From 27b128a6ea0e552627eeb72692100df7d9a33c82 Mon Sep 17 00:00:00 2001
From: Riccardo Azzolini <riccardo4096@gmail.com>
Date: Fri, 23 Nov 2018 18:52:36 +0100
Subject: [PATCH] Add single and multi-line comments

---
 .../warppi/math/rules/dsl/frontend/Lexer.java | 21 ++++++++++++++++++-
 .../math/rules/dsl/frontend/LexerTest.java    | 14 ++++++-------
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/core/src/main/java/it/cavallium/warppi/math/rules/dsl/frontend/Lexer.java b/core/src/main/java/it/cavallium/warppi/math/rules/dsl/frontend/Lexer.java
index ea0f5ccc..7a79ff7a 100644
--- a/core/src/main/java/it/cavallium/warppi/math/rules/dsl/frontend/Lexer.java
+++ b/core/src/main/java/it/cavallium/warppi/math/rules/dsl/frontend/Lexer.java
@@ -52,7 +52,6 @@ public class Lexer {
 			case ']': emitToken(RIGHT_BRACKET); break;
 			case '=': emitToken(EQUALS); break;
 			case '*': emitToken(TIMES); break;
-			case '/': emitToken(DIVIDE); break;
 			case '^': emitToken(POWER); break;
 
 			case '+':
@@ -71,6 +70,16 @@ public class Lexer {
 				}
 				break;
 
+			case '/':
+				if (matchChar('/')) {
+					singleLineComment();
+				} else if (matchChar('*')) {
+					multiLineComment();
+				} else {
+					emitToken(DIVIDE);
+				}
+				break;
+
 			default:
 				if (isAsciiDigit(current)) {
 					number();
@@ -82,6 +91,16 @@ public class Lexer {
 		}
 	}
 
+	private void singleLineComment() {
+		matchWhile(c -> c != '\n');
+	}
+
+	private void multiLineComment() {
+		while (!(matchChar('*') && matchChar('/'))) {
+			popChar();
+		}
+	}
+
 	private void number() {
 		matchWhile(Lexer::isAsciiDigit);
 		if (matchChar('.') && matchWhile(Lexer::isAsciiDigit) == 0) {
diff --git a/core/src/test/java/it/cavallium/warppi/math/rules/dsl/frontend/LexerTest.java b/core/src/test/java/it/cavallium/warppi/math/rules/dsl/frontend/LexerTest.java
index 5eea2ccf..2aca9d8c 100644
--- a/core/src/test/java/it/cavallium/warppi/math/rules/dsl/frontend/LexerTest.java
+++ b/core/src/test/java/it/cavallium/warppi/math/rules/dsl/frontend/LexerTest.java
@@ -14,9 +14,9 @@ public class LexerTest {
 		final Lexer lexer = new Lexer(
 				"reduction TestRule_123:\n" +
 						"  x + y * z = -(a_123 +- 3 / 2.2) -> [\n" +
-						"    x^a_123 = cos(pi) - log(e, e),\n" +
-						"    undefined,\n" +
-						"]\n"
+						"    x^a_123 = cos(pi) - log(e, e), // comment\n" +
+						"    undefined, /*\n" +
+						"comment */ ]\n"
 		);
 		final List<Token> expected = Arrays.asList(
 				new Token(REDUCTION, "reduction", 0),
@@ -54,10 +54,10 @@ public class LexerTest {
 				new Token(E, "e", 94),
 				new Token(RIGHT_PAREN, ")", 95),
 				new Token(COMMA, ",", 96),
-				new Token(UNDEFINED, "undefined", 102),
-				new Token(COMMA, ",", 111),
-				new Token(RIGHT_BRACKET, "]", 113),
-				new Token(EOF, "", 115)
+				new Token(UNDEFINED, "undefined", 113),
+				new Token(COMMA, ",", 122),
+				new Token(RIGHT_BRACKET, "]", 138),
+				new Token(EOF, "", 140)
 		);
 		assertEquals(expected, lexer.lex());
 	}