Added functionality for the basic array functionality, i'm going to make tests even thoug they are tedius as fuck, i'm way more interested in making tests for the lexer itself

include/lexer.h

@@ -23,6 +23,7 @@ typedef enum {
     ARRAY_EMPTY,
     ARRAY_OUT_OF_BOUNDS,
     ARRAY_NULL_ARG,
+    ARRAY_ALLOC,
 } ASTNodeArrayErr;
 
 typedef enum {

src/lexer.c

@@ -1,8 +1,80 @@
 #include "lexer.h"
+#include <stdlib.h>
+#include <strings.h>
 
+#define NODE_ARRAY_DEFAULT_SIZE 64
 // Helps  state machine for the lexer :)
 typedef enum {
     WAIT_FOR_NUMBER,
     WAIT_FOR_OPERATOR,
 } LexerState;
 
+ASTNodeArray ASTNodeArray_init(size_t size) {
+    ASTNodeArray new;
+    new.len = 0;      // if 0 then use default
+    new.cap = size == 0 ? NODE_ARRAY_DEFAULT_SIZE : size;
+    new.data = malloc(new.cap * sizeof(ASTNode));
+    return new;
+}
+
+void ASTNodeArray_free(ASTNodeArray *arr) {
+    free(arr->data);
+    arr->cap = 0;
+    arr->len = 0;
+}
+
+ASTNodeArrayErr ASTNodeArray_get(const ASTNodeArray arr, size_t index, ASTNode *out) {
+    if (out == NULL) {
+        return ARRAY_NULL_ARG;
+    }
+
+    if (arr.len == 0) {
+        return ARRAY_EMPTY;
+    }
+
+    if (index >= arr.len) {
+        return ARRAY_OUT_OF_BOUNDS;
+    }
+
+    *out = arr.data[index];
+
+    return ARRAY_OK;
+}
+
+ASTNodeArrayErr ASTNodeArray_push(ASTNodeArray arr, ASTNode node) {
+    if (arr.len >= arr.cap) {
+        size_t new_cap = arr.cap * 2;
+        ASTNode *tmp = realloc(arr.data, new_cap * sizeof(ASTNode));
+        if (tmp == NULL) {
+            return ARRAY_ALLOC;
+        }
+        arr.data = tmp;
+        arr.cap = new_cap;
+    }
+
+    arr.data[arr.len] = node;
+    arr.len += 1;
+
+    return ARRAY_OK;
+}
+
+ASTNodeArrayErr ASTNodeArray_pop(ASTNodeArray arr, size_t index, ASTNode *out) {
+    if (arr.len == 0) {
+        return ARRAY_EMPTY;
+    }
+
+    if (index >= arr.len) {
+        return ARRAY_OUT_OF_BOUNDS;
+    }
+    
+    if (out != NULL) {
+        ASTNode node_to_delete = arr.data[index];
+        *out = node_to_delete;
+    }
+
+    for (size_t i = index; i < arr.len - 1; i++) {
+        arr.data[index] = arr.data[index + 1];
+    }
+
+    return ARRAY_OK;
+}