Adding expression syntax for console colors.

lib/spack/spack/color.py

@@ -0,0 +1,162 @@
+"""
+This file implements an expression syntax, similar to printf, for adding
+ANSI colors to text.
+
+See colorize(), cwrite(), and cprint() for routines that can generate
+colored output.
+
+colorize will take a string and replace all color expressions with
+ANSI control codes.  If the isatty keyword arg is set to False, then
+the color expressions will be converted to null strings, and the
+returned string will have no color.
+
+cwrite and cprint are equivalent to write() and print() calls in
+python, but they colorize their output.  If the stream argument is
+not supplied, they write to sys.stdout.
+
+Here are some example color expressions:
+
+  @r         Turn on red coloring
+  @R         Turn on bright red coloring
+  @*b        Turn on bold, blue text
+  @_B        Turn on bright blue text with an underline
+  @.         Revert to plain formatting
+  @*g{green} Print out 'green' in bold, green text, then reset to plain.
+  @*ggreen@. Print out 'green' in bold, green text, then reset to plain.
+
+The syntax consists of:
+
+  color-expr    = '@' [style] color-code '{' text '}' | '@.' | '@@'
+  style         = '*' | '_'
+  color-code    = [krgybmcwKRGYBMCW]
+  text          = .*
+
+'@' indicates the start of a color expression.  It can be followed
+by an optional * or _ that indicates whether the font should be bold or
+underlined.  If * or _ is not provided, the text will be plain.  Then
+an optional color code is supplied.  This can be [krgybmcw] or [KRGYBMCW],
+where the letters map to  black(k), red(r), green(g), yellow(y), blue(b),
+magenta(m), cyan(c), and white(w).  Lowercase letters denote normal ANSI
+colors and capital letters denote bright ANSI colors.
+
+Finally, the color expression can be followed by text enclosed in {}.  If
+braces are present, only the text in braces is colored.  If the braces are
+NOT present, then just the control codes to enable the color will be output.
+The console can be reset later to plain text with '@.'.
+
+To output an @, use '@@'.  To output a } inside braces, use '}}'.
+"""
+import re
+import sys
+import spack.error
+
+class ColorParseError(spack.error.SpackError):
+    """Raised when a color format fails to parse."""
+    def __init__(self, message):
+        super(ColorParseError, self).__init__(message)
+
+# Text styles for ansi codes
+styles = {'*'  : '1;%s',       # bold
+          '_'  : '4:%s',       # underline
+          None : '0;%s' }      # plain
+
+# Dim and bright ansi colors
+colors = {'k' : 30, 'K' : 90,  # black
+          'r' : 31, 'R' : 91,  # red
+          'g' : 32, 'G' : 92,  # green
+          'y' : 33, 'Y' : 93,  # yellow
+          'b' : 34, 'B' : 94,  # blue
+          'm' : 35, 'M' : 95,  # magenta
+          'c' : 36, 'C' : 96,  # cyan
+          'w' : 37, 'W' : 97 } # white
+
+# Regex to be used for color formatting
+color_re = r'@(?:@|\.|([*_])?([a-zA-Z])?(?:{((?:[^}]|}})*)})?)'
+
+
+class match_to_ansi(object):
+    def __init__(self, color=True):
+        self.color = color
+
+    def escape(self, s):
+        """Returns a TTY escape sequence for a color"""
+        if self.color:
+            return "\033[%sm" % s
+        else:
+            return ''
+
+    def __call__(self, match):
+        """Convert a match object generated by color_re into an ansi color code
+           This can be used as a handler in re.sub.
+        """
+        style, color, text = match.groups()
+        m = match.group(0)
+
+        if m == '@@':
+            return '@'
+        elif m == '@.':
+            return self.escape(0)
+        elif m == '@' or (style and not color):
+            raise ColorParseError("Incomplete color format: '%s'" % m)
+        elif color not in colors:
+            raise ColorParseError("invalid color specifier: '%s'" % color)
+
+        colored_text = ''
+        if text:
+            colored_text = text + self.escape(0)
+
+        if style == '*':
+            color_code = self.escape(styles[style] % colors[color])
+        elif style == '_':
+            color_code = self.escape(styles[style] % colors[color])
+        else:
+            color_code = self.escape(styles[style] % colors[color])
+
+        return color_code + colored_text
+
+
+def colorize(string, **kwargs):
+    """Take a string and replace all color expressions with ANSI control
+       codes.  Return the resulting string.
+       If color=False is supplied, output will be plain text without
+       control codes, for output to non-console devices.
+    """
+    color = kwargs.get('color', True)
+    return re.sub(color_re, match_to_ansi(color), string)
+
+
+def cwrite(string, stream=sys.stdout, color=None):
+    """Replace all color expressions in string with ANSI control
+       codes and write the result to the stream.  If color is
+       False, this will write plain text with o color.  If True,
+       then it will always write colored output.  If not supplied,
+       then it will be set based on stream.isatty().
+    """
+    if color == None:
+        color = stream.isatty()
+    stream.write(colorize(string, color=color))
+
+
+def cprint(string, stream=sys.stdout, color=None):
+    """Same as cwrite, but writes a trailing newline to the stream."""
+    cwrite(string + "\n", stream, color)
+
+
+class ColorStream(object):
+    def __init__(self, stream, color=None):
+        self.__class__ = type(stream.__class__.__name__,
+                              (self.__class__, stream.__class__), {})
+        self.__dict__ = stream.__dict__
+        self.color = color
+        self.stream = stream
+
+    def write(self, string, **kwargs):
+        if kwargs.get('raw', False):
+            super(ColorStream, self).write(string)
+        else:
+            cwrite(string, self.stream, self.color)
+
+    def writelines(self, sequence, **kwargs):
+        raw = kwargs.get('raw', False)
+        for string in sequence:
+            self.write(string, self.color, raw=raw)