Add tokenlist, a linked list of lexer tokens

The linked list is doubly linked so the parser can look forward into it
and error reporting can look backward.

This commmit also reworks main to use the tokenlist instead of dealing
with the lexer manually.

src/main.c

@@ -1,5 +1,6 @@
 #include "error.h"
 #include "lexer.h"
+#include "tokenlist.h"
 
 #include <limits.h>
 #include <stdio.h>
@@ -39,24 +40,33 @@ int main(int argc, char *argv[]) {
         print_fn = print_value;
     }
 
-    lexer_t lex = {0};
+    lexer_t *lex = &(lexer_t){};
-    lexer_token_t token;
+    error_t *err = lexer_open(lex, filename);
-    error_t *err = lexer_open(&lex, filename);
+    if (err)
-    if (err) {
+        goto cleanup_error;
+
+    tokenlist_t *list;
+    err = tokenlist_alloc(&list);
+    if (err)
+        goto cleanup_lexer;
+
+    err = tokenlist_fill(list, lex);
+    if (err)
+        goto cleanup_tokens;
+
+    for (auto entry = list->head; entry; entry = entry->next) {
+        print_fn(&entry->token);
+    }
+    tokenlist_free(list);
+    error_free(err);
+    return 0;
+
+cleanup_tokens:
+    tokenlist_free(list);
+cleanup_lexer:
+    lexer_close(lex);
+cleanup_error:
     puts(err->message);
     error_free(err);
     return 1;
-    }
-
-    bool keep_going = true;
-    while (keep_going && (err = lexer_next(&lex, &token)) == nullptr) {
-        keep_going = print_fn(&token);
-        free(token.value);
-    }
-
-    if (err && err != err_eof) {
-        puts(err->message);
-    }
-    error_free(err);
-    return 0;
 }

src/tokenlist.c

@@ -0,0 +1,83 @@
+#include "tokenlist.h"
+#include "error.h"
+#include "lexer.h"
+#include <stdlib.h>
+
+error_t *tokenlist_alloc(tokenlist_t **output) {
+    *output = nullptr;
+
+    tokenlist_t *list = calloc(1, sizeof(tokenlist_t));
+    if (list == nullptr)
+        return err_allocation_failed;
+
+    list->head = nullptr;
+    list->tail = nullptr;
+
+    *output = list;
+    return nullptr;
+}
+
+error_t *tokenlist_entry_alloc(tokenlist_entry_t **output) {
+    *output = nullptr;
+
+    tokenlist_entry_t *entry = calloc(1, sizeof(tokenlist_entry_t));
+    if (entry == nullptr)
+        return err_allocation_failed;
+
+    entry->next = nullptr;
+    entry->prev = nullptr;
+
+    *output = entry;
+    return nullptr;
+}
+
+void tokenlist_append(tokenlist_t *list, tokenlist_entry_t *entry) {
+    if (list->head == nullptr) {
+        list->head = entry;
+        list->tail = entry;
+        entry->next = nullptr;
+        entry->prev = nullptr;
+    } else {
+        entry->prev = list->tail;
+        entry->next = nullptr;
+        list->tail->next = entry;
+        list->tail = entry;
+    }
+}
+
+void tokenlist_entry_free(tokenlist_entry_t *entry) {
+    lexer_token_cleanup(&entry->token);
+    free(entry);
+}
+
+void tokenlist_free(tokenlist_t *list) {
+    if (list == nullptr)
+        return;
+
+    tokenlist_entry_t *current = list->head;
+    while (current) {
+        tokenlist_entry_t *next = current->next;
+        tokenlist_entry_free(current);
+        current = next;
+    }
+
+    free(list);
+}
+
+error_t *tokenlist_fill(tokenlist_t *list, lexer_t *lex) {
+    error_t *err = nullptr;
+    lexer_token_t token = {};
+    while ((err = lexer_next(lex, &token)) == nullptr) {
+        tokenlist_entry_t *entry;
+        err = tokenlist_entry_alloc(&entry);
+        if (err) {
+            lexer_token_cleanup(&token);
+            return err;
+        }
+        entry->token = token;
+        tokenlist_append(list, entry);
+    }
+    if (err != err_eof)
+        return err;
+    return nullptr;
+}

src/tokenlist.h

@@ -0,0 +1,30 @@
+#ifndef INCLUDE_SRC_TOKENLIST_H_
+#define INCLUDE_SRC_TOKENLIST_H_
+#include "lexer.h"
+
+typedef struct tokenlist_entry tokenlist_entry_t;
+
+struct tokenlist_entry {
+    lexer_token_t token;
+    tokenlist_entry_t *next;
+    tokenlist_entry_t *prev;
+};
+
+typedef struct tokenlist {
+    tokenlist_entry_t *head;
+    tokenlist_entry_t *tail;
+} tokenlist_t;
+
+/**
+ * @brief Allocate a new doubly linked list of lexer tokens
+ */
+error_t *tokenlist_alloc(tokenlist_t **list);
+
+/**
+ * Consume all tokens from the lexer and add them to the list
+ */
+error_t *tokenlist_fill(tokenlist_t *list, lexer_t *lex);
+
+void tokenlist_free(tokenlist_t *list);
+
+#endif // INCLUDE_SRC_TOKENLIST_H_