Nim

在 Nim 中使用 ANSI 转义码 —— std/terminal、\e、十进制 \27

Nim 的标准库 `std/terminal` 是任何编译型语言中最全面的、开箱即用的终端模块 —— 一次 import 就拥有 SGR 颜色（`setForegroundColor(fgRed)`）、文本样式（`setStyle({styleBright, styleUnderscore})`）、通过 `Color(...)` 的 256-palette、truecolor（需要显式 `enableTrueColors()` 启用）、光标定位、清屏、终端大小查询、raw-mode 切换、isatty 检查 —— 全在一个地方。多数应用的依赖列表到此为止。字符串字面量形式：Nim 接受 `"\e"`（ESC 命名转义）、`"\x1b"`（十六进制，恰好 2 位）、`"\u001b"`（4 位 Unicode）、`"\u{1b}"`（变长 Unicode）。**Nim 的妙处** —— 也是本页的主要 SERP 差异化 —— 在于 `"\NNN"` 是**十进制**，不像所有 C 族语言那样是八进制。Nim 中 `"\27"` 是字节 27（ESC）；同一字面量在 C、Crystal、Python、Ruby 中是字节 `\002` 后跟字符 `'7'`。若你正从其他语言移植 ANSI 代码而 `"\033[31m"` 抛出解析错误，修复方法是 `"\27[31m"`（十进制）或 `"\x1b[31m"`（十六进制）或 —— 最可读 —— `"\e[31m"`。 `std/terminal` 之外选用：**`std/colors`**（标准库颜色名表 —— `colWhite`、`colAliceBlue`，完整 HTML/CSS 调色板作为 `Color` 常量，搭配 `enableTrueColors()` 从命名常量发出 `38;2;R;G;B`）；**`chronicles`**（status-im 的结构化日志库 —— Nim 规范日志库，开箱即用 ANSI 着色主题 / 级别 / 时间戳格式化，被所有 Nim 以太坊 / 区块链栈使用）；**`illwill`**（johnnovak 的无 curses TUI 库 —— Nim 对 ncurses 的现代回答，自带 ANSI 后端，与 `std/terminal` 干净组合用于非全屏输出）。能力门控：`std/terminal` 的 `isatty(stdout)` 在 stdout 重定向时返回 `false`。搭配 `getEnv("NO_COLOR")` 处理通用退出、`getEnv("FORCE_COLOR")` 处理强制启用。Windows VT 模式：`std/terminal` 在首次使用任何颜色辅助时自动用 `ENABLE_VIRTUAL_TERMINAL_PROCESSING` 调用 `SetConsoleMode`，所以你不需要在颜色调用周围加 `when defined(windows)` 门 —— Nim 处理它。Windows 10 1709 之前的构建（无 VT 支持的 Conhost）回退到直接 Win32 console-API 颜色调用，对你的代码透明。

常用写法

直接 stdout.write 配合 \e —— 以及 \NNN-是-十进制的 Nim 妙处

# Nim accepts four ESC forms in "..." literals.
# Pick whichever your team reads fastest — all four
# compile to the same single byte (0x1b = 27).
#
#   "\e"      — ESC named escape (most readable)
#   "\27"    — \NNN is DECIMAL (the Nim twist!)
#   "\x1b"   — hex (exactly 2 digits)
#   "\u001b" — Unicode 4-digit
#
# THE NIM TWIST: \NNN is DECIMAL — not octal like C,
# Crystal, Python, Ruby, etc. Nim's "\27" is byte 27.
# C's "\27" is byte \002 followed by character '7'.
# Porting from C? "\033" won't compile — use "\27"
# (decimal), "\x1b" (hex), or — best — "\e".

stdout.write "\e[1;31merror:\e[0m permission denied\n"
stdout.write "\27[33mwarn:\27[0m deprecated flag\n"
stdout.write "\x1b[32mok:\x1b[0m 142 tests passed\n"
stdout.write "\u001b[36minfo:\u001b[0m skipping cache\n"

# echo writes to stdout and adds a newline:
echo "\e[38;2;255;128;0morange truecolor\e[0m"
echo "\e[38;5;196m256-palette bright red\e[0m"

# Reusable helper — no stdlib needed:
proc esc(sgr, text: string): string =
  "\e[" & sgr & "m" & text & "\e[0m"

echo esc("1;31", "FATAL"), " server crashed"
echo esc("32",   "ok:"),   " 142 tests passed"
echo esc("38;2;255;128;0", "truecolor orange")

std/terminal —— setForegroundColor、styledEcho、truecolor 开启

# Ships with every Nim install.
import std/terminal

# Basic SGR — fgRed/fgGreen/fgYellow/fgBlue/fgMagenta/fgCyan/fgWhite,
# bgRed/bgGreen/...; styleBright/styleDim/styleItalic/
# styleUnderscore/styleBlink/styleReverse/styleHidden/
# styleStrikethrough.
setForegroundColor(fgRed)
setStyle({styleBright})
stdout.write "error: "
resetAttributes()
echo "permission denied"

# styledEcho — one-liner, auto-reset, accepts an
# interleaved sequence of styles + strings:
styledEcho(fgGreen, styleBright, "ok: ", resetStyle, "142 tests passed")
styledEcho(fgYellow, "warn: ", resetStyle, "deprecated flag")
styledEcho(bgYellow, fgBlack, " CAUTION ", resetStyle, " brakes wet")

# 256-palette — Color() with a 0..255 index requires
# enableTrueColors() first (it switches stdout to the
# extended-color back end):
enableTrueColors()
for n in countup(0, 255, 16):
  setForegroundColor(stdout, Color(n shl 16 or n shl 8 or n))
  stdout.write n, " "
resetAttributes()
echo ""

# Truecolor — Color() built from 0xRRGGBB:
setForegroundColor(stdout, Color(0xFF8000))   # orange
echo "hot orange truecolor"
setForegroundColor(stdout, Color(0x006E82))   # deep teal
setStyle({styleBright})
echo "deep teal bold"
resetAttributes()

# Cursor + screen helpers — same module:
hideCursor()
setCursorPos(0, 0)
eraseScreen()
showCursor()

std/colors + chronicles —— 命名颜色表与结构化日志

# std/colors — 147 HTML/CSS named colours as Color
# constants; combine with std/terminal for readable output.
import std/[terminal, colors]

enableTrueColors()

# Named CSS colours as readable constants:
setForegroundColor(stdout, colCornflowerBlue)
echo "cornflower blue heading"
setForegroundColor(stdout, colTomato)
echo "tomato red error"
setForegroundColor(stdout, colMediumSeaGreen)
echo "medium sea green ok"

# parseColor() — read hex strings at runtime
# (e.g. from config files):
setForegroundColor(stdout, parseColor("#ff8000"))
echo "from hex string"

# mix() — interpolate between two colours,
# useful for gradient-coloured output:
let a = colRed
let b = colYellow
for t in 0..10:
  setForegroundColor(stdout, mix(a, b, t.float / 10.0))
  stdout.write "█"
resetAttributes()
echo ""

# ─── chronicles structured logging ───
# nimble install chronicles
import chronicles

# Compile-time topic filter — disabled topics cost zero
# at runtime. Enable via -d:chronicles_enabled_topics=...
logScope:
  topics = "api"
  service = "users"

info "request received", method = "GET", path = "/users/42"
warn "slow query",       ms = 1240, table = "users"
error "auth failed",     user_id = 42, reason = "expired_token"

# Output on a TTY:
#   INF 2026-05-19 22:01:15.123 request received  topics="api" ...
# Output piped to a file: plain JSON, no escapes.
# Auto-detection — no config needed.

能力门控 + illwill TUI —— isatty、NO_COLOR、双缓冲绘制

# Capability gating in Nim:
#   isatty(stdout)        — std/terminal, returns false when
#                            stdout is piped/redirected
#   getEnv("NO_COLOR")    — universal opt-out env var
#   getEnv("FORCE_COLOR") — universal opt-in env var
#
# std/terminal auto-enables Windows VT on first colour call,
# so you do NOT need a "when defined(windows)" gate around
# your setForegroundColor calls — Nim handles it.

import std/[terminal, os]

proc ansiCapable(): bool =
  if existsEnv("NO_COLOR"):    return false
  if existsEnv("FORCE_COLOR"): return true
  isatty(stdout)

proc styled(text, sgr: string): string =
  if ansiCapable(): "\e[" & sgr & "m" & text & "\e[0m"
  else: text

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

# ─── illwill — pure-Nim TUI, no ncurses ───
# nimble install illwill
import illwill

proc exitProc() {.noconv.} =
  illwillDeinit()
  showCursor()
  quit(0)

illwillInit(fullscreen = true)
setControlCHook(exitProc)
hideCursor()

var tb = newTerminalBuffer(terminalWidth(), terminalHeight())

while true:
  tb.clear()
  tb.write(2, 1, fgYellow, "illwill demo — q to quit",
                  resetStyle)
  tb.write(2, 3, fgGreen,  "✓ ok       ", resetStyle, "142 tests passed")
  tb.write(2, 4, fgRed,    "✗ FAIL     ", resetStyle, "3 tests failed")
  tb.write(2, 5, fgCyan,   "ℹ info     ", resetStyle, "skipping cache")
  tb.display()

  let key = getKey()
  case key
  of Key.Q, Key.Escape: exitProc()
  else: discard

  sleep(20)

在 Nim 中使用 ANSI 转义码 —— std/terminal、\e、十进制 \27

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