1.3.3. Graph explorer</a></li>
<li><a href="flow_graphs.html#_branch-walker">22.1.3.4. Branch walker</a></li>
<li><a href="flow_graphs.html#_example-1-compute-string-for-each-path">22.1.3.5. Example 1: Compute string for each path</a></li>
<li><a href="flow_graphs.html#_path-quantor">22.1.3.6. Path quantor</a></li>
</ul>
</li>
<li><a href="flow_graphs.html#_control-flow-analyses">22.1.4. Control flow analyses</a>
<ul class="sectlevel4">
<li><a href="flow_graphs.html#_dead-code-analysis">22.1.4.1. Dead code analysis</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="flow_graphs.html#sec:dataflow">22.2. Dataflow</a>
<ul class="sectlevel3">
<li><a href="flow_graphs.html#_dataflow-graph">22.2.1. Dataflow graph</a></li>
<li><a href="flow_graphs.html#_dataflow-analyses">22.2.2. Dataflow analyses</a>
<ul class="sectlevel4">
<li><a href="flow_graphs.html#_def-def-def-nothing-analysis">22.2.2.1. Def&#8594;Def / Def&#8594;Nothing analysis</a></li>
<li><a href="flow_graphs.html#_def-use-decl-analysis">22.2.2.2. Def|Use&#8592;Decl analysis</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><a href="publish_npms.html#sec:publish-npms-to-public">23. Publish npms</a>
<ul class="sectlevel2">
<li><a href="publish_npms.html#sec:publish-npms-n4js-maven">23.1. Publish n4js-libs to during maven build</a></li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:Hints">Appendix A: Hints</a>
<ul class="sectlevel2">
<li><a href="appendix_a_hints.html#sec:XtextInjection">A.1. Xtext Injection</a>
<ul class="sectlevel3">
<li><a href="appendix_a_hints.html#sec:DI_MultipleInjectors_Singletons">A.1.1. Multiple Injectors and Singletons</a>
<ul class="sectlevel4">
<li><a href="appendix_a_hints.html#sec:DI_avoid_duplicate_singletons">A.1.1.1. Avoiding duplicate singletons</a>
<ul class="sectlevel5">
<li><a href="appendix_a_hints.html#sec:DI_binding_in_shared">A.1.1.1.1. Defining binding in the shared injector</a></li>
<li><a href="appendix_a_hints.html#sec:DI_binding_in_custom">A.1.1.1.2. Defining binding in the custom injector</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:DI_Hints">A.1.2. Dependency Injection Hints</a>
<ul class="sectlevel4">
<li><a href="appendix_a_hints.html#sec:DI_custom_bundle">A.1.2.1. Use DI in custom bundle, use DI with extensions</a>
<ul class="sectlevel5">
<li><a href="appendix_a_hints.html#sec:DI_custom_bundle_problem">A.1.2.1.1. Problem</a></li>
<li><a href="appendix_a_hints.html#sec:DI_custom_bundle_solution">A.1.2.1.2. Solution</a></li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:Access_Other_DSL_Injector">A.1.2.2. How do I get the Guice Injector of my language?</a>
<ul class="sectlevel5">
<li><a href="appendix_a_hints.html#sec:DSL_Injector_UI_context">A.1.2.2.1. UI context</a></li>
<li><a href="appendix_a_hints.html#sec:DSL_Injector_Non_UI_context">A.1.2.2.2. Non UI context but with injection context</a></li>
<li><a href="appendix_a_hints.html#sec:DSL_Injector_Non_UI_non_injection_context">A.1.2.2.3. Non UI context without injection context</a></li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:Cancel_Indicator">A.1.2.3. How do I get cancel indicators in different contexts?</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:Eclipse">A.2. Eclipse</a>
<ul class="sectlevel3">
<li><a href="appendix_a_hints.html#sec:Show_Xtext_Index">A.2.1. Show the current Xtext index</a></li>
<li><a href="appendix_a_hints.html#sec:Plugin_spy">A.2.2. Plug-in spy</a></li>
</ul>
</li>
<li><a href="appendix_a_hints.html#sec:Maven-hints">A.3. Maven</a>
<ul class="sectlevel3">
<li><a href="appendix_a_hints.html#how-to-check-for-maven-mojo-updates">A.3.1. How to check for Maven MOJO updates</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#_module-loading">Appendix B: Module Loading</a>
<ul class="sectlevel2">
<li><a href="appendix_b_module_loading.html#sec:Dependency_Management">B.1. Dependency Management</a></li>
<li><a href="appendix_b_module_loading.html#ecmascript-modules">B.2. ECMAScript Modules</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#sec:ES5_Modules_Systems">B.2.1. ES5 Modules Systems</a></li>
<li><a href="appendix_b_module_loading.html#sec:ES6_Modules">B.2.2. ES6 Modules</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:ECMAScript_Module_Loaders">B.3. ECMAScript Module Loaders</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#sec:ES6_Module_Loaders">B.3.1. ES6 Module Loaders</a></li>
<li><a href="appendix_b_module_loading.html#sec:Polyfills_for_ES6_Module_Loaders">B.3.2. Polyfills for ES6 Module Loaders</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:es6_module_loader">B.3.2.1. es6-module-loader</a></li>
<li><a href="appendix_b_module_loading.html#sec:SystemJS">B.3.2.2. SystemJS</a></li>
<li><a href="appendix_b_module_loading.html#sec:Demo">B.3.2.3. Demo</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#case-study-typescript">B.4. Case Study : TypeScript</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#sec:ES6_Modules_Support">B.4.1. ES6 Modules Support</a></li>
<li><a href="appendix_b_module_loading.html#sec:TypeScript_and_Module_Loading">B.4.2. TypeScript and Module Loading</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:Cyclic_Dependencies">B.5. Cyclic Dependencies</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#sec:Setup">B.5.1. Setup</a></li>
<li><a href="appendix_b_module_loading.html#sec:Transpile_and_Execute">B.5.2. Transpile and Execute</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:Module_Format___AMD">B.5.2.1. Module Format = AMD</a></li>
<li><a href="appendix_b_module_loading.html#sec:Module_Format___CommonJS">B.5.2.2. Module Format = CommonJS</a></li>
<li><a href="appendix_b_module_loading.html#sec:Module_Format___SystemJS">B.5.2.3. Module Format = SystemJS</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:Conclusion">B.5.3. Conclusion</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#system.register-as-transpilation-target">B.6. System.register as transpilation target</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#sec:Introduction">B.6.1. Introduction</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:External_Transpilers">B.6.1.1. External Transpilers</a></li>
<li><a href="appendix_b_module_loading.html#sec:Example_of_a_System_register_module">B.6.1.2. Example of a System.register module</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:Structure_of_a_System_register_module">B.6.2. Structure of a System.register module</a></li>
<li><a href="appendix_b_module_loading.html#_transpilation-hints">B.6.3. Transpilation Hints</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:Handling_Imports">B.6.3.1. Handling Imports</a></li>
<li><a href="appendix_b_module_loading.html#sec:__exportFn__">B.6.3.2. &lt;&lt;exportFn&gt;&gt;</a></li>
<li><a href="appendix_b_module_loading.html#sec:Handling_Exports">B.6.3.3. Handling Exports</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:Examples_w__Circular_Dependencies">B.6.4. Examples w/ Circular Dependencies</a></li>
<li><a href="appendix_b_module_loading.html#sec:N4JS_Examples_w__Circular_Dependencies">B.6.5. N4JS Examples w/ Circular Dependencies</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:Unresolved_Cyclic_Dependencies">B.6.5.1. Unresolved Cyclic Dependencies</a></li>
<li><a href="appendix_b_module_loading.html#sec:Variables___Functions">B.6.5.2. Examples with Variables &amp; Functions</a></li>
<li><a href="appendix_b_module_loading.html#sec:Classes">B.6.5.3. Examples with Classes</a></li>
<li><a href="appendix_b_module_loading.html#sec:Examples_with_SubClassing">B.6.5.4. Examples with SubClassing</a></li>
<li><a href="appendix_b_module_loading.html#sec:Miscellaneous">B.6.5.5. Miscellaneous</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#_resources">B.6.6. Resources</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#sec:CommonJS_as_transpilation_target">B.7. CommonJS as transpilation target</a>
<ul class="sectlevel3">
<li><a href="appendix_b_module_loading.html#_introduction-2">B.7.1. Introduction</a></li>
<li><a href="appendix_b_module_loading.html#sec:Transpilation_Hints">B.7.2. Transpilation Hints</a>
<ul class="sectlevel4">
<li><a href="appendix_b_module_loading.html#sec:Import_Statements">B.7.2.1. Import Statements</a></li>
<li><a href="appendix_b_module_loading.html#sec:Export_Statements">B.7.2.2. Export Statements</a></li>
<li><a href="appendix_b_module_loading.html#sec:Tracking_Live_Bindings">B.7.2.3. Tracking Live Bindings</a></li>
<li><a href="appendix_b_module_loading.html#sec:A_complete_example">B.7.2.4. A complete example</a></li>
</ul>
</li>
<li><a href="appendix_b_module_loading.html#_resources-2">B.7.3. Resources</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="appendix_c_license.html#sec:License">Appendix C: License</a></li>
<li><a href="appendix_d_acronyms.html#sec:Acronyms">Appendix D: Acronyms</a></li>
<li><a href="appendix_e_bibliography_and_footnotes.html#_bibliography-and-footnotes">Appendix E: Bibliography and Footnotes</a></li>
</ul>
</div>
</div>
<div id="content"><div class="sect1">
<h2 id="_parser"><a class="anchor" href="#_parser"></a><a class="link" href="#_parser">5. Parser</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Some of the concepts described here were presented at
<a href="https://www.youtube.com/watch?v=Xm-7aE1UMGY&amp;feature=youtu.be">EclipseCon 2013</a> and
<a href="https://vimeo.com/channels/xtextcon/98446435">XtextCon 2014</a>. Note that the material presented at the linked videos may be outdated.</p>
</div>
<div class="sect2">
<h3 id="sec:Parser_Overview"><a class="anchor" href="#sec:Parser_Overview"></a><a class="link" href="#sec:Parser_Overview">5.1. Overview</a></h3>
<div class="paragraph">
<p>The parser is created from an Xtext grammar. Actually, there are several grammars used as shown in <a href="#fig:cd_grammars">Figure CD Grammars</a>. These grammars and the parsers generated from them are described more closely in the following sections.</p>
</div>
<div id="fig:cd_grammars" class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/cd_grammars.svg" alt="cd grammars">
</div>
<div class="title">Figure 2. N4 Grammars</div>
</div>
</div>
<div class="sect2">
<h3 id="sec:N4JS_Parser"><a class="anchor" href="#sec:N4JS_Parser"></a><a class="link" href="#sec:N4JS_Parser">5.2. N4JS Parser</a></h3>
<div class="paragraph">
<p>One of the most tricky parts of JavaScript is the parsing because there is a conceptual mismatch between the <a href="appendix_d_acronyms.html#AC">ANTLR</a> runtime and the specified grammar. Another challenge is the disambiguation of regular expressions and binary operations. Both features require significant customizing of the generated parser (see figure below).</p>
</div>
<div id="fig:cd_ASIParser" class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/cd_ASIParser.svg" alt="cd ASIParser">
</div>
<div class="title">Figure 3. Overview custom parser implementation (runtime only)</div>
</div>
</div>
<div class="sect2 language-bash">
<h3 id="sec:Parser_Generation_Post_Processing"><a class="anchor" href="#sec:Parser_Generation_Post_Processing"></a><a class="link" href="#sec:Parser_Generation_Post_Processing">5.3. Parser Generation Post-Processing</a></h3>
<div class="paragraph">
<p>The ANTLR grammar that is generated by Xtext is post-processed to inject custom code into the grammar file before it is passed to the ANTLR tool. This is required in particular due to <a href="appendix_d_acronyms.html#AC">ASI</a> (Automated Semicolon Insertion), but for some other reasons as well.</p>
</div>
<div class="paragraph">
<p>Actually, there are several injections:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Due to Xtext restrictions, the generated ANTLR grammar file (<strong>*.g</strong>) is modified. This means that some some additional actions are added and some rules are rewritten.</p>
</li>
<li>
<p>Due to ANTLR restrictions, the generated ANTLR Java parser (<strong>*.java</strong>) os modified. This means that some generated rules are slightly modified to match certain requirements.</p>
</li>
<li>
<p>Due to Java restrictions, the generated Java parser needs to be preprocessed in order to reduce the size of certain methods since they must not exceed 64k characters. This is implemented by means of an MWE fragment, activated after the other post processing steps are done.</p>
</li>
</ol>
</div>
<div class="paragraph">
<p>The first two steps are handled by <code>AntlrGeneratorWithCustomKeywordLogic</code>, which is configured with additional helpers in <code>GenerateN4JS.mwe2</code>. shows the customized classes which modify the code generation. These classes are all part of the <code>releng.utils</code> bundle.</p>
</div>
<div class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/cd_parsergeneration.svg" alt="cd parsergeneration">
</div>
<div class="title">Figure 4. Class Diagram Parser Generation</div>
</div>
<div class="sect3">
<h4 id="sec:Automatic_Semicolon_Insertion"><a class="anchor" href="#sec:Automatic_Semicolon_Insertion"></a><a class="link" href="#sec:Automatic_Semicolon_Insertion">5.3.1. Automatic Semicolon Insertion</a></h4>
<div class="paragraph">
<p>The EcmaScript specification mandates that valid implementations automatically insert a semicolon as a statement delimiter if it is missing and the input file would become invalid due to the missing semicolon. This is known as <a href="appendix_d_acronyms.html#AC">ASI</a>. It implies that not only valid implementations have to perform this, but a valid parser has to mimic this behavior in order to parse executable code. The <a href="appendix_d_acronyms.html#AC">ASI</a> is implemented by two different means.</p>
</div>
<div class="paragraph">
<p>The parser’s error recovery strategy is customized so it attempts to insert a semicolon if it was expected. Both strategies have to work hand in hand in order to consume all sorts of legal JavaScript code.</p>
</div>
<div class="sect4">
<h5 id="sec:Injected_code_in_the_Antlr_grammar_file"><a class="anchor" href="#sec:Injected_code_in_the_Antlr_grammar_file"></a><a class="link" href="#sec:Injected_code_in_the_Antlr_grammar_file">5.3.1.1. Injected code in the Antlr grammar file</a></h5>
<div class="paragraph">
<p>Under certain circumstances, the parser has to actively promote a token to become a semicolon even though it may be a syntactically a closing brace or line break. This has to happen before that token is consumed thus the rules for return statements, continue statements and break statements are enhanced to actively promote these tokens to semicolons.</p>
</div>
<div class="paragraph">
<p>The same rule is applied to promote line breaks between an expression and a possible postfix operator <code>++</code> or <code></code>. At this location the line break is always treated as a semicolon even though the operator may be validly consumed and produce a postfix expression.</p>
</div>
<div class="paragraph">
<p>In both cases, the method <code>promoteEOL()</code> is used to move a token that may serve as an automatically injected semicolon from the so called hidden token channel to the semantic channel. The hidden tokens are usually not handled by the parser explicitly thus they are semantically invisible (therefore the term hidden token). Nevertheless, they can be put on the semantic channel explicitly to make them recognizable. That’s implemented in the EOL promotion. The offending tokens include the hidden line terminators and multi-line comments that include line breaks. Furthermore, closing braces (right curly brackets) are included in the set of offending tokens as well as explicit semicolons.</p>
</div>
</div>
<div class="sect4">
<h5 id="sec:Customized_error_recovery"><a class="anchor" href="#sec:Customized_error_recovery"></a><a class="link" href="#sec:Customized_error_recovery">5.3.1.2. Customized error recovery</a></h5>
<div class="paragraph">
<p>Since the EOL promotion does not work well with Antlr prediction mode, another customization complements that feature. As soon as an invalid token sequence is attempted to be parsed and missing semicolon would make that sequence valid, an offending token is sought and moved to the semantic channel. This is implemented in the custom recovery strategy.</p>
</div>
</div>
</div>
<div class="sect3">
<h4 id="sec:_No_line_terminator_allowed_here__handling"><a class="anchor" href="#sec:_No_line_terminator_allowed_here__handling"></a><a class="link" href="#sec:_No_line_terminator_allowed_here__handling">5.3.2. Async and <code>No line terminator allowed here</code> Handling</a></h4>
<div class="paragraph">
<p>There is no way of directly defining <code>No line terminator allowed here</code>. This is required not only for <a href="appendix_d_acronyms.html#AC">ASI</a>, but also for <code>async</code>. This requires not only a special rule (using some rules from <a href="#sec:Automatic_Semicolon_Insertion">ASI</a>), but also a special error recovery since the token ’async’ may be rejected (by the manually enriched rule) which is of course unexpected behavior from the generated source code.</p>
</div>
</div>
<div class="sect3">
<h4 id="sec:Regular_Expression"><a class="anchor" href="#sec:Regular_Expression"></a><a class="link" href="#sec:Regular_Expression">5.3.3. Regular Expression</a></h4>
<div class="paragraph">
<p>The ANTLR parsing process can basically be divided into three steps. First of all, the file contents has to be read from disk. This includes the proper encoding of bytes to characters. The second step is the lexing or tokenizing of the character stream. A token is a basically a typed region in the stream, that is a triplet of token-id, offset and length. The last step is the parsing of these tokens. The result is a semantic model that is associated with a node tree. All necessary information to validate the model can be deduced from these two interlinked representations.</p>
</div>
<div class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/ad_parsing_simplified.svg" alt="ad parsing simplified">
</div>
<div class="title">Figure 5. Simplified visualization of the parsing</div>
</div>
<div class="paragraph">
<p>Since the default semantics and control flow of Antlr generated parsers do not really fit the requirements of a fully working JavaScript parser, some customizations are necessary. <strong>Regular expression literals in JavaScript cannot be syntactically disambiguated from div operations without contextual information.</strong> Nevertheless, the spec clearly describes, where a regular expression may appear and where it is prohibited. Unfortunately, it is not possible to implement these rules in the lexer alone, since it does not have enough contextual information. Therefore, the parser has been enhanced to establish a communication channel with the lexer. It announces when it expects a regular expression rather than a binary operation.</p>
</div>
<div class="paragraph">
<p>This required a reworking of the Antlr internals. Instead of a completely pre-populated <code>TokenStream</code>, the parser works on a lazy implementation that only reads as many characters as possible without a disambiguation between regular expression literals and divide operators.</p>
</div>
<div class="paragraph">
<p>Only after the parser has read this buffered tokens and potentially announced that it expects a regular expression, another batch of characters is processed by the lexer until the next ambiguous situation occurs. This is fundamentally different from the default behavior of Antlr.</p>
</div>
<div class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/sd_parsing_sequence.svg" alt="sd parsing sequence">
</div>
<div class="title">Figure 6. Abstract control and object flow during parsing</div>
</div>
<div class="paragraph">
<p>shows the involved classes which allow for this lexer-parser communication.</p>
</div>
<div class="imageblock center">
<div class="content">
<img src="chapters/05_parser/images/cd_parserlexercommunication.svg" alt="cd parserlexercommunication">
</div>
<div class="title">Figure 7. Class Diagram Parser-Lexer Communication</div>
</div>
</div>
<div class="sect3">
<h4 id="sec:Unicode"><a class="anchor" href="#sec:Unicode"></a><a class="link" href="#sec:Unicode">5.3.4. Unicode</a></h4>
<div class="paragraph">
<p>Unicode support in JavaScript includes the possibility to use unicode escape sequences in identifiers, string literals and regular expression literals. Another issue in this field is the specification of valid identifiers in JavaScript. They are described by means of unicode character classes. These have to be enumerated in the terminal rules in order to fully accept or reject valid or invalid JS identifiers.</p>
</div>
<div class="paragraph">
<p>For that purpose, a small code generator is used to define the terminal fragments for certain unicode categories. The <code>UnicodeGrammarGenerator</code> basically iterates all characters from <code>Character.MIN_VALUE</code> to <code>Character.MAX_VALUE</code> and adds them as alternatives to the respective terminal fragments, e.g. <code>UNICODE_DIGIT_FRAGMENT</code>.</p>
</div>
<div class="paragraph">
<p>The real terminal rules are defined as a composition of these generated fragments. Besides that, each character in an identifier, in a string literal or in a regular expression literal may be represented by its unicode escape value, e.g. ` u0060`. These escape sequences are handled and validated by the <code>IValueConverter</code> for the corresponding terminal rules.</p>
</div>
<div class="paragraph">
<p>The second piece of the puzzle are the unicode escaped sequences that may be used in keywords. This issue is covered by the <code>UnicodeKeywordHelper</code> which replaces the default terminal representation in the generated Antlr grammar by more elaborated alternatives. The keyword <code>if</code> is not only lexed as <code>’if’</code> but as seen in snippet
<a href="#lst:terminal_if">Terminal if listing</a>.</p>
</div>
<div id="lst:terminal_if" class="listingblock">
<div class="title">Terminal if</div>
<div class="content">
<pre class="highlight"><code>If :
( 'i' | '\\' 'u' '0`` 0`` 6`` 9' )
( 'f' | '\\' 'u' '0`` 0`` 6`` 6' );</code></pre>
</div>
</div>
</div>
<div class="sect3">
<h4 id="sec:Literals"><a class="anchor" href="#sec:Literals"></a><a class="link" href="#sec:Literals">5.3.5. Literals</a></h4>
<div class="paragraph">
<p>Template literals are also to be handled specially, see <code>TemplateLiteralDisambiguationInjector</code> for details.</p>
</div>
</div>
</div>
<div class="sect2 language-n4js">
<h3 id="sec:Modifiers"><a class="anchor" href="#sec:Modifiers"></a><a class="link" href="#sec:Modifiers">5.4. Modifiers</a></h3>
<div class="paragraph">
<p>On the AST side, all modifiers are included in a single enumeration <code>N4Modifier</code>. In the types model however, the individual modifiers are mapped to two different enumerations of <em>access</em> modifiers (namely <code>TypeAccessModifier</code> and <code>MemberAccessModifier</code>) and a number of boolean properties (in case of non-access modifiers such as <code>abstract</code> or <code>static</code>). This mapping is done by the types builder, mostly by calling methods in class <code>ModifierUtils</code>.</p>
</div>
<div class="paragraph">
<p>The grammar allows the use of certain modifiers in many places that are actually invalid. Rules where a certain modifier may appear in the AST are implemented in method isValid(EClass,N4Modifier) in class <code>ModifierUtils</code> and checked via several validations in <code>N4JSSyntaxValidator</code>. Those validations also check for a particular order of modifiers that is not enforced by the grammar.</p>
</div>
<div class="paragraph">
<p>See API documentation of enumeration <code>N4Modifier</code> in file <code>N4JS.xcore</code> and the utility class <code>ModifierUtils</code> for more details.</p>
</div>
</div>
<div class="sect2 language-n4js">
<h3 id="sec:Conflict_Resolutions"><a class="anchor" href="#sec:Conflict_Resolutions"></a><a class="link" href="#sec:Conflict_Resolutions">5.5. Conflict Resolutions</a></h3>
<div class="sect3">
<h4 id="sec:Reserved_Keywords_vs__Identifier_Names"><a class="anchor" href="#sec:Reserved_Keywords_vs__Identifier_Names"></a><a class="link" href="#sec:Reserved_Keywords_vs__Identifier_Names">5.5.1. Reserved Keywords vs. Identifier Names</a></h4>
<div class="paragraph">
<p>Keywords and identifiers have to be distinguished by the lexer. Therefore, there is no means to decide upfront whether a certain keyword is actually used as a keyword or whether it is used as an identifier in a given context. This limitation is idiomatically overcome by a data type rule for valid identifiers. This data type rule enumerates all keywords which may be used as identifiers and the pure IDENTIFIER terminal rule as seen in <a href="#lst:keywords_as_identifier">Keywords as Identifier listing</a>.</p>
</div>
<div id="lst:keywords_as_identifier" class="listingblock">
<div class="title">Keywords as Identifier</div>
<div class="content">
<pre class="highlight"><code class="language-ebnf" data-lang="ebnf">N4JSIdentifier: IDENTIFIER
| 'get'
| 'set'
...
;</code></pre>
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<div class="sect3">
<h4 id="sec:Operators_and_Generics"><a class="anchor" href="#sec:Operators_and_Generics"></a><a class="link" href="#sec:Operators_and_Generics">5.5.2. Operators and Generics</a></h4>
<div class="paragraph">
<p>The ambiguity between shift operators and nested generics arises also from the fact, that Antlr lexer upfront without any contextual information. When implemented naively, the grammar will be broken, since a token sequence <code>a&gt;&gt;b</code> can either be part of <code>List&lt;List&lt;a&gt;&gt; b</code> or it can be part of a binary operation <code>int c = a &gt;&gt; b</code>. Therefore the shift operator may not be defined with a single token but has to be composed from individual characters (see <a href="#lst:shift_operator">Shift Operator listing</a>).</p>
</div>
<div id="lst:shift_operator" class="listingblock">
<div class="title">Shift Operator listing</div>
<div class="content">
<pre class="highlight"><code class="language-ebnf" data-lang="ebnf">ShiftOperator:
'&gt;' '&gt;' '&gt;'?
| '&lt;' '&lt;'
;</code></pre>
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<div class="sect2 language-n4js">
<h3 id="sec:Content_Assist_Parser"><a class="anchor" href="#sec:Content_Assist_Parser"></a><a class="link" href="#sec:Content_Assist_Parser">5.6. Content-Assist Parser</a></h3>
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<div class="paragraph">
<p>The <a href="appendix_d_acronyms.html#AC">CA</a> parser also needs adjustments for supporting automatic semicolon insertion and regular expressions. Instead of modifying the <a href="appendix_d_acronyms.html#AC">CA</a> parser generator similar to the normal parser, the former reuses parts of the latter as far as possible. That is, the token sequence that is produced during production parsing is used as is for the content assist parser. Semicolons have already been inserted where appropriate and regular expression are successfully distinguished from divide operators.</p>
</div>
<div class="paragraph">
<p>Since the n4js grammar uses syntactic predicates, the content assist parser is compiled with backtracking enabled. This is always the case for Xtext’s CA parsers that rely on backtracking or predicates (local backtracking) in the production parser. This approach is both good (CA works in general) and bad (unpredictable decisions in case of error at locations prior to the cursor). Since parsing with backtracking enabled makes for a fundamental difference in how the prediction and parsing works and how the parser decides which decision paths to take, the customization patterns from the production parser are not applied 1:1 to the CA parser, but adapted instead. The content assist parser doesn’t use a freshly lexed token stream with unicode support, ASI or regular expression literals, but instead uses a synthesized token sequence which is rebuilt from the existing node model.</p>
</div>
<div class="paragraph">
<p>The token stream that is consumed by the content assist parser is therefore not created by a lexer but by the <code>org.eclipse.n4js.ui.contentassist.NodeModelTokenSource</code>.
It traverses the existing node model that is contained in the resource and was produced by the production parser. This approach has the significant advantage that any decision that was made by that parser is also immediately applicable to the content assist infrastructure. For that purpose, the leaf nodes of the node model are mapped to ANTLR token types.
This is achieved by the <code>org.eclipse.n4js.ui.contentassist.ContentAssistTokenTypeMapper</code> which is capable to provide the untyped ANTLR token type (primitive int) for a given grammar element.</p>
</div>
<div class="paragraph">
<p>Special considerations have been made for the last token in the produced source. If it overlaps with an existing leaf node but does not fully cover it, the plain Antlr lexer is used to consume the prefix that is overlapping. Since the terminals will never overlap with each other the longest match always wins without backtracking in the lexer, it is save to assume that only one token is produced from the prefix. The very last token in the <code>org.eclipse.n4js.ui.contentassist.NodeModelTokenSource</code> is always the EOF token (<code>org.antlr.runtime.Token.EOF_TOKEN</code>).</p>
</div>
<div class="paragraph">
<p>Given that the token source is equal to the prefix in the production token source, some more thought has to be put into the synthesized end of file. The production parser used the complete file to decide where to automatically insert a semicolon and where not to. This would potentially change if there was another token next to the artificial EOF. Therefore, two cases have to considered. The first one describes CA request next to an automatically inserted semicolon and the second one describes CA requests at a position where a semicolon could have been inserted if the token to the right was another one. The <code>org.eclipse.n4js.ui.contentassist.CustomN4JSParser</code> reflects these cases. Heuristics are applied to the end of the token sequence to decide whether a second pass has to be performed to collect yet more following elements. Based on the concrete sequence, the last automatically inserted semicolon is removed from the sequence prior to the second pass or such is a token is explicitly synthesized and appended. Besides the second pass, another special treatment is made for postfix expressions. Those may not be interrupted by a hidden semicolon so those are filtered from the resulting follow set if appropriate.</p>
</div>
<div class="paragraph">
<p>The parser is used by the <code>org.eclipse.n4js.ui.contentassist.ContentAssistContextFactory</code> where all relevant entry points from the super class are specialized to pass the node model in the the parser facade (<code>org.eclipse.n4js.ui.contentassist.CustomN4JSParser</code>). In that sense, the ContentAssistContextFactory serves as a drop-in replacement binding the default <code>ParserBasedContentAssistContextFactory.StatefulFactory</code>.</p>
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