Adding upstream version 3.0.36.upstream/3.0.36upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 1478 insertions, 0 deletions

diff --git a/src/prompt_toolkit/styles/__init__.py b/src/prompt_toolkit/styles/__init__.py
new file mode 100644
index 0000000..c270ae0
--- /dev/null
+++ b/src/prompt_toolkit/styles/__init__.py
@@ -0,0 +1,64 @@
+"""
+Styling for prompt_toolkit applications.
+"""
+from .base import (
+    ANSI_COLOR_NAMES,
+    DEFAULT_ATTRS,
+    Attrs,
+    BaseStyle,
+    DummyStyle,
+    DynamicStyle,
+)
+from .defaults import default_pygments_style, default_ui_style
+from .named_colors import NAMED_COLORS
+from .pygments import (
+    pygments_token_to_classname,
+    style_from_pygments_cls,
+    style_from_pygments_dict,
+)
+from .style import Priority, Style, merge_styles, parse_color
+from .style_transformation import (
+    AdjustBrightnessStyleTransformation,
+    ConditionalStyleTransformation,
+    DummyStyleTransformation,
+    DynamicStyleTransformation,
+    ReverseStyleTransformation,
+    SetDefaultColorStyleTransformation,
+    StyleTransformation,
+    SwapLightAndDarkStyleTransformation,
+    merge_style_transformations,
+)
+
+__all__ = [
+    # Base.
+    "Attrs",
+    "DEFAULT_ATTRS",
+    "ANSI_COLOR_NAMES",
+    "BaseStyle",
+    "DummyStyle",
+    "DynamicStyle",
+    # Defaults.
+    "default_ui_style",
+    "default_pygments_style",
+    # Style.
+    "Style",
+    "Priority",
+    "merge_styles",
+    "parse_color",
+    # Style transformation.
+    "StyleTransformation",
+    "SwapLightAndDarkStyleTransformation",
+    "ReverseStyleTransformation",
+    "SetDefaultColorStyleTransformation",
+    "AdjustBrightnessStyleTransformation",
+    "DummyStyleTransformation",
+    "ConditionalStyleTransformation",
+    "DynamicStyleTransformation",
+    "merge_style_transformations",
+    # Pygments.
+    "style_from_pygments_cls",
+    "style_from_pygments_dict",
+    "pygments_token_to_classname",
+    # Named colors.
+    "NAMED_COLORS",
+]
diff --git a/src/prompt_toolkit/styles/base.py b/src/prompt_toolkit/styles/base.py
new file mode 100644
index 0000000..aa77b9a
--- /dev/null
+++ b/src/prompt_toolkit/styles/base.py
@@ -0,0 +1,181 @@
+"""
+The base classes for the styling.
+"""
+from abc import ABCMeta, abstractmethod, abstractproperty
+from typing import Callable, Dict, Hashable, List, NamedTuple, Optional, Tuple
+
+__all__ = [
+    "Attrs",
+    "DEFAULT_ATTRS",
+    "ANSI_COLOR_NAMES",
+    "ANSI_COLOR_NAMES_ALIASES",
+    "BaseStyle",
+    "DummyStyle",
+    "DynamicStyle",
+]
+
+
+#: Style attributes.
+class Attrs(NamedTuple):
+    color: Optional[str]
+    bgcolor: Optional[str]
+    bold: Optional[bool]
+    underline: Optional[bool]
+    strike: Optional[bool]
+    italic: Optional[bool]
+    blink: Optional[bool]
+    reverse: Optional[bool]
+    hidden: Optional[bool]
+
+
+"""
+:param color: Hexadecimal string. E.g. '000000' or Ansi color name: e.g. 'ansiblue'
+:param bgcolor: Hexadecimal string. E.g. 'ffffff' or Ansi color name: e.g. 'ansired'
+:param bold: Boolean
+:param underline: Boolean
+:param strike: Boolean
+:param italic: Boolean
+:param blink: Boolean
+:param reverse: Boolean
+:param hidden: Boolean
+"""
+
+#: The default `Attrs`.
+DEFAULT_ATTRS = Attrs(
+    color="",
+    bgcolor="",
+    bold=False,
+    underline=False,
+    strike=False,
+    italic=False,
+    blink=False,
+    reverse=False,
+    hidden=False,
+)
+
+
+#: ``Attrs.bgcolor/fgcolor`` can be in either 'ffffff' format, or can be any of
+#: the following in case we want to take colors from the 8/16 color palette.
+#: Usually, in that case, the terminal application allows to configure the RGB
+#: values for these names.
+#: ISO 6429 colors
+ANSI_COLOR_NAMES = [
+    "ansidefault",
+    # Low intensity, dark.  (One or two components 0x80, the other 0x00.)
+    "ansiblack",
+    "ansired",
+    "ansigreen",
+    "ansiyellow",
+    "ansiblue",
+    "ansimagenta",
+    "ansicyan",
+    "ansigray",
+    # High intensity, bright. (One or two components 0xff, the other 0x00. Not supported everywhere.)
+    "ansibrightblack",
+    "ansibrightred",
+    "ansibrightgreen",
+    "ansibrightyellow",
+    "ansibrightblue",
+    "ansibrightmagenta",
+    "ansibrightcyan",
+    "ansiwhite",
+]
+
+
+# People don't use the same ANSI color names everywhere. In prompt_toolkit 1.0
+# we used some unconventional names (which were contributed like that to
+# Pygments). This is fixed now, but we still support the old names.
+
+# The table below maps the old aliases to the current names.
+ANSI_COLOR_NAMES_ALIASES: Dict[str, str] = {
+    "ansidarkgray": "ansibrightblack",
+    "ansiteal": "ansicyan",
+    "ansiturquoise": "ansibrightcyan",
+    "ansibrown": "ansiyellow",
+    "ansipurple": "ansimagenta",
+    "ansifuchsia": "ansibrightmagenta",
+    "ansilightgray": "ansigray",
+    "ansidarkred": "ansired",
+    "ansidarkgreen": "ansigreen",
+    "ansidarkblue": "ansiblue",
+}
+assert set(ANSI_COLOR_NAMES_ALIASES.values()).issubset(set(ANSI_COLOR_NAMES))
+assert not (set(ANSI_COLOR_NAMES_ALIASES.keys()) & set(ANSI_COLOR_NAMES))
+
+
+class BaseStyle(metaclass=ABCMeta):
+    """
+    Abstract base class for prompt_toolkit styles.
+    """
+
+    @abstractmethod
+    def get_attrs_for_style_str(
+        self, style_str: str, default: Attrs = DEFAULT_ATTRS
+    ) -> Attrs:
+        """
+        Return :class:`.Attrs` for the given style string.
+
+        :param style_str: The style string. This can contain inline styling as
+            well as classnames (e.g. "class:title").
+        :param default: `Attrs` to be used if no styling was defined.
+        """
+
+    @abstractproperty
+    def style_rules(self) -> List[Tuple[str, str]]:
+        """
+        The list of style rules, used to create this style.
+        (Required for `DynamicStyle` and `_MergedStyle` to work.)
+        """
+        return []
+
+    @abstractmethod
+    def invalidation_hash(self) -> Hashable:
+        """
+        Invalidation hash for the style. When this changes over time, the
+        renderer knows that something in the style changed, and that everything
+        has to be redrawn.
+        """
+
+
+class DummyStyle(BaseStyle):
+    """
+    A style that doesn't style anything.
+    """
+
+    def get_attrs_for_style_str(
+        self, style_str: str, default: Attrs = DEFAULT_ATTRS
+    ) -> Attrs:
+        return default
+
+    def invalidation_hash(self) -> Hashable:
+        return 1  # Always the same value.
+
+    @property
+    def style_rules(self) -> List[Tuple[str, str]]:
+        return []
+
+
+class DynamicStyle(BaseStyle):
+    """
+    Style class that can dynamically returns an other Style.
+
+    :param get_style: Callable that returns a :class:`.Style` instance.
+    """
+
+    def __init__(self, get_style: Callable[[], Optional[BaseStyle]]):
+        self.get_style = get_style
+        self._dummy = DummyStyle()
+
+    def get_attrs_for_style_str(
+        self, style_str: str, default: Attrs = DEFAULT_ATTRS
+    ) -> Attrs:
+        style = self.get_style() or self._dummy
+
+        return style.get_attrs_for_style_str(style_str, default)
+
+    def invalidation_hash(self) -> Hashable:
+        return (self.get_style() or self._dummy).invalidation_hash()
+
+    @property
+    def style_rules(self) -> List[Tuple[str, str]]:
+        return (self.get_style() or self._dummy).style_rules
diff --git a/src/prompt_toolkit/styles/defaults.py b/src/prompt_toolkit/styles/defaults.py
new file mode 100644
index 0000000..4ac5545
--- /dev/null
+++ b/src/prompt_toolkit/styles/defaults.py
@@ -0,0 +1,231 @@
+"""
+The default styling.
+"""
+from prompt_toolkit.cache import memoized
+
+from .base import ANSI_COLOR_NAMES, BaseStyle
+from .named_colors import NAMED_COLORS
+from .style import Style, merge_styles
+
+__all__ = [
+    "default_ui_style",
+    "default_pygments_style",
+]
+
+#: Default styling. Mapping from classnames to their style definition.
+PROMPT_TOOLKIT_STYLE = [
+    # Highlighting of search matches in document.
+    ("search", "bg:ansibrightyellow ansiblack"),
+    ("search.current", ""),
+    # Incremental search.
+    ("incsearch", ""),
+    ("incsearch.current", "reverse"),
+    # Highlighting of select text in document.
+    ("selected", "reverse"),
+    ("cursor-column", "bg:#dddddd"),
+    ("cursor-line", "underline"),
+    ("color-column", "bg:#ccaacc"),
+    # Highlighting of matching brackets.
+    ("matching-bracket", ""),
+    ("matching-bracket.other", "#000000 bg:#aacccc"),
+    ("matching-bracket.cursor", "#ff8888 bg:#880000"),
+    # Styling of other cursors, in case of block editing.
+    ("multiple-cursors", "#000000 bg:#ccccaa"),
+    # Line numbers.
+    ("line-number", "#888888"),
+    ("line-number.current", "bold"),
+    ("tilde", "#8888ff"),
+    # Default prompt.
+    ("prompt", ""),
+    ("prompt.arg", "noinherit"),
+    ("prompt.arg.text", ""),
+    ("prompt.search", "noinherit"),
+    ("prompt.search.text", ""),
+    # Search toolbar.
+    ("search-toolbar", "bold"),
+    ("search-toolbar.text", "nobold"),
+    # System toolbar
+    ("system-toolbar", "bold"),
+    ("system-toolbar.text", "nobold"),
+    # "arg" toolbar.
+    ("arg-toolbar", "bold"),
+    ("arg-toolbar.text", "nobold"),
+    # Validation toolbar.
+    ("validation-toolbar", "bg:#550000 #ffffff"),
+    ("window-too-small", "bg:#550000 #ffffff"),
+    # Completions toolbar.
+    ("completion-toolbar", "bg:#bbbbbb #000000"),
+    ("completion-toolbar.arrow", "bg:#bbbbbb #000000 bold"),
+    ("completion-toolbar.completion", "bg:#bbbbbb #000000"),
+    ("completion-toolbar.completion.current", "bg:#444444 #ffffff"),
+    # Completions menu.
+    ("completion-menu", "bg:#bbbbbb #000000"),
+    ("completion-menu.completion", ""),
+    ("completion-menu.completion.current", "bg:#888888 #ffffff"),
+    ("completion-menu.meta.completion", "bg:#999999 #000000"),
+    ("completion-menu.meta.completion.current", "bg:#aaaaaa #000000"),
+    ("completion-menu.multi-column-meta", "bg:#aaaaaa #000000"),
+    # Fuzzy matches in completion menu (for FuzzyCompleter).
+    ("completion-menu.completion fuzzymatch.outside", "fg:#444444"),
+    ("completion-menu.completion fuzzymatch.inside", "bold"),
+    ("completion-menu.completion fuzzymatch.inside.character", "underline"),
+    ("completion-menu.completion.current fuzzymatch.outside", "fg:default"),
+    ("completion-menu.completion.current fuzzymatch.inside", "nobold"),
+    # Styling of readline-like completions.
+    ("readline-like-completions", ""),
+    ("readline-like-completions.completion", ""),
+    ("readline-like-completions.completion fuzzymatch.outside", "#888888"),
+    ("readline-like-completions.completion fuzzymatch.inside", ""),
+    ("readline-like-completions.completion fuzzymatch.inside.character", "underline"),
+    # Scrollbars.
+    ("scrollbar.background", "bg:#aaaaaa"),
+    ("scrollbar.button", "bg:#444444"),
+    ("scrollbar.arrow", "noinherit bold"),
+    # Start/end of scrollbars. Adding 'underline' here provides a nice little
+    # detail to the progress bar, but it doesn't look good on all terminals.
+    # ('scrollbar.start',                          'underline #ffffff'),
+    # ('scrollbar.end',                            'underline #000000'),
+    # Auto suggestion text.
+    ("auto-suggestion", "#666666"),
+    # Trailing whitespace and tabs.
+    ("trailing-whitespace", "#999999"),
+    ("tab", "#999999"),
+    # When Control-C/D has been pressed. Grayed.
+    ("aborting", "#888888 bg:default noreverse noitalic nounderline noblink"),
+    ("exiting", "#888888 bg:default noreverse noitalic nounderline noblink"),
+    # Entering a Vi digraph.
+    ("digraph", "#4444ff"),
+    # Control characters, like ^C, ^X.
+    ("control-character", "ansiblue"),
+    # Non-breaking space.
+    ("nbsp", "underline ansiyellow"),
+    # Default styling of HTML elements.
+    ("i", "italic"),
+    ("u", "underline"),
+    ("s", "strike"),
+    ("b", "bold"),
+    ("em", "italic"),
+    ("strong", "bold"),
+    ("del", "strike"),
+    ("hidden", "hidden"),
+    # It should be possible to use the style names in HTML.
+    # <reverse>...</reverse>  or <noreverse>...</noreverse>.
+    ("italic", "italic"),
+    ("underline", "underline"),
+    ("strike", "strike"),
+    ("bold", "bold"),
+    ("reverse", "reverse"),
+    ("noitalic", "noitalic"),
+    ("nounderline", "nounderline"),
+    ("nostrike", "nostrike"),
+    ("nobold", "nobold"),
+    ("noreverse", "noreverse"),
+    # Prompt bottom toolbar
+    ("bottom-toolbar", "reverse"),
+]
+
+
+# Style that will turn for instance the class 'red' into 'red'.
+COLORS_STYLE = [(name, "fg:" + name) for name in ANSI_COLOR_NAMES] + [
+    (name.lower(), "fg:" + name) for name in NAMED_COLORS
+]
+
+
+WIDGETS_STYLE = [
+    # Dialog windows.
+    ("dialog", "bg:#4444ff"),
+    ("dialog.body", "bg:#ffffff #000000"),
+    ("dialog.body text-area", "bg:#cccccc"),
+    ("dialog.body text-area last-line", "underline"),
+    ("dialog frame.label", "#ff0000 bold"),
+    # Scrollbars in dialogs.
+    ("dialog.body scrollbar.background", ""),
+    ("dialog.body scrollbar.button", "bg:#000000"),
+    ("dialog.body scrollbar.arrow", ""),
+    ("dialog.body scrollbar.start", "nounderline"),
+    ("dialog.body scrollbar.end", "nounderline"),
+    # Buttons.
+    ("button", ""),
+    ("button.arrow", "bold"),
+    ("button.focused", "bg:#aa0000 #ffffff"),
+    # Menu bars.
+    ("menu-bar", "bg:#aaaaaa #000000"),
+    ("menu-bar.selected-item", "bg:#ffffff #000000"),
+    ("menu", "bg:#888888 #ffffff"),
+    ("menu.border", "#aaaaaa"),
+    ("menu.border shadow", "#444444"),
+    # Shadows.
+    ("dialog shadow", "bg:#000088"),
+    ("dialog.body shadow", "bg:#aaaaaa"),
+    ("progress-bar", "bg:#000088"),
+    ("progress-bar.used", "bg:#ff0000"),
+]
+
+
+# The default Pygments style, include this by default in case a Pygments lexer
+# is used.
+PYGMENTS_DEFAULT_STYLE = {
+    "pygments.whitespace": "#bbbbbb",
+    "pygments.comment": "italic #408080",
+    "pygments.comment.preproc": "noitalic #bc7a00",
+    "pygments.keyword": "bold #008000",
+    "pygments.keyword.pseudo": "nobold",
+    "pygments.keyword.type": "nobold #b00040",
+    "pygments.operator": "#666666",
+    "pygments.operator.word": "bold #aa22ff",
+    "pygments.name.builtin": "#008000",
+    "pygments.name.function": "#0000ff",
+    "pygments.name.class": "bold #0000ff",
+    "pygments.name.namespace": "bold #0000ff",
+    "pygments.name.exception": "bold #d2413a",
+    "pygments.name.variable": "#19177c",
+    "pygments.name.constant": "#880000",
+    "pygments.name.label": "#a0a000",
+    "pygments.name.entity": "bold #999999",
+    "pygments.name.attribute": "#7d9029",
+    "pygments.name.tag": "bold #008000",
+    "pygments.name.decorator": "#aa22ff",
+    # Note: In Pygments, Token.String is an alias for Token.Literal.String,
+    #       and Token.Number as an alias for Token.Literal.Number.
+    "pygments.literal.string": "#ba2121",
+    "pygments.literal.string.doc": "italic",
+    "pygments.literal.string.interpol": "bold #bb6688",
+    "pygments.literal.string.escape": "bold #bb6622",
+    "pygments.literal.string.regex": "#bb6688",
+    "pygments.literal.string.symbol": "#19177c",
+    "pygments.literal.string.other": "#008000",
+    "pygments.literal.number": "#666666",
+    "pygments.generic.heading": "bold #000080",
+    "pygments.generic.subheading": "bold #800080",
+    "pygments.generic.deleted": "#a00000",
+    "pygments.generic.inserted": "#00a000",
+    "pygments.generic.error": "#ff0000",
+    "pygments.generic.emph": "italic",
+    "pygments.generic.strong": "bold",
+    "pygments.generic.prompt": "bold #000080",
+    "pygments.generic.output": "#888",
+    "pygments.generic.traceback": "#04d",
+    "pygments.error": "border:#ff0000",
+}
+
+
+@memoized()
+def default_ui_style() -> BaseStyle:
+    """
+    Create a default `Style` object.
+    """
+    return merge_styles(
+        [
+            Style(PROMPT_TOOLKIT_STYLE),
+            Style(COLORS_STYLE),
+            Style(WIDGETS_STYLE),
+        ]
+    )
+
+
+@memoized()
+def default_pygments_style() -> Style:
+    """
+    Create a `Style` object that contains the default Pygments style.
+    """
+    return Style.from_dict(PYGMENTS_DEFAULT_STYLE)
diff --git a/src/prompt_toolkit/styles/named_colors.py b/src/prompt_toolkit/styles/named_colors.py
new file mode 100644
index 0000000..37bd6de
--- /dev/null
+++ b/src/prompt_toolkit/styles/named_colors.py
@@ -0,0 +1,161 @@
+"""
+All modern web browsers support these 140 color names.
+Taken from: https://www.w3schools.com/colors/colors_names.asp
+"""
+from typing import Dict
+
+__all__ = [
+    "NAMED_COLORS",
+]
+
+
+NAMED_COLORS: Dict[str, str] = {
+    "AliceBlue": "#f0f8ff",
+    "AntiqueWhite": "#faebd7",
+    "Aqua": "#00ffff",
+    "Aquamarine": "#7fffd4",
+    "Azure": "#f0ffff",
+    "Beige": "#f5f5dc",
+    "Bisque": "#ffe4c4",
+    "Black": "#000000",
+    "BlanchedAlmond": "#ffebcd",
+    "Blue": "#0000ff",
+    "BlueViolet": "#8a2be2",
+    "Brown": "#a52a2a",
+    "BurlyWood": "#deb887",
+    "CadetBlue": "#5f9ea0",
+    "Chartreuse": "#7fff00",
+    "Chocolate": "#d2691e",
+    "Coral": "#ff7f50",
+    "CornflowerBlue": "#6495ed",
+    "Cornsilk": "#fff8dc",
+    "Crimson": "#dc143c",
+    "Cyan": "#00ffff",
+    "DarkBlue": "#00008b",
+    "DarkCyan": "#008b8b",
+    "DarkGoldenRod": "#b8860b",
+    "DarkGray": "#a9a9a9",
+    "DarkGreen": "#006400",
+    "DarkGrey": "#a9a9a9",
+    "DarkKhaki": "#bdb76b",
+    "DarkMagenta": "#8b008b",
+    "DarkOliveGreen": "#556b2f",
+    "DarkOrange": "#ff8c00",
+    "DarkOrchid": "#9932cc",
+    "DarkRed": "#8b0000",
+    "DarkSalmon": "#e9967a",
+    "DarkSeaGreen": "#8fbc8f",
+    "DarkSlateBlue": "#483d8b",
+    "DarkSlateGray": "#2f4f4f",
+    "DarkSlateGrey": "#2f4f4f",
+    "DarkTurquoise": "#00ced1",
+    "DarkViolet": "#9400d3",
+    "DeepPink": "#ff1493",
+    "DeepSkyBlue": "#00bfff",
+    "DimGray": "#696969",
+    "DimGrey": "#696969",
+    "DodgerBlue": "#1e90ff",
+    "FireBrick": "#b22222",
+    "FloralWhite": "#fffaf0",
+    "ForestGreen": "#228b22",
+    "Fuchsia": "#ff00ff",
+    "Gainsboro": "#dcdcdc",
+    "GhostWhite": "#f8f8ff",
+    "Gold": "#ffd700",
+    "GoldenRod": "#daa520",
+    "Gray": "#808080",
+    "Green": "#008000",
+    "GreenYellow": "#adff2f",
+    "Grey": "#808080",
+    "HoneyDew": "#f0fff0",
+    "HotPink": "#ff69b4",
+    "IndianRed": "#cd5c5c",
+    "Indigo": "#4b0082",
+    "Ivory": "#fffff0",
+    "Khaki": "#f0e68c",
+    "Lavender": "#e6e6fa",
+    "LavenderBlush": "#fff0f5",
+    "LawnGreen": "#7cfc00",
+    "LemonChiffon": "#fffacd",
+    "LightBlue": "#add8e6",
+    "LightCoral": "#f08080",
+    "LightCyan": "#e0ffff",
+    "LightGoldenRodYellow": "#fafad2",
+    "LightGray": "#d3d3d3",
+    "LightGreen": "#90ee90",
+    "LightGrey": "#d3d3d3",
+    "LightPink": "#ffb6c1",
+    "LightSalmon": "#ffa07a",
+    "LightSeaGreen": "#20b2aa",
+    "LightSkyBlue": "#87cefa",
+    "LightSlateGray": "#778899",
+    "LightSlateGrey": "#778899",
+    "LightSteelBlue": "#b0c4de",
+    "LightYellow": "#ffffe0",
+    "Lime": "#00ff00",
+    "LimeGreen": "#32cd32",
+    "Linen": "#faf0e6",
+    "Magenta": "#ff00ff",
+    "Maroon": "#800000",
+    "MediumAquaMarine": "#66cdaa",
+    "MediumBlue": "#0000cd",
+    "MediumOrchid": "#ba55d3",
+    "MediumPurple": "#9370db",
+    "MediumSeaGreen": "#3cb371",
+    "MediumSlateBlue": "#7b68ee",
+    "MediumSpringGreen": "#00fa9a",
+    "MediumTurquoise": "#48d1cc",
+    "MediumVioletRed": "#c71585",
+    "MidnightBlue": "#191970",
+    "MintCream": "#f5fffa",
+    "MistyRose": "#ffe4e1",
+    "Moccasin": "#ffe4b5",
+    "NavajoWhite": "#ffdead",
+    "Navy": "#000080",
+    "OldLace": "#fdf5e6",
+    "Olive": "#808000",
+    "OliveDrab": "#6b8e23",
+    "Orange": "#ffa500",
+    "OrangeRed": "#ff4500",
+    "Orchid": "#da70d6",
+    "PaleGoldenRod": "#eee8aa",
+    "PaleGreen": "#98fb98",
+    "PaleTurquoise": "#afeeee",
+    "PaleVioletRed": "#db7093",
+    "PapayaWhip": "#ffefd5",
+    "PeachPuff": "#ffdab9",
+    "Peru": "#cd853f",
+    "Pink": "#ffc0cb",
+    "Plum": "#dda0dd",
+    "PowderBlue": "#b0e0e6",
+    "Purple": "#800080",
+    "RebeccaPurple": "#663399",
+    "Red": "#ff0000",
+    "RosyBrown": "#bc8f8f",
+    "RoyalBlue": "#4169e1",
+    "SaddleBrown": "#8b4513",
+    "Salmon": "#fa8072",
+    "SandyBrown": "#f4a460",
+    "SeaGreen": "#2e8b57",
+    "SeaShell": "#fff5ee",
+    "Sienna": "#a0522d",
+    "Silver": "#c0c0c0",
+    "SkyBlue": "#87ceeb",
+    "SlateBlue": "#6a5acd",
+    "SlateGray": "#708090",
+    "SlateGrey": "#708090",
+    "Snow": "#fffafa",
+    "SpringGreen": "#00ff7f",
+    "SteelBlue": "#4682b4",
+    "Tan": "#d2b48c",
+    "Teal": "#008080",
+    "Thistle": "#d8bfd8",
+    "Tomato": "#ff6347",
+    "Turquoise": "#40e0d0",
+    "Violet": "#ee82ee",
+    "Wheat": "#f5deb3",
+    "White": "#ffffff",
+    "WhiteSmoke": "#f5f5f5",
+    "Yellow": "#ffff00",
+    "YellowGreen": "#9acd32",
+}
diff --git a/src/prompt_toolkit/styles/pygments.py b/src/prompt_toolkit/styles/pygments.py
new file mode 100644
index 0000000..382e5e3
--- /dev/null
+++ b/src/prompt_toolkit/styles/pygments.py
@@ -0,0 +1,67 @@
+"""
+Adaptor for building prompt_toolkit styles, starting from a Pygments style.
+
+Usage::
+
+    from pygments.styles.tango import TangoStyle
+    style = style_from_pygments_cls(pygments_style_cls=TangoStyle)
+"""
+from typing import TYPE_CHECKING, Dict, Type
+
+from .style import Style
+
+if TYPE_CHECKING:
+    from pygments.style import Style as PygmentsStyle
+    from pygments.token import Token
+
+
+__all__ = [
+    "style_from_pygments_cls",
+    "style_from_pygments_dict",
+    "pygments_token_to_classname",
+]
+
+
+def style_from_pygments_cls(pygments_style_cls: Type["PygmentsStyle"]) -> Style:
+    """
+    Shortcut to create a :class:`.Style` instance from a Pygments style class
+    and a style dictionary.
+
+    Example::
+
+        from prompt_toolkit.styles.from_pygments import style_from_pygments_cls
+        from pygments.styles import get_style_by_name
+        style = style_from_pygments_cls(get_style_by_name('monokai'))
+
+    :param pygments_style_cls: Pygments style class to start from.
+    """
+    # Import inline.
+    from pygments.style import Style as PygmentsStyle
+
+    assert issubclass(pygments_style_cls, PygmentsStyle)
+
+    return style_from_pygments_dict(pygments_style_cls.styles)
+
+
+def style_from_pygments_dict(pygments_dict: Dict["Token", str]) -> Style:
+    """
+    Create a :class:`.Style` instance from a Pygments style dictionary.
+    (One that maps Token objects to style strings.)
+    """
+    pygments_style = []
+
+    for token, style in pygments_dict.items():
+        pygments_style.append((pygments_token_to_classname(token), style))
+
+    return Style(pygments_style)
+
+
+def pygments_token_to_classname(token: "Token") -> str:
+    """
+    Turn e.g. `Token.Name.Exception` into `'pygments.name.exception'`.
+
+    (Our Pygments lexer will also turn the tokens that pygments produces in a
+    prompt_toolkit list of fragments that match these styling rules.)
+    """
+    parts = ("pygments",) + token
+    return ".".join(parts).lower()
diff --git a/src/prompt_toolkit/styles/style.py b/src/prompt_toolkit/styles/style.py
new file mode 100644
index 0000000..6e4bd1f
--- /dev/null
+++ b/src/prompt_toolkit/styles/style.py
@@ -0,0 +1,399 @@
+"""
+Tool for creating styles from a dictionary.
+"""
+import itertools
+import re
+import sys
+from enum import Enum
+from typing import Dict, Hashable, List, Set, Tuple, TypeVar
+
+from prompt_toolkit.cache import SimpleCache
+
+from .base import (
+    ANSI_COLOR_NAMES,
+    ANSI_COLOR_NAMES_ALIASES,
+    DEFAULT_ATTRS,
+    Attrs,
+    BaseStyle,
+)
+from .named_colors import NAMED_COLORS
+
+__all__ = [
+    "Style",
+    "parse_color",
+    "Priority",
+    "merge_styles",
+]
+
+_named_colors_lowercase = {k.lower(): v.lstrip("#") for k, v in NAMED_COLORS.items()}
+
+
+def parse_color(text: str) -> str:
+    """
+    Parse/validate color format.
+
+    Like in Pygments, but also support the ANSI color names.
+    (These will map to the colors of the 16 color palette.)
+    """
+    # ANSI color names.
+    if text in ANSI_COLOR_NAMES:
+        return text
+    if text in ANSI_COLOR_NAMES_ALIASES:
+        return ANSI_COLOR_NAMES_ALIASES[text]
+
+    # 140 named colors.
+    try:
+        # Replace by 'hex' value.
+        return _named_colors_lowercase[text.lower()]
+    except KeyError:
+        pass
+
+    # Hex codes.
+    if text[0:1] == "#":
+        col = text[1:]
+
+        # Keep this for backwards-compatibility (Pygments does it).
+        # I don't like the '#' prefix for named colors.
+        if col in ANSI_COLOR_NAMES:
+            return col
+        elif col in ANSI_COLOR_NAMES_ALIASES:
+            return ANSI_COLOR_NAMES_ALIASES[col]
+
+        # 6 digit hex color.
+        elif len(col) == 6:
+            return col
+
+        # 3 digit hex color.
+        elif len(col) == 3:
+            return col[0] * 2 + col[1] * 2 + col[2] * 2
+
+    # Default.
+    elif text in ("", "default"):
+        return text
+
+    raise ValueError("Wrong color format %r" % text)
+
+
+# Attributes, when they are not filled in by a style. None means that we take
+# the value from the parent.
+_EMPTY_ATTRS = Attrs(
+    color=None,
+    bgcolor=None,
+    bold=None,
+    underline=None,
+    strike=None,
+    italic=None,
+    blink=None,
+    reverse=None,
+    hidden=None,
+)
+
+
+def _expand_classname(classname: str) -> List[str]:
+    """
+    Split a single class name at the `.` operator, and build a list of classes.
+
+    E.g. 'a.b.c' becomes ['a', 'a.b', 'a.b.c']
+    """
+    result = []
+    parts = classname.split(".")
+
+    for i in range(1, len(parts) + 1):
+        result.append(".".join(parts[:i]).lower())
+
+    return result
+
+
+def _parse_style_str(style_str: str) -> Attrs:
+    """
+    Take a style string, e.g.  'bg:red #88ff00 class:title'
+    and return a `Attrs` instance.
+    """
+    # Start from default Attrs.
+    if "noinherit" in style_str:
+        attrs = DEFAULT_ATTRS
+    else:
+        attrs = _EMPTY_ATTRS
+
+    # Now update with the given attributes.
+    for part in style_str.split():
+        if part == "noinherit":
+            pass
+        elif part == "bold":
+            attrs = attrs._replace(bold=True)
+        elif part == "nobold":
+            attrs = attrs._replace(bold=False)
+        elif part == "italic":
+            attrs = attrs._replace(italic=True)
+        elif part == "noitalic":
+            attrs = attrs._replace(italic=False)
+        elif part == "underline":
+            attrs = attrs._replace(underline=True)
+        elif part == "nounderline":
+            attrs = attrs._replace(underline=False)
+        elif part == "strike":
+            attrs = attrs._replace(strike=True)
+        elif part == "nostrike":
+            attrs = attrs._replace(strike=False)
+
+        # prompt_toolkit extensions. Not in Pygments.
+        elif part == "blink":
+            attrs = attrs._replace(blink=True)
+        elif part == "noblink":
+            attrs = attrs._replace(blink=False)
+        elif part == "reverse":
+            attrs = attrs._replace(reverse=True)
+        elif part == "noreverse":
+            attrs = attrs._replace(reverse=False)
+        elif part == "hidden":
+            attrs = attrs._replace(hidden=True)
+        elif part == "nohidden":
+            attrs = attrs._replace(hidden=False)
+
+        # Pygments properties that we ignore.
+        elif part in ("roman", "sans", "mono"):
+            pass
+        elif part.startswith("border:"):
+            pass
+
+        # Ignore pieces in between square brackets. This is internal stuff.
+        # Like '[transparent]' or '[set-cursor-position]'.
+        elif part.startswith("[") and part.endswith("]"):
+            pass
+
+        # Colors.
+        elif part.startswith("bg:"):
+            attrs = attrs._replace(bgcolor=parse_color(part[3:]))
+        elif part.startswith("fg:"):  # The 'fg:' prefix is optional.
+            attrs = attrs._replace(color=parse_color(part[3:]))
+        else:
+            attrs = attrs._replace(color=parse_color(part))
+
+    return attrs
+
+
+CLASS_NAMES_RE = re.compile(r"^[a-z0-9.\s_-]*$")  # This one can't contain a comma!
+
+
+class Priority(Enum):
+    """
+    The priority of the rules, when a style is created from a dictionary.
+
+    In a `Style`, rules that are defined later will always override previous
+    defined rules, however in a dictionary, the key order was arbitrary before
+    Python 3.6. This means that the style could change at random between rules.
+
+    We have two options:
+
+    - `DICT_KEY_ORDER`: This means, iterate through the dictionary, and take
+       the key/value pairs in order as they come. This is a good option if you
+       have Python >3.6. Rules at the end will override rules at the beginning.
+    - `MOST_PRECISE`: keys that are defined with most precision will get higher
+      priority. (More precise means: more elements.)
+    """
+
+    DICT_KEY_ORDER = "KEY_ORDER"
+    MOST_PRECISE = "MOST_PRECISE"
+
+
+# We don't support Python versions older than 3.6 anymore, so we can always
+# depend on dictionary ordering. This is the default.
+default_priority = Priority.DICT_KEY_ORDER
+
+
+class Style(BaseStyle):
+    """
+    Create a ``Style`` instance from a list of style rules.
+
+    The `style_rules` is supposed to be a list of ('classnames', 'style') tuples.
+    The classnames are a whitespace separated string of class names and the
+    style string is just like a Pygments style definition, but with a few
+    additions: it supports 'reverse' and 'blink'.
+
+    Later rules always override previous rules.
+
+    Usage::
+
+        Style([
+            ('title', '#ff0000 bold underline'),
+            ('something-else', 'reverse'),
+            ('class1 class2', 'reverse'),
+        ])
+
+    The ``from_dict`` classmethod is similar, but takes a dictionary as input.
+    """
+
+    def __init__(self, style_rules: List[Tuple[str, str]]) -> None:
+        class_names_and_attrs = []
+
+        # Loop through the rules in the order they were defined.
+        # Rules that are defined later get priority.
+        for class_names, style_str in style_rules:
+            assert CLASS_NAMES_RE.match(class_names), repr(class_names)
+
+            # The order of the class names doesn't matter.
+            # (But the order of rules does matter.)
+            class_names_set = frozenset(class_names.lower().split())
+            attrs = _parse_style_str(style_str)
+
+            class_names_and_attrs.append((class_names_set, attrs))
+
+        self._style_rules = style_rules
+        self.class_names_and_attrs = class_names_and_attrs
+
+    @property
+    def style_rules(self) -> List[Tuple[str, str]]:
+        return self._style_rules
+
+    @classmethod
+    def from_dict(
+        cls, style_dict: Dict[str, str], priority: Priority = default_priority
+    ) -> "Style":
+        """
+        :param style_dict: Style dictionary.
+        :param priority: `Priority` value.
+        """
+        if priority == Priority.MOST_PRECISE:
+
+            def key(item: Tuple[str, str]) -> int:
+                # Split on '.' and whitespace. Count elements.
+                return sum(len(i.split(".")) for i in item[0].split())
+
+            return cls(sorted(style_dict.items(), key=key))
+        else:
+            return cls(list(style_dict.items()))
+
+    def get_attrs_for_style_str(
+        self, style_str: str, default: Attrs = DEFAULT_ATTRS
+    ) -> Attrs:
+        """
+        Get `Attrs` for the given style string.
+        """
+        list_of_attrs = [default]
+        class_names: Set[str] = set()
+
+        # Apply default styling.
+        for names, attr in self.class_names_and_attrs:
+            if not names:
+                list_of_attrs.append(attr)
+
+        # Go from left to right through the style string. Things on the right
+        # take precedence.
+        for part in style_str.split():
+            # This part represents a class.
+            # Do lookup of this class name in the style definition, as well
+            # as all class combinations that we have so far.
+            if part.startswith("class:"):
+                # Expand all class names (comma separated list).
+                new_class_names = []
+                for p in part[6:].lower().split(","):
+                    new_class_names.extend(_expand_classname(p))
+
+                for new_name in new_class_names:
+                    # Build a set of all possible class combinations to be applied.
+                    combos = set()
+                    combos.add(frozenset([new_name]))
+
+                    for count in range(1, len(class_names) + 1):
+                        for c2 in itertools.combinations(class_names, count):
+                            combos.add(frozenset(c2 + (new_name,)))
+
+                    # Apply the styles that match these class names.
+                    for names, attr in self.class_names_and_attrs:
+                        if names in combos:
+                            list_of_attrs.append(attr)
+
+                    class_names.add(new_name)
+
+            # Process inline style.
+            else:
+                inline_attrs = _parse_style_str(part)
+                list_of_attrs.append(inline_attrs)
+
+        return _merge_attrs(list_of_attrs)
+
+    def invalidation_hash(self) -> Hashable:
+        return id(self.class_names_and_attrs)
+
+
+_T = TypeVar("_T")
+
+
+def _merge_attrs(list_of_attrs: List[Attrs]) -> Attrs:
+    """
+    Take a list of :class:`.Attrs` instances and merge them into one.
+    Every `Attr` in the list can override the styling of the previous one. So,
+    the last one has highest priority.
+    """
+
+    def _or(*values: _T) -> _T:
+        "Take first not-None value, starting at the end."
+        for v in values[::-1]:
+            if v is not None:
+                return v
+        raise ValueError  # Should not happen, there's always one non-null value.
+
+    return Attrs(
+        color=_or("", *[a.color for a in list_of_attrs]),
+        bgcolor=_or("", *[a.bgcolor for a in list_of_attrs]),
+        bold=_or(False, *[a.bold for a in list_of_attrs]),
+        underline=_or(False, *[a.underline for a in list_of_attrs]),
+        strike=_or(False, *[a.strike for a in list_of_attrs]),
+        italic=_or(False, *[a.italic for a in list_of_attrs]),
+        blink=_or(False, *[a.blink for a in list_of_attrs]),
+        reverse=_or(False, *[a.reverse for a in list_of_attrs]),
+        hidden=_or(False, *[a.hidden for a in list_of_attrs]),
+    )
+
+
+def merge_styles(styles: List[BaseStyle]) -> "_MergedStyle":
+    """
+    Merge multiple `Style` objects.
+    """
+    styles = [s for s in styles if s is not None]
+    return _MergedStyle(styles)
+
+
+class _MergedStyle(BaseStyle):
+    """
+    Merge multiple `Style` objects into one.
+    This is supposed to ensure consistency: if any of the given styles changes,
+    then this style will be updated.
+    """
+
+    # NOTE: previously, we used an algorithm where we did not generate the
+    #       combined style. Instead this was a proxy that called one style
+    #       after the other, passing the outcome of the previous style as the
+    #       default for the next one. This did not work, because that way, the
+    #       priorities like described in the `Style` class don't work.
+    #       'class:aborted' was for instance never displayed in gray, because
+    #       the next style specified a default color for any text. (The
+    #       explicit styling of class:aborted should have taken priority,
+    #       because it was more precise.)
+    def __init__(self, styles: List[BaseStyle]) -> None:
+        self.styles = styles
+        self._style: SimpleCache[Hashable, Style] = SimpleCache(maxsize=1)
+
+    @property
+    def _merged_style(self) -> Style:
+        "The `Style` object that has the other styles merged together."
+
+        def get() -> Style:
+            return Style(self.style_rules)
+
+        return self._style.get(self.invalidation_hash(), get)
+
+    @property
+    def style_rules(self) -> List[Tuple[str, str]]:
+        style_rules = []
+        for s in self.styles:
+            style_rules.extend(s.style_rules)
+        return style_rules
+
+    def get_attrs_for_style_str(
+        self, style_str: str, default: Attrs = DEFAULT_ATTRS
+    ) -> Attrs:
+        return self._merged_style.get_attrs_for_style_str(style_str, default)
+
+    def invalidation_hash(self) -> Hashable:
+        return tuple(s.invalidation_hash() for s in self.styles)
diff --git a/src/prompt_toolkit/styles/style_transformation.py b/src/prompt_toolkit/styles/style_transformation.py
new file mode 100644
index 0000000..91308f9
--- /dev/null
+++ b/src/prompt_toolkit/styles/style_transformation.py
@@ -0,0 +1,375 @@
+"""
+Collection of style transformations.
+
+Think of it as a kind of color post processing after the rendering is done.
+This could be used for instance to change the contrast/saturation; swap light
+and dark colors or even change certain colors for other colors.
+
+When the UI is rendered, these transformations can be applied right after the
+style strings are turned into `Attrs` objects that represent the actual
+formatting.
+"""
+from abc import ABCMeta, abstractmethod
+from colorsys import hls_to_rgb, rgb_to_hls
+from typing import Callable, Hashable, Optional, Sequence, Tuple, Union
+
+from prompt_toolkit.cache import memoized
+from prompt_toolkit.filters import FilterOrBool, to_filter
+from prompt_toolkit.utils import AnyFloat, to_float, to_str
+
+from .base import ANSI_COLOR_NAMES, Attrs
+from .style import parse_color
+
+__all__ = [
+    "StyleTransformation",
+    "SwapLightAndDarkStyleTransformation",
+    "ReverseStyleTransformation",
+    "SetDefaultColorStyleTransformation",
+    "AdjustBrightnessStyleTransformation",
+    "DummyStyleTransformation",
+    "ConditionalStyleTransformation",
+    "DynamicStyleTransformation",
+    "merge_style_transformations",
+]
+
+
+class StyleTransformation(metaclass=ABCMeta):
+    """
+    Base class for any style transformation.
+    """
+
+    @abstractmethod
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        """
+        Take an `Attrs` object and return a new `Attrs` object.
+
+        Remember that the color formats can be either "ansi..." or a 6 digit
+        lowercase hexadecimal color (without '#' prefix).
+        """
+
+    def invalidation_hash(self) -> Hashable:
+        """
+        When this changes, the cache should be invalidated.
+        """
+        return f"{self.__class__.__name__}-{id(self)}"
+
+
+class SwapLightAndDarkStyleTransformation(StyleTransformation):
+    """
+    Turn dark colors into light colors and the other way around.
+
+    This is meant to make color schemes that work on a dark background usable
+    on a light background (and the other way around).
+
+    Notice that this doesn't swap foreground and background like "reverse"
+    does. It turns light green into dark green and the other way around.
+    Foreground and background colors are considered individually.
+
+    Also notice that when <reverse> is used somewhere and no colors are given
+    in particular (like what is the default for the bottom toolbar), then this
+    doesn't change anything. This is what makes sense, because when the
+    'default' color is chosen, it's what works best for the terminal, and
+    reverse works good with that.
+    """
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        """
+        Return the `Attrs` used when opposite luminosity should be used.
+        """
+        # Reverse colors.
+        attrs = attrs._replace(color=get_opposite_color(attrs.color))
+        attrs = attrs._replace(bgcolor=get_opposite_color(attrs.bgcolor))
+
+        return attrs
+
+
+class ReverseStyleTransformation(StyleTransformation):
+    """
+    Swap the 'reverse' attribute.
+
+    (This is still experimental.)
+    """
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        return attrs._replace(reverse=not attrs.reverse)
+
+
+class SetDefaultColorStyleTransformation(StyleTransformation):
+    """
+    Set default foreground/background color for output that doesn't specify
+    anything. This is useful for overriding the terminal default colors.
+
+    :param fg: Color string or callable that returns a color string for the
+        foreground.
+    :param bg: Like `fg`, but for the background.
+    """
+
+    def __init__(
+        self, fg: Union[str, Callable[[], str]], bg: Union[str, Callable[[], str]]
+    ) -> None:
+
+        self.fg = fg
+        self.bg = bg
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        if attrs.bgcolor in ("", "default"):
+            attrs = attrs._replace(bgcolor=parse_color(to_str(self.bg)))
+
+        if attrs.color in ("", "default"):
+            attrs = attrs._replace(color=parse_color(to_str(self.fg)))
+
+        return attrs
+
+    def invalidation_hash(self) -> Hashable:
+        return (
+            "set-default-color",
+            to_str(self.fg),
+            to_str(self.bg),
+        )
+
+
+class AdjustBrightnessStyleTransformation(StyleTransformation):
+    """
+    Adjust the brightness to improve the rendering on either dark or light
+    backgrounds.
+
+    For dark backgrounds, it's best to increase `min_brightness`. For light
+    backgrounds it's best to decrease `max_brightness`. Usually, only one
+    setting is adjusted.
+
+    This will only change the brightness for text that has a foreground color
+    defined, but no background color. It works best for 256 or true color
+    output.
+
+    .. note:: Notice that there is no universal way to detect whether the
+              application is running in a light or dark terminal. As a
+              developer of an command line application, you'll have to make
+              this configurable for the user.
+
+    :param min_brightness: Float between 0.0 and 1.0 or a callable that returns
+        a float.
+    :param max_brightness: Float between 0.0 and 1.0 or a callable that returns
+        a float.
+    """
+
+    def __init__(
+        self, min_brightness: AnyFloat = 0.0, max_brightness: AnyFloat = 1.0
+    ) -> None:
+
+        self.min_brightness = min_brightness
+        self.max_brightness = max_brightness
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        min_brightness = to_float(self.min_brightness)
+        max_brightness = to_float(self.max_brightness)
+        assert 0 <= min_brightness <= 1
+        assert 0 <= max_brightness <= 1
+
+        # Don't do anything if the whole brightness range is acceptable.
+        # This also avoids turning ansi colors into RGB sequences.
+        if min_brightness == 0.0 and max_brightness == 1.0:
+            return attrs
+
+        # If a foreground color is given without a background color.
+        no_background = not attrs.bgcolor or attrs.bgcolor == "default"
+        has_fgcolor = attrs.color and attrs.color != "ansidefault"
+
+        if has_fgcolor and no_background:
+            # Calculate new RGB values.
+            r, g, b = self._color_to_rgb(attrs.color or "")
+            hue, brightness, saturation = rgb_to_hls(r, g, b)
+            brightness = self._interpolate_brightness(
+                brightness, min_brightness, max_brightness
+            )
+            r, g, b = hls_to_rgb(hue, brightness, saturation)
+            new_color = f"{int(r * 255):02x}{int(g * 255):02x}{int(b * 255):02x}"
+
+            attrs = attrs._replace(color=new_color)
+
+        return attrs
+
+    def _color_to_rgb(self, color: str) -> Tuple[float, float, float]:
+        """
+        Parse `style.Attrs` color into RGB tuple.
+        """
+        # Do RGB lookup for ANSI colors.
+        try:
+            from prompt_toolkit.output.vt100 import ANSI_COLORS_TO_RGB
+
+            r, g, b = ANSI_COLORS_TO_RGB[color]
+            return r / 255.0, g / 255.0, b / 255.0
+        except KeyError:
+            pass
+
+        # Parse RRGGBB format.
+        return (
+            int(color[0:2], 16) / 255.0,
+            int(color[2:4], 16) / 255.0,
+            int(color[4:6], 16) / 255.0,
+        )
+
+        # NOTE: we don't have to support named colors here. They are already
+        #       transformed into RGB values in `style.parse_color`.
+
+    def _interpolate_brightness(
+        self, value: float, min_brightness: float, max_brightness: float
+    ) -> float:
+        """
+        Map the brightness to the (min_brightness..max_brightness) range.
+        """
+        return min_brightness + (max_brightness - min_brightness) * value
+
+    def invalidation_hash(self) -> Hashable:
+        return (
+            "adjust-brightness",
+            to_float(self.min_brightness),
+            to_float(self.max_brightness),
+        )
+
+
+class DummyStyleTransformation(StyleTransformation):
+    """
+    Don't transform anything at all.
+    """
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        return attrs
+
+    def invalidation_hash(self) -> Hashable:
+        # Always return the same hash for these dummy instances.
+        return "dummy-style-transformation"
+
+
+class DynamicStyleTransformation(StyleTransformation):
+    """
+    StyleTransformation class that can dynamically returns any
+    `StyleTransformation`.
+
+    :param get_style_transformation: Callable that returns a
+        :class:`.StyleTransformation` instance.
+    """
+
+    def __init__(
+        self, get_style_transformation: Callable[[], Optional[StyleTransformation]]
+    ) -> None:
+
+        self.get_style_transformation = get_style_transformation
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        style_transformation = (
+            self.get_style_transformation() or DummyStyleTransformation()
+        )
+        return style_transformation.transform_attrs(attrs)
+
+    def invalidation_hash(self) -> Hashable:
+        style_transformation = (
+            self.get_style_transformation() or DummyStyleTransformation()
+        )
+        return style_transformation.invalidation_hash()
+
+
+class ConditionalStyleTransformation(StyleTransformation):
+    """
+    Apply the style transformation depending on a condition.
+    """
+
+    def __init__(
+        self, style_transformation: StyleTransformation, filter: FilterOrBool
+    ) -> None:
+
+        self.style_transformation = style_transformation
+        self.filter = to_filter(filter)
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        if self.filter():
+            return self.style_transformation.transform_attrs(attrs)
+        return attrs
+
+    def invalidation_hash(self) -> Hashable:
+        return (self.filter(), self.style_transformation.invalidation_hash())
+
+
+class _MergedStyleTransformation(StyleTransformation):
+    def __init__(self, style_transformations: Sequence[StyleTransformation]) -> None:
+        self.style_transformations = style_transformations
+
+    def transform_attrs(self, attrs: Attrs) -> Attrs:
+        for transformation in self.style_transformations:
+            attrs = transformation.transform_attrs(attrs)
+        return attrs
+
+    def invalidation_hash(self) -> Hashable:
+        return tuple(t.invalidation_hash() for t in self.style_transformations)
+
+
+def merge_style_transformations(
+    style_transformations: Sequence[StyleTransformation],
+) -> StyleTransformation:
+    """
+    Merge multiple transformations together.
+    """
+    return _MergedStyleTransformation(style_transformations)
+
+
+# Dictionary that maps ANSI color names to their opposite. This is useful for
+# turning color schemes that are optimized for a black background usable for a
+# white background.
+OPPOSITE_ANSI_COLOR_NAMES = {
+    "ansidefault": "ansidefault",
+    "ansiblack": "ansiwhite",
+    "ansired": "ansibrightred",
+    "ansigreen": "ansibrightgreen",
+    "ansiyellow": "ansibrightyellow",
+    "ansiblue": "ansibrightblue",
+    "ansimagenta": "ansibrightmagenta",
+    "ansicyan": "ansibrightcyan",
+    "ansigray": "ansibrightblack",
+    "ansiwhite": "ansiblack",
+    "ansibrightred": "ansired",
+    "ansibrightgreen": "ansigreen",
+    "ansibrightyellow": "ansiyellow",
+    "ansibrightblue": "ansiblue",
+    "ansibrightmagenta": "ansimagenta",
+    "ansibrightcyan": "ansicyan",
+    "ansibrightblack": "ansigray",
+}
+assert set(OPPOSITE_ANSI_COLOR_NAMES.keys()) == set(ANSI_COLOR_NAMES)
+assert set(OPPOSITE_ANSI_COLOR_NAMES.values()) == set(ANSI_COLOR_NAMES)
+
+
+@memoized()
+def get_opposite_color(colorname: Optional[str]) -> Optional[str]:
+    """
+    Take a color name in either 'ansi...' format or 6 digit RGB, return the
+    color of opposite luminosity (same hue/saturation).
+
+    This is used for turning color schemes that work on a light background
+    usable on a dark background.
+    """
+    if colorname is None:  # Because color/bgcolor can be None in `Attrs`.
+        return None
+
+    # Special values.
+    if colorname in ("", "default"):
+        return colorname
+
+    # Try ANSI color names.
+    try:
+        return OPPOSITE_ANSI_COLOR_NAMES[colorname]
+    except KeyError:
+        # Try 6 digit RGB colors.
+        r = int(colorname[:2], 16) / 255.0
+        g = int(colorname[2:4], 16) / 255.0
+        b = int(colorname[4:6], 16) / 255.0
+
+        h, l, s = rgb_to_hls(r, g, b)
+
+        l = 1 - l
+
+        r, g, b = hls_to_rgb(h, l, s)
+
+        r = int(r * 255)
+        g = int(g * 255)
+        b = int(b * 255)
+
+        return f"{r:02x}{g:02x}{b:02x}"