Files
cl-tty/org/modern-backend.org
Hermes Agent c77c6b9d02 literate: convert org/modern-backend.org from doc-only to tangle source
Now tangles to modern.lisp + modern-tests.lisp.
Deleted hand-written originals and regenerated from org — GREEN.
2026-05-12 17:14:37 +00:00

544 lines
21 KiB
Org Mode

#+TITLE: Modern Backend
#+STARTUP: content
#+FILETAGS: :cl-tty:backend:
* Overview
The modern backend provides full-featured terminal rendering using raw
escape sequences. It supports truecolor 24-bit color, OSC 8 hyperlinks,
DECICM synchronized updates, SGR mouse tracking, kitty keyboard protocol,
and Unicode box-drawing characters (single, double, rounded).
All rendering functions produce CSI/OSC escape sequences directly — no
ncurses, no terminfo, no FFI. Color resolution handles named colors
(~:red~, ~:blue~, etc.), hex strings (~"#FFD700"~), and semantic theme
roles (~:accent~, ~:error~) via the ~*theme-colors*~ hash table.
* Contract
** Color and attribute helpers
- ~(hex-to-rgb hex)~ → (values r g b) — parse "#RRGGBB" or "#RGB"
- ~(sgr-fg color)~ → escape string — foreground color escape
- ~(sgr-bg color)~ → escape string — background color escape
- ~(sgr-attr attr)~ → escape string — attribute escape (bold, italic, etc.)
** Cursor helpers
- ~(cursor-move-escape x y)~ → escape string — CSI cursor position
- ~(cursor-style-escape shape blink)~ → escape string — DECSTR cursor shape
** Sync and link helpers
- ~(decicm-begin)~ → escape string — enable synchronized updates
- ~(decicm-end)~ → escape string — disable synchronized updates
- ~(osc8-link url text)~ → escape string — OSC 8 hyperlink wrapper
** Border helpers
- ~(border-char style pos)~ → string — Unicode box-drawing character
** Modern backend class
- ~(make-modern-backend &key output-stream)~ → modern-backend
- Implements all ~backend~ protocol methods with escape sequences
* Tests
#+BEGIN_SRC lisp :tangle ../src/backend/modern-tests.lisp
(defpackage :cl-tty-modern-backend-test
(:use :cl :fiveam :cl-tty.backend)
(:export #:run-tests))
(in-package :cl-tty-modern-backend-test)
(def-suite modern-backend-suite :description "Modern backend tests")
(in-suite modern-backend-suite)
(defun run-tests ()
(let ((result (run 'modern-backend-suite)))
(fiveam:explain! result)
(uiop:quit 0)))
;; ── Constructor ────────────────────────────────────────────────
(test make-modern-backend-creates
"make-modern-backend returns a modern-backend instance"
(let ((b (make-modern-backend)))
(is (typep b 'cl-tty.backend::modern-backend))))
;; ── Escape Generation ──────────────────────────────────────────
(test sgr-truecolor-foreground
"SGR truecolor foreground escape is correct"
(is (equal (cl-tty.backend::sgr-fg "#FFD700")
(format nil "~C[38;2;255;215;0m" #\Esc))))
(test sgr-truecolor-background
"SGR truecolor background escape is correct"
(is (equal (cl-tty.backend::sgr-bg "#1a1b26")
(format nil "~C[48;2;26;27;38m" #\Esc))))
(test sgr-named-colors
"SGR named colors resolve to 8-color codes"
(is (equal (cl-tty.backend::sgr-fg :red)
(format nil "~C[31m" #\Esc)))
(is (equal (cl-tty.backend::sgr-bg :blue)
(format nil "~C[44m" #\Esc))))
(test sgr-bold-italic
"SGR attribute escapes are correct"
(is (equal (cl-tty.backend::sgr-attr :bold) (format nil "~C[1m" #\Esc)))
(is (equal (cl-tty.backend::sgr-attr :italic) (format nil "~C[3m" #\Esc)))
(is (equal (cl-tty.backend::sgr-attr :underline) (format nil "~C[4m" #\Esc)))
(is (equal (cl-tty.backend::sgr-attr :reset) (format nil "~C[0m" #\Esc))))
;; ── Cursor ─────────────────────────────────────────────────────
(test cursor-move-escape
"cursor-move generates correct CSI escape"
(let ((b (make-modern-backend)))
(is (equal (cl-tty.backend::cursor-move-escape 5 10)
(format nil "~C[11;6H" #\Esc)))))
(test cursor-style-block
"cursor-style :block generate correct escape"
(let ((b (make-modern-backend)))
(is (equal (cl-tty.backend::cursor-style-escape :block nil)
(format nil "~C[2 q" #\Esc)))))
(test cursor-style-bar
"cursor-style :bar generate correct escape"
(let ((b (make-modern-backend)))
(is (equal (cl-tty.backend::cursor-style-escape :bar nil)
(format nil "~C[6 q" #\Esc)))))
(test cursor-style-underline-blink
"cursor-style :underline with blink"
(let ((b (make-modern-backend)))
(is (equal (cl-tty.backend::cursor-style-escape :underline t)
(format nil "~C[5 q" #\Esc)))))
;; ── Synchronization ────────────────────────────────────────────
(test decicm-escapes
"DECICM synchronized update escapes"
(is (equal (cl-tty.backend::decicm-begin) (format nil "~C[?2026h" #\Esc)))
(is (equal (cl-tty.backend::decicm-end) (format nil "~C[?2026l" #\Esc))))
;; ── OSC 8 Hyperlinks ──────────────────────────────────────────
(test osc8-escape
"OSC 8 hyperlink escape wraps text"
(is (equal (cl-tty.backend::osc8-link "http://example.com" "click here")
(format nil "~C]8;;http://example.com~C\\\\click here~C]8;;~C\\\\"
#\Esc #\Esc #\Esc #\Esc))))
;; ── Hex Parsing ────────────────────────────────────────────────
(test hex-color-parsing
"hex-to-rgb parses valid hex colors"
(multiple-value-bind (r g b) (cl-tty.backend::hex-to-rgb "#FFD700")
(is (= r 255))
(is (= g 215))
(is (= b 0))))
(test hex-color-black
"hex-to-rgb parses black"
(multiple-value-bind (r g b) (cl-tty.backend::hex-to-rgb "#000000")
(is (= r 0))
(is (= g 0))
(is (= b 0))))
(test hex-color-short-form
"hex-to-rgb parses 3-digit hex"
(multiple-value-bind (r g b) (cl-tty.backend::hex-to-rgb "#F00")
(is (= r 255))
(is (= g 0))
(is (= b 0))))
;; ── Border Characters ──────────────────────────────────────────
(test border-char-rounded
"modern-border-char returns Unicode box-drawing for rounded style"
(is (equal (cl-tty.backend::border-char :rounded :top-left) "╭"))
(is (equal (cl-tty.backend::border-char :rounded :horizontal) "─"))
(is (equal (cl-tty.backend::border-char :rounded :vertical) "│"))
(is (equal (cl-tty.backend::border-char :rounded :bottom-right) "╯")))
(test border-char-double
"modern-border-char returns double-line chars"
(is (equal (cl-tty.backend::border-char :double :top-left) "╔"))
(is (equal (cl-tty.backend::border-char :double :horizontal) "═"))
(is (equal (cl-tty.backend::border-char :double :vertical) "║")))
#+END_SRC
* Implementation
** Color and attribute helpers
~hex-to-rgb~ parses hex color strings into (r g b) triplets. Handles
both 6-digit (fully specified) and 3-digit (shorthand) formats.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(in-package :cl-tty.backend)
(defun hex-to-rgb (hex)
"Parse a hex color string like \"#FFD700\" into (values r g b).
Also handles 3-digit hex like \"#F00\" (expands to \"#FF0000\")."
(let ((clean (string-trim '(#\# #\Space) hex)))
(if (= (length clean) 3)
;; Expand 3-digit: #F00 -> #FF0000
(let* ((r (parse-integer (subseq clean 0 1) :radix 16 :junk-allowed t))
(g (parse-integer (subseq clean 1 2) :radix 16 :junk-allowed t))
(b (parse-integer (subseq clean 2 3) :radix 16 :junk-allowed t)))
(values (+ r (* r 16)) (+ g (* g 16)) (+ b (* b 16))))
(values (parse-integer (subseq clean 0 2) :radix 16 :junk-allowed t)
(parse-integer (subseq clean 2 4) :radix 16 :junk-allowed t)
(parse-integer (subseq clean 4 6) :radix 16 :junk-allowed t)))))
#+END_SRC
Named color mapping and theme color store:
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defparameter *named-colors*
'((:black . 0) (:red . 1) (:green . 2) (:yellow . 3)
(:blue . 4) (:magenta . 5) (:cyan . 6) (:white . 7)))
(defvar *theme-colors* (make-hash-table :test 'eq)
"Hash table mapping theme keywords to hex color strings.
Populated by the theme system's load-preset. Checked by sgr-fg/sgr-bg
as a fallback when a keyword is not in *named-colors*.")
#+END_SRC
~sgr-fg~ and ~sgr-bg~ produce the actual escape sequences. The
resolution chain is: hex → named color → theme semantic role → empty.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defun sgr-fg (color)
"Return SGR foreground escape for COLOR."
(if (null color) ""
(cond ((and (stringp color) (char= (char color 0) #\#))
(multiple-value-bind (r g b) (hex-to-rgb color)
(format nil "~C[38;2;~d;~d;~dm" #\Esc r g b)))
((keywordp color)
(let ((index (cdr (assoc color *named-colors*))))
(if index
(format nil "~C[~dm" #\Esc (+ 30 index))
(let ((hex (gethash color *theme-colors*)))
(if hex
(multiple-value-bind (r g b) (hex-to-rgb hex)
(format nil "~C[38;2;~d;~d;~dm" #\Esc r g b))
"")))))
(t ""))))
#+END_SRC
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defun sgr-bg (color)
"Return SGR background escape for COLOR."
(if (null color) ""
(cond ((and (stringp color) (char= (char color 0) #\#))
(multiple-value-bind (r g b) (hex-to-rgb color)
(format nil "~C[48;2;~d;~d;~dm" #\Esc r g b)))
((keywordp color)
(let ((index (cdr (assoc color *named-colors*))))
(if index
(format nil "~C[~dm" #\Esc (+ 40 index))
(let ((hex (gethash color *theme-colors*)))
(if hex
(multiple-value-bind (r g b) (hex-to-rgb hex)
(format nil "~C[48;2;~d;~d;~dm" #\Esc r g b))
"")))))
(t ""))))
#+END_SRC
Attribute codes map keywords to SGR numbers:
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defparameter *sgr-attr-codes*
'((:bold . 1) (:dim . 2) (:italic . 3) (:underline . 4)
(:blink . 5) (:reverse . 7) (:reset . 0)))
(defun sgr-attr (attr)
"Return SGR attribute escape for ATTR keyword."
(let ((code (cdr (assoc attr *sgr-attr-codes*))))
(if code
(format nil "~C[~dm" #\Esc code)
"")))
#+END_SRC
** Cursor escapes
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defun cursor-move-escape (x y)
"Return CSI escape to move cursor to (x, y), 1-indexed."
(format nil "~C[~d;~dH" #\Esc (1+ y) (1+ x)))
(defun cursor-style-escape (shape blink)
"Return DECSTR escape for cursor shape."
(let* ((base (case shape
(:block 2) (:underline 4) (:bar 6)
(t 2)))
(code (if blink (1+ base) base)))
(format nil "~C[~d q" #\Esc code)))
#+END_SRC
** Sync and link escapes
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defun decicm-begin ()
"Return escape to enable synchronized updates."
(format nil "~C[?2026h" #\Esc))
(defun decicm-end ()
"Return escape to disable synchronized updates."
(format nil "~C[?2026l" #\Esc))
(defun osc8-link (url text)
"Wrap TEXT in an OSC 8 hyperlink to URL."
(format nil "~C]8;;~A~C\\\\~A~C]8;;~C\\\\"
#\Esc url #\Esc text #\Esc #\Esc))
#+END_SRC
** Border characters
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defparameter *border-chars*
'(((:single :top-left) . "┌") ((:single :top-right) . "┐")
((:single :bottom-left) . "└") ((:single :bottom-right) . "┘")
((:single :horizontal) . "─") ((:single :vertical) . "│")
((:double :top-left) . "╔") ((:double :top-right) . "╗")
((:double :bottom-left) . "╚") ((:double :bottom-right) . "╝")
((:double :horizontal) . "═") ((:double :vertical) . "║")
((:rounded :top-left) . "╭") ((:rounded :top-right) . "╮")
((:rounded :bottom-left) . "╰") ((:rounded :bottom-right) . "╯")
((:rounded :horizontal) . "─") ((:rounded :vertical) . "│")))
(defun border-char (style pos)
"Return the Unicode box-drawing character for STYLE at POS."
(let ((char (cdr (assoc (list style pos) *border-chars* :test #'equal))))
(or char (if (member pos '(:horizontal :vertical))
(case pos (:horizontal "─") (:vertical "│"))
"+"))))
#+END_SRC
** Modern backend class
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defclass modern-backend (backend)
((output-stream :initform *standard-output*
:initarg :output-stream
:accessor backend-output-stream)
(in-sync-p :initform nil :accessor in-sync-p)))
(defun make-modern-backend (&key color-palette output-stream)
(declare (ignore color-palette))
(make-instance 'modern-backend :output-stream (or output-stream *standard-output*)))
#+END_SRC
** Lifecycle
~initialize-backend~ enters the alt screen, enables mouse tracking,
bracketed paste, and kitty keyboard protocol. ~shutdown-backend~
restores everything.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod initialize-backend ((b modern-backend))
(backend-write b (format nil "~C[?1049h" #\Esc)) ; alt screen
(backend-write b (format nil "~C[?1000h" #\Esc)) ; mouse basic
(backend-write b (format nil "~C[?1002h" #\Esc)) ; mouse drag
(backend-write b (format nil "~C[?1006h" #\Esc)) ; SGR mouse
(backend-write b (format nil "~C[?2004h" #\Esc)) ; bracketed paste
(backend-write b (format nil "~C[?u" #\Esc)) ; kitty keyboard
(cursor-hide b)
(finish-output (backend-output-stream b))
b)
(defmethod shutdown-backend ((b modern-backend))
(cursor-show b)
(backend-write b (format nil "~C[?u" #\Esc))
(backend-write b (format nil "~C[?2004l" #\Esc))
(backend-write b (format nil "~C[?1006l" #\Esc))
(backend-write b (format nil "~C[?1002l" #\Esc))
(backend-write b (format nil "~C[?1000l" #\Esc))
(backend-write b (format nil "~C[?1049l" #\Esc)) ; normal screen
(finish-output (backend-output-stream b))
(values))
#+END_SRC
** Backend-size via ioctl
Uses TIOCGWINSZ to query actual terminal dimensions. The alien-sap
wrapper ensures compatibility across SBCL versions.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod backend-size ((b modern-backend))
(let* ((+tiocgwinsz+ 21523) ; 0x5413 on Linux
(winsize (sb-alien:make-alien sb-alien:unsigned-short 4)))
(unwind-protect
(progn
(sb-unix:unix-ioctl (sb-sys:fd-stream-fd (backend-output-stream b))
+tiocgwinsz+
(sb-alien:alien-sap winsize))
(values (sb-alien:deref winsize 1) ;; cols
(sb-alien:deref winsize 0))) ;; rows
(sb-alien:free-alien winsize))))
#+END_SRC
** Capability query and write
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod backend-write ((b modern-backend) string)
(let ((stream (backend-output-stream b)))
(write-string string stream)
(finish-output stream)
(length string)))
(defmethod capable-p ((b modern-backend) feature)
(member feature '(:truecolor :osc8 :sync :mouse
:bracketed-paste :cursor-style
:kitty-keyboard)))
#+END_SRC
** Drawing
~draw-text~ combines cursor positioning, SGR colors, attributes, the
text itself, and a reset into a single string. This minimizes ioctl
calls — one write per draw operation.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod draw-text ((b modern-backend) x y string fg bg
&key bold italic underline reverse dim blink)
(let ((parts (list (cursor-move-escape x y)
(sgr-fg fg) (sgr-bg bg)
(when bold (sgr-attr :bold))
(when italic (sgr-attr :italic))
(when underline (sgr-attr :underline))
(when reverse (sgr-attr :reverse))
(when dim (sgr-attr :dim))
(when blink (sgr-attr :blink))
string
(sgr-attr :reset))))
(backend-write b (apply #'concatenate 'string parts))))
#+END_SRC
~draw-border~ builds the full border as three string parts (top with
optional title, mid with sides, bottom) and writes them with minimal
output calls.
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod draw-border ((b modern-backend) x y width height
&key style fg bg title title-align)
(let* ((s (or style :single))
(tl (border-char s :top-left))
(tr (border-char s :top-right))
(bl (border-char s :bottom-left))
(br (border-char s :bottom-right))
(h (border-char s :horizontal))
(v (border-char s :vertical))
(fg-esc (sgr-fg fg))
(bg-esc (sgr-bg bg))
(reset (sgr-attr :reset))
(inner-width (- width 2))
(hc (char h 0))
(top (if (and title (plusp (length title)))
(let* ((align (or title-align :left))
(max-tlen (- inner-width 2))
(tlen (min (length title) max-tlen))
(trunc-title (subseq title 0 tlen)))
(ecase align
(:left
(let ((right-hyphens (- inner-width tlen 2)))
(concatenate 'string
fg-esc bg-esc tl (string #\Space)
trunc-title (string #\Space)
(make-string (max 0 right-hyphens) :initial-element hc)
tr reset (string #\Newline))))
(:center
(let* ((total-pad (- inner-width tlen))
(left-pad (floor total-pad 2))
(right-pad (- total-pad left-pad)))
(concatenate 'string
fg-esc bg-esc tl
(make-string left-pad :initial-element hc)
trunc-title
(make-string right-pad :initial-element hc)
tr reset (string #\Newline))))))
(concatenate 'string
fg-esc bg-esc tl
(make-string inner-width :initial-element hc)
tr reset (string #\Newline))))
(mid (concatenate 'string
fg-esc bg-esc v
(make-string inner-width :initial-element #\Space)
v reset (string #\Newline)))
(bot (concatenate 'string
fg-esc bg-esc bl
(make-string inner-width :initial-element hc)
br reset)))
(backend-write b top)
(loop repeat (- height 2) do (backend-write b mid))
(backend-write b bot)))
#+END_SRC
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod draw-rect ((b modern-backend) x y width height &key bg)
(let* ((bg-esc (sgr-bg bg))
(reset (sgr-attr :reset))
(line (concatenate 'string
bg-esc
(make-string width :initial-element #\Space)
reset (string #\Newline))))
(loop :for row :from 0 :below height :do
(backend-write b (cursor-move-escape x (+ y row)))
(backend-write b line))))
(defmethod draw-link ((b modern-backend) x y string url
&key fg bg)
(let ((parts (list (cursor-move-escape x y)
(sgr-fg fg) (sgr-bg bg)
(osc8-link url string)
(sgr-attr :reset))))
(backend-write b (apply #'concatenate 'string parts))))
(defmethod draw-ellipsis ((b modern-backend) x y width
&key fg bg)
(declare (ignore width))
(let ((dots "..."))
(draw-text b x y dots fg bg)))
#+END_SRC
** Cursor and input methods
#+BEGIN_SRC lisp :tangle ../src/backend/modern.lisp
(defmethod cursor-move ((b modern-backend) x y)
(backend-write b (cursor-move-escape x y)))
(defmethod cursor-hide ((b modern-backend))
(backend-write b (format nil "~C[?25l" #\Esc)))
(defmethod cursor-show ((b modern-backend))
(backend-write b (format nil "~C[?25h" #\Esc)))
(defmethod cursor-style ((b modern-backend) shape &key blink)
(backend-write b (cursor-style-escape shape blink)))
(defmethod enable-mouse ((b modern-backend))
(backend-write b (format nil "~C[?1000h" #\Esc))
(backend-write b (format nil "~C[?1002h" #\Esc))
(backend-write b (format nil "~C[?1006h" #\Esc))
(finish-output (backend-output-stream b)))
(defmethod enable-bracketed-paste ((b modern-backend))
(backend-write b (format nil "~C[?2004h" #\Esc))
(finish-output (backend-output-stream b)))
(defmethod begin-sync ((b modern-backend))
(setf (in-sync-p b) t)
(backend-write b (decicm-begin)))
(defmethod end-sync ((b modern-backend))
(setf (in-sync-p b) nil)
(backend-write b (decicm-end))
(finish-output (backend-output-stream b)))
#+END_SRC