突出显示 RichTextBox C# Windows 窗体中的不平衡括号

Question

我目前设置了一个Windows窗体，该窗体在RichTextBox中获取数学表达式，并在表达式中搜索任何不平衡的括号。 我的表单由 RichTextBox 和一个显示"Check Parens"的按钮组成。 我也在尝试使用堆栈检查不平衡的括号。 我想要的是以某种方式指出哪些括号是不平衡的。 我想通过突出显示或加粗 RichTextBox 中的括号来做到这一点。 有没有办法用我现在设置的代码来做到这一点？ 这是我下面的代码，任何建设性的反馈将不胜感激！

public partial class checkParentheses : Form
{
    const char leftParens = '(';
    const char rightParens = ')';
    public checkParentheses()
    {
        InitializeComponent();
    }
    public void checkParensButton_Click(object sender, EventArgs e)
    {
        int value;
        checkBalancedParens(mathEquation.Text, out value);
    }
    bool checkBalancedParens(string expression, out int error)
    {
        var parens = new Stack<int>(expression.Length);//Create stack
        error = -1; //Error at -1
        for (int i = 0; i < expression.Length; i++)//Check for unbalanced Parentheses
        {
            char p = expression[i];
            if (p == leftParens)//if p finds left parens
            {
                parens.Push(i);//push to top of stack
            }
            else if (p == rightParens)//if p finds right parens
            {
                if (parens.Count == 0)//if stack has zero items
                {
                    error = i + 1;
                    return false;
                }
                parens.Pop();//Returns to top of stack
            }
        }
        if (parens.Count > 0)//if stack has more than 0 items
        {
            error = parens.Peek() + 1; //Peek at top of stack
            MessageBox.Show("Unbalanced");
            return false;
        }
        MessageBox.Show("Balanced");//Otherwise, expression is balanced
        return true;
    }
}

Answer 1

此处

描述的 RichEdit 中的突出显示文本.完整的解决方案：

private void checkParensButton_Click(object sender, EventArgs e)
{
  // clean up previous selection
  mathEquation.SelectAll();
  mathEquation.SelectionBackColor = Color.White;
  var indexes = EnumerateUnbalancedParentheses(mathEquation.Text);
  foreach (var index in indexes)
  {
    mathEquation.Select(index, 1);
    mathEquation.SelectionBackColor = Color.Aqua;
  }
}
private static IEnumerable<int> EnumerateUnbalancedParentheses(string expression)
{
  var openingParentheses = new Stack<int>();
  var closingParentheses = new Stack<int>();
  for (var i = 0; i < expression.Length; ++i)
  {
    var symbol = expression[i];
    if (symbol == '(')
    {
      openingParentheses.Push(i);
    }
    else if (symbol == ')')
    {
      if (openingParentheses.Count > 0)
        openingParentheses.Pop();
      else
        closingParentheses.Push(i);
    }
  }
  return openingParentheses.Concat(closingParentheses);
}

Answer 2

编辑：鉴于下面的解决方案，这是较差的。如果要加粗文本，则仍包含示例。您可以将 HighlightOffenders 方法替换为

private void HighlightOffenders(IEnumerable<int> listOfIndexes)
    {
        foreach (var index in listOfIndexes.Reverse())
        {
            mathEquation.Select(index,1);
            mathEquation.SelectionFont = new Font(mathEquation.Font, FontStyle.Bold);
        }
    }

因此，您应该跟踪左参数索引和右参数索引。然后只需从各自的堆栈中弹出匹配对即可。

至于显示文本，我不知道这是否是最好的方法，但这是一种可行的方法。它需要重新生成字符串，但它会将正确的结果放在 RichTextBox 中。您需要忽略我的表单称为"Form1"的事实，并将其替换为"检查括号"。可能有一种方法可以在实际字符之上突出显示，但我不熟悉它。

public partial class Form1 : Form
{
    const char leftParenChar = '(';
    const char rightParenChar = ')';
    public Form1()
    {
        InitializeComponent();
    }
    public void checkParensButton_Click(object sender, EventArgs e)
    {
        checkBalancedParens(mathEquation.Text);
    }
    bool checkBalancedParens(string expression)
    {
        var leftParensIndexes = new Stack<int>(expression.Length);
        var rightParensIndexes = new Stack<int>(expression.Length);
        var isError = false;

        for (int i = 0; i < expression.Length; i++)//Check for unbalanced Parentheses
        {
            char p = expression[i];
            if (p == leftParenChar)//if p finds left parens
            {
                leftParensIndexes.Push(i);//push to top of stack
            }
            else if (p == rightParenChar)//if p finds right parens
            {
                rightParensIndexes.Push(i);
                //keep a record if there is an error, but don't stop yet.
                if (leftParensIndexes.Count == 0)
                {
                    isError = true;
                }
                else
                {
                    //eliminate the matching pair if it exists
                    rightParensIndexes.Pop();
                    leftParensIndexes.Pop();
                }

            }
        }
        if (leftParensIndexes.Count > 0)//if stack has more than 0 items
        {
            isError = true;
        }
        HighlightOffenders(rightParensIndexes.Concat(leftParensIndexes));
        return !isError;
    }
    private void HighlightOffenders(IEnumerable<int> listOfIndexes)
    {
        var text = mathEquation.Text;
        mathEquation.Clear();
        int lastIndex = 0; //store the last index you finished at (for string math)
        int count = 0; //the number of items that we've added (also for string math)
        foreach (var index in listOfIndexes.Reverse())
        {
            mathEquation.AppendText(text.Substring(lastIndex, index - lastIndex - count));
            mathEquation.SelectionFont = new Font(mathEquation.Font, FontStyle.Bold);
            mathEquation.AppendText(text.Substring(index,1));
            mathEquation.SelectionFont = new Font(mathEquation.Font, FontStyle.Regular);
            lastIndex = index;
            count++;
        }
        mathEquation.AppendText(text.Substring(lastIndex + count-1, text.Length - lastIndex - count + 1));
    }
}