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extractor.js
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extractor.js
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const Response = require('./response');
class Extractor {
constructor() {
this.path = '';
this.pathHasArrays = false;
this.decodedPath = [];
this.filters = {};
this.arrayRegex = /^\[.*\]$/;
this.result = undefined;
this.hasResult = false;
}
extractFrom(object) {
this._checkArgumentType(object, 'object', 'object');
if (this.decodedPath.length == 0) {
throw new Error('Path not found');
}
this.result = (this.pathHasArrays) ? [] : undefined;
this.hasResult = false;
this._parseRecursively(object, 0);
return new Response(this.result, this.hasResult);
}
setPath(path) {
this._checkArgumentType(path, 'string', 'path');
this.path = path;
this.decodedPath = this._decodePath(this.path);
}
setFilter(name, callback) {
this._checkArgumentType(name, 'string', 'name');
this._checkArgumentType(callback, 'function', 'callback');
this.filters[name] = callback;
}
removeFilter(name) {
this._checkArgumentType(name, 'string', 'name');
delete this.filters[name];
}
removeAllFilters() {
this.filters = {};
}
_parseRecursively(object, segmentIdx) {
if (this._isEndOfPath(segmentIdx)) {
this.hasResult = true;
if (this.pathHasArrays) {
this.result.push(object);
}
else {
this.result = object;
}
return;
}
let currentSegment = this.decodedPath[segmentIdx];
if (currentSegment.type === 'array' && Array.isArray(object)) {
let array = object;
if (currentSegment.filter !== '') {
if (!(currentSegment.filter in this.filters)) {
throw new Error(`Filter ${currentSegment.filter} not defined`);
}
array = object.filter(this.filters[currentSegment.filter]);
}
for (let arrayIdx in array) {
let element = array[arrayIdx];
this._parseRecursively(element, segmentIdx + 1);
}
}
else if (currentSegment.type === 'object' && (typeof object === 'object') && object !== null) {
if (segmentIdx > 0) {
let name = currentSegment.name;
if (name in object) {
this._parseRecursively(object[name], segmentIdx + 1);
}
}
else {
this._parseRecursively(object, segmentIdx + 1);
}
}
}
_isEndOfPath(segmentIdx) {
return (segmentIdx > (this.decodedPath.length - 1));
}
_checkArgumentType(argument, type, argumentName) {
if ((typeof argument !== type) || (argument === null && type !== 'null')) {
throw new Error(`Argument '${argumentName}' isn't ${type}`);
}
}
_decodePath(path) {
let parts = path.split('.');
let decodedPath = [];
this.pathHasArrays = false;
parts.forEach((currentPart, index) => {
if (this.arrayRegex.test(currentPart)) {
let filterName = currentPart.substring(1, currentPart.length - 1);
decodedPath.push({
type: 'array',
filter: filterName
});
this.pathHasArrays = true;
}
else if (currentPart.length > 0) {
decodedPath.push({
type: 'object',
name: currentPart
});
}
else {
throw new Error('Template segment is empty string');
}
});
return decodedPath;
}
}
module.exports = Extractor;