From scratch forth text editor.

This commit is contained in:
Kyle Isom 2019-04-23 18:28:32 -07:00
parent 1d483e23ca
commit ebb8172551
2 changed files with 204 additions and 0 deletions

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from_scratch/editor.rb Normal file
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#!/usr/bin/env ruby
# This is a simple forth editor written in Ruby, following along with
# the DAS "from scratch" text editor tutorial.
require "io/console"
class Editor
def initialize(filename="")
if filename.length > 0
if File.exists? filename
lines = File.readlines(filename).map do |line|
line.sub(/\n$/, "")
end
else
lines = ['']
end
else
filename = "untitled.txt"
lines = ['']
end
@filename = filename
@buffer = Buffer.new(lines)
@cursor = Cursor.new
@history = []
end
def run
IO.console.raw do
loop do
render
handle_input
end
end
rescue
50.times { puts }
raise
end
def render
ANSI.clear_screen
ANSI.move_cursor(0, 0)
@buffer.render
ANSI.move_cursor(@cursor.row, @cursor.col)
end
def handle_input
char = $stdin.getc
case char
when "\C-q" then exit(0)
# operating on the cursor makes undo easier
when "\C-p" then @cursor = @cursor.up(@buffer)
when "\C-n" then @cursor = @cursor.down(@buffer)
when "\C-b" then @cursor = @cursor.left(@buffer)
when "\C-f" then @cursor = @cursor.right(@buffer)
when "\C-s" then @buffer.write(@filename)
when "\C-u" then restore_snapshot
when "\C-e" then
@cursor = @cursor.move_to_col(@buffer.line_length(@cursor.row))
when "\C-a" then @cursor = @cursor.move_to_col(0)
when "\C-r" then forth
when 127.chr
if @cursor.col > 0
save_snapshot
@buffer = @buffer.delete(@cursor.row, @cursor.col-1)
@cursor = @cursor.left(@buffer)
end
when "\r"
# in raw mode, enter sends \r
save_snapshot
@buffer = @buffer.split_line(@cursor.row, @cursor.col)
@cursor = @cursor.down(@buffer).move_to_col(0)
else
save_snapshot
# keep buffer immutable so we can do undo
@buffer = @buffer.insert(char, @cursor.row, @cursor.col)
# lot of the implemenation of basic actions is ensuring
# cursor consistency
@cursor = @cursor.right(@buffer)
end
end
def save_snapshot
@history <<[@buffer, @cursor]
end
def restore_snapshot
if @history.length > 0
@buffer, @cursor = @history.pop
end
end
def forth
ANSI.clear_screen
puts "gforth {@filename}\r\n"
puts "------\r\n"
output = `gforth #{@filename}`.split("\n")
Buffer.new(output).render
puts "-----\r\n"
puts "Press <enter> to exit...\r\n"
loop do
char = $stdin.getc
case char
when "\r" then break
end
end
end
end
class Buffer
def initialize(lines)
@lines = lines
end
def render
@lines.each do |line|
$stdout.write(line + "\r\n")
end
end
def insert(char, row, col)
lines = @lines.map(&:dup)
lines.fetch(row).insert(col, char)
Buffer.new(lines)
end
def delete(row, col)
lines = @lines.map(&:dup)
lines.fetch(row).slice!(col)
Buffer.new(lines)
end
def split_line(row, col)
lines = @lines.map(&:dup)
line = lines.fetch(row)
lines[row..row] = [line[0...col], line[col..-1]]
Buffer.new(lines)
end
def line_count
@lines.count
end
def line_length(row)
@lines.fetch(row).length
end
def write(filename)
File.write(filename, @lines.join("\n"))
end
end
class Cursor
attr_reader :row, :col
def initialize(row=0, col=0)
@row = row
@col = col
end
def left(buffer)
Cursor.new(@row, @col-1).clamp(buffer)
end
def right(buffer)
Cursor.new(@row, @col+1).clamp(buffer)
end
def up(buffer)
Cursor.new(@row-1, @col).clamp(buffer)
end
def down(buffer)
Cursor.new(@row+1, @col).clamp(buffer)
end
def clamp(buffer)
row = @row.clamp(0, buffer.line_count - 1)
col = @col.clamp(0, buffer.line_length(row))
Cursor.new(row, col)
end
def move_to_col(col)
Cursor.new(row, col)
end
end
class ANSI
def self.clear_screen
$stdout.write("\e[2J")
end
def self.move_cursor(row, col)
$stdout.write("\e[#{row+1};#{col+1}H")
end
end
filename = ""
if ARGV.length > 0
filename = ARGV[0]
end
Editor.new(filename).run

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