import sys, re class TerminalController: """ A class that can be used to portably generate formatted output to a terminal. `TerminalController` defines a set of instance variables whose values are initialized to the control sequence necessary to perform a given action. These can be simply included in normal output to the terminal: >>> term = TerminalController() >>> print 'This is '+term.GREEN+'green'+term.NORMAL Alternatively, the `render()` method can used, which replaces '${action}' with the string required to perform 'action': >>> term = TerminalController() >>> print term.render('This is ${GREEN}green${NORMAL}') If the terminal doesn't support a given action, then the value of the corresponding instance variable will be set to ''. As a result, the above code will still work on terminals that do not support color, except that their output will not be colored. Also, this means that you can test whether the terminal supports a given action by simply testing the truth value of the corresponding instance variable: >>> term = TerminalController() >>> if term.CLEAR_SCREEN: ... print 'This terminal supports clearning the screen.' Finally, if the width and height of the terminal are known, then they will be stored in the `COLS` and `LINES` attributes. """ # Cursor movement: BOL = '' #: Move the cursor to the beginning of the line UP = '' #: Move the cursor up one line DOWN = '' #: Move the cursor down one line LEFT = '' #: Move the cursor left one char RIGHT = '' #: Move the cursor right one char # Deletion: CLEAR_SCREEN = '' #: Clear the screen and move to home position CLEAR_EOL = '' #: Clear to the end of the line. CLEAR_BOL = '' #: Clear to the beginning of the line. CLEAR_EOS = '' #: Clear to the end of the screen # Output modes: BOLD = '' #: Turn on bold mode BLINK = '' #: Turn on blink mode DIM = '' #: Turn on half-bright mode REVERSE = '' #: Turn on reverse-video mode NORMAL = '' #: Turn off all modes # Cursor display: HIDE_CURSOR = '' #: Make the cursor invisible SHOW_CURSOR = '' #: Make the cursor visible # Terminal size: COLS = None #: Width of the terminal (None for unknown) LINES = None #: Height of the terminal (None for unknown) # Foreground colors: BLACK = BLUE = GREEN = CYAN = RED = MAGENTA = YELLOW = WHITE = '' # Background colors: BG_BLACK = BG_BLUE = BG_GREEN = BG_CYAN = '' BG_RED = BG_MAGENTA = BG_YELLOW = BG_WHITE = '' _STRING_CAPABILITIES = """ BOL=cr UP=cuu1 DOWN=cud1 LEFT=cub1 RIGHT=cuf1 CLEAR_SCREEN=clear CLEAR_EOL=el CLEAR_BOL=el1 CLEAR_EOS=ed BOLD=bold BLINK=blink DIM=dim REVERSE=rev UNDERLINE=smul NORMAL=sgr0 HIDE_CURSOR=cinvis SHOW_CURSOR=cnorm""".split() _COLORS = """BLACK BLUE GREEN CYAN RED MAGENTA YELLOW WHITE""".split() def __init__(self, term_stream=sys.stdout): """ Create a `TerminalController` and initialize its attributes with appropriate values for the current terminal. `term_stream` is the stream that will be used for terminal output; if this stream is not a tty, then the terminal is assumed to be a dumb terminal (i.e., have no capabilities). """ # Curses isn't available on all platforms try: import curses except: return # If the stream isn't a tty, then assume it has no capabilities. if not term_stream.isatty(): return # Check the terminal type. If we fail, then assume that the # terminal has no capabilities. try: curses.setupterm() except: return # Look up numeric capabilities. self.COLS = curses.tigetnum('cols') self.LINES = curses.tigetnum('lines') # Look up string capabilities. for capability in self._STRING_CAPABILITIES: (attrib, cap_name) = capability.split('=') setattr(self, attrib, self._tigetstr(cap_name) or '') # Colors set_fg = self._tigetstr('setf') if set_fg: for i,color in zip(range(len(self._COLORS)), self._COLORS): setattr(self, color, curses.tparm(set_fg, i) or '') set_bg = self._tigetstr('setb') if set_bg: for i,color in zip(range(len(self._COLORS)), self._COLORS): setattr(self, 'BG_'+color, curses.tparm(set_bg, i) or '') def _tigetstr(self, cap_name): # String capabilities can include "delays" of the form "$<2>". # For any modern terminal, we should be able to just ignore # these, so strip them out. import curses cap = curses.tigetstr(cap_name) or '' return re.sub(r'\$<\d+>[/*]?', '', cap) def render(self, template): """ Replace each $-substitutions in the given template string with the corresponding terminal control string (if it's defined) or '' (if it's not). """ return re.sub(r'\$\$|\${\w+}', self._render_sub, template) def _render_sub(self, match): s = match.group() if s == '$$': return s else: return getattr(self, s[2:-1]) ####################################################################### # Example use case: progress bar ####################################################################### class ProgressBar: """ A 3-line progress bar, which looks like:: Header 20% [===========----------------------------------] progress message The progress bar is colored, if the terminal supports color output; and adjusts to the width of the terminal. """ BAR = '%3d%% ${GREEN}[${BOLD}%s%s${NORMAL}${GREEN}]${NORMAL}\n' HEADER = '${BOLD}${CYAN}%s${NORMAL}\n\n' def __init__(self, term, header): self.term = term if not (self.term.CLEAR_EOL and self.term.UP and self.term.BOL): raise ValueError("Terminal isn't capable enough -- you " "should use a simpler progress dispaly.") self.width = self.term.COLS or 75 self.bar = term.render(self.BAR) self.header = self.term.render(self.HEADER % header.center(self.width)) self.cleared = 1 #: true if we haven't drawn the bar yet. self.update(0, '') def update(self, percent, message): if self.cleared: sys.stdout.write(self.header) self.cleared = 0 n = int((self.width-10)*percent) sys.stdout.write( self.term.BOL + self.term.UP + self.term.CLEAR_EOL + (self.bar % (100*percent, '='*n, '-'*(self.width-10-n))) + self.term.CLEAR_EOL + message.center(self.width)) def clear(self): if not self.cleared: sys.stdout.write(self.term.BOL + self.term.CLEAR_EOL + self.term.UP + self.term.CLEAR_EOL + self.term.UP + self.term.CLEAR_EOL) self.cleared = 1