[RFC] Colour quoted text

alot/defaults/alot.rc.spec

@@ -20,6 +20,12 @@ exclude_tags = force_list(default=list())
 # display background colors set by ANSI character escapes
 interpret_ansi_background = boolean(default=True)
 
+# Enable colouring message based on quote-level
+parse_quotes = boolean(default=True)
+
+# Set what quote symbol should be used (regex symbol is possible)
+quote_symbol = string(default='>')
+
 # confirm exit
 bug_on_exit = boolean(default=False)
 

alot/defaults/theme.spec

@@ -51,6 +51,13 @@
             width = widthtuple(default=None)
             alignment = align(default=None)
 [thread]
+    quote_level_1 = attrtriple(default=None)
+    quote_level_2 = attrtriple(default=None)
+    quote_level_3 = attrtriple(default=None)
+    quote_level_4 = attrtriple(default=None)
+    quote_level_5 = attrtriple(default=None)
+    quote_level_6 = attrtriple(default=None)
+    quote_level_7 = attrtriple(default=None)
     arrow_heads = attrtriple
     arrow_bars = attrtriple
     attachment = attrtriple

alot/widgets/ansi.py

@@ -3,6 +3,7 @@
 # For further details see the COPYING file
 
 import urwid
+import re
 
 
 class ANSIText(urwid.WidgetWrap):
@@ -33,8 +34,11 @@ def keypress(self, size, key):
 
 ECODES = {
     '1': {'bold': True},
+    '3': {'italics': True},
     '4': {'underline': True},
+    '5': {'blink': True},
     '7': {'standout': True},
+    '9': {'strikethrough': True},
     '30': {'fg': 'black'},
     '31': {'fg': 'dark red'},
     '32': {'fg': 'dark green'},
@@ -53,67 +57,98 @@ def keypress(self, size, key):
     '47': {'bg': 'light gray'},
 }
 
+URWID_MODS = [
+    'bold',
+    'underline',
+    'standout',
+    'blink',
+    'italics',
+    'strikethrough',
+]
+
 
 def parse_escapes_to_urwid(text, default_attr=None, default_attr_focus=None,
                            parse_background=True):
     """This function converts a text with ANSI escape for terminal
     attributes and returns a list containing each part of text and its
     corresponding Urwid Attributes object, it also returns a dictionary which
     maps all attributes applied here to focused attribute.
+
+    This will only translate (a subset of) CSI sequences:
+    we interpret only SGR parameters that urwid supports (excluding true color)
+    See https://en.wikipedia.org/wiki/ANSI_escape_code#CSI_sequences
     """
 
-    text = text.split("\033[")
-    urwid_text = [text[0]]
+    b1 = r'\033\['  # Control Sequence Introducer
+    b2 = r'[0-9:;<=>?]*'  # parameter bytes
+    b3 = r'[ !\"#$%&\'()*+,-./]*'  # intermediate bytes
+    b4 = r'[A-Z[\]^_`a-z{|}~]'  # final byte"
+    esc_pattern = b1 \
+        + r'(?P<pb>' + b2 + ')' \
+        + r'(?P<ib>' + b3 + ')' \
+        + r'(?P<fb>' + b4 + ')'
+
+    # these two will be returned
+    urwid_text = []  # we will accumulate text (with attributes) here
+    # mapping from included attributes to focused attr
     urwid_focus = {None: default_attr_focus}
 
     # Escapes are cumulative so we always keep previous values until it's
     # changed by another escape.
-    attr = dict(fg=default_attr._foreground_color, bg=default_attr.background,
+    attr = dict(fg=default_attr.foreground, bg=default_attr.background,
                 bold=default_attr.bold, underline=default_attr.underline,
                 standout=default_attr.underline)
-    for part in text[1:]:
-        esc_code, esc_substr = part.split('m', 1)
-        esc_code = esc_code.split(';')
-
-        if not esc_code:
-            attr.update(fg=default_attr._foreground_color,
-                        bg=default_attr.background, bold=default_attr.bold,
-                        underline=default_attr.underline,
-                        standout=default_attr.underline)
-        else:
-            i = 0
-            while i < len(esc_code):
-                code = esc_code[i]
-                if code == 0:
-                    attr.update({'bold': default_attr.bold,
-                                 'underline': default_attr.underline,
-                                 'standout': default_attr.standout})
-                if code in ECODES:
-                    attr.update(ECODES[code])
-                # 256 codes
-                elif code == '38':
-                    attr.update(fg='h' + esc_code[i+2])
-                    i += 2
-                elif code == '48':
-                    attr.update(bg='h'+esc_code[i+2])
-                    i += 2
-                i += 1
-
-        # If there is no string in esc_substr we skip it, the above
-        # attributes will accumulate to the next escapes.
-        if esc_substr:
-            # Construct Urwid attributes
-            urwid_fg = attr['fg']
-            urwid_bg = default_attr.background
-            if attr['bold']:
-                urwid_fg += ',bold'
-            if attr['underline']:
-                urwid_fg += ',underline'
-            if attr['standout']:
-                urwid_fg += ',standout'
-            if parse_background:
-                urwid_bg = attr['bg']
-            urwid_attr = urwid.AttrSpec(urwid_fg, urwid_bg)
-            urwid_focus[urwid_attr] = default_attr_focus
-            urwid_text.append((urwid_attr, esc_substr))
+
+    def append_themed_infix(infix):
+        # add using prev attribute
+        urwid_fg = attr['fg']
+        urwid_bg = default_attr.background
+        for mod in URWID_MODS:
+            if mod in attr and attr[mod]:
+                urwid_fg += ',' + mod
+        if parse_background:
+            urwid_bg = attr['bg']
+        urwid_attr = urwid.AttrSpec(urwid_fg, urwid_bg)
+        urwid_focus[urwid_attr] = default_attr_focus
+        urwid_text.append((urwid_attr, infix))
+
+    def reset_attr():
+        attr.update(fg=default_attr.foreground,
+                    bg=default_attr.background, bold=default_attr.bold,
+                    underline=default_attr.underline,
+                    standout=default_attr.underline)
+
+    def update_attr(m):
+        # parameter, intermediate, final bytes in the esc seq
+        pb, _, fb, = m.groups()
+        if fb == 'm':
+            # selector bit found. this means theming changes
+            if not pb:  # no bit r zero  --> reset
+                reset_attr()
+            elif pb.startswith('38;5;'):
+                # 8-bit colour foreground
+                col = pb[5:]
+                attr.update(fg='h' + col)
+            elif pb.startswith('48;5;') and parse_background:
+                # 8-bit colour background
+                col = pb[5:]
+                attr.update(bg='h' + col)
+            else:
+                # Several attributes can be set in the same sequence,
+                # separated by semicolons. Interpret them acc to ECODES
+                codes = pb.split(';')
+                for code in codes:
+                    if code in ECODES:
+                        attr.update(ECODES[code])
+
+    # iterate over text
+    start = 0  # points to start of current infix
+
+    for m in re.finditer(esc_pattern, text):
+        infix = text[start:m.start()]  # text beween last and this Esc seq
+        update_attr(m)
+        append_themed_infix(infix)  # add using prev attribute
+        start = m.end()  # start of next infix is after this esc sec
+
+    append_themed_infix(text[start:])  # add final infix
     return urwid_text, urwid_focus

alot/widgets/colour_text.py

@@ -0,0 +1,65 @@
+# Copyright (C) 2011-2020  Patrick Totzke <patricktotzke@gmail.com>
+# Copyright © 2019-2020 Chloé Dequeker <contact@nelyah.eu>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+import logging
+import re
+
+from urwid import AttrSpec
+from ..settings.const import settings
+
+
+def parse_text_colour(line):
+    """Get colour attribute for the line
+
+    :param str line: line of text to be parsed
+    :return: The theme attribute to apply
+    """
+    if settings.get('parse_quotes'):
+        return parse_quotes(line)
+    else:
+        return None
+
+
+def parse_quotes(line):
+    """Search for quotes.
+    Only search up to the 7th quote level.
+
+    :param str line: The line of text to be parsed
+    :return: Theming attribute, None if no quote are available
+    """
+
+    # The value is arbitrarily set because we need to define
+    # the corresponding attributes in the theming configuration spec.
+    max_quote_level = 7
+    quote_colour = get_quote_colour(line, max_quote_level)
+
+    if isinstance(quote_colour, AttrSpec):
+        return quote_colour
+    else:
+        return None
+
+
+def get_quote_colour(line, max_quote_level):
+    """Cycle through quotation levels for the line
+
+    :param str line: The line of text to be parsed
+    :param int max_quote_level: Search for quotes up to that level
+    :return: quote_colour (either string 'default' or an AttrSpec object)
+    """
+    symbol = settings.get('quote_symbol')
+    quote_colour = None
+
+    for quote_level in range(1, max_quote_level+1):
+        quote_regex = r'^ *({} *){{{}}}'.format(symbol, quote_level)
+        if re.match(quote_regex, line):
+            logging.debug(
+                'Requesting attribute quote_level_{}'.format(quote_level))
+            quote_colour = settings.get_theming_attribute(
+                'thread', 'quote_level_{}'.format(quote_level))
+
+        else:
+            # If there is no match at some point,
+            # we simply use the last level match colour
+            break
+    return quote_colour

alot/widgets/thread.py

@@ -17,6 +17,7 @@
 from ..db.attachment import Attachment
 from ..db.utils import decode_header, X_SIGNATURE_MESSAGE_HEADER
 from ..helper import string_sanitize
+from .colour_text import parse_text_colour
 
 ANSI_BACKGROUND = settings.get("interpret_ansi_background")
 
@@ -84,13 +85,19 @@ def __init__(self, content, attr=None, attr_focus=None):
         for each line in content.
         """
         structure = []
+        attr_parse = attr
 
         # depending on this config setting, we either add individual lines
         # or the complete context as focusable objects.
         if settings.get('thread_focus_linewise'):
             for line in content.splitlines():
-                structure.append((ANSIText(line, attr, attr_focus,
+                attr_parse = parse_text_colour(line)
+
+                if attr_parse is None:
+                    attr_parse = attr
+                structure.append((ANSIText(line, attr_parse, attr_focus,
                                            ANSI_BACKGROUND), None))
+                attr_parse = attr
         else:
             structure.append((ANSIText(content, attr, attr_focus,
                                        ANSI_BACKGROUND), None))
@@ -107,6 +114,7 @@ class DictList(SimpleTree):
     its sibblings will be the other pairs and first|last_child will always
     be None.
     """
+
     def __init__(self, content, key_attr, value_attr, gaps_attr=None):
         """
         :param headerslist: list of key/value pairs to display
@@ -145,6 +153,7 @@ class MessageTree(CollapsibleTree):
 
     Collapsing this message corresponds to showing the summary only.
     """
+
     def __init__(self, message, odd=True):
         """
         :param message: Message to display
@@ -359,6 +368,7 @@ class ThreadTree(Tree):
     messages. As MessageTreess are *not* urwid widgets themself this is to be
     used in combination with :class:`NestedTree` only.
     """
+
     def __init__(self, thread):
         self._thread = thread
         self.root = thread.get_toplevel_messages()[0].get_message_id()

docs/source/configuration/alotrc_table

@@ -462,6 +462,16 @@
     :default: 2
 
 
+.. _parse-quotes:
+
+.. describe:: parse_quotes
+
+     Enable colouring message based on quote-level
+
+    :type: boolean
+    :default: True
+
+
 .. _periodic-hook-frequency:
 
 .. describe:: periodic_hook_frequency
@@ -525,6 +535,16 @@
     :default: "> "
 
 
+.. _quote-symbol:
+
+.. describe:: quote_symbol
+
+     Set what quote symbol should be used (regex symbol is possible)
+
+    :type: string
+    :default: ">"
+
+
 .. _reply-account-header-priority:
 
 .. describe:: reply_account_header_priority