Files

David Gwilliam bfcad4963a Add mouse wheel and keyboard scrolling support to REPL

- Add scroll_offset to REPLState (max 50 lines)
- Modify _render_repl() to use manual scroll position
- Add scroll_output(delta) method for scroll control
- Add PageUp/PageDown keyboard support (scroll 10 lines)
- Add mouse wheel support via SGR mouse tracking
- Update HUD to show scroll percentage (like vim) and position
- Reset scroll when new output arrives
- Add tests for scroll functionality

2026-03-22 17:27:00 -07:00

3.6 KiB

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REPL Usage Guide

The REPL (Read-Eval-Print Loop) effect provides an interactive command-line interface for controlling Mainline's pipeline in real-time.

How to Access the REPL

Method 1: Using CLI Arguments (Recommended)

Run Mainline with the repl effect added to the effects list:

# With empty source (for testing)
python mainline.py --pipeline-source empty --pipeline-effects repl

# With headlines source (requires network)
python mainline.py --pipeline-source headlines --pipeline-effects repl

# With poetry source
python mainline.py --pipeline-source poetry --pipeline-effects repl

Method 2: Using a Preset

Add a preset to your ~/.config/mainline/presets.toml or ./presets.toml:

[presets.repl]
description = "Interactive REPL control"
source = "headlines"
display = "terminal"
effects = ["repl"]
viewport_width = 80
viewport_height = 24

Then run:

python mainline.py --preset repl

Method 3: Using Graph Config

Create a TOML file (e.g., repl_config.toml):

source = "empty"
display = "terminal"
effects = ["repl"]

Then run:

python mainline.py --graph-config repl_config.toml

REPL Commands

Once the REPL is active, you can type commands:

help - Show available commands
status - Show pipeline status and metrics
effects - List all effects in the pipeline
effect <name> <on|off> - Toggle an effect
param <effect> <param> <value> - Set effect parameter
pipeline - Show current pipeline order
clear - Clear output buffer
quit/exit - Show exit message (use Ctrl+C to actually exit)

Keyboard Controls

Enter - Execute command
Up/Down arrows - Navigate command history
Backspace - Delete last character
Ctrl+C - Exit Mainline

Visual Features

The REPL displays:

HUD header (top 3 lines): Shows FPS, frame time, command count, and output buffer size
Content area: Main content from the data source
Separator line: Visual divider
REPL area: Output buffer and input prompt

Example Session

MAINLINE REPL | FPS: 60.0 | 12.5ms
COMMANDS: 3 | [2/3]
OUTPUT: 5 lines
────────────────────────────────────────
Content from source appears here...
More content...
────────────────────────────────────────
> help
Available commands:
  help - Show this help
  status - Show pipeline status
  effects - List all effects
  effect <name> <on|off> - Toggle effect
  param <effect> <param> <value> - Set parameter
  pipeline - Show current pipeline order
  clear - Clear output buffer
  quit - Show exit message
> effects
Pipeline effects:
  1. repl
> effect repl off
Effect 'repl' set to off

Scrolling Support

The REPL output buffer supports scrolling through command history:

Keyboard Controls:

PageUp - Scroll up 10 lines
PageDown - Scroll down 10 lines
Mouse wheel up - Scroll up 3 lines
Mouse wheel down - Scroll down 3 lines

Scroll Features:

Scroll percentage shown in HUD (like vim, e.g., "50%")
Scroll position shown in output line (e.g., "(5/20)")
Auto-reset - Scroll resets to bottom when new output arrives
Max buffer - 50 lines (excluding empty lines)

Notes

The REPL effect needs a content source to overlay on (e.g., headlines, poetry, empty)
The REPL uses terminal display with raw input mode
Command history is preserved across sessions (up to 50 commands)
Pipeline mutations (enabling/disabling effects) are handled automatically

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