garandos/cheatsheets/emacs/emacs.code-completion.cheatsheet.md

Doom Emacs Code Completion & Lookup Cheatsheet

🚀 What You Have (Like nvim-cmp + blink.cmp)

If your Doom config includes:

• Company Mode - Auto-completion framework
• LSP Mode - Language Server Protocol support
• Tree-sitter - Advanced syntax parsing
• Lookup tools - Documentation and definition lookup

⌨️ Code Completion (Company)

Auto-completion Controls:

• TAB or C-SPC - Accept completion
• C-n / j - Next completion (evil mode)
• C-p / k - Previous completion (evil mode)
• C-w - Show documentation for completion
• C-s - Search/filter completions
• ESC or C-g - Cancel completion

Manual Completion:

• M-/ - Complete at point (manual trigger)
• C-M-/ - Expand abbreviation

🔍 Code Lookup & Navigation

Go to Definition/References:

• gd - Go to definition (evil mode)
• gD - Go to declaration
• gr - Go to references
• SPC c d - Find definition
• SPC c D - Find references
• SPC c i - Find implementations

Documentation Lookup:

• K - Lookup documentation (evil mode)
• SPC c k - Lookup documentation
• SPC c K - Lookup in docsets
• C-h f - Describe function
• C-h v - Describe variable

Symbol Navigation:

• SPC c j - Jump to symbol in buffer
• SPC c J - Jump to symbol in project
• SPC s i - Search for symbol

🛠️ LSP Features (Language Server)

LSP Actions:

• SPC c a - Code actions (refactor, fix, etc.)
• SPC c r - Rename symbol
• SPC c f - Format buffer/region
• SPC c o - Organize imports

Error Navigation:

• ]e - Next error
• [e - Previous error
• SPC c x - List errors

LSP Info:

• SPC c l - LSP menu
• SPC c h - Show hover info
• SPC c s - Show signature

🎯 Language-Specific Features

C/C++ (clang-tools)

• Full completion for functions, variables, types
• Go to definition across files
• Error checking and diagnostics
• Code formatting with clang-format

Nix (nil LSP)

• Nix language completion
• Function documentation
• Syntax checking
• Go to definition for Nix expressions

JSON (vscode-json-languageserver)

• Schema-based completion
• Validation and error checking
• Go to definition in JSON files

⚡ Pro Tips

Fuzzy Search Everything:

• SPC f f - Find files
• SPC / - Search in project
• SPC s s - Search buffer
• SPC p p - Switch projects

Better Navigation:

• C-o - Go back (after jumping to definition)
• C-i - Go forward
• SPC j j - Jump to character (like easymotion)

Completion Tweaks:

• Completions appear after 0.2 seconds of typing
• Minimum 1 character to trigger
• Shows documentation in popup
• Works with both Company and LSP

🔧 Troubleshooting

If completion isn't working:

1. Check if LSP server is running: SPC c l
2. Restart LSP: SPC c l r
3. Check syntax errors: SPC c x

Performance:

• LSP servers auto-start when you open supported files
• Completion is optimized for fast response
• Use SPC h r r to reload Doom config after changes

🚀 Quick Start Workflow

1. Open a code file (.c, .nix, .json)
2. Start typing - completions appear automatically
3. Navigate with j/k and accept with TAB
4. Use gd to jump to definitions
5. Use K to see documentation
6. Use SPC c a for code actions

📚 Language Servers Included

• C/C++: clang-tools (clangd)
• Nix: nil
• JSON: vscode-json-languageserver
• More can be added per language as needed!