emacs Code Navigation

This is a summary and record of the tools and methods I use in emacs for editing and browsing code. I use these in my daily development projects. Some of the shortcuts are default, while others are custom; if you are not used to them, you can redefine them as needed.

I have uploaded my emacs configuration directory to: gitee and github. You can use it directly as your .emacs.d. It works for both emacs 28 and 29.

Online Code Search

You can search code directly here, though I rarely use it. grep.app and sourcegraph

Project File Search

• You can use command-line tools outside of emacs:

  fd, find, locate, which

• In emacs, you can use helm-projectile

The most commonly used is helm-projectile-find-file (C-c p f) to search for files. For example, to quickly locate the file “plugin/reassemble/app_smtp.c”:

After pressing C-c p f, just type smtp.c, then press space to locate it.

For stepwise narrowing, type:

plug (space) reas (space) smtp

This way, you don’t need to look through the list file by file; you can quickly locate and open files via fuzzy search. Other useful commands include:

helm-projectile-find-file-dwim

helm-projectile-find-dir

helm-projectile-recentf

All these commands can be found via the C-c p menu, which also shows their shortcuts.

Code Navigation

global

global can generate gtags, allowing emacs to search code based on index files. It’s more convenient when used with helm-gtags. You need to run gtags in the code directory first to generate the index files before searching. For example:

• Jump to definition:

  helm-gtags-dwim M-.

• Find references to a function or variable:

  helm-gtags-find-rtag M-r

• Return after jumping:

  helm-gtags-pop-stack M-,

• Project-wide search:

  helm-gtags-select C-c h

lsp

global is sufficient for C language and is simple to install with few dependencies. But nowadays, lsp is even better and supports more languages. For some new languages, global’s indexing is not as effective.

• Jump to the definition at the cursor:

  xref-find-definitions M-.

• Find references at the cursor:

  lsp-find-references M-r

• Return after jumping:

  xref-go-back M-,

• Search for functions and variables within the buffer:

  helm-imenu C-c i

  lsp-ui-imenu M-j (no fuzzy search)

  lsp-treemacs-symbols C-c C-c S (no fuzzy search)

• Search for functions and variables project-wide:

  helm-lsp-workspace-symbol C-c x i

• Search for references project-wide:

  lsp-find-references M-r

  lsp-treemacs-references

  lsp-ui-peek-find-references C-c C-p r

• Call hierarchy:

  lsp-treemacs-call-hierarchy C-c C-c h

• Jump back within the buffer

After jumping to a position with imenu, C-u C-SPC will return to the previous position. This only works within the current buffer using imenu. You can temporarily mark a position with C-SPC, and after moving elsewhere, use C-u C-SPC to jump back. If you mark multiple positions, you can return in reverse order, also only within the current buffer.

Keyword Search

• Search for keywords within the buffer:

  isearch C-s

  There are also isearch series searches in the M-s menu

• Faster keyword search in the current buffer:

  helm-occur C-c o or C-x c M-s o (interactive)

  occur M-s o (lists all matches, allows preview, but does not auto-fill the keyword when running the command)

• Highlight keywords in the buffer:

  isearch C-s

  isearch-forward-symbol-at-point M-s . Highlights the current “thing” at the cursor (regardless of position), faster than C-s, and is syntax-aware for variables

  isearch-forward-thing-at-point M-s M-. Highlights the current “thing” at the cursor (regardless of position), faster than C-s, with an extra M key

  symbol-overlay M-i Highlights symbols within the function scope. Can lock, cancel, and highlight multiple symbols.

• Search for keywords in files:

  rg (ripgrep). Powerful and fast

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