CommentStripper.ts

import { Error, IO, Uri } from "@cogneco/mend"

export class CommentStripper extends IO.Reader {
	private backend: IO.BufferedReader
	private last: string | undefined
	private disableUntil?: string
	get readable(): boolean { return this.backend.readable }
	get opened(): boolean { return this.backend.opened }
	get tabSize(): number { return this.backend.tabSize }
	get isEmpty(): boolean {
		return this.backend.isEmpty
	}
	get resource(): Uri.Locator {
		return this.backend.resource
	}
	get location(): Error.Location {
		return this.backend.location
	}
	get region(): Error.Region {
		return this.backend.region
	}
	constructor(backend: IO.Reader) {
		super()
		this.backend = backend instanceof IO.BufferedReader ? backend as IO.BufferedReader : IO.BufferedReader.create(backend)
	}
	read(): string | undefined {
		const peeked = this.backend.peek(2)
		switch (peeked) {
			case "++": // diagram block
			case "%%": // code block
				this.disableUntil = !this.disableUntil ? peeked : this.disableUntil == peeked ? undefined : this.disableUntil
				break
			case "//":
				if (!this.disableUntil && this.last != ":")
					while (this.backend.peek() != "\n")
						this.backend.read()
				break
			case "/*":
				if (!this.disableUntil) {
					while (this.backend.peek(2) != "*/")
						this.backend.read()
					this.backend.read(2)
				}
				break
		}
		return this.last = this.backend.read()
	}
	mark(): Error.Region {
		return this.backend.mark()
	}
	close(): Promise<boolean> {
		return this.backend.close()
	}
}