From 9fa48520c7f5b28d94ee7d3b6b61990f76dccaf4 Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Wed, 4 May 2022 22:58:06 -0500
Subject: [PATCH] Added support for 'labels' in the Scanner.

---
 includes/token.h |  1 +
 src/scanner.c    | 37 +++++++++++++++++++++++++------------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/includes/token.h b/includes/token.h
index 4e1b6c1..e01efa6 100644
--- a/includes/token.h
+++ b/includes/token.h
@@ -16,6 +16,7 @@ typedef enum {
     COMMA,
     STRING,
     IDENTIFIER,
+    LABEL,
     NUMBER,
     HEX,
     //Keywords
diff --git a/src/scanner.c b/src/scanner.c
index 48ffe8e..f842619 100644
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -92,14 +92,18 @@ Token* ParseNumber(void) {
         while(!ScannerAtEnd() && isdigit(PeekScanner())) AdvanceScanner();
     }
 
-    char* lexeme = calloc(Position - start + 1, sizeof(char));
+    int length = Position - start;
+
+    if (length == 0) return NULL;
+
+    char* lexeme = calloc(sizeof(char), length);
 
     if (!lexeme) {
         fprintf(stderr, "Failed to calloc space for number.\n");
         return NULL;
     }
 
-    memcpy(lexeme, &SourceCode[start], Position - start);
+    memcpy(lexeme, &SourceCode[start], length);
 
     if (base == 10) return CreateToken(NUMBER, lexeme);
 
@@ -110,17 +114,19 @@ Token* ParseDirective(void) {
     int start = Position;
 
     while(!ScannerAtEnd() && PeekScanner() != ' ' && PeekScanner() != '\n') AdvanceScanner();
-        
-    if (start == Position) return NULL;
 
-    char* directive = calloc(Position - start + 1, sizeof(char));
+    int length = Position - start;
+
+    if (length == 0) return NULL;
+
+    char* directive = calloc(sizeof(char), length);
 
     if (!directive) {
         fprintf(stderr, "Failed to calloc for the assmebler directive.\n");
         return NULL;
     }
 
-    memcpy(directive, &SourceCode[start], Position - start);
+    memcpy(directive, &SourceCode[start], length);
 
     if (strcmp(directive, ".db") == 0) {
         return CreateToken(DB, directive);
@@ -154,8 +160,12 @@ Token* ParseString(void) {
         AdvanceScanner();
     }
 
-    char* lexeme = calloc(Position - start, sizeof(char));
-    memcpy(lexeme, &SourceCode[start], Position - start);
+    int length = Position - start;
+
+    if (length == 0) return NULL;
+
+    char* lexeme = calloc(sizeof(char), length);
+    memcpy(lexeme, &SourceCode[start], length);
 
     AdvanceScanner(); //Consume the trailing double quote.
 
@@ -171,14 +181,17 @@ Token* ParseIdentifier(void) {
         AdvanceScanner();
     }
 
-    if (Position - start == 0) return NULL;
+    int length = Position - start;
+
+    if (length == 0) return NULL;
     
-    char* lexeme = calloc(Position - start, sizeof(char));
-    TokenType type;
-    memcpy(lexeme, &SourceCode[start], Position - start);
+    TokenType type;    
+    char* lexeme = calloc(sizeof(char), length);
+    memcpy(lexeme, &SourceCode[start], length);
 
     if (IsOpcode(lexeme, &type)) return CreateToken(type, lexeme);
     if (IsRegister(lexeme, &type)) return CreateToken(type, lexeme);
+    if (lexeme[length - 1] == ':') return CreateToken(LABEL, lexeme);
 
     return CreateToken(IDENTIFIER, lexeme);
 }