@masala/parser/src/lib/stream/bufferedstream.js

Masala Parser

/*
 * Masala Parser
 * https://github.com/masala/masala-parser
 *
 * Copyright (c) 2016-2025 Didier Plaindoux & Nicolas Zozol
 * Licensed under the LGPL3 license.
 */
import Stream from './stream.js'

/**
 * Buffered stream class
 */
class BufferedStream extends Stream {
    constructor(source) {
        super()
        this.source = source
        this.cache = {}
    }

    location(index) {
        return this.source.location(index)
    }

    // BufferedStream 'a => unit -> boolean
    endOfStream(index) {
        return this.source.endOfStream(index)
    }

    // override, BufferedStream 'a => number -> Try 'a
    get(index) {
        var self = this

        if (!self.cache[index]) {
            self.cache[index] = self.source.get(index)
        }

        return self.cache[index]
    }
}

function factory(source) {
    return new BufferedStream(source)
}

export default factory