readline: basic reading on linux

vlib/readline/readline_lin.v

@@ -0,0 +1,105 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+// Linux version
+// Will serve as more advanced input method
+// Based on the work of https://github.com/AmokHuginnsson/replxx 
+
+module readline
+
+#include <termios.h>
+
+struct termios {
+mut:
+  c_iflag int
+  c_oflag int
+  c_cflag int
+  c_lflag int
+  c_cc [12]int //NCCS == 12. Cant use the defined value here
+}
+
+struct Readline {
+pub mut:
+  is_raw bool
+  orig_termios termios
+}
+
+// Toggle raw mode of the terminal by changing its attributes
+pub fn (r mut Readline) enable_raw_mode() {
+  if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
+    panic('No tty')
+  }
+  mut raw := r.orig_termios
+  raw.c_iflag &= ~( C.BRKINT | C.ICRNL | C.INPCK | C.ISTRIP | C.IXON )
+  raw.c_cflag |=  ( C.CS8 )
+  raw.c_lflag &= ~( C.ECHO | C.ICANON | C.IEXTEN | C.ISIG )
+  raw.c_cc[C.VMIN] = 1
+  raw.c_cc[C.VTIME] = 0
+  C.tcsetattr(0, C.TCSADRAIN, &raw)
+  r.is_raw = true
+}
+
+// Not catching the SIGUSER (CTRL+C) Signal
+pub fn (r Readline) enable_raw_mode2() {
+  if ( C.tcgetattr(0, &r.orig_termios) == -1 ) {
+    panic('No tty')
+  }
+  mut raw := r.orig_termios
+  raw.c_iflag &= ~( C.BRKINT | C.ICRNL | C.INPCK | C.ISTRIP | C.IXON )
+  raw.c_cflag |=  ( C.CS8 )
+  raw.c_lflag &= ~( C.ECHO | C.ICANON | C.IEXTEN )
+  raw.c_cc[C.VMIN] = 1
+  raw.c_cc[C.VTIME] = 0
+  C.tcsetattr(0, C.TCSADRAIN, &raw)
+}
+
+// Reset back the terminal to its default value
+pub fn (r Readline) disable_raw_mode() {
+  if r.is_raw {
+    C.tcsetattr(0, C.TCSADRAIN, &r.orig_termios)
+  }
+}
+
+// Read single char
+fn (r Readline) read_char() byte {
+  return C.getchar()
+}
+
+// Delete character in the string and in the terminal
+fn (r Readline) delete_character(s string, cursor int) string {
+  print('\b \b')
+  return s.left(cursor - 1) + s.right(cursor)
+} 
+
+pub fn (r Readline) read_line() string {
+  mut s := ''
+  mut cursor := 0
+  
+  for {
+    c := r.read_char()
+    // Check if ending string
+    if c == `\0` || c == 0x3 || c == 0x4 || c == 255 {
+      break
+    }
+    // Check if backspace
+    if c == `\b` || c == 127 {
+      if cursor > 0 {
+        s = r.delete_character(s, cursor)
+        cursor--
+      }
+    } else {
+      // Add new character according to cursor position
+      s = s.left(cursor) + c.str() + s.right(cursor)
+      cursor++
+    }
+    // Check if enter
+    if c == `\n` || c == `\r` {
+      println('')
+      break
+    } else {
+      print(c.str())
+    }
+  }
+  return s
+}