Eccelerators.Cli

src/CliLineEditor.lvt

namespace Eccelerators.Cli

/**
 * Tracks bounded command-line length, terminal line endings, and editing state.
 */
component CliLineEditor
{
	/**
	 * Maximum number of printable ASCII bytes accepted in one command line.
	 */
	public const MAX_LINE_LENGTH: int = 64

	const CARRIAGE_RETURN: byte = 0x0D

	const LINE_FEED: byte = 0x0A

	const BACKSPACE: byte = 0x08

	const DELETE: byte = 0x7F

	length: byte

	complete: bool

	overflow: bool

	ignoreNextLineFeed: bool

	/**
	 * Accepts one byte and returns true when the byte was consumed.
	 */
	public fn AcceptByte(value: byte) bool
	{
		if (this.complete == true) { return false }

		if (this.ignoreNextLineFeed == true) {
			this.ignoreNextLineFeed = false

			if (value == LINE_FEED) { return true }
		}

		if (value == CARRIAGE_RETURN) {
			this.complete = true
			this.ignoreNextLineFeed = true
			return true
		}

		if (value == LINE_FEED) {
			this.complete = true
			return true
		}

		if (value == BACKSPACE || value == DELETE) {
			var currentLength: int = this.length as int

			if (currentLength != 0) {
				this.length = (currentLength - 1) as byte
			}

			return true
		}

		if (value < 0x20 || value > 0x7E) { return true }

		if ((this.length as int) >= MAX_LINE_LENGTH) {
			this.overflow = true
			return true
		}

		var nextLength: int = (this.length as int) + 1
		this.length = nextLength as byte
		return true
	}

	/**
	 * Returns the number of printable bytes currently accepted for the line.
	 */
	public fn GetLength() int
	{
		return this.length as int
	}

	/**
	 * Returns true after a supported line ending has been received.
	 */
	public fn IsComplete() bool
	{
		return this.complete
	}

	/**
	 * Returns true when printable input exceeded the line capacity.
	 */
	public fn HasOverflow() bool
	{
		return this.overflow
	}

	/**
	 * Clears the current line while preserving pending CRLF suppression.
	 */
	public fn ResetLine()
	{
		this.length = 0
		this.complete = false
		this.overflow = false
	}

	/**
	 * Clears the current line and all line-ending state.
	 */
	public fn Clear()
	{
		this.ResetLine()
		this.ignoreNextLineFeed = false
	}
}