Started work on create keyword - I need unique as a keyword first

source/parse-create-tree.js

@@ -0,0 +1,142 @@
+//build the tokens into a single object of types representing the initial query
+const parseCreateTree = (tokens, typeGraph, options) => {
+	let current = 1; //primed
+
+	//check this is a create command
+	if (tokens[current - 1] != 'create') {
+		throw 'Expected create keyword at the beginning of create command';
+	}
+
+	current++;
+
+	//get a token that matches a type
+	if (!typeGraph[tokens[current - 1]]) {
+		throw `Expected a type in the type graph (found ${tokens[current - 1]})`;
+	}
+
+	//check that there are the correct number of '{' and '}'
+	if (tokens.reduce((running, tok) => tok == '{' ? running + 1 : tok == '}' ? running - 1 : running, 0) != 0) {
+		throw `Unequal number of '{' and '}' found`;
+	}
+
+	//check that there are the correct number of '[' and ']'
+	if (tokens.reduce((running, tok) => tok == '[' ? running + 1 : tok == ']' ? running - 1 : running, 0) != 0) {
+		throw `Unequal number of '[' and ']' found`;
+	}
+
+	//the return
+	const result = [];
+
+	if (tokens[current] == '[') {
+		current++;
+	}
+
+	do {
+		//read the block of lines
+		const [block, pos] = readBlock(tokens, current, tokens[current - 1], typeGraph, options);		
+
+		//insert the typename into the top-level block
+		block['typeName'] = tokens[current - 1];
+
+		//insert create into the top-level block
+		block['create'] = true;
+
+		current = pos;
+
+		result.push(block);
+	} while (tokens[current] && tokens[current] != ']');
+
+	//finally
+	return result;
+};
+
+const readBlock = (tokens, current, superType, typeGraph, options) => {
+	//scan the '{'
+	if (tokens[current++] != '{') {
+		throw `Expected '{' at beginning of a block (found ${tokens[current - 1]})`;
+	}
+
+	//result
+	const result = {};
+
+	//scan each "line" in this block
+	while(tokens[current++] && tokens[current - 1] != '}') {
+		//check for block-level keywords (modifiers need to form a chain from the leaf)
+		let modifier = null;
+		if (['create', 'match'].includes(tokens[current - 1])) {
+			modifier = tokens[current - 1];
+			current++;
+		}
+
+		//read field name
+		const fieldName = tokens[current - 1];
+
+		if (options.debug) {
+			console.log(`Trying to process field ${fieldName}`);
+		}
+
+		//if the field is not present in the type
+		if (!typeGraph[superType][fieldName]) {
+			throw `Unexpected field name ${fieldName} in type ${superType}`;
+		}
+
+		//if the field is non-scalar, read the sub-block
+		if (!typeGraph[typeGraph[superType][fieldName].typeName].scalar) {
+			if (tokens[current] == '[') {
+				current++;
+			}
+
+			do {
+				//recurse
+				const [block, pos] = readBlock(tokens, current, typeGraph[superType][fieldName].typeName, typeGraph, options);
+
+				//insert the typename into the block
+				block['typeName'] = typeGraph[superType][fieldName].typeName;
+
+				//insert the block-level modifier signal
+				if (modifier) {
+					block[modifier] = true;
+				} else {
+					throw `Modifier expected for ${fieldName} (either create or match)`;
+				}
+
+				//insert into result
+				result[fieldName] = result[fieldName] || [];
+				result[fieldName].push(block);
+
+				current = pos; //pos points past the end of the block
+
+				if (options.debug) {
+					console.log(`${fieldName}:`);
+					console.dir(result[fieldName], { depth: null });
+				}
+			} while (tokens[current] && tokens[current] == '{');
+			current++;
+
+			continue;
+		}
+
+		//scalar
+		else {
+			//save the typeGraph type into result
+			result[fieldName] = JSON.parse(JSON.stringify( typeGraph[ typeGraph[superType][fieldName].typeName ] ));
+
+			//insert the block-level modifier signal
+			if (modifier) {
+				result[fieldName][modifier] = tokens[current++];
+			} else {
+				result[fieldName]['set'] = tokens[current++];
+			}
+
+			if (options.debug) {
+				console.log(`${fieldName}: `, result[fieldName]);
+			}
+
+			continue;
+		}
+	}
+
+	return [result, current];
+};
+
+module.exports = parseCreateTree;