Added support for parentheses

Thieum · Feb 27, 2012 · 46d4b41 · 46d4b41
1 parent f1017a7
commit 46d4b41
Show file tree

Hide file tree

Showing 2 changed files with 28 additions and 1 deletion.
diff --git a/SimpleExpressionEvaluator.Tests/ExpressionEvaluatorTests.cs b/SimpleExpressionEvaluator.Tests/ExpressionEvaluatorTests.cs
@@ -82,5 +82,17 @@ public void Can_Add_Subtract_Multiply_Divide_Multiple_Numbers()
  Assert.That(engine.Evaluate("25/3+1.34*2.56+1.49+2.36/1.48"), Is.EqualTo(25 / 3m + 1.34m * 2.56m + 1.49m + 2.36m / 1.48m));
  Assert.That(engine.Evaluate("2*3+5-4-2*5+7"), Is.EqualTo(2 * 3 + 5 - 4 - 2 * 5 + 7));
  }
+
+ [Test]
+ public void Supports_Parentheses()
+ {
+ Assert.That(engine.Evaluate("2*(5+3)"), Is.EqualTo(2 * (5 + 3)));
+ Assert.That(engine.Evaluate("(5+3)*2"), Is.EqualTo((5 + 3) * 2));
+ Assert.That(engine.Evaluate("(5+3)*5-2"), Is.EqualTo((5 + 3) * 5 - 2));
+ Assert.That(engine.Evaluate("(5+3)*(5-2)"), Is.EqualTo((5 + 3) * (5 - 2)));
+ Assert.That(engine.Evaluate("((5+3)*3-(8-2)/2)/2"), Is.EqualTo(((5 + 3) * 3 - (8 - 2) / 2) / 2m));
+ Assert.That(engine.Evaluate("(4*(3+5)-4-8/2-(6-4)/2)*((2+4)*4-(8-5)/3)-5"), Is.EqualTo((4 * (3 + 5) - 4 - 8 / 2 - (6 - 4) / 2) * ((2 + 4) * 4 - (8 - 5) / 3) - 5));
+ Assert.That(engine.Evaluate("(((9-6/2)*2-4)/2-6-1)/(2+24/(2+4))"), Is.EqualTo((((9 - 6 / 2) * 2 - 4) / 2m - 6 - 1) / (2 + 24 / (2 + 4))));
+ }
  }
 }
diff --git a/SimpleExpressionEvaluator/ExpressionEvaluator.cs b/SimpleExpressionEvaluator/ExpressionEvaluator.cs
@@ -37,13 +37,28 @@ public decimal Evaluate(string expression)
  {
  var currentOperation = ReadOperation(reader);
 
- EvaluateWhile(() => operatorStack.Count > 0 &&
+ EvaluateWhile(() => operatorStack.Count > 0 && operatorStack.Peek() != '(' &&
  currentOperation.Precedence <= ((Operation)operatorStack.Peek()).Precedence);
 
  operatorStack.Push(next);
  continue;
  }
 
+ if (next == '(')
+ {
+ reader.Read();
+ operatorStack.Push('(');
+ continue;
+ }
+
+ if (next == ')')
+ {
+ reader.Read();
+ EvaluateWhile(() => operatorStack.Count > 0 && operatorStack.Peek() != '(');
+ operatorStack.Pop();
+ continue;
+ }
+
  if (next != ' ')
  {
  throw new ArgumentException(string.Format("Encountered invalid character {0}", next), "expression");