Implemented ASTCompareExpr :)

Author: tsg100

src/main/java/com/compiler/ExpressionParser.java

@@ -157,7 +157,19 @@ ASTExprNode getShiftExpr() throws Exception {
     }
 
     ASTExprNode getCompareExpr() throws Exception {
-        return getShiftExpr();
+        ASTExprNode result = getShiftExpr();
+        while (
+                m_lexer.lookAhead().m_type == Type.EQUAL ||
+                m_lexer.lookAhead().m_type == Type.GREATER ||
+                m_lexer.lookAhead().m_type == Type.LESS
+        ){
+            Token curToken = m_lexer.lookAhead();
+            m_lexer.advance();
+            ASTExprNode operand = getShiftExpr();
+            result = new ASTCompareExprNode(result, operand, curToken.m_type);
+        }
+
+        return result;
     }
 
     ASTExprNode getAndExpr() throws Exception {

src/main/java/com/compiler/ast/ASTCompareExprNode.java

@@ -0,0 +1,33 @@
+package com.compiler.ast;
+
+import com.compiler.TokenIntf;
+
+import java.io.OutputStreamWriter;
+
+public class ASTCompareExprNode extends ASTExprNode{
+
+    ASTExprNode m_operand0;
+    ASTExprNode m_operand1;
+    TokenIntf.Type m_operator;
+
+    public ASTCompareExprNode(ASTExprNode operand0, ASTExprNode operand1, TokenIntf.Type operator) {
+        m_operand0 = operand0;
+        m_operand1 = operand1;
+        m_operator = operator;
+    }
+
+    public int eval() {
+        int operand0 = m_operand0.eval();
+        int operand1 = m_operand1.eval();
+
+
+        return switch (m_operator) {
+            case GREATER -> operand0 > operand1 ? 1 : 0;
+            case LESS -> operand0 < operand1 ? 1 : 0;
+            case EQUAL -> operand0 == operand1 ? 1 : 0;
+            default -> 0;
+        };
+    }
+
+    public void print(OutputStreamWriter outStream, String indent) throws Exception {}
+}

src/test/java/com/compiler/TestCompareExpression.java

@@ -0,0 +1,16 @@
+package com.compiler;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class TestCompareExpression extends TestExpressionEvaluatorBase {
+
+    @Test
+    public void testCompareExpAST() throws Exception {
+        assertEquals(1, evalExpression("2>0"));
+        assertEquals(1, evalExpression("2>0>-2"));
+        assertEquals(0, evalExpression("2>0>2"));
+    }
+
+}