This code reads a .cs source file in the \bin folder and parses the C# code in it. The program outputs keywords, identifiers, separators and numerical constants.
How could it be improved?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Tema3Compilatoare
{
class LexicalAnalysis
{
string[] keywords = { "abstract", "as", "base", "bool", "break", "by",
"byte", "case", "catch", "char", "checked", "class", "const",
"continue", "decimal", "default", "delegate", "do", "double",
"descending", "explicit", "event", "extern", "else", "enum",
"false", "finally", "fixed", "float", "for", "foreach", "from",
"goto", "group", "if", "implicit", "in", "int", "interface",
"internal", "into", "is", "lock", "long", "new", "null", "namespace",
"object", "operator", "out", "override", "orderby", "params",
"private", "protected", "public", "readonly", "ref", "return",
"switch", "struct", "sbyte", "sealed", "short", "sizeof",
"stackalloc", "static", "string", "select", "this",
"throw", "true", "try", "typeof", "uint", "ulong", "unchecked",
"unsafe", "ushort", "using", "var", "virtual", "volatile",
"void", "while", "where", "yield" };
string[] separator = { ";", "{","}","\r","\n","\r\n"};
string[] comments = { "//", "/*", "*/" };
string[] operators = { "+", "-", "*", "/", "%", "&","(",")","[","]",
"|", "^", "!", "~", "&&", "||",",",
"++", "--", "<<", ">>", "==", "!=", "<", ">", "<=",
">=", "=", "+=", "-=", "*=", "/=", "%=", "&=", "|=",
"^=", "<<=", ">>=", ".", "[]", "()", "?:", "=>", "??" };
public string Parse(string item)
{
StringBuilder str = new StringBuilder();
int ok;
if (Int32.TryParse(item, out ok))
{
str.Append("(numerical constant, " +item + ") ");
return str.ToString();
}
if (item.Equals("\r\n"))
{
return "\r\n";
}
if(CheckKeyword(item) ==true)
{
str.Append("(keyword, " + item + ") ");
return str.ToString();
}
if (CheckOperator(item) == true)
{
str.Append("(operator, " + item + ") ");
return str.ToString();
}
if (CheckDelimiter(item) == true)
{
str.Append("(separator, " + item + ") ");
return str.ToString();
}
str.Append("(identifier, " + item + ") ");
return str.ToString();
}
private bool CheckOperator(string str)
{
if (Array.IndexOf(operators, str) > -1)
return true;
return false;
}
private bool CheckDelimiter(string str)
{
if (Array.IndexOf(separator, str) > -1)
return true;
return false;
}
private bool CheckKeyword(string str)
{
if (Array.IndexOf(keywords, str) > -1)
return true;
return false;
}
private bool CheckComments(string str)
{
if (Array.IndexOf(comments, str) > -1)
return true;
return false;
}
public string GetNextLexicalAtom(ref string item)
{
StringBuilder token = new StringBuilder();
for (int i = 0; i < item.Length; i++)
{
if (CheckDelimiter(item[i].ToString()))
{
if (i + 1 < item.Length && CheckDelimiter(item.Substring(i, 2)))
{
token.Append(item.Substring(i, 2));
item = item.Remove(i, 2);
return Parse(token.ToString());
}
else
{
token.Append(item[i]);
item = item.Remove(i, 1);
return Parse(token.ToString());
}
}
else if (CheckOperator(item[i].ToString()))
{
if (i + 1 < item.Length && (CheckOperator(item.Substring(i, 2))))
if (i + 2 < item.Length && CheckOperator(item.Substring(i, 3)))
{
token.Append(item.Substring(i, 3));
item = item.Remove(i, 3);
return Parse(token.ToString());
}
else
{
token.Append(item.Substring(i, 2));
item = item.Remove(i, 2);
return Parse(token.ToString());
}
else if (CheckComments(item.Substring(i, 2)))
{
if(item.Substring(i,2).Equals("//"))
{
do
{
i++;
} while (item[i] != '\n');
item = item.Remove(0, i + 1);
item = item.Trim(' ', '\t', '\r', '\n');
i = -1;
}
else
{
do
{
i++;
} while (item.Substring(i, 2).Equals("*/") == false);
item = item.Remove(0, i + 2);
item = item.Trim(' ', '\t','\r','\n');
i = -1;
}
}
else
{
int ok;
if (item[i] == '-' && Int32.TryParse(item[i + 1].ToString(), out ok))
continue;
token.Append(item[i]);
item = item.Remove(i,1);
return Parse(token.ToString());
}
}
else
if (item[i] == '\'' )
{
int j = i + 1;
if (item[j] == '\\')
j += 2;
else
j++;
token.Append("(literal constant, ").Append(item.Substring(i, j - i + 1)).Append(") ");
item = item.Remove(i, j - i + 1);
return token.ToString();
}
else
if (item[i]=='"' )
{
int j = i + 1;
while (item[j] != '"' )
j++;
token.Append("(literal constant, ").Append(item.Substring(i, j - i+1)).Append(") ");
item = item.Remove(i, j - i + 1);
return token.ToString();
}
else
if(item[i+1].ToString().Equals(" ") || CheckDelimiter(item[i+1].ToString())==true || CheckOperator(item[i+1].ToString())==true)
{
if (Parse(item.Substring(0, i+1)).Contains("numerical constant") && item[i+1]=='.')
{
int j = i + 2;
while (item[j].ToString().Equals(" ") == false && CheckDelimiter(item[j].ToString()) == false && CheckOperator(item[j].ToString()) == false)
j++;
int ok;
if (Int32.TryParse(item.Substring(i + 2, j - i-2), out ok))
{
token.Append("(numerical constant, ").Append(item.Substring(0, j )).Append(") ");
item = item.Remove(0, j );
return token.ToString();
}
}
token.Append(item.Substring(0, i+1));
item=item.Remove(0, i+1);
return Parse(token.ToString());
}
}
return null;
}
}
class Program
{
static void Main(string[] args)
{
string text = System.IO.File.ReadAllText("Program.cs");
//string[] elements = text.Split(new char[] { ' ', '\r', '\n' },StringSplitOptions.RemoveEmptyEntries);
LexicalAnalysis analyzer = new LexicalAnalysis();
// analyzer.Parse(text);
while(text!=null)
{
text = text.Trim(' ','\t');
string token=analyzer.GetNextLexicalAtom(ref text);
System.Console.Write(token);
}
//foreach (string item in elements)
//{
// analyzer.Parse(item);
//}
//System.Console.WriteLine(text);
System.Console.Read();
}
}
}
varis not keyword andyieldis a contextual keyword. – CodesInChaos Dec 11 '15 at 9:44