Fixed error that can be caused by invalid numbers [KALIEDOSCOPE]

[sushmaunnibhavi]

Summary

There isn't proper error checking in the code : It will incorrectly read “1.23.45.67” and handle it as if you typed in “1.23”. Fixed this error.

[xgupta]

Sorry, @sushmaunnibhavi It is not saying to extend it in the original tutorial, It is a personal exercise. The first chapter needs to as simple as possible.

[sushmaunnibhavi]

In D101314#2717488, @xgupta wrote:

Sorry, @sushmaunnibhavi It is not saying to extend it in the original tutorial, It is a personal exercise. The first chapter needs to as simple as possible.

Okay!

[xgupta]

Yeah, I think you should abandon/close this revision by selecting it from the Add Action drop-down menu.

llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl01.rst

 Note that this code sets the '``IdentifierStr``' global whenever it
 lexes an identifier. Also, since language keywords are matched by the
 same loop, we handle them here inline. Numeric values are similar:
 
 .. code-block:: c++
 
       if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
         std::string NumStr;
+        int count=0;/*Counts number of '.'. If it is greater than 1 should return error. For example if we have the input as “1.23.45.67”, it should return an error since this is invalid*/
         do {
           NumStr += LastChar;
           LastChar = getchar();
+          if(LastChar == '.'){
+            count++;
+          }
+          if(count>1){
+            return LogError("Invalid number");
+          }
         } while (isdigit(LastChar) || LastChar == '.');
 
         NumVal = strtod(NumStr.c_str(), 0);
         return tok_number;
       }
 
 This is all pretty straightforward code for processing input. When
 reading a numeric value from input, we use the C ``strtod`` function to
-convert it to a numeric value that we store in ``NumVal``. Note that
-this isn't doing sufficient error checking: it will incorrectly read
-"1.23.45.67" and handle it as if you typed in "1.23". Feel free to
-extend it!  Next we handle comments:
+convert it to a numeric value that we store in ``NumVal``.Next we handle comments:
 
 .. code-block:: c++
 
       if (LastChar == '#') {
         // Comment until end of line.
         do
           LastChar = getchar();
         while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');

llvm/examples/Kaleidoscope/Chapter2/toy.cpp

if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
 
     if (IdentifierStr == "def")
       return tok_def;
     if (IdentifierStr == "extern")
       return tok_extern;
     return tok_identifier;
   }
 
-  if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
+  if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
     std::string NumStr;
+    int count=0; // Counts number of '.'. If it is greater than 1 should return false. For example if we have the input as “1.23.45.67”, it should return an error since this is invalid
     do {
       NumStr += LastChar;
       LastChar = getchar();
+      if(LastChar == '.') {
+        count++;
+      }
+      if(count > 1) {
+        return LogError("Invalid number");;
+      }
     } while (isdigit(LastChar) || LastChar == '.');
 
-    NumVal = strtod(NumStr.c_str(), nullptr);
+    NumVal = strtod(NumStr.c_str(), 0);
     return tok_number;
   }
 
   if (LastChar == '#') {
     // Comment until end of line.
     do
       LastChar = getchar();
     while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');