codegraph/DELPHI-SUPPORT.md

Pascal / Delphi Support for CodeGraph

Why Delphi?

Delphi (Object Pascal) remains one of the most widely used languages for Windows desktop and enterprise applications. With an estimated 1.5–3 million active developers and a strong presence in industries like healthcare, finance, logistics, and government, Delphi projects often involve large, long-lived codebases that benefit significantly from semantic code intelligence.

Many Delphi codebases have grown over decades — making structural understanding, impact analysis, and cross-file navigation exactly the kind of tooling gap CodeGraph is designed to fill.

Adding Delphi support positions CodeGraph as a uniquely valuable tool for a community that has historically been underserved by modern static analysis and AI-assisted development tools.

What Was Implemented

Pascal / Object Pascal (tree-sitter)

Full extraction support for .pas, .dpr, .dpk, and .lpr files using the tree-sitter-pascal grammar:

Feature	NodeKind	Details
Units / Programs	module	unit, program, package, library
Classes	class	Including inheritance and interface implementation
Records	class	Treated as classes (consistent with AST structure)
Interfaces	interface	With GUID support
Methods	method	Constructor, destructor, procedures, functions
Functions / Procedures	function	Top-level (non-class) routines
Properties	property	With read/write accessors
Fields	field	Class and record fields
Constants	constant	const declarations
Enums	enum	With enum members
Type Aliases	type_alias	type TFoo = ...
Uses / Imports	import	uses clause extraction
Function Calls	—	calls edges for call graph
Visibility	—	public, private, protected on methods/fields
Static Methods	—	class function / class procedure
Containment	—	contains edges (class → method, unit → type, etc.)
Inheritance	—	extends / implements edges

DFM / FMX Form Files (custom extractor)

Support for Delphi form files (.dfm for VCL, .fmx for FireMonkey) using a regex-based custom extractor — no tree-sitter grammar exists for this format:

Feature	NodeKind / EdgeKind	Details
Components	component	object Button1: TButton
Nested hierarchy	contains	Panel1 → Button1
Event handlers	references (unresolved)	OnClick = Button1Click → links UI to Pascal methods
inherited keyword	component	Inherited form components
Multi-line properties	—	Correctly skipped during parsing
Item collections	—	<item>...</end> blocks correctly handled

The DFM ↔ PAS linkage via event handlers enables cross-file impact analysis: renaming a method in .pas immediately reveals which UI components reference it.

Architecture

The implementation follows CodeGraph's established patterns:

• Pascal extraction uses the standard TreeSitterExtractor with a Pascal-specific LanguageExtractor configuration and a visitPascalNode() hook for AST nodes that require special handling (e.g., declType wrappers, defProc implementation bodies)
• DFM/FMX extraction uses a DfmExtractor class — analogous to LiquidExtractor and SvelteExtractor — that parses the line-based format with regex
• Routing in extractFromSource() dispatches .dfm/.fmx files to DfmExtractor before reaching the tree-sitter path
• tree-sitter-pascal is declared as an optionalDependency (consistent with all other grammars), pinned to a specific commit for reproducible builds

Files Changed

File	Change
src/types.ts	Added 'pascal' to Language type, file patterns to DEFAULT_CONFIG.include
src/extraction/grammars.ts	Grammar loader, extension mappings (.pas, .dpr, .dpk, .lpr, .dfm, .fmx), display name
src/extraction/tree-sitter.ts	Pascal LanguageExtractor, visitPascalNode() with 7 helper methods, DfmExtractor class, routing in extractFromSource()
package.json	tree-sitter-pascal in optionalDependencies (pinned commit)
__tests__/extraction.test.ts	36 new tests covering all Pascal and DFM extraction features

Test Results

• 36 new tests, all passing
• 0 regressions — the same 28 pre-existing failures (unrelated: missing Swift/Dart grammars, database path issues, MCP truncation test) are unchanged
• Tests cover: language detection, modules, imports, classes, records, interfaces, methods, visibility, static methods, enums, properties, constants, type aliases, calls, containment, full fixture files (UAuth.pas, UTypes.pas, MainForm.dfm)

Dependency Note

The npm package tree-sitter-pascal@0.0.1 is outdated (uses NAN bindings, incompatible with Node.js v24+). The implementation uses the actively maintained GitHub repository (Isopod/tree-sitter-pascal, v0.10.2) with a pinned commit hash for deterministic builds. This is consistent with how @sengac/tree-sitter-dart handles a similar situation.