Enhancing Debugging Ergonomics With Custom Dap Keymaps

Streamlining execution flow during an active debugging session requires fast, intuitive keyboard shortcuts. In commit ca95bed6 to my nvim-config repository, I added four custom keybindings to make evaluating expressions, managing conditional breakpoints, and terminating debug sessions much cleaner.

Here is a breakdown of the new additions to lua/plugins/dap.lua.

1. Floating Expression Evaluation (<Leader>de)

Inspecting variables on the fly without switching focus into the DAP UI panels keeps your focus on the code structure:

-- Evaluate the word under the cursor (or selected text in Visual mode) in a float
vim.keymap.set({ "n", "v" }, "<Leader>de", function()
  dapui.eval()
end, { desc = "Debug: Evaluate in Float" })

Works seamlessly in both Normal mode (evaluating the word directly under the cursor) and Visual mode (evaluating complex highlighted expressions).

2. Evaluate & Focus Floating Window (<Leader>dE)

Sometimes a simple preview float isn’t enough—you might need to scroll through a large data structure or inspect nested attributes inside the floating window.

-- Double-tap/Focus float: Open and jump cursor straight into the floating window
vim.keymap.set("n", "<Leader>dE", function()
  dapui.eval(nil, { enter = true })
end, { desc = "Debug: Evaluate and Focus Float" })

By passing { enter = true } to dapui.eval(), NeoVim immediately shifts cursor focus into the pop-up float, allowing you to scroll, copy text, or close it with standard window navigation.

3. Quick Session Termination (<Leader>dq)

To quickly tear down an active debugging session and reset your environment:

-- Terminate the current debugging session
vim.keymap.set("n", "<Leader>dq", function()
  dap.terminate()
end, { desc = "Debug: Stop/Terminate Session" })

Mapping dap.terminate() to <Leader>dq (“Debug Quit”) provides an easy-to-remember exit shortcut once your session finishes.

4. Conditional Breakpoints (<Leader>dB)

Stopping execution inside large loops or recursive algorithms requires conditional breakpoints:

-- Prompt for a condition string and set a conditional breakpoint on the current line
vim.keymap.set("n", "<Leader>dB", function()
  dap.set_breakpoint(vim.fn.input("Breakpoint condition: "))
end, { desc = "Debug: Set Conditional Breakpoint" })

Using <Leader>dB prompts directly for a condition string (e.g., i == 42 or ptr == NULL) and sets a conditional breakpoint without requiring manual GDB console setup.

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