1 files changed, 17 insertions, 4 deletions
diff --git a/lexer.cpp b/lexer.cpp
index 9cfb2f7..666b999 100644
--- a/lexer.cpp
+++ b/lexer.cpp
@@ -16,6 +16,7 @@ Lexer::Lexer(string text): current_token(nil, {}){
 void Lexer::setText(string text){
   this->text = text;
   // Inicializamos el lexer.
+  current_char = 0;
   current_token = nextToken();
   var_name = '\0';
 }
@@ -24,8 +25,8 @@ Token Lexer::getCurrentToken(){
   return current_token;
 }
 
-bool Lexer::matchFunction(string function_name){
-  string name = text.substr(current_char, 2);
+bool Lexer::matchFunction(const string &function_name){
+  string name = text.substr(current_char, 3);
   bool matched = name == function_name;
 
   // Si hubo una coincidencia movemos el puntero.
@@ -48,8 +49,12 @@ string Lexer::createNumber(){
 }
 
 Token Lexer::match(){
+  // Si ya consumimos todo el texto,
+  // regresamos nil.
+  if(current_char >= text.length())
+    return Token(nil, {});
   // Probamos las funciones.
-  if(current_char + 2 < text.length())
+  if(isalpha(text[current_char]) && current_char + 2 <= text.length())
   {
     if(matchFunction("sin"))
       return Token(function, "sin");
@@ -71,7 +76,12 @@ Token Lexer::match(){
     /* Si es la primera vez que se lee un token variable o
        si la variable leída es igual a la anteriormente leída. */
     if(var_name == '\0' || var_name == text[current_char])
+    {
+      var_name = text[current_char];
+      ++current_char;
+      
       return Token(variable, string(1, var_name));
+    }
 
     // Error, se introdujo una expresión con dos o más variables.
     throw LexerException("Encontrada más de una variable.");
@@ -103,11 +113,14 @@ Token Lexer::match(){
     ++current_char;
     return Token(right_parens, {});
   default:
-    throw LexerException("Carácter inválido.");
+    return Token(nil, {});
   }
 }
 
 Token Lexer::nextToken(){
+  if(text[current_char] == ' ')
+    ++current_char;
+  
   current_token = match();
   
   return current_token;