From fd878a4f7be0a210aed0f12f503e659caeced664 Mon Sep 17 00:00:00 2001
From: hneemann <helmut.neemann@arcor.de>
Date: Thu, 29 Jun 2017 20:29:40 +0200
Subject: [PATCH] expression parser allows to omit the and operator

---
 .../digital/analyse/parser/Parser.java        | 16 ++++++++++----
 .../digital/analyse/parser/ParserTest.java    | 21 +++++++++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/main/java/de/neemann/digital/analyse/parser/Parser.java b/src/main/java/de/neemann/digital/analyse/parser/Parser.java
index 4e9f3881b..d835883af 100644
--- a/src/main/java/de/neemann/digital/analyse/parser/Parser.java
+++ b/src/main/java/de/neemann/digital/analyse/parser/Parser.java
@@ -83,11 +83,19 @@ public class Parser {
 
     private Expression parseAnd() throws IOException, ParseException {
         Expression ex = parseSimpleExp();
-        while (tokenizer.peek() == AND) {
-            tokenizer.consume();
-            ex = Operation.and(ex, parseSimpleExp());
+        while (true) {
+            if (tokenizer.peek() == AND) {
+                tokenizer.consume();
+                ex = Operation.and(ex, parseSimpleExp());
+            } else if (isSimpleEx(tokenizer.peek())) {
+                ex = Operation.and(ex, parseSimpleExp());
+            } else
+                return ex;
         }
-        return ex;
+    }
+
+    private boolean isSimpleEx(Tokenizer.Token tok) {
+        return tok == NOT || tok == OPEN || tok == IDENT || tok == ONE || tok == ZERO;
     }
 
     private Expression parseSimpleExp() throws IOException, ParseException {
diff --git a/src/test/java/de/neemann/digital/analyse/parser/ParserTest.java b/src/test/java/de/neemann/digital/analyse/parser/ParserTest.java
index 41a794fda..50abc7ab3 100644
--- a/src/test/java/de/neemann/digital/analyse/parser/ParserTest.java
+++ b/src/test/java/de/neemann/digital/analyse/parser/ParserTest.java
@@ -47,6 +47,7 @@ public class ParserTest extends TestCase {
         assertTrue(createSingle("a∧b") instanceof Operation.And);
         assertTrue(createSingle("a&b") instanceof Operation.And);
         assertTrue(createSingle("a&&b") instanceof Operation.And);
+        assertTrue(createSingle("a b") instanceof Operation.And);
     }
 
     public void testParseParenthesis() throws Exception {
@@ -100,6 +101,16 @@ public class ParserTest extends TestCase {
         assertEquals(new Variable("B"), simplified);
     }
 
+    public void testParseRegressionOmitAnd() throws Exception {
+        Expression e = createSingle("B(B+A)(B+C)(A+B+C)");
+        Expression simplified = QuineMcCluskey.simplify(e);
+        assertEquals(new Variable("B"), simplified);
+
+        e = createSingle("B (B+A) (B+C) (A+B+C)");
+        simplified = QuineMcCluskey.simplify(e);
+        assertEquals(new Variable("B"), simplified);
+    }
+
     public void testParseRegression2() throws Exception {
         Expression e = createSingle("(C ∨ B) ∧ (A ∨ C) ∧ (B ∨ ¬C) ∧ (C ∨ ¬A)");
         Expression simplified = QuineMcCluskey.simplify(e);
@@ -110,6 +121,16 @@ public class ParserTest extends TestCase {
         assertEquals(new Variable("C"), expList.get(1));
     }
 
+    public void testParseRegression2OmitAnd() throws Exception {
+        Expression e = createSingle("(C ∨ B)  (A ∨ C)  (B ∨ ¬C)  (C ∨ ¬A)");
+        Expression simplified = QuineMcCluskey.simplify(e);
+        assertTrue(simplified instanceof Operation.And);
+        ArrayList<Expression> expList = ((Operation) simplified).getExpressions();
+        assertEquals(2, expList.size());
+        assertEquals(new Variable("B"), expList.get(0));
+        assertEquals(new Variable("C"), expList.get(1));
+    }
+
     public void testParseException() throws Exception {
         Parser p = new Parser("C+");
         try {