Base parsing of Figlet fonts

Will be used later to fancy-print text!

figlet.lisp

@@ -0,0 +1,67 @@
+;;;; Copyright © 2023, Jaidyn Ann <jadedctrl@posteo.at>
+;;;;
+;;;; This program is free software: you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License as
+;;;; published by the Free Software Foundation, either version 3 of
+;;;; the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+;;;; FIGLET
+;;;; A package for parsing Figlet fonts into simple associative lists, for
+;;;; devious text-rendering purposes.
+
+(in-package :figlet)
+
+
+(defun string->integer (string)
+  "Convert a string to a number, potentially in 0x… hexadecimal form.
+If no number is parsed out, return NIL."
+  (let ((radix (if (str:starts-with-p "0x" string)
+                   16 10))
+        (string (if (str:starts-with-p "0x" string)
+                    (subseq string 2) string)))
+    (ignore-errors (parse-integer string :radix radix))))
+
+
+(defun parse-lines (lines &optional (font-plist '()) (current-symbol 32))
+  "Parse a list of lines from a Figlet font-file (.FLF) into a plist
+associating a character with its respective string in the font-file.
+  (#\A \"TEXT-ART-A\" #\B \"TEXT-ART-B\" …)"
+  (if lines
+    (let* ((line (car lines))
+           (sans-@ (cl:string-trim "@" line))
+           (last-of-symbol-p (str:ends-with-p "@@" line))
+           (not-art-line (not (str:ends-with-p "@" line)))
+           (first-word (car (str:split " " line)))
+           (first-word-num (string->integer first-word))
+           (new-symbol-header-p (and not-art-line first-word-num)))
+      (cond (new-symbol-header-p
+             (parse-lines (cdr lines) font-plist first-word-num))
+            ((not not-art-line)
+             (setf (getf font-plist (code-char current-symbol))
+                   (format nil "~A~A~%"
+                           (or (getf font-plist (code-char current-symbol))
+                               "")
+                           sans-@))
+             (parse-lines (cdr lines) font-plist (if last-of-symbol-p
+                                                     (+ current-symbol 1)
+                                                     current-symbol)))
+            ('t
+             (parse-lines (cdr lines) font-plist current-symbol))))
+    font-plist))
+
+
+(defun figlet-font-plist (path)
+  "Parse a Figlet font-file (.FLF) into a plist associating a character
+with its respective string in the font-file.
+  (#\A \"TEXT-ART-A\" #\B \"TEXT-ART-B\" …)"
+  (parse-lines
+   (str:lines
+    (alexandria:read-file-into-string path))))

packages.lisp

@@ -97,3 +97,6 @@
    :flora-search-aurora.overworld :flora-search-aurora.dialogue
    :flora-search-aurora.ui))
 
+(defpackage :figlet-font-plist
+  (:export #:parse-figlet-font-file)
+  (:use cl))