From db54e8f888e5a306f8ff18ea5157f2a931d4173f Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Mon, 14 Feb 2022 17:06:30 +0000
Subject: [PATCH] Added Peek() and Match() as well as a bugged '!=' detection.

---
 lox.c     |  5 +++++
 scanner.c | 51 +++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/lox.c b/lox.c
index 2c31437..8881c00 100644
--- a/lox.c
+++ b/lox.c
@@ -24,6 +24,11 @@ void Print(TokenList* list) {
     char lexeme[100];
 
     for(int i = 0; i < list->size; i++) {
+        if (list->tokens[i]->type == EndOF) {
+            printf("EOF\n");\
+            return;
+        }
+
         printf("[Line %d] ", list->tokens[i]->line);
         for(int j = 0; j < list->tokens[i]->length; j++) {
             printf("%c", list->tokens[i]->lexeme[j]);
diff --git a/scanner.c b/scanner.c
index a36758e..486c64a 100644
--- a/scanner.c
+++ b/scanner.c
@@ -11,9 +11,12 @@ int length;
 int line = 1;
 
 const char* Advance(void);
-int IsAtend(void);
+int IsAtEnd(void);
 void ScanToken(TokenList*);
 TokenList* CreateList(void);
+int AddTokenToList(TokenType, const char*, int, TokenList*);
+int Match(char);
+char Peek(void);
 
 TokenList* ScanTokens(const char* source) {
     if (!source) return NULL;
@@ -25,12 +28,14 @@ TokenList* ScanTokens(const char* source) {
 
     TokenList* tokens = CreateList();
 
-    while(!IsAtend()) {
+    while(!IsAtEnd()) {
         start = current;
         ScanToken(tokens);
     }
 
     //Add EOF token and return list once that's set up.
+    AddTokenToList(EndOF, NULL, 0, tokens);
+    
     return tokens;
 }
 
@@ -79,10 +84,11 @@ int AddTokenToList(TokenType type, const char* lexeme, int length, TokenList* to
 
     token->lexeme = lexeme;
     token->type = type;
-    token->length = length; //Set the length of the lexeme (which is just a pointer into the complete soure listing).
+    token->length = length; //Set the length of the lexeme (which is just a pointer into the complete source listing).
+    token->line = line;
 
     if ((tokens->size + 1) > tokens->capacity) {
-        void* new_ptr = realloc(tokens->tokens, sizeof(Token*) * tokens->capacity * 2);//calloc(tokens->capacity * 2, sizeof(Token*));
+        void* new_ptr = realloc(tokens->tokens, sizeof(Token*) * tokens->capacity * 2);
 
         if (!new_ptr) {
             fprintf(stderr, "Failed to realloc TokenList to size %d.\n", tokens->capacity * 2);
@@ -101,7 +107,7 @@ int AddTokenToList(TokenType type, const char* lexeme, int length, TokenList* to
 
 void ScanToken(TokenList* tokens) {
     const char* c = Advance();
-
+    
     switch (*c) {
     case '(':
         AddTokenToList(LParen, c, 1, tokens);
@@ -133,13 +139,46 @@ void ScanToken(TokenList* tokens) {
     case '*':
         AddTokenToList(Star, c, 1, tokens);
         break;
+    case '!':
+        if (Match('=')) AddTokenToList(Bang_Equal, "!=", 2, tokens);
+        else AddTokenToList(Bang, c, 1, tokens);
+    case '/':
+        if (Match('/')) {
+            while(Peek() != '\n' && !IsAtEnd()) Advance();
+        }
+        else {
+            AddTokenToList(Slash, c, 1, tokens);
+        }
+        break;
+    case ' ':
+    case '\r':
+    case '\t':
+        break; //Ignore whitespace
+    case '\n':
+        line++;
+        break;
     }
 }
 
-int IsAtend() {
+int IsAtEnd() {
     return current >= length;
 }
 
 const char* Advance() {
     return &source_code[current++];
+}
+
+int Match(char expected) {
+    if (IsAtEnd()) return 0;
+    if (source_code[current] != expected) return 0;
+
+    current++;
+
+    return 1;
+}
+
+char Peek() {
+    if (IsAtEnd()) return '\0';
+
+    return source_code[current];
 }
\ No newline at end of file