Load the JULIA_*_COLOR env vars for compat

As we change more code to use the StyledStrings approach, it would be
nice to try to maintain compatibility with old user customisations as
much as possible.

src/StyledStrings.jl

@@ -12,10 +12,12 @@ include("faces.jl")
 include("regioniterator.jl")
 include("io.jl")
 include("stylemacro.jl")
+include("legacy.jl")
 
 function __init__()
     userfaces = joinpath(first(DEPOT_PATH), "config", "faces.toml")
     isfile(userfaces) && loaduserfaces!(userfaces)
+    Legacy.load_env_colors!()
 end
 
 if Base.generating_output()

src/legacy.jl

@@ -0,0 +1,134 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# StyledStrings provides a new way of handling colored output, however the
+# ~decade of colored printing in Julia before now has left us with a legacy,
+# and we should try to maintain compatibility as much as reasonable possible.
+
+module Legacy
+
+using ..StyledStrings: SimpleColor, Face, loadface!
+
+"""
+A mapping from 256-color codes to 8-bit colours, represented with
+`SimpleColor`-compatible `UInt32`s.
+"""
+const ANSI_256_COLORS = Dict{Int, UInt32}(
+    0   => 0x000000, 1   => 0x800000, 2   => 0x008000, 3   => 0x808000, 4   => 0x000080,
+    5   => 0x800080, 6   => 0x008080, 7   => 0xc0c0c0, 8   => 0x808080, 9   => 0xff0000,
+    10  => 0x00ff00, 11  => 0xffff00, 12  => 0x0000ff, 13  => 0xff00ff, 14  => 0x00ffff,
+    15  => 0xffffff, 16  => 0x000000, 17  => 0x00005f, 18  => 0x000087, 19  => 0x0000af,
+    20  => 0x0000d7, 21  => 0x0000ff, 22  => 0x005f00, 23  => 0x005f5f, 24  => 0x005f87,
+    25  => 0x005faf, 26  => 0x005fd7, 27  => 0x005fff, 28  => 0x008700, 29  => 0x00875f,
+    30  => 0x008787, 31  => 0x0087af, 32  => 0x0087d7, 33  => 0x0087ff, 34  => 0x00af00,
+    35  => 0x00af5f, 36  => 0x00af87, 37  => 0x00afaf, 38  => 0x00afd7, 39  => 0x00afff,
+    40  => 0x00d700, 41  => 0x00d75f, 42  => 0x00d787, 43  => 0x00d7af, 44  => 0x00d7d7,
+    45  => 0x00d7ff, 46  => 0x00ff00, 47  => 0x00ff5f, 48  => 0x00ff87, 49  => 0x00ffaf,
+    50  => 0x00ffd7, 51  => 0x00ffff, 52  => 0x5f0000, 53  => 0x5f005f, 54  => 0x5f0087,
+    55  => 0x5f00af, 56  => 0x5f00d7, 57  => 0x5f00ff, 58  => 0x5f5f00, 59  => 0x5f5f5f,
+    60  => 0x5f5f87, 61  => 0x5f5faf, 62  => 0x5f5fd7, 63  => 0x5f5fff, 64  => 0x5f8700,
+    65  => 0x5f875f, 66  => 0x5f8787, 67  => 0x5f87af, 68  => 0x5f87d7, 69  => 0x5f87ff,
+    70  => 0x5faf00, 71  => 0x5faf5f, 72  => 0x5faf87, 73  => 0x5fafaf, 74  => 0x5fafd7,
+    75  => 0x5fafff, 76  => 0x5fd700, 77  => 0x5fd75f, 78  => 0x5fd787, 79  => 0x5fd7af,
+    80  => 0x5fd7d7, 81  => 0x5fd7ff, 82  => 0x5fff00, 83  => 0x5fff5f, 84  => 0x5fff87,
+    85  => 0x5fffaf, 86  => 0x5fffd7, 87  => 0x5fffff, 88  => 0x870000, 89  => 0x87005f,
+    90  => 0x870087, 91  => 0x8700af, 92  => 0x8700d7, 93  => 0x8700ff, 94  => 0x875f00,
+    95  => 0x875f5f, 96  => 0x875f87, 97  => 0x875faf, 98  => 0x875fd7, 99  => 0x875fff,
+    100 => 0x878700, 101 => 0x87875f, 102 => 0x878787, 103 => 0x8787af, 104 => 0x8787d7,
+    105 => 0x8787ff, 106 => 0x87af00, 107 => 0x87af5f, 108 => 0x87af87, 109 => 0x87afaf,
+    110 => 0x87afd7, 111 => 0x87afff, 112 => 0x87d700, 113 => 0x87d75f, 114 => 0x87d787,
+    115 => 0x87d7af, 116 => 0x87d7d7, 117 => 0x87d7ff, 118 => 0x87ff00, 119 => 0x87ff5f,
+    120 => 0x87ff87, 121 => 0x87ffaf, 122 => 0x87ffd7, 123 => 0x87ffff, 124 => 0xaf0000,
+    125 => 0xaf005f, 126 => 0xaf0087, 127 => 0xaf00af, 128 => 0xaf00d7, 129 => 0xaf00ff,
+    130 => 0xaf5f00, 131 => 0xaf5f5f, 132 => 0xaf5f87, 133 => 0xaf5faf, 134 => 0xaf5fd7,
+    135 => 0xaf5fff, 136 => 0xaf8700, 137 => 0xaf875f, 138 => 0xaf8787, 139 => 0xaf87af,
+    140 => 0xaf87d7, 141 => 0xaf87ff, 142 => 0xafaf00, 143 => 0xafaf5f, 144 => 0xafaf87,
+    145 => 0xafafaf, 146 => 0xafafd7, 147 => 0xafafff, 148 => 0xafd700, 149 => 0xafd75f,
+    150 => 0xafd787, 151 => 0xafd7af, 152 => 0xafd7d7, 153 => 0xafd7ff, 154 => 0xafff00,
+    155 => 0xafff5f, 156 => 0xafff87, 157 => 0xafffaf, 158 => 0xafffd7, 159 => 0xafffff,
+    160 => 0xd70000, 161 => 0xd7005f, 162 => 0xd70087, 163 => 0xd700af, 164 => 0xd700d7,
+    165 => 0xd700ff, 166 => 0xd75f00, 167 => 0xd75f5f, 168 => 0xd75f87, 169 => 0xd75faf,
+    170 => 0xd75fd7, 171 => 0xd75fff, 172 => 0xd78700, 173 => 0xd7875f, 174 => 0xd78787,
+    175 => 0xd787af, 176 => 0xd787d7, 177 => 0xd787ff, 178 => 0xd7af00, 179 => 0xd7af5f,
+    180 => 0xd7af87, 181 => 0xd7afaf, 182 => 0xd7afd7, 183 => 0xd7afff, 184 => 0xd7d700,
+    185 => 0xd7d75f, 186 => 0xd7d787, 187 => 0xd7d7af, 188 => 0xd7d7d7, 189 => 0xd7d7ff,
+    190 => 0xd7ff00, 191 => 0xd7ff5f, 192 => 0xd7ff87, 193 => 0xd7ffaf, 194 => 0xd7ffd7,
+    195 => 0xd7ffff, 196 => 0xff0000, 197 => 0xff005f, 198 => 0xff0087, 199 => 0xff00af,
+    200 => 0xff00d7, 201 => 0xff00ff, 202 => 0xff5f00, 203 => 0xff5f5f, 204 => 0xff5f87,
+    205 => 0xff5faf, 206 => 0xff5fd7, 207 => 0xff5fff, 208 => 0xff8700, 209 => 0xff875f,
+    210 => 0xff8787, 211 => 0xff87af, 212 => 0xff87d7, 213 => 0xff87ff, 214 => 0xffaf00,
+    215 => 0xffaf5f, 216 => 0xffaf87, 217 => 0xffafaf, 218 => 0xffafd7, 219 => 0xffafff,
+    220 => 0xffd700, 221 => 0xffd75f, 222 => 0xffd787, 223 => 0xffd7af, 224 => 0xffd7d7,
+    225 => 0xffd7ff, 226 => 0xffff00, 227 => 0xffff5f, 228 => 0xffff87, 229 => 0xffffaf,
+    230 => 0xffffd7, 231 => 0xffffff, 232 => 0x080808, 233 => 0x121212, 234 => 0x1c1c1c,
+    235 => 0x262626, 236 => 0x303030, 237 => 0x3a3a3a, 238 => 0x444444, 239 => 0x4e4e4e,
+    240 => 0x585858, 241 => 0x626262, 242 => 0x6c6c6c, 243 => 0x767676, 244 => 0x808080,
+    245 => 0x8a8a8a, 246 => 0x949494, 247 => 0x9e9e9e, 248 => 0xa8a8a8, 249 => 0xb2b2b2,
+    250 => 0xbcbcbc, 251 => 0xc6c6c6, 252 => 0xd0d0d0, 253 => 0xdadada, 254 => 0xe4e4e4,
+    255 => 0xeeeeee)
+
+"""
+A mapping from old named colours to the new names, specifically from `light_*`
+to `bright_*`.
+"""
+const RENAMED_COLORS = Dict{Symbol, Symbol}(
+    :light_black => :bright_black,
+    :light_red => :bright_red,
+    :light_green => :bright_green,
+    :light_yellow => :bright_yellow,
+    :light_blue => :bright_blue,
+    :light_magenta => :bright_magenta,
+    :light_cyan => :bright_cyan,
+    :light_white => :bright_white)
+
+legacy_color(color::Symbol) = SimpleColor(get(RENAMED_COLORS, color, color))
+function legacy_color(color256::Int)
+    if 0 <= color256 <= 256
+        SimpleColor(ANSI_256_COLORS[color256])
+    else
+        nothing
+    end
+end
+
+"""
+    legacy_color(color::Union{String, Symbol, Int})
+
+Attempt to obtain a `SimpleColor` for a "legacy" color value `color`.
+
+When this is not possible, `nothing` is returned.
+"""
+function legacy_color(color::String)
+    namedcolours = ("black", "red", "green", "yellow", "blue", "magenta", "cyan", "white",
+                    "bright_black", "grey", "gray", "bright_red", "bright_green", "bright_yellow",
+                    "bright_blue", "bright_magenta", "bright_cyan", "bright_white",
+                    "light_black", "light_red", "light_green", "light_yellow",
+                    "light_blue", "light_magenta", "light_cyan", "light_white")
+    if color in namedcolours
+        legacy_color(Symbol(namedcolours))
+    elseif 0 <= (color256 = something(tryparse(Int, ecolor), -1)) <= 255
+        legacy_color(color256)
+    else
+        nothing
+    end
+end
+
+"""
+    load_env_colors!()
+
+Try to emulate the effect of the various `*_color()` functions of `Base`, by
+loading any specified colours as foregrounds of the relevant faces.
+"""
+function load_env_colors!()
+    for (fname, envkey) in ((:error, "JULIA_ERROR_COLOR"),
+                            (:warn, "JULIA_WARN_COLOR"),
+                            (:info, "JULIA_INFO_COLOR"),
+                            (:log_debug, "JULIA_DEBUG_COLOR"))
+        if haskey(ENV, envkey)
+            ecolor = legacy_color(ENV[envkey])
+            if !isnothing(ecolor)
+                loadface!(fname => Face(foreground = ecolor))
+            end
+        end
+    end
+end
+
+end