From 49c5ca908eca0ef1837fdb3e4168c7e9b5dbbd0c Mon Sep 17 00:00:00 2001
From: Kraemerd <Dominic_Daniel.Kraemer@Student.Reutlingen-University.de>
Date: Mon, 9 Jan 2023 12:08:03 +0100
Subject: [PATCH] implemented the evaluator, can handle all operations
(variables are not working yet)
---
expressions.txt | 10 +++++---
src/Application.java | 2 ++
src/Evaluator.java | 59 +++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 66 insertions(+), 5 deletions(-)
diff --git a/expressions.txt b/expressions.txt
index 55a3a7c..ce8c319 100644
--- a/expressions.txt
+++ b/expressions.txt
@@ -1,4 +1,6 @@
-1 + x*y^2 - (31 * x)-y
-1 + x^2 - (3 * x)
-2-x + 0.5*x^2 - 1
-(5*2-(5^2)+3*(201.01-15))
\ No newline at end of file
+5
+x
+4+2
+3+(2^3)
+2*2*2+3
+(23+2*(2*3))-5
\ No newline at end of file
diff --git a/src/Application.java b/src/Application.java
index f185a6a..096051b 100644
--- a/src/Application.java
+++ b/src/Application.java
@@ -41,7 +41,9 @@ public class Application {
try {
Parser.Expression exp = parser.parse(tokens);
ASTPrinter printer = new ASTPrinter();
+ Evaluator evaluator = new Evaluator();
System.out.println("Printing: '" + printer.visit(exp) + "'");
+ System.out.println("Evaluating: '" + evaluator.visit(exp) + "'");
}
catch (ParserException e) {
System.out.println(e.getMessage());
diff --git a/src/Evaluator.java b/src/Evaluator.java
index 4599b70..2c65e1b 100644
--- a/src/Evaluator.java
+++ b/src/Evaluator.java
@@ -1,2 +1,59 @@
-public class Evaluator {
+public class Evaluator implements Visitor<Double>{
+
+ @Override
+ public Double visit(final Parser.BinaryOperation binaryOP) {
+ double result = binaryOP.leftExpression.accept(this);
+ double rOperand = binaryOP.rightExpression.accept(this);
+ switch (binaryOP.operator.charAt(0)) {
+ case '+':
+ result += rOperand;
+ break;
+ case '-':
+ result -= rOperand;
+ break;
+ case '*':
+ result *= rOperand;
+ break;
+ case '/':
+ if (rOperand != 0) {
+ result /= rOperand;
+ }
+ else {
+ result = result;
+ //throw new ArithmeticException("Arithmetic Error: division by zero detected");
+ }
+ break;
+ case '^':
+ for(int i=1; i<rOperand; i++) {
+ result = result*result;
+ }
+ break;
+ default:
+ throw new RuntimeException("SematicError: unknown operand found in AST: "
+ + binaryOP.operator);
+ }
+ return result;
+ }
+
+ @Override
+ public Double visit(final Parser.Variable variable) {
+ return 0.0;
+ }
+
+ @Override
+ public Double visit(final Parser.Number number) {
+ return Double.valueOf(number.digits);
+ }
+
+ @Override
+ public Double visit(final Parser.Decimal decimal) {
+ return Double.valueOf(decimal.afterDot.digits + "." + decimal.beforeDot.digits);
+ }
+
+ public double visit(final Parser.Expression ast) {
+ if(ast==null) {
+ return 0.0;
+ }
+ return ast.accept(this);
+ }
}
--
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