检查字符串的语法 - C#

Question

我试图找出如何分析C#中句子的语法.在我的情况下,我有一个句法,每个句子必须遵循.语法如下所示:

'B'是'C'.

每个句子都必须包含五个单词.我的句子的第一个词必须是'A',第三个'是'和第四个'a'.

现在我想检查一个测试句子,如果它符合我的语法.

测试句子:

狗不是猫.

在这个例子中,测试句子是错误的,因为第四个单词是'no'而不是'a'它应该基于语法.

我读了LINQ,我可以查询包含一组指定单词的句子.

代码看起来像这样:

//Notice the third sentence would have the correct syntax
string text = "A Dog is no Cat. My Dog is a Cat. A Dog is a Cat.";

//Splitting text into single sentences
string[] sentences = text.Split(new char[] { '.'});

//Defining the search terms
string[] wordToMatch ={"A", "is"};

//Find sentences that contain all terms I'm looking for
var sentenceQuery = from sentence in sentences
        let w = sentence.Split(new Char[] {'.'})
        where w.Distinct().Intersect(wordsToMatch).Count == wordsToMatch.Count()
        select sentence;

使用此代码,我可以检查句子是否包含我正在寻找的术语,但问题是它不是检查句子中单词的位置.有没有办法可以检查位置,或者用C#检查句子语法的更好方法？

Answer 1

尝试使用正则表达式,如下所示:

using System.Text.RegularExpressions;

...

string source = "A Dog is no Cat.";

bool result = Regex.IsMatch(source, @"^A\s+[A-Za-z0-9]+\s+is\s+a\s+[A-Za-z0-9]+\.$");  

模式说明:

 ^           - start of the string (anchor)
 A           - Letter A 
\s+          - one or more whitelines (spaces)
[A-Za-z0-9]+ - 1st word (can contain A..Z, a..z letters and 0..9 digits)
\s+          - one or more whitelines (spaces) 
 is          - is 
\s+          - one or more whitelines (spaces) 
 a           - a
\s+          - one or more whitelines (spaces)
[A-Za-z0-9]+ - 2nd word (can contain A..Z, a..z letters and 0..9 digits)
\.           - full stop 
 $           - end of the string (anchor)

您可以稍微修改代码并获取实际的第1和第2个字符串的值:

string source = "A Dog is a Cat."; // valid string

string pattern =
   @"^A\s+(?<First>[A-Za-z0-9]+)\s+is\s+a\s+(?<Second>[A-Za-z0-9]+)\.$";

var match = Regex.Match(source, pattern); 

if (match.Success) {
  string first = match.Groups["First"].Value;   // "Dog"
  string second = match.Groups["Second"].Value; // "Cat"

  ... 
}