Merge pull request #604 from eldipa/Issue-587-Example-Pyte

Examples of how to use Pexpect and Pyte (issue #587)

1 files changed, 120 insertions, 0 deletions

diff --git a/examples/terminal_emulation.py b/examples/terminal_emulation.py
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+++ b/examples/terminal_emulation.py
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+#!/usr/bin/env python
+
+'''These examples show how to integrate pexpect with pyte, an ANSI terminal
+emulator.
+
+These examples were taken from:
+https://byexamples.github.io/byexample
+
+We will execute three commands:
+    - an 'echo' of a colored message to show how the ANSI colors can be removed.
+    - an 'echo' of a very large message to show how pyte emulates the terminal
+    geometry
+    - a 'less' of a very small file to show how pyte handles not only
+    the terminal geometry but also how interprets ANSI commands that control
+    the position of the cursor.
+
+See also https://github.com/pexpect/pexpect/issues/587
+
+PEXPECT LICENSE
+
+    This license is approved by the OSI and FSF as GPL-compatible.
+        http://opensource.org/licenses/isc-license.txt
+
+    Copyright (c) 2012, Noah Spurrier <noah@noah.org>
+    PERMISSION TO USE, COPY, MODIFY, AND/OR DISTRIBUTE THIS SOFTWARE FOR ANY
+    PURPOSE WITH OR WITHOUT FEE IS HEREBY GRANTED, PROVIDED THAT THE ABOVE
+    COPYRIGHT NOTICE AND THIS PERMISSION NOTICE APPEAR IN ALL COPIES.
+    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+'''
+
+from __future__ import print_function
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import pexpect
+import pyte
+import os
+
+# The geometry of the terminal. Typically this is 24x80
+# but we are going to us set a much smaller terminal
+# to show how to change the default.
+ROWS, COLS = 10, 40
+
+# We create the Screen with the correct geometry and
+# a Stream to process the output coming from pexpect.
+screen = pyte.Screen(COLS, ROWS)
+stream = pyte.Stream(screen)
+
+# Spawn a process using pexpect.spawn as usual
+# with a particularity: it sets the geometry of the terminal
+# using the environment variables *and* using the 'dimensions'
+# parameter of pexpect.spawn.
+# This is needed because no all the program honors the geometry
+# set by pexpect or by the env vars.
+def spawn_process(cmd):
+    env = os.environ.copy()
+    env.update({'LINES': str(ROWS), 'COLUMNS': str(COLS)})
+
+    return pexpect.spawn(cmd, echo=False, encoding='utf-8', dimensions=(ROWS, COLS), env=env)
+
+# Send the raw output to pyte.Stream and get the emulated output
+# from pyte.Screen.
+# In each call we *reset* the display so we don't get the same
+# emulated output twice.
+#
+# Pyte emulates the whole terminal so it will return us ROWS rows
+# of each COLS columns each one completed with spaces.
+#
+# Optionally we strip the whitespace on the right and any empty line
+def emulate_ansi_terminal(raw_output, clean=True):
+    stream.feed(raw_output)
+
+    lines = screen.display
+    screen.reset()
+
+    if clean:
+        lines = (line.rstrip() for line in lines)
+        lines = (line for line in lines if line)
+
+    return '\n'.join(lines)
+
+def pprint(out):
+    print("-" * COLS)
+    print(out)
+    print("-" * COLS)
+
+print("\nFirst example: echo a message with ANSI color sequences.")
+child = spawn_process(r'echo -e "\033[31mThis message should not be in red\033[0m"')
+child.expect(pexpect.EOF)
+out = emulate_ansi_terminal(child.before)
+
+print("This should *not* print any escape sequence,",
+      "those were emulated and discarded by pyte.\n")
+pprint(out)
+
+print("\nSecond example: echo a very large message.")
+msg = ("aaaabbbb" * 8)
+child = spawn_process('echo "%s"' % msg)
+child.expect(pexpect.EOF)
+out = emulate_ansi_terminal(child.before)
+
+print("This should print the message in *two* lines because we",
+      "configured a terminal very small and the message will",
+      "not fit in one line.\n")
+pprint(out)
+
+
+print("\nThird example: run the less program.")
+child = spawn_process('''bash -c "head -n7 '%s' | less"''' % __file__)
+child.expect(pexpect.TIMEOUT, timeout=5)
+out = emulate_ansi_terminal(child.before, clean=False)
+
+pprint(out)