在 Julia 中使用 ANSI 转义码 —— \e、printstyled、Crayons.jl

# Julia supports \e (backslash-e), \x1b (hex), \033 (octal),
# and \u1b (Unicode) in string literals — all parse to byte 27.
# \e reads cleanest; pick whichever you prefer.

println("\e[1;31merror:\e[0m permission denied")
println("\e[33mwarn:\e[0m deprecated flag")
println("\e[32mok:\e[0m 142 tests passed")

# Truecolor — 38;2;R;G;B
println("\e[38;2;255;128;0morange truecolor\e[0m")

# Idiomatic Julia: printstyled wraps the bytes for you.
printstyled("error: "; color = :red, bold = true)
println("permission denied")
printstyled("warn: "; color = :yellow);  println("deprecated flag")
printstyled("ok: ";   color = :green);   println("142 tests passed")

# 256-colour — integer 0-255:
printstyled("orange (256-palette)\n"; color = 208)

# Truecolor — (r, g, b) tuple:
printstyled("orange (truecolor)\n"; color = (255, 128, 0))

# Underline + bold + reverse all compose as keyword args:
printstyled("FATAL\n"; color = :red, bold = true, reverse = true)

# import Pkg; Pkg.add("Crayons")
using Crayons

# A Crayon is a reusable style; print(c, "x") applies it,
# print(Crayon(reset = true), ...) returns to default.
red = Crayon(foreground = :red, bold = true)
print(red, "error: ")
println(Crayon(reset = true), "permission denied")

# Compose via * — combine attributes into a single Crayon:
heading = Crayon(foreground = :blue, bold = true) * Crayon(underline = true)
println(heading, "Section 1", Crayon(reset = true))

# Box wraps content with start + reset bytes automatically:
println(Box("warm orange"; foreground = (255, 128, 0)))

# 256-palette — pass an Int 0-255:
println(Crayon(foreground = 208), "orange256", Crayon(reset = true))

# Background colour (named symbol):
println(
  Crayon(background = :yellow, foreground = :black),
  " CAUTION ",
  Crayon(reset = true),
  " brakes wet",
)

# String-interpolation friendly — Crayons stringify cleanly:
status = string(Crayon(foreground = :green), "PASS", Crayon(reset = true))
println("build: $(status)")

# Base.have_color is set at Julia startup from --color=:
#   --color=auto (default): true when stdout is a TTY AND
#                           $NO_COLOR is unset
#   --color=yes / true:      always true (force-enable)
#   --color=no  / false:     always false (force-disable)
#
# Julia handles automatically:
#   - Piping stdout to a file → have_color = false
#   - $NO_COLOR set           → have_color = false
#
# CRUCIAL Jupyter / Pluto caveat: have_color = false in
# notebook front-ends — ANSI passes through as raw text.
# Switch to HTML / MIME-typed display there:
#
#   display("text/html", "<span style='color:red'>err</span>")

function styled(text::AbstractString, sgr::AbstractString)
    Base.have_color || return text
    return "\e[$(sgr)m$(text)\e[0m"
end

# Roll your own check when you don't want to depend on the
# startup flag — useful in libraries that may run under
# IOContext wrappers that reset have_color:
function ansi_capable(io::IO = stdout)
    haskey(ENV, "NO_COLOR") && return false
    return get(io, :color, false) === true || isa(io, Base.TTY)
end

println(styled("OK",   "32"))
println(styled("FAIL", "1;31"))

# Force-enable in scripts where capture wrapper resets have_color
# (e.g. tests with IOBuffer):
let buf = IOBuffer()
    ctx = IOContext(buf, :color => true)
    printstyled(ctx, "captured red\n"; color = :red)
    println(String(take!(buf)))   # contains real \e[31m bytes
end

# To force colour on at startup:  julia --color=yes script.jl

# stdlib — no Pkg.add needed.
using REPL.TerminalMenus

# Single-select arrow-key menu — same API Pkg.jl uses.
choice = request(
    "Pick a build profile:",
    RadioMenu(
        ["debug", "release", "release-with-debug-info"];
        pagesize = 5,
    ),
)
println("selected: ", choice)   # 1-based index; -1 if cancelled

# Multi-select: SPACE toggles, ENTER confirms, q/Ctrl-C cancels.
picks = request(
    "Pick test groups (space to toggle, enter to confirm):",
    MultiSelectMenu(
        ["unit", "integration", "e2e", "perf"];
        pagesize = 5,
    ),
)
println("selected: ", picks)    # Set{Int}, 1-based indices

# Menus emit raw ANSI — they work in every TTY-attached
# Julia REPL but NOT under IJulia / Pluto (no raw-mode stdin).
# Guard with isinteractive() + isa(stdin, Base.TTY) before
# calling request() in library code.