Slash Tree for Obsidian

English | 简体中文

Turn a fixed-format text into a slash-style binary tree drawing with one command. Built for algorithm notes: the input is one line per level, parent: left right lines, a LeetCode-style level-order array, or an indented list, and the output is the / \ tree you would sketch by hand, not a ├── directory tree.

[3,9,20,null,null,15,7]      →        3
                                     / \
                                    9   20
                                       /  \
                                     15    7

Slashes are strict 45° diagonals, every parent is centered over its children, and labels of any width (including CJK characters) stay aligned at any depth.

Input formats

The format is detected automatically. Pick whichever feels natural; the input dialog shows which one it recognised.

1. Levels, one line per level (recommended)

Write the root on the first line, then each level on its own line. Use | to group the children by parent, in the same order as the previous line, and _ for an empty slot.

3
9 20
_ | 15 7

• Line 3 has two groups: the children of 9 (none) and the children of 20 (15 7).
• A group holds at most two values, left right. _ 7 means right child only, 15 alone means left child only, and an empty group means no children.
• Every parent gets exactly one group, so a wrong count is reported immediately, with the parents listed, instead of silently shifting the tree.
• Without |, a line must contain exactly two values per parent, like a LeetCode array: 4 5 _ 6.

A bigger example, [5,4,8,11,null,13,4,7,2,null,null,null,1]:

5
4 8
11 _ | 13 4
7 2 | | _ 1

2. Parent and children

One line per node that has children: parent: left right. The first line's parent is the root; every later parent must already appear as a child on an earlier line. Leaves are simply not mentioned.

3: 9 20
20: 15 7

If several nodes share a label, each line refers to the first such node, in order of appearance, that has not been given children yet, so writing lines level by level does the right thing.

3. Level-order array (LeetCode style)

[1,2,3,null,4]
1,2,3,null,4
1 2 3 # 4

• Brackets are optional; separate values with commas or spaces. Quotes are stripped.
• Empty slots are null / None / nil / # / _ (case-insensitive, configurable). An empty string also counts as an empty slot.
• By default the array is read the LeetCode way: an empty slot does not reserve positions for its children. Switch to heap mode in settings to use fixed indices (2i+1, 2i+2).

4. Indented list

1
  2
    4
    5
  3
    null
    6

• A deeper-indented line is a child of the line above it. The first child is the left one, the second is the right one; use null to skip the left slot.
• Markdown list markers (- 1) are fine. You can also set the side explicitly with L: / R::

- 1
  - R: 2
    - 3

Three ways to use it

Mode	How	Result
Convert in place	Select the text (or put the cursor on the array line) and run Convert selection to slash tree from the command palette or the right-click menu	The selection is replaced by a fenced code block containing the tree
Input dialog	Run Insert slash tree…	Live preview while you type; ⌘/Ctrl+Enter inserts at the cursor
Live rendering	Write a ```tree code block containing the source format	Rendered as a tree in Reading view and Live Preview; the source stays editable, hover to copy

Live rendering example:

```tree
[5,3,8,1,4,null,9]
```

More output samples:

[1,2,3,4,5,6,7]      [5,3,8,1,4,null,9,null,2]      [100,20,3000,1,null,null,45]

     1                   5                               100
    / \                 / \                             /   \
   /   \               3   8                          20     3000
  2     3             / \   \                        /           \
 / \   / \           1   4   9                      1             45
4   5 6   7           \
                       2

Installation

From the community plugin browser

Once the plugin is listed: Settings → Community plugins → Browse, search for Slash Tree, install and enable it.

With BRAT (before it is listed)

1. Install the BRAT plugin.
2. Run BRAT: Add a beta plugin for testing and enter AdamLTy/obsidian-slash-tree.
3. Enable Slash Tree in Settings → Community plugins.

Manually from a release

Download main.js, manifest.json and styles.css from the latest release, put them in <vault>/.obsidian/plugins/slash-tree/, then enable the plugin.

From source

git clone https://github.com/AdamLTy/obsidian-slash-tree.git
cd obsidian-slash-tree
npm install
scripts/install.sh "/path/to/your/vault"

The plugin UI follows Obsidian's interface language: Chinese when Obsidian is set to 简体中文 / 繁體中文, English otherwise.

Settings

• Minimum subtree gap – how many blank columns to keep between adjacent subtrees (default 1).
• Null tokens – comma-separated list of tokens that mean "empty node".
• Level-order interpretation – LeetCode or heap.
• Code block language – the fence tag that is rendered live (default tree; reload the plugin after changing it).
• Output fence language – the fence tag used by the convert command (default empty). Keep it different from the previous setting, or the rendered tree would be parsed again.

Development

npm test        # unit tests + property tests on random trees
npm run demo    # print sample trees in the terminal
npm run dev     # rebuild main.js on change
npm run build   # type-check + production bundle

All layout logic lives in src/tree.ts and has no Obsidian dependency, so it can be reused on its own.

License

MIT