Notepad3/.github/copilot-instructions.md

Copilot Instructions for Notepad3

Build

Notepad3 is a Windows-only C/C++ application built with Visual Studio 2026 (toolset v145) and MSBuild. The solution file is Notepad3.sln.

Build commands

# Full build (all platforms: Win32, x64, x64_AVX2, ARM64)
Build\BuildAll.cmd [Release|Debug]

# Single platform
Build\Build_x64.cmd [Release|Debug]
Build\Build_Win32.cmd [Release|Debug]
Build\Build_ARM64.cmd [Release|Debug]
Build\Build_x64_AVX2.cmd [Release|Debug]

# MSBuild directly (used by CI)
msbuild Notepad3.sln /m /p:Configuration=Release /p:Platform=x64

# Clean
Build\Clean.cmd

# NuGet restore (required before first build)
nuget restore

Default configuration is Release. The build scripts delegate to PowerShell scripts in Build\scripts\.

Versioning

Run Version.ps1 before building to generate src\VersionEx.h from templates in Versions\. Version format is Major.YY.Mdd.Build where the build number is persisted in Versions\build.txt.

Tests

Tests live in test\ and run via AppVeyor CI:

cd test
TestFileVersion.cmd       # Verifies built binary version info
TestAhkNotepad3.cmd       # AutoHotkey-based GUI tests (requires AutoHotkey)

CI

GitHub Actions workflow at .github/workflows/build.yml builds all four platforms (Win32, x64, x64_AVX2, ARM64) in Release on windows-2022 runners, triggered on push/PR to master.

Architecture

Notepad3 is a Win32 desktop text editor built on the Scintilla editing component with Lexilla for syntax highlighting. It ships with two companion tools: MiniPath (file browser) and grepWinNP3 (file search/grep).

Core modules (in src\)

• Notepad3.c/h — Application entry point (wWinMain), window procedure, global state structs (GLOBALS_T, SETTINGS_T, FLAGS_T, PATHS_T)
• Edit.c/h — Text manipulation (find/replace, encoding conversion, clipboard, indentation, sorting)
• Styles.c/h — Scintilla styling, lexer selection, theme management
• Dialogs.c/h — All dialog boxes and UI interactions
• Encoding.c/h — Character encoding detection and conversion
• SciCall.h — Type-safe inline wrappers for Scintilla direct function calls (avoids SendMessage overhead)
• DynStrg.c/h — Custom dynamic wide-string type (HSTRINGW) with automatic buffer management
• PathLib.c/h — Path manipulation via opaque HPATHL handle
• TypeDefs.h — Core type definitions (DocPos, DocLn, cpi_enc_t), Windows version targeting, compiler macros

Vendored dependencies

• scintilla\ — Scintilla editor component with Notepad3-specific patches in np3_patches\
• scintilla\doc\ - Scintilla documentation offline
• lexilla\ — Lexilla syntax highlighting engine with custom patches
• lexilla\doc\ — Lexilla documentation offline
• src\uchardet\ — Character encoding detector
• src\tinyexpr\ / src\tinyexprcpp\ — Expression evaluator for statusbar
• src\uthash\ — Hash table library (C macros)
• Boost Regex & IOStreams — Managed via vcpkg.json

Syntax highlighting lexers (src\StyleLexers\)

Each language has its own styleLexXXX.c file (~50+ languages). All lexers follow the EDITLEXER struct pattern defined in EditLexer.h:

EDITLEXER lexXXX = {
    SCLEX_XXX,          // Scintilla lexer ID
    "lexerName",        // Lexilla lexer name (case-sensitive)
    IDS_LEX_XXX_STR,    // Resource string ID
    L"Config Name",     // INI section name
    L"ext1; ext2",      // Default file extensions
    L"",                // Extension buffer (runtime)
    &KeyWords_XXX,      // Keyword lists
    { /* EDITSTYLE array — must be last member */ }
};

Localization (language\)

Resource-based MUI system with 27+ locales. Each locale has a directory np3_LANG_COUNTRY\ containing resource .rc files. Language DLLs are built as separate projects in the solution.

Conventions

Code style

• Formatting: LLVM-based .clang-format in src\ — 4-space indentation, Stroustrup brace style, left-aligned pointers, no column limit, no include sorting
• Editor config: .editorconfig enforces UTF-8/CRLF for source files, 4-space indentation for C/C++; Lexilla code uses tabs (preserved from upstream)
• String safety: Uses strsafe.h throughout; deprecated string functions are disabled

Type conventions

• Use DocPos / DocPosU / DocLn for Scintilla document positions and line numbers (not raw int)
• Use cpi_enc_t for encoding identifiers
• Use HSTRINGW and HPATHL (opaque handle types) instead of raw WCHAR* buffers for dynamic strings and paths
• NOMINMAX is defined globally — use min()/max() macros or typed equivalents

Scintilla interaction

Always use SciCall.h wrappers (e.g., SciCall_GetTextLength()) instead of raw SendMessage(hwnd, SCI_XXX, ...). The wrappers use Scintilla's direct function pointer for performance. Add missing wrapper calls to SciCall.h if needed.

Adding a new syntax lexer

1. Create src\StyleLexers\styleLexNEW.c following existing lexer patterns
2. Define EDITLEXER struct with lexer ID, name, extensions, keywords, and styles
3. Register it in Styles.c lexer array
4. Add localization string IDs to resource files

Global state

Application state is centralized in global structs in Notepad3.c — Globals, Settings, Settings2, Flags, Paths. Prefer accessing these through their defined interfaces rather than adding new globals.