# Atom
[Atom](https://atom.io/)
([Wikipedia](https://en.wikipedia.org/wiki/Atom_(text_editor))) is a
multi-platform code editor that is itself based on Chromium.
[Turtles aside](https://en.wikipedia.org/wiki/Turtles_all_the_way_down), Atom
has a growing community and base of installable plugins and themes.
You can download and install via links from the
[main Atom site](https://atom.io/). If you're interested in checking out the
code and contributing, see the
[developer page](https://github.com/atom/atom/blob/master/docs/build-instructions/linux.md).
[TOC]
## Workflow
A typical Atom workflow consists of the following.
1. Use `Ctrl-Shift-R` to find a symbol in the `.tags` file or `Ctrl-P` to find
a file by name.
2. Switch between the header and the source using `Alt-O`(`Ctrl-Opt-S` on OSX).
3. While editing, `you-complete-me` package helps with C++ auto-completion and
shows compile errors through `lint` package.
4. Press `Ctrl-Shift-P` and type `format<Enter>` to format the code.
5. Select the target to build by pressing `F7` and typing, for example,
`base_unittests`.
6. Rebuild again by pressing `F9`.
## Atom packages
To setup this workflow, install Atom packages for Chrome development.
```
$ apm install build build-ninja clang-format \
linter linter-cpplint linter-eslint switch-header-source you-complete-me
```
## Autocomplete
Install C++ auto-completion engine.
```
$ git clone https://github.com/Valloric/ycmd.git ~/.ycmd
$ cd ~/.ycmd
$ ./build.py --clang-completer
```
On Mac, replace the last command above with the following.
```
$ ./build.py --clang-completer --system-libclang
```
## JavaScript lint
Install JavaScript linter for Blink web tests.
```
$ npm install -g eslint eslint-config-google
```
Configure the JavaScript linter to use the Google style by default by replacing
the contents of `~/.eslintrc` with the following.
```
{
"extends": "google",
"env": {
"browser": true
}
}
```
## Configuration
Configure Atom by replacing the contents of `~/.atom/config.cson` with the
following. Replace `<path-of-your-home-dir>` and
`<path-of-your-chrome-checkout>` with the actual full paths of your home
directory and chrome checkout. For example, these can be `/Users/bob` and
`/Users/bob/chrome/src`.
```
"*":
# Configure ninja builder.
"build-ninja":
ninjaOptions: [
# The number of jobs to use when running ninja. Adjust to taste.
"-j10"
]
subdirs: [
# The location of your build.ninja file.
"out/gn"
]
# Do not auto-format entire files on save.
"clang-format":
formatCOnSave: false
formatCPlusPlusOnSave: false
core:
# Treat .h files as C++.
customFileTypes:
"source.cpp": [
"h"
]
# Don't send metrics if you're working on anything sensitive.
disabledPackages: [
"metrics"
"exception-reporting"
]
# Use spaces instead of tabs.
editor:
tabType: "soft"
# Show lint errors only when you save the file.
linter:
lintOnFly: false
# Configure JavaScript lint.
"linter-eslint":
eslintrcPath: "<path-of-your-home-dir>/.eslintrc"
useGlobalEslint: true
# Don't show ignored files in the project file browser.
"tree-view":
hideIgnoredNames: true
hideVcsIgnoredFiles: true
# Configure C++ autocomplete and lint.
"you-complete-me":
globalExtraConfig: "<path-of-your-chrome-checkout>/tools/vim/chromium.ycm_extra_conf.py"
ycmdPath: "<path-of-your-home-dir>/.ycmd/"
# Java uses 4 space indents and 100 character lines.
".java.source":
editor:
preferredLineLength: 100
tabLength: 4
```
## Symbol lookup
Atom fuzzy file finder is slow to index all files in Chrome. If you're working
on a project that frequently uses `foo` or `bar` in files names, you can create
a small `.tags` file to efficiently search the symbols within these files. Be
sure to use "Exuberant Ctags."
```
$ git ls | egrep -i "foo|bar" | ctags -f .tags -L -
```
Don't create a ctags file for the full Chrome repository, as that would result
in ~9GB tag file that will not be usable in Atom.
Codebase Browser
chromium