From d1816df4c029447f94963355cbdce5c434063ee6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Sun, 24 Aug 2025 19:50:56 -0300
Subject: Add cursors

---
 cursor.lisp  | 31 +++++++++++++++++++++++++++++++
 package.lisp | 10 ++++++++++
 utils.asd    |  5 +++--
 3 files changed, 44 insertions(+), 2 deletions(-)
 create mode 100644 cursor.lisp

diff --git a/cursor.lisp b/cursor.lisp
new file mode 100644
index 0000000..d3012ab
--- /dev/null
+++ b/cursor.lisp
@@ -0,0 +1,31 @@
+(in-package #:cursor)
+
+(defclass text ()
+  ((data :type simple-string :initarg :data :reader data :initform "")
+   (index :type (unsigned-byte 44) :initarg :index :accessor index :initform 0)))
+
+(defun has-data? (cursor)
+  (< (index cursor) (length (data cursor))))
+
+(defun peek (cursor)
+  (char (data cursor)
+        (index cursor)))
+
+(defun advance (cursor)
+  (make-instance 'text
+                 :data (data cursor)
+                 :index (+ (index cursor) 1)))
+
+(defun distance (from to)
+  (- (index to)
+     (index from)))
+
+(defmethod print-object ((obj text) stream)
+  (print-unreadable-object (obj stream :type t)
+    (let ((str (if (has-data? obj)
+                 (format nil "~{~a~a~a~}"
+                         (str:context-window (data obj)
+                                             (index obj)
+                                             :side-length 10))
+                 "END OF DATA")))
+      (substitute #\↲ #\Newline str))))
diff --git a/package.lisp b/package.lisp
index d170039..e6ed7b5 100644
--- a/package.lisp
+++ b/package.lisp
@@ -1,3 +1,13 @@
+(defpackage #:cursor
+  (:use #:cl)
+  (:export #:text
+           #:index
+           #:data
+           #:has-data?
+           #:peek
+           #:advance
+           #:distance))
+
 (defpackage #:color
   (:use #:cl)
   (:export #:hsl->rgb))
diff --git a/utils.asd b/utils.asd
index 4a126d6..f4974e0 100644
--- a/utils.asd
+++ b/utils.asd
@@ -1,4 +1,4 @@
-(defsystem #:utils
+(defsystem "utils"
   :serial nil
   :components
   ((:file "package")
@@ -6,4 +6,5 @@
    (:file "char")
    (:file "symbol")
    (:file "color")
-   (:file "str")))
+   (:file "str")
+   (:file "cursor")))
-- 
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