Setup a skeleton for the scanner.

lox.c

@@ -22,7 +22,7 @@ int main(int argc, char** argv) {
 void RunFile(const char* path) {
     printf("Running '%s'\n", path);
     char* contents = GetFileContents(path);
-    printf("%s", contents);
+    //Tokenize(contents);
 }
 
 char* GetFileContents(const char* path) {

scanner.c

@@ -0,0 +1,55 @@
+#include "scanner.h"
+#include <string.h>
+
+const char* source_code;
+//Start and Current hold the offsets that index into the string source_code.
+int start;   //Points to the first character in the lexeme being scanned.
+int current; //points to the character currently being considered.
+int length;
+int line = 1;
+
+char Advance(void);
+int IsAtend(void);
+void ScanToken(void);
+
+void ScanTokens(const char* source) {
+    if (!source) return;
+    
+    source_code = source;
+    length = strlen(source);
+
+    if (length == 0) return;
+
+    while(!IsAtend()) {
+        start = current;
+        ScanToken();
+    }
+
+    //Add EOF token and return list once that's set up.
+}
+
+void ScanToken() {
+    char c = Advance();
+
+    switch (c) {
+    case '(':
+    case ')':
+    case '{':
+    case '}':
+    case ',':
+    case '.':
+    case '-':
+    case '+':
+    case ';':
+    case '*':
+    break;
+    }
+}
+
+int IsAtEnd() {
+    return current >= length;
+}
+
+char Advance() {
+    return source_code[current++];
+}

scanner.h

@@ -0,0 +1,32 @@
+#ifndef SCANNER_H
+#define SCANNER_H
+
+typedef enum {
+    //Single-character tokens
+    LParen, RParen,
+    LBrace, RBrace,
+    Comma,
+    Dot,
+    Minus, Plus,
+    Semicolon,
+    Slash, Star,
+    //One or two character tokens
+    Bang, Bang_Equal,
+    Equal, Equal_Equal,
+    Greater, Greater_Equal,
+    Less, Less_Equal,
+    //Literals
+    Identifier,
+    String,
+    Number,
+    //Keywords
+    AND, CLASS, ELSE, FALSE, FUN,
+    FOR, IF, NIL, OR, PRINT, RETURN,
+    SUPER, THIS, TRUE, VAR, WHILE,
+
+    EndOF
+} TokenType;
+
+void ScanTokens(const char*);
+
+#endif