public void Parse_WithBinaryExpressions_HonorsPrecedences(
[ValueSource(nameof(BinaryOperators))] TokenKind op1,
[ValueSource(nameof(BinaryOperators))] TokenKind op2)
{
// Arrange
var op1Precedence = op1.BinaryOperatorPrecedence();
var op2Precedence = op2.BinaryOperatorPrecedence();
var op1Text = op1.GetText();
var op2Text = op2.GetText();
var text = $"a {op1.GetText()} b {op2.GetText()} c";
// Act
var expression = ParseExpression(text);
// Assert
Assert.That(op1Text, Is.Not.Null);
Assert.That(op2Text, Is.Not.Null);
// Assert
if (op1Precedence >= op2Precedence)
{
// Expected:
// op2
// / \
// op1 c
// / \
// a b
using var e = expression.Enumerate();
e.AssertBinaryExpression(op2);
e.AssertBinaryExpression(op1);
e.AssertNameExpression("a");
e.AssertNameExpression("b");
e.AssertNameExpression("c");
}
else
{
// Expected:
// op1
// / \
// a op2
// / \
// b c
using var e = expression.Enumerate();
e.AssertBinaryExpression(op1);
e.AssertNameExpression("a");
e.AssertBinaryExpression(op2);
e.AssertNameExpression("b");
e.AssertNameExpression("c");
}
}
public void UnaryOperatorPrecedence_HigherThanBinaryOperatorPrecedence(
[ValueSource(nameof(UnaryOperators))] TokenKind unaryOp,
[ValueSource(nameof(BinaryOperators))] TokenKind binaryOp)
{
// Arrange
var unaryPrecedence = unaryOp.UnaryOperatorPrecedence();
var binaryPrecedence = binaryOp.BinaryOperatorPrecedence();
// Act
var highter = unaryPrecedence > binaryPrecedence;
// Assert
Assert.That(highter, Is.True);
}
public void Parse_WithBinaryUnaryPair_HonorsPrecedences(
[ValueSource(nameof(UnaryOperators))] TokenKind unaryOp,
[ValueSource(nameof(BinaryOperators))] TokenKind binaryOp)
{
// Arrange
var unaryPrecedence = unaryOp.UnaryOperatorPrecedence();
var binaryPrecedence = binaryOp.BinaryOperatorPrecedence();
var unaryText = unaryOp.GetText();
var binaryText = binaryOp.GetText();
var text = $"{unaryText} a {binaryText} b";
// Act
var expression = ParseExpression(text);
// Assert
if (unaryPrecedence >= binaryPrecedence)
{
// Expected:
// binary
// / \
// unary b
// |
// a
using var e = expression.Enumerate();
e.AssertBinaryExpression(binaryOp);
e.AssertUnaryExpression(unaryOp);
e.AssertNameExpression("a");
e.AssertNameExpression("b");
}
else
{
// Expected:
// unary
// |
// binary
// / \
// a b
using var e = expression.Enumerate();
e.AssertUnaryExpression(unaryOp);
e.AssertBinaryExpression(binaryOp);
e.AssertNameExpression("a");
e.AssertNameExpression("b");
}
}
public static bool IsBinaryOperator(this TokenKind kind) => kind.BinaryOperatorPrecedence() > 0;
