/* This program reads a C# file and generates a cross reference list for it.
   The source code is printed with line numbers and the word list is sorted.
   Keywords are excluded as well as words occurring in comments or strings.
*/
using System;
using System.IO;
using System.Collections;
using System.Text;

class Xref {
  static SortedList names = new SortedList(); // the names in the cross reference list
  static string[] keys = {
    "abstract","as","base","bool","break","byte","case","catch","char","checked",
    "class","const","continue","decimal","default","delegate","do","double","else",
    "enum","event","explicit","extern","false","finally","fixed","float","for",
    "foreach","goto","if","implicit","in","int","interface","internal","is","lock",
    "long","namespace","new","null","object","operator","out","override","params",
    "private","protected","public","readonly","ref","return","sbyte","sealed","short",
    "sizeof","stackalloc","static","string","struct","this","switch","throw","true",
    "try","typeof","uint","ulong","unchecked","unsafe","ushort","using","virtual",
    "void","while"};
    
  static StreamReader r;    // source code reader
  static StreamWriter w;    // output of cross reference list
  static int lineNo = 1;    // current line number
  static int c;             // current input character
  
  const int eof = -1;
  
  static int Read() {
    c = r.Read();
    if (c == '\n') lineNo++;
    return c;
  }
  
  // Print the source code with line numbers
  static void PrintSourceFile() {
    int lnr = 1;
    string line = r.ReadLine();
    while (line != null) {
      w.WriteLine("{0,4} {1}", lnr++, line);
      line = r.ReadLine();
    }
    w.WriteLine();
  }
  
  // Return true if the word is in the keyword table
  static bool IsKey(string word) {
    int i = 0, j = keys.Length-1;
    while (i <= j) {
      int m = (i + j) / 2;
      if (keys[m] == word) return true;
      if (word.CompareTo(keys[m]) < 0) j = m - 1; else i = m + 1;
    }
    return false;
  }
  
  // Read a word and add it to the cross reference list if it is not a keyword
  static void AddWord() {
    StringBuilder b = new StringBuilder();
    while (Char.IsLetterOrDigit((char)c) || c == '_') {
      b.Append((char)c);
      c = Read();
    }
    string word = b.ToString();
    if (!IsKey(word)) { // no keyword => collect line number of this word
      ArrayList lineNumbers = (ArrayList)names[word];
      if (lineNumbers == null) {lineNumbers = new ArrayList(); names[word] = lineNumbers;}
      lineNumbers.Add(lineNo);
    }
  }
  
  static void SkipString(char end) {
    for (;;) {
      c = Read();
      if (c == end) { c = Read(); break; }
      else if (c == eof) break;
      else if (c == '\\') c = Read();
    }
  }
  
  static void SkipComment() {
    c = Read();
    if (c == '/') {
      do c = Read(); while (c != eof && c != '\n');
    } else if (c == '*') {
      c = Read();
      do {
       while (c != eof && c != '*') Read();
       if (c != eof) c = Read();
      } while (c != eof && c != '/');
      if (c != eof) c = Read();
    }
  }
  
  // Read the source code and add all words to the cross reference list
  static void CollectWords() {
    c = Read();
    while (c != eof) {
      if (Char.IsLetter((char)c) || c == '_') AddWord();
      else if (c == '"' || c == '\'') SkipString((char)c);
      else if (c == '/') SkipComment();
      else c = Read();
    }
  }
  
  // Print the cross reference list
  static void PrintXrefList() {
    foreach (string word in names.Keys) {
      ArrayList lineNumbers = (ArrayList)names[word];
      w.Write("{0, -10}", word);
      foreach (int n in lineNumbers) w.Write(" " + n);
      w.WriteLine();
    }
  }
  
  public static void Main(string[] arg) {
    if (arg.Length == 1) {
      try {
        FileStream s1 = new FileStream(arg[0], FileMode.Open);
        FileStream s2 = new FileStream(arg[0] + ".xref", FileMode.Create);
        r = new StreamReader(s1);
        w = new StreamWriter(s2);
        PrintSourceFile();
        s1.Seek(0, SeekOrigin.Begin);
        CollectWords();
        PrintXrefList();
        r.Close(); w.Close();
      } catch (Exception e) {
        Console.WriteLine(e.ToString());
      }
    } else Console.WriteLine("-- file name expected");
  }
}

   1 using System;
   2 
   3 class Test {
   4   
   5   static void Clear(int[] arr, params int[] indexes) {
   6     foreach (int i in indexes) arr[i] = 0;
   7   }
   8   
   9   public static void Main() {
  10     int[] a = {1, 2, 3, 4, 5, 6, 7, 8, 9};
  11     Clear(a, 3, 4, 8);
  12     foreach (int val in a) Console.Write(val + " ");
  13     Console.WriteLine();
  14   }
  15 }

a          10 11 12
arr        5 6
Clear      5 11
Console    12 13
i          6 6
indexes    5 6
Main       9
System     1
Test       3
val        12 12
Write      12
WriteLine  13