clj-commons.ansi
Help with generating textual output that includes ANSI escape codes for formatting.
The compose function is the best starting point.
Reference: ANSI Escape Codes @ Wikipedia.
Help with generating textual output that includes ANSI escape codes for formatting. The [[compose]] function is the best starting point. Reference: [ANSI Escape Codes @ Wikipedia](https://en.wikipedia.org/wiki/ANSI_escape_code#SGR).
*color-enabled*clj
Determines if ANSI colors are enabled; color is a deliberate misnomer, as we lump other font characteristics (bold, underline, italic, etc.) along with colors.
This will be false if the environment variable NO_COLOR is non-blank.
Otherwise, the JVM system property clj-commons.ansi.enabled (if present) determines
the value; "true" enables colors, any other value disables colors.
If the property is null, then the default is a best guess based on the environment:
if either the nrepl.core namespace is present, or the JVM has a console (via (System/console)),
then color will be enabled.
The nrepl.core check has been verified to work with Cursive, with lein repl, and with clojure (or clj).
Determines if ANSI colors are enabled; color is a deliberate misnomer, as we lump other font characteristics (bold, underline, italic, etc.) along with colors. This will be false if the environment variable NO_COLOR is non-blank. Otherwise, the JVM system property `clj-commons.ansi.enabled` (if present) determines the value; "true" enables colors, any other value disables colors. If the property is null, then the default is a best guess based on the environment: if either the `nrepl.core` namespace is present, or the JVM has a console (via `(System/console)`), then color will be enabled. The nrepl.core check has been verified to work with Cursive, with `lein repl`, and with `clojure` (or `clj`).
composeclj
(compose & inputs)Given a Hiccup-inspired data structure, composes and returns a string that includes ANSI formatting codes for font color and other characteristics.
The data structure may consist of literal values (strings, numbers, etc.) that are formatted
with str and concatenated.
Nested sequences are composed recursively; this (for example) allows the output from
map or for to be mixed into the composed string seamlessly.
Nested vectors represent spans, a sequence of values with a specific visual representation. The first element in a span vector declares the visual properties of the span: the color (including other characteristics such as bold or underline), and the width and padding (described later). Spans may be nested.
The declaration is usually a keyword, to define just the font. The font def contains one or more terms, separated by periods.
The terms:
| Characteristic | Values |
|---|---|
| foreground color | red or bright-red (for each color) |
| background color | same as foreground color, with a -bg suffix (e.g., red-bg) |
| boldness | bold, faint, or plain |
| italics | italic or roman |
| inverse | inverse or normal |
| underline | underlined or not-underlined |
e.g.
(compose [:yellow "Warning: the " [:bold.bright-white.bright-red-bg "reactor"]
" is about to "
[:italic.bold.red "meltdown!"]])
=> ...
The order of the terms does not matter. Behavior for conflicting terms (e.g., :blue.green.black)
is not defined.
Font defs apply on top of the font def of the enclosing span, and the outer span's font def
is restored at the end of the inner span, e.g. [:red " RED " [:bold "RED/BOLD"] " RED "].
A font def may also be nil, to indicate no change in font.
compose presumes that on entry the current font is plain (default foreground and background, not bold,
or inverse, or italic, or underlined) and appends a reset sequence to the end of the returned string to
ensure that later output is also plain.
The core colors are black, red, green, yellow, blue, magenta, cyan, and white.
When *color-enabled* is false, then any font defs are validated, but otherwise ignored (no ANSI codes
will be included in the composed string).
The span's font declaration may also be a map with the following keys:
| Key | Type | Description |
|---|---|---|
| :font | keyword | The font declaration |
| :width | number | The visual width of the span |
| :pad | keyword | Where to pad the span, :left, :right, or :both; default is :left |
The map form of the font declaration is typically only used when a span width is specified.
The span will be padded with spaces to ensure that it is the specified width. compose tracks the number
of characters inside the span, excluding any ANSI code sequences injected by compose.
Padding adds spaces; thus aligning the text on the left means padding on the right, and vice-versa.
Setting the padding to :both will add spaces to both the left and the right; the content will be centered. If the necessary amount of padding is odd, the extra space will appear on the left.
compose doesn't consider the characters when calculating widths;
if the strings contain tabs, newlines, or ANSI code sequences not generated by compose,
the calculation of the span width will be incorrect.
Example:
[{:font :red
:width 20} message]
This will output the value of message in red text, padded with spaces on the left to be 20 characters.
compose does not truncate a span to a width, it only pads if the span in too short.
Given a Hiccup-inspired data structure, composes and returns a string that includes ANSI formatting codes
for font color and other characteristics.
The data structure may consist of literal values (strings, numbers, etc.) that are formatted
with `str` and concatenated.
Nested sequences are composed recursively; this (for example) allows the output from
`map` or `for` to be mixed into the composed string seamlessly.
Nested vectors represent _spans_, a sequence of values with a specific visual representation.
The first element in a span vector declares the visual properties of the span: the color (including
other characteristics such as bold or underline), and the width and padding (described later).
Spans may be nested.
The declaration is usually a keyword, to define just the font.
The font def contains one or more terms, separated by periods.
The terms:
Characteristic | Values
--- |---
foreground color | `red` or `bright-red` (for each color)
background color | same as foreground color, with a `-bg` suffix (e.g., `red-bg`)
boldness | `bold`, `faint`, or `plain`
italics | `italic` or `roman`
inverse | `inverse` or `normal`
underline | `underlined` or `not-underlined`
e.g.
```
(compose [:yellow "Warning: the " [:bold.bright-white.bright-red-bg "reactor"]
" is about to "
[:italic.bold.red "meltdown!"]])
=> ...
```
The order of the terms does not matter. Behavior for conflicting terms (e.g., `:blue.green.black`)
is not defined.
Font defs apply on top of the font def of the enclosing span, and the outer span's font def
is restored at the end of the inner span, e.g. `[:red " RED " [:bold "RED/BOLD"] " RED "]`.
A font def may also be nil, to indicate no change in font.
`compose` presumes that on entry the current font is plain (default foreground and background, not bold,
or inverse, or italic, or underlined) and appends a reset sequence to the end of the returned string to
ensure that later output is also plain.
The core colors are `black`, `red`, `green`, `yellow`, `blue`, `magenta`, `cyan`, and `white`.
When [[*color-enabled*]] is false, then any font defs are validated, but otherwise ignored (no ANSI codes
will be included in the composed string).
The span's font declaration may also be a map with the following keys:
Key | Type | Description
--- |--- |---
:font | keyword | The font declaration
:width | number | The visual width of the span
:pad | keyword | Where to pad the span, :left, :right, or :both; default is :left
The map form of the font declaration is typically only used when a span width is specified.
The span will be padded with spaces to ensure that it is the specified width. `compose` tracks the number
of characters inside the span, excluding any ANSI code sequences injected by `compose`.
Padding adds spaces; thus aligning the text on the left means padding on the right, and vice-versa.
Setting the padding to :both will add spaces to both the left and the right; the content will be centered.
If the necessary amount of padding is odd, the extra space will appear on the left.
`compose` doesn't consider the characters when calculating widths;
if the strings contain tabs, newlines, or ANSI code sequences not generated by `compose`,
the calculation of the span width will be incorrect.
Example:
[{:font :red
:width 20} message]
This will output the value of `message` in red text, padded with spaces on the left to be 20 characters.
`compose` does not truncate a span to a width, it only pads if the span in too short.pcomposeclj
(pcompose & inputs)Composes its inputs as with compose and then prints the results, with a newline.
Composes its inputs as with [[compose]] and then prints the results, with a newline.
perrclj
(perr & inputs)Composes its inputs as with compose and then prints the result with a newline to *err*.
Composes its inputs as with [[compose]] and then prints the result with a newline to `*err*`.
when-color-enabledcljmacro
(when-color-enabled & body)Evaluates its body only when *color-enabled* is true.
Evaluates its body only when [[*color-enabled*]] is true.
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