Make RegExp groups foldable

[drom]

Make RegExp groups foldable

https://en.wikipedia.org/wiki/Code_folding

In WaveQL -- every line with RegExp "/foo/" is a foldable section that populates all empty lines after RegEx line with matching signals.

[drom]

Key Bindings for Code Folding

Here are the standard key bindings for code folding in the most popular text editors and IDEs. Note that on macOS, the Ctrl key is usually replaced by Cmd (⌘) or Option (⌥).

1. Visual Studio Code (VS Code)

VS Code uses a "block" approach. The K chord (pressing Ctrl+K first) is essential for global commands.

Action	Windows / Linux	macOS
Fold (Collapse)	Ctrl + Shift + [	Cmd + Option + [
Unfold (Expand)	Ctrl + Shift + ]	Cmd + Option + ]
Fold All	Ctrl + K, then Ctrl + 0	Cmd + K, then Cmd + 0
Unfold All	Ctrl + K, then Ctrl + J	Cmd + K, then Cmd + J
Fold Level (1-9)	Ctrl + K, then Ctrl + [1-9]	Cmd + K, then Cmd + [1-9]

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2. JetBrains (IntelliJ, PyCharm, WebStorm)

JetBrains uses the Numpad keys + and - by default, but standard number keys often work depending on the keymap scheme.

Action	Windows / Linux	macOS
Fold Selection	Ctrl + .	Cmd + .
Collapse Block	Ctrl + - (Minus)	Cmd + - (Minus)
Expand Block	Ctrl + + (Plus)	Cmd + + (Plus)
Collapse All	Ctrl + Shift + -	Cmd + Shift + -
Expand All	Ctrl + Shift + +	Cmd + Shift + +

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3. Vim / Neovim

Vim commands must be typed in Normal Mode. The mnemonic for folding is z (visualize a zipper).

• za : Toggle fold at cursor (Most useful).
• zc : Close fold at cursor.
• zo : Open fold at cursor.
• zM : Close All (Mnemonic: "More" folding).
• zR : Open All (Mnemonic: "Reduce" folding).
• zj / zk : Jump to next / previous fold.

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4. Sublime Text

Sublime shares very similar bindings with VS Code for single blocks.

Action	Windows / Linux	macOS
Fold	Ctrl + Shift + [	Cmd + Option + [
Unfold	Ctrl + Shift + ]	Cmd + Option + ]
Fold All	Ctrl + K, then Ctrl + 1	Cmd + K, then Cmd + 1
Unfold All	Ctrl + K, then Ctrl + J	Cmd + K, then Cmd + J

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5. Notepad++

Notepad++ relies heavily on the Alt key combined with numbers.

• Collapse Current Level: Ctrl + Alt + F
• Collapse Level [1-8]: Alt + [1-8]
• Unfold All: Alt + Shift + 0
• Fold All: Alt + 0

Summary Table: The "Big Three" Actions

Action	VS Code	JetBrains	Vim
Toggle	Ctrl+Shift+[	Ctrl+.	za
Fold All	Ctrl+K, 0	Ctrl+Shift+-	zM
Unfold All	Ctrl+K, J	Ctrl+Shift++	zR

[drom]

Visual Language of Foldable Regions

The "visual language" for foldable regions (often called disclosure widgets or accordions in UI design) relies on specific iconography and behaviors to tell the user: "There is more content here, and you can reveal it."

In the context of text editors and IDEs, this language is standardized into three main components: The Trigger, The Gutter, and The Placeholder.

1. The Trigger (Icons & Glyphs)

This is the icon you click to toggle the visibility. The style varies by operating system and software generation.

Icon Style	Visual	Common Usage
Chevrons	> rotates to v	Modern Standard. (VS Code, MacOS Finder). A right-pointing arrow means "collapsed," a down-pointing arrow means "expanded."
Carets	▸ rotates to ▾	Classic. Similar to chevrons but using filled triangles. Common in older versions of Sublime Text and Eclipse.
Boxed Signs	[+] switches to [-]	Legacy / Tree View. Known as the "Tree Control" style. Common in older Windows apps (Notepad++, File Explorer classic).
Ribbon/Bar	`	` highlights

2. The Gutter (The Container)

In text editors, foldable regions almost always live in the Gutter—the gray vertical strip on the left side of the window that holds line numbers.

• Hover-Reveal: To reduce visual noise, modern editors (like VS Code) often hide folding icons until you move your mouse into the gutter.
• Scope Lines: When you hover over a fold marker, a faint vertical line often appears in the editor connecting the start and end of the region (e.g., from the opening { to the closing }).

3. The Placeholder (The "Folded" State)

When a region is collapsed, the editor must visually indicate that code has vanished. This is usually done with a glyph that replaces the hidden text.

• The Ellipsis: ... (Most common). The code block disappears and is replaced by a small box containing three dots.
• The Double Arrow: < > or ↔. Indicates text has been "pinched" together.
• The Badge: Some editors (like IntelliJ) show a summary of what's inside, e.g., { code... } or <editor-fold...>

4. General UI vs. Code Editors

If you are designing a UI (like a website) versus writing code, the terminology changes slightly:

• In Code: It is called Code Folding.
• In Web/App Design: It is called an Accordion (stacked headers that expand) or a Disclosure Widget (a simple detail/summary toggle).

Summary of the Visual Metaphor

The visual language relies on Orientation as State:

• Right (>) = "Closed" (The flow moves past this item).
• Down (v) = "Open" (The flow moves into this item).