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Parser: Multiplication, division and parenthesis.

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This commit is contained in:
Valeriano A.R.
2019-12-01 16:50:29 +01:00
parent 49941a7861
commit 0fe4e54bcb
8 changed files with 146 additions and 9 deletions
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68
VAR.ExpressionEvaluator.Tests/ParserTests.cs
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@@ -5,6 +5,8 @@ namespace VAR.ExpressionEvaluator.Tests
[TestClass()]
public class ParserTests
{
#region Plus and Minus
[TestMethod()]
public void ParseString__Ten_EqualsTen()
{
@@ -37,6 +39,10 @@ namespace VAR.ExpressionEvaluator.Tests
Assert.AreEqual(900000m, result);
}
#endregion Plus and minus
#region Number signs
[TestMethod()]
public void ParseString__MinusTen()
{
@@ -77,5 +83,67 @@ namespace VAR.ExpressionEvaluator.Tests
Assert.AreEqual(-40m, result);
}
#endregion Number signs
#region Multiplication and division
[TestMethod()]
public void ParseString__10MutiplyBy2()
{
string expression = "10 * 2";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(20m, result);
}
[TestMethod()]
public void ParseString__10DividedBy2()
{
string expression = "10 / 2";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(5m, result);
}
[TestMethod()]
public void ParseString__5DividedBy2()
{
string expression = "5 / 2";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(2.5m, result);
}
[TestMethod()]
public void ParseString__5DividedBy2Plus1()
{
string expression = "5 / 2 + 1";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(3.5m, result);
}
[TestMethod()]
public void ParseString__1Plus5DividedBy2()
{
string expression = "1 + 5 / 2";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(3.5m, result);
}
[TestMethod()]
public void ParseString__5DividedByParen1Plus1()
{
string expression = "5 / (1 + 1)";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(2.5m, result);
}
[TestMethod()]
public void ParseString__Paren2Plus2DividedByParen1Plus1()
{
string expression = "(2 + 2) / (1 + 1)";
object result = Parser.EvaluateString(expression);
Assert.AreEqual(2m, result);
}
#endregion Multiplication and division
}
}

4
VAR.ExpressionEvaluator.Tests/TokenizerTests.cs
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@@ -120,7 +120,7 @@ namespace VAR.ExpressionEvaluator.Tests
var t = new Tokenizer(new StringReader(testString));
// "("
Assert.AreEqual(t.Token, Token.ParentesisStart);
Assert.AreEqual(t.Token, Token.ParenthesisStart);
t.NextToken();
// "10"
@@ -138,7 +138,7 @@ namespace VAR.ExpressionEvaluator.Tests
t.NextToken();
// ")"
Assert.AreEqual(t.Token, Token.ParentesisEnd);
Assert.AreEqual(t.Token, Token.ParenthesisEnd);
t.NextToken();
// "*"

15
VAR.ExpressionEvaluator/ExpressionDivisionNode.cs Normal file
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@@ -0,0 +1,15 @@
namespace VAR.ExpressionEvaluator
{
public class ExpressionDivisionNode : ExpressionBinaryNode
{
public ExpressionDivisionNode(IExpressionNode leftNode, IExpressionNode rightNode) :
base(leftNode, rightNode, DivisionOp)
{
}
private static object DivisionOp(object leftValue, object rightValue)
{
return (decimal)leftValue / (decimal)rightValue;
}
}
}

15
VAR.ExpressionEvaluator/ExpressionMultiplyNode.cs Normal file
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@@ -0,0 +1,15 @@
namespace VAR.ExpressionEvaluator
{
public class ExpressionMultiplyNode : ExpressionBinaryNode
{
public ExpressionMultiplyNode(IExpressionNode leftNode, IExpressionNode rightNode) :
base(leftNode, rightNode, MultiplyOp)
{
}
private static object MultiplyOp(object leftValue, object rightValue)
{
return (decimal)leftValue * (decimal)rightValue;
}
}
}

43
VAR.ExpressionEvaluator/Parser.cs
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@@ -26,19 +26,19 @@ namespace VAR.ExpressionEvaluator
public IExpressionNode ParsePlusAndMinus()
{
IExpressionNode leftNode = ParseUnary();
IExpressionNode leftNode = ParseMultiplyDivision();
while (true)
{
if (_tokenizer.Token == Token.Plus)
{
_tokenizer.NextToken();
IExpressionNode rightNode = ParseUnary();
IExpressionNode rightNode = ParseMultiplyDivision();
leftNode = new ExpressionPlusNode(leftNode, rightNode);
}
else if (_tokenizer.Token == Token.Minus)
{
_tokenizer.NextToken();
IExpressionNode rightNode = ParseUnary();
IExpressionNode rightNode = ParseMultiplyDivision();
leftNode = new ExpressionMinusNode(leftNode, rightNode);
}
else
@@ -48,6 +48,31 @@ namespace VAR.ExpressionEvaluator
}
}
private IExpressionNode ParseMultiplyDivision()
{
IExpressionNode lhs = ParseUnary();
while (true)
{
if (_tokenizer.Token == Token.Multiply)
{
_tokenizer.NextToken();
IExpressionNode rhs = ParseUnary();
lhs = new ExpressionMultiplyNode(lhs, rhs);
}
else if (_tokenizer.Token == Token.Division)
{
_tokenizer.NextToken();
IExpressionNode rhs = ParseUnary();
lhs = new ExpressionDivisionNode(lhs, rhs);
}
else
{
return lhs;
}
}
}
private IExpressionNode ParseUnary()
{
if (_tokenizer.Token == Token.Plus)
@@ -73,6 +98,18 @@ namespace VAR.ExpressionEvaluator
return node;
}
if (_tokenizer.Token == Token.ParenthesisStart)
{
_tokenizer.NextToken();
var node = ParsePlusAndMinus();
if (_tokenizer.Token != Token.ParenthesisEnd)
{
throw new Exception("Missing close parenthesis");
}
_tokenizer.NextToken();
return node;
}
throw new Exception(string.Format("Unexpected token: {0}", _tokenizer.Token.ToString()));
}

4
VAR.ExpressionEvaluator/Token.cs
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@@ -13,8 +13,8 @@
GreaterOrEqualThan,
LessThan,
LessOrEqualThan,
ParentesisStart,
ParentesisEnd,
ParenthesisStart,
ParenthesisEnd,
Keyword,
String,
Number,

4
VAR.ExpressionEvaluator/Tokenizer.cs
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@@ -93,12 +93,12 @@ namespace VAR.ExpressionEvaluator
case '(':
NextChar();
_currentToken = Token.ParentesisStart;
_currentToken = Token.ParenthesisStart;
return;
case ')':
NextChar();
_currentToken = Token.ParentesisEnd;
_currentToken = Token.ParenthesisEnd;
return;
case '=':

2
VAR.ExpressionEvaluator/VAR.ExpressionEvaluator.csproj
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@@ -41,6 +41,8 @@
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="ExpressionDivisionNode.cs" />
<Compile Include="ExpressionMultiplyNode.cs" />
<Compile Include="ExpressionUnaryNode.cs" />
<Compile Include="ExpressionBinaryNode.cs" />
<Compile Include="ExpressionMinusNode.cs" />