I tried, and I failed. Mad props to those who wrote graphQL

server/database.js

@@ -30,7 +30,7 @@ authors = authors.map(a => {
 	return a;
 });
 
-//get the book array
+//get the books array
 let books = [];
 
 authors.forEach(a => books = books.concat(a.books));

server/handler.js

@@ -7,6 +7,24 @@ const handler = {
 	Book: scalars => {
 		//takes an array of scalar types as objects: { typeName: 'String', name: 'title' }
 		//must return an array of objects containing the results
+
+		return database.books.map(b => {
+			const ret = {};
+
+			if (scalars.some(s => s.name == 'title')) {
+				ret.title = b.title;
+			}
+
+			if (scalars.some(s => s.name == 'author')) {
+				ret.author = b.author;
+			}
+
+			if (scalars.some(s => s.name == 'published')) {
+				ret.published = b.published;
+			}
+
+			return ret;
+		});
 	},
 
 	Author: scalars => {

server/server.js

@@ -1,6 +1,8 @@
 //express for testing
 const express = require('express');
+const bodyParser = require('body-parser');
 const app = express();
+app.use(bodyParser.text());
 
 //test the library
 const schema = require('./schema.js');

server/simpleQL/index.js

@@ -6,7 +6,34 @@ const main = (schema, handler) => {
 
 	//the receiving function - this will be called multiple times
 	return reqBody => {
-		return [200, ''];
+		//parse the query
+		const tokens = reqBody.split(/(\s+)/).filter(s => s.trim().length > 0);
+		let pos = 0;
+
+		try {
+			//check for keywords
+			switch(tokens[pos++]) {
+				case 'create':
+				case 'update':
+				case 'delete':
+					throw 'keyword not implemented';
+					//TODO
+					break;
+
+				//no leading keyword - regular query
+				default:
+					const [result] = parseQuery(handler, tokens, pos, typeGraph[tokens[pos - 1]], typeGraph);
+
+					return [200, result];
+
+					//TODO
+					break;
+			}
+		}
+		catch(e) {
+			console.log('caught', e);
+			return [400, e.stack || e];
+		}
 	};
 };
 
@@ -14,10 +41,10 @@ const main = (schema, handler) => {
 const buildTypeGraph = schema => {
 	//the default graph
 	let graph = {
-		String: { scalar: true },
+		String: { scalar: true, nullable: true },
-		Integer: { scalar: true },
+		Integer: { scalar: true, nullable: true },
-		Float: { scalar: true },
+		Float: { scalar: true, nullable: true },
-		Boolean: { scalar: true },
+		Boolean: { scalar: true, nullable: true },
 	};
 
 	//parse the schema
@@ -92,8 +119,54 @@ const parseCompoundType = (tokens, pos) => {
 	}
 
 	return compound;
+};
+
+const parseQuery = (handler, tokens, pos, typeGraph, superTypeGraph) => {
+	//cache this for later
+	const startPos = pos;
+
+	//the opening brace
+	if (tokens[pos++] != '{') {
+		throw 'Expected \'{\' in query, found ' + tokens[pos - 1];
 	}
 
+	//the fields to pass to the handler
+	const queryFields = [];
+
+	//while not at the end
+	while (tokens[pos] != '}') {
+		//not the end of the query
+		if (!tokens[pos]) {
+			throw 'Expected field in query, got end';
+		}
+
+		//prevent using keywords
+		if (['create', 'update', 'delete', 'set', 'match'].includes(tokens[pos])) {
+			throw 'Unexpected keyword ' + tokens[pos];
+		}
+
+		//type is a scalar, and can be queried
+		if (superTypeGraph[typeGraph[tokens[pos]].typeName].scalar) {
+			//push the scalar object to the queryFields
+			queryFields.push({ typeName: typeGraph[tokens[pos]].typeName, name: tokens[pos] });
+
+			pos++;
+		} else {
+			//parse the subquery using the correct sub-typegraph
+			const [result, increment] = parseQuery(handler, tokens, pos + 1, superTypeGraph[typeGraph[tokens[pos]].typeName], superTypeGraph);
+
+			queryFields.push({ ...typeGraph[tokens[pos]], name: tokens[pos], subquery: handler[typeGraph[tokens[pos]].typeName](result) });
+
+			pos += increment + 1;
+		}
+	}
+
+	console.log(' handler', queryFields);
+
+	return [queryFields, pos - startPos];
+};
+
+//utils
 const checkAlphaNumeric = (str) => {
 	if (!/^[a-z0-9]+$/i.test(str)) {
 		throw 'Unexpected string ' + str;