Grouping, assignment tests

README.md

@@ -24,6 +24,7 @@ concatenation = a, b, c;
 alternation = a | b | c;
 optional = [a, b];
 repetition = {a};
+grouping = (a, b, c);
 ```
 
 ## Usage

Sources/Gramophone/BNFParser.swift

@@ -123,6 +123,20 @@ public class BNFParser {
 		return .repetition(rule)
 	}
 
+	private func parseGrouping(_ lexer: BNFLexerReference) throws -> Rule.Kind {
+		guard let _ = lexer.nextIf({ $0.kind == .openParen }) else {
+			throw BNFParserError.unexpectedToken
+		}
+
+		let rule = try parsePrimaryExpression(lexer)
+
+		guard let _ = lexer.nextIf({ $0.kind == .closeParen }) else {
+			throw BNFParserError.unexpectedToken
+		}
+
+		return .grouping(rule)
+	}
+
     private func parsePrimaryExpression(_ lexer: BNFLexerReference) throws -> Rule.Kind {
         switch lexer.peek()?.kind {
         case .quote, .doubleQuote:
@@ -133,6 +147,8 @@ public class BNFParser {
             return try parseReference(lexer)
 		case .openBrace:
 			return try parseRepetition(lexer)
+		case .openParen:
+			return try parseGrouping(lexer)
         default:
             throw BNFParserError.unexpectedToken
         }

Sources/Gramophone/Rule.swift

@@ -7,8 +7,9 @@ public struct Rule {
         case alternation(Kind, Kind)
         case optional(Kind)
         case repetition(Kind)
-        case grouping
+        case grouping(Kind)
         case terminalString(String)
+		case oneOrMore
         case comment
         case specialSequence
         case exception

Tests/GramophoneTests/ParserTests.swift

@@ -2,6 +2,32 @@ import XCTest
 @testable import Gramophone
 
 final class ParserTests: XCTestCase {
+	func testAssignment() throws {
+		let string = "test = 'a';"
+		let parser = BNFParser()
+
+		let rules = try parser.parse(string).get()
+
+		XCTAssertEqual(rules.count, 1)
+
+		let expectedRule = Rule(name: "test",
+								kind: .terminalString("a"))
+		XCTAssertEqual(rules[0], expectedRule)
+	}
+
+	func testAssignmentWithArrow() throws {
+		let string = "test → 'a';"
+		let parser = BNFParser()
+
+		let rules = try parser.parse(string).get()
+
+		XCTAssertEqual(rules.count, 1)
+
+		let expectedRule = Rule(name: "test",
+								kind: .terminalString("a"))
+		XCTAssertEqual(rules[0], expectedRule)
+	}
+
     func testAlternation() throws {
         let string = "test = 'a' | 'b';"
         let parser = BNFParser()
@@ -53,4 +79,17 @@ final class ParserTests: XCTestCase {
 								kind: .repetition(.terminalString("a")))
 		XCTAssertEqual(rules[0], expectedRule)
 	}
+
+	func testGrouping() throws {
+		let string = "test = ('a');"
+		let parser = BNFParser()
+
+		let rules = try parser.parse(string).get()
+
+		XCTAssertEqual(rules.count, 1)
+
+		let expectedRule = Rule(name: "test",
+								kind: .grouping(.terminalString("a")))
+		XCTAssertEqual(rules[0], expectedRule)
+	}
 }