Add third_party/pexpect

third_party/pexpect/pexpect/utils.py

Index: third_party/pexpect/pexpect/utils.py
diff --git a/third_party/pexpect/pexpect/utils.py b/third_party/pexpect/pexpect/utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..737f0eda05afb70140021999e48cc48e8a2d89f2
--- /dev/null
+++ b/third_party/pexpect/pexpect/utils.py
@@ -0,0 +1,112 @@
+import os
+import sys
+import stat
+
+
+def is_executable_file(path):
+    """Checks that path is an executable regular file, or a symlink towards one.
+
+    This is roughly ``os.path isfile(path) and os.access(path, os.X_OK)``.
+    """
+    # follow symlinks,
+    fpath = os.path.realpath(path)
+
+    if not os.path.isfile(fpath):
+        # non-files (directories, fifo, etc.)
+        return False
+
+    mode = os.stat(fpath).st_mode
+
+    if (sys.platform.startswith('sunos')
+            and os.getuid() == 0):
+        # When root on Solaris, os.X_OK is True for *all* files, irregardless
+        # of their executability -- instead, any permission bit of any user,
+        # group, or other is fine enough.
+        #
+        # (This may be true for other "Unix98" OS's such as HP-UX and AIX)
+        return bool(mode & (stat.S_IXUSR |
+                            stat.S_IXGRP |
+                            stat.S_IXOTH))
+
+    return os.access(fpath, os.X_OK)
+
+
+def which(filename):
+    '''This takes a given filename; tries to find it in the environment path;
+    then checks if it is executable. This returns the full path to the filename
+    if found and executable. Otherwise this returns None.'''
+
+    # Special case where filename contains an explicit path.
+    if os.path.dirname(filename) != '' and is_executable_file(filename):
+        return filename
+    if 'PATH' not in os.environ or os.environ['PATH'] == '':
+        p = os.defpath
+    else:
+        p = os.environ['PATH']
+    pathlist = p.split(os.pathsep)
+    for path in pathlist:
+        ff = os.path.join(path, filename)
+        if is_executable_file(ff):
+            return ff
+    return None
+
+
+def split_command_line(command_line):
+
+    '''This splits a command line into a list of arguments. It splits arguments
+    on spaces, but handles embedded quotes, doublequotes, and escaped
+    characters. It's impossible to do this with a regular expression, so I
+    wrote a little state machine to parse the command line. '''
+
+    arg_list = []
+    arg = ''
+
+    # Constants to name the states we can be in.
+    state_basic = 0
+    state_esc = 1
+    state_singlequote = 2
+    state_doublequote = 3
+    # The state when consuming whitespace between commands.
+    state_whitespace = 4
+    state = state_basic
+
+    for c in command_line:
+        if state == state_basic or state == state_whitespace:
+            if c == '\\':
+                # Escape the next character
+                state = state_esc
+            elif c == r"'":
+                # Handle single quote
+                state = state_singlequote
+            elif c == r'"':
+                # Handle double quote
+                state = state_doublequote
+            elif c.isspace():
+                # Add arg to arg_list if we aren't in the middle of whitespace.
+                if state == state_whitespace:
+                    # Do nothing.
+                    None
+                else:
+                    arg_list.append(arg)
+                    arg = ''
+                    state = state_whitespace
+            else:
+                arg = arg + c
+                state = state_basic
+        elif state == state_esc:
+            arg = arg + c
+            state = state_basic
+        elif state == state_singlequote:
+            if c == r"'":
+                state = state_basic
+            else:
+                arg = arg + c
+        elif state == state_doublequote:
+            if c == r'"':
+                state = state_basic
+            else:
+                arg = arg + c
+
+    if arg != '':
+        arg_list.append(arg)
+    return arg_list