expexp/src/modelDeserializer.js

The express model io and express model and data representation.

import nearley from 'nearley'
import grammar from './grammar.js'
import {traverse, path2str} from './tree.js'

const GEN_TLOG_FOR_TESTS = false

function pruneParsingInfo(cJson) {
	const pruningFct = function(json, path, ii) {
		if (GEN_TLOG_FOR_TESTS) console.log('A', path2str(ii, path, json))
		delete json.p
	}
	const beforeFct = function(json, path, ii) {
		if (GEN_TLOG_FOR_TESTS) console.log('B', path2str(ii, path, json))
	}
	// TODO still so many levels - cJson[0] - ?
	const PRESORT = (GEN_TLOG_FOR_TESTS?[]:undefined)
	traverse(cJson[0], pruningFct, beforeFct, PRESORT)
}

// This model deserializer is just a slim wrapper arround the actual logic written as
// nearley parser with moo in the grammar.ne file.
export function ModelDeserializer() {
	const me = {}

	let parser

	me.withParsingInfo = false

	const setup = function() {
		parser = new nearley.Parser(nearley.Grammar.fromCompiled(grammar))
	}

	// The arrBuf must be the expressive data model file.
	me.syntaxJsonFromArrayBuffer = function(arrBuff) {
		const str = String.fromCharCode.apply(null, new Uint16Array(arrBuf))
		return me.syntaxJsonFromString(str)
	}

	me.syntaxJsonFromString = function(string) {
		parser.feed(string)
		// TODO check results.length == 0 or <1
		const json = parser.results[0]
		if (me.withParsingInfo == false) {
			pruneParsingInfo(json)
		}
		return json[0]
	}

	setup()
	return me
}