initial

README.md

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+# t
+
+Yet another simple terminal editor, based on [this
+screenshot](https://www.destroyallsoftware.com/screencasts/catalog/text-editor-from-scratch)
+by Gary Bernhardt, ported to Python and with multimodality added.

t.py

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+#!/usr/bin/env python
+
+import copy
+import sys
+import tty
+import termios
+
+NORMAL = 0
+EDIT = 1
+META = 2
+
+UP = 1000
+DOWN = 1001
+LEFT = 1002
+RIGHT = 1003
+
+
+class Editor():
+    def __init__(self, f):
+        lines = [l.replace("\n", "") for l in f]
+        self.buffer = Buffer(lines)
+        self.cursor = Cursor(0, 0)
+        self.mode = NORMAL
+        self.history = []
+
+    def set_raw(self):
+        fd = sys.stdin.fileno()
+        self.old_settings = termios.tcgetattr(fd)
+        tty.setraw(fd)
+
+    def unset_raw(self):
+        fd = sys.stdin.fileno()
+        termios.tcsetattr(fd, termios.TCSADRAIN, self.old_settings)
+
+    def run(self):
+        self.running = True
+        self.set_raw()
+        while self.running:
+            self.render()
+            if self.mode == NORMAL: self.handle_input()
+            if self.mode == EDIT: self.handle_edit()
+            if self.mode == META: self.handle_meta()
+        self.unset_raw()
+
+    def render(self):
+        ANSI.clear_screen()
+        ANSI.move_cursor(0, 0)
+        self.buffer.render()
+        ANSI.move_cursor(self.cursor.row, self.cursor.col)
+
+    def handle_meta(self):
+        char = sys.stdin.read(1)
+
+        if char == 'q': self.running = False
+
+    def handle_edit(self):
+        char = self.read_input()
+
+        if char == chr(27): # ESC
+            self.mode = NORMAL
+        elif char == chr(127) and self.cursor.col: # BACK
+            self.save_snapshot()
+            self.buffer = self.buffer.delete(self.cursor)
+            self.cursor = self.cursor.left(self.buffer)
+        elif char == '\r':
+            self.save_snapshot()
+            self.buffer = self.buffer.split_line(self.cursor)
+            self.cursor = Cursor(self.cursor.row+1, 0)
+        elif char == UP: self.cursor = self.cursor.up(self.buffer)
+        elif char == DOWN: self.cursor = self.cursor.down(self.buffer)
+        elif char == LEFT: self.cursor = self.cursor.left(self.buffer)
+        elif char == RIGHT: self.cursor = self.cursor.right(self.buffer)
+        else:
+            self.save_snapshot()
+            self.buffer = self.buffer.insert(char, self.cursor)
+            self.cursor = self.cursor.right(self.buffer)
+
+    def read_input(self):
+        char = sys.stdin.read(1)
+
+        if char == '\x1b':
+            nchar = sys.stdin.read(1)
+
+            if nchar != '[': return char
+
+            char = sys.stdin.read(1)
+
+            if char == 'A': return UP
+            if char == 'B': return DOWN
+            if char == 'C': return RIGHT
+            if char == 'D': return LEFT
+
+        return char
+
+    def handle_input(self):
+        char = self.read_input()
+
+        if char == ':': self.mode = META
+        elif char == 'w' or char == UP:
+            self.cursor = self.cursor.up(self.buffer)
+        elif char == 's' or char == DOWN:
+            self.cursor = self.cursor.down(self.buffer)
+        elif char == 'a' or char == LEFT:
+            self.cursor = self.cursor.left(self.buffer)
+        elif char == 'd' or char == RIGHT:
+            self.cursor = self.cursor.right(self.buffer)
+        elif char == 'u': self.restore_snapshot()
+        elif char == 'e': self.mode = EDIT
+
+    def save_snapshot(self):
+        self.history.append([self.buffer, self.cursor])
+
+    def restore_snapshot(self):
+        if len(self.history): self.buffer, self.cursor = self.history.pop()
+
+
+class ANSI():
+    @staticmethod
+    def ansi(s):
+        return "\x1b[" + s
+
+    @staticmethod
+    def clear_screen():
+        sys.stdout.write(ANSI.ansi("2J"))
+
+    @staticmethod
+    def move_cursor(x, y):
+        sys.stdout.write(ANSI.ansi("{};{}H".format(x+1, y+1)))
+
+
+
+class Buffer():
+    def __init__(self, lines):
+        self.lines = lines
+
+    def render(self):
+        for line in self.lines:
+            sys.stdout.write(line + "\r\n")
+
+    def line_count(self):
+        return len(self.lines)
+
+    def line_length(self, x):
+        return len(self.lines[x])
+
+    def insert(self, char, cursor):
+        lines = copy.copy(self.lines)
+        line = lines[cursor.row]
+        lines[cursor.row] = line[:cursor.col] + char + line[cursor.col:]
+        return Buffer(lines)
+
+    def delete(self, cursor):
+        lines = copy.copy(self.lines)
+        line = lines[cursor.row]
+        lines[cursor.row] = line[:cursor.col-1] + line[cursor.col:]
+        return Buffer(lines)
+
+    def split_line(self, cursor):
+        lines = copy.copy(self.lines)
+        line = lines[cursor.row]
+        before, after = line[:cursor.col], line[cursor.col:]
+        lines[cursor.row] = before
+        lines.insert(cursor.row+1, after)
+        return Buffer(lines)
+
+
+class Cursor():
+    def __init__(self, row=0, col=0):
+        self.row = row
+        self.col = col
+
+    def up(self, buf):
+        return Cursor(self.row-1, self.col).clamp(buf)
+
+    def down(self, buf):
+        return Cursor(self.row+1, self.col).clamp(buf)
+
+    def left(self, buf):
+        return Cursor(self.row, self.col-1).clamp(buf)
+
+    def right(self, buf):
+        return Cursor(self.row, self.col+1).clamp(buf)
+
+    def clamp(self, buf):
+        row = max(0, min(self.row, buf.line_count()-1))
+        col = max(0, min(self.col, buf.line_length(row)))
+        return Cursor(row, col)
+
+
+with open(sys.argv[1]) as f:
+    Editor(f).run()