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Revert "Merge pull request sass#755 from sass/calcfunctions"
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This reverts commit 495d514, reversing
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Israel-4Ever committed Aug 17, 2023
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1 change: 0 additions & 1 deletion source/_data/documentation.yml
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- CSS Variable Syntax: /documentation/breaking-changes/css-vars/
- Duplicate Variable Flags: /documentation/breaking-changes/duplicate-var-flags/
- Default Exports: /documentation/breaking-changes/default-export/
- abs() Percentage: /documentation/breaking-changes/abs-percent/
- Command Line: /documentation/cli/
:children:
- Dart Sass: /documentation/cli/dart-sass/
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21 changes: 0 additions & 21 deletions source/documentation/breaking-changes/abs-percent.md
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4 changes: 0 additions & 4 deletions source/documentation/breaking-changes/index.md
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Expand Up @@ -22,10 +22,6 @@ time-sensitive, so they may be released with new minor version numbers instead.

These breaking changes are coming soon or have recently been released:

* [Passing a percentage unit to the global `abs()` is
  deprecated](/documentation/breaking-changes/abs-percent/) beginning in Dart
Sass 1.65.0.

* [Passing `null` as an alpha channel to `new SassColor()` is changing
behavior](/documentation/breaking-changes/null-alpha) beginning in Dart
Sass 1.64.3.
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243 changes: 39 additions & 204 deletions source/documentation/values/calculations.md
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Expand Up @@ -156,119 +156,59 @@ CSS to unitless numbers:
@debug calc(-infinity) < math.$min-number // true
{% endcodeExample %}

## Calculation Functions
## `min()` and `max()`

{% compatibility 'dart: "1.65.0"', 'libsass: false', 'ruby: false', 'feature: "Additional functions"' %}
Versions of Dart Sass subsequent to 1.65.0 handle the execution of these
calculation functions: `round()`, `mod()`, `rem()`, `sin()`, `cos()`, `tan()`,
`asin()`, `acos()`, `atan()`, `atan2()`, `pow()`, `sqrt()`, `hypot()`,
`log()`, `exp()`, `abs()`, and `sign()`.
{% endcompatibility %}

Sass parses the following functions as [calculations]:
* Comparison Functions: [`min()`], [`max()`], and [`clamp()`]
* Stepped Value Functions: [`round()`], [`mod()`], and [`rem()`].
* Trigonometric Functions: [`sin()`], [`cos()`], [`tan()`], [`asin()`], [`acos()`],
[`atan()`], and [`atan2()`].
* Exponential Functions: [`pow()`], [`sqrt()`], [`hypot()`], [`log()`], and [`exp()`].
* Sign-Related Functions: [`abs()`] and [`sign()`].

[calculations]: https://www.w3.org/TR/css-values-4/#math
[`min()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/min
[`max()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/max
[`clamp()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/clamp
[`round()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/round
[`abs()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/abs
[`sin()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/sin
[`cos()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/cos
[`tan()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/tan
[`asin()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/asin
[`acos()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/acos
[`atan()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/atan
[`atan2()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/atan2
[`pow()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/pow
[`sqrt()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/sqrt
[`hypot()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/hypot
[`log()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/log
[`exp()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/exp
[`mod()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/mod
[`rem()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/rem
[`sign()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/sign

### Legacy Global Functions

CSS added support for [mathematical expressions] in Values and Units Level
4. However, Sass supported its own [`round()`], [`abs()`], [`min()`] and
[`max()`] long before this, and it needed to be backwards-compatible with all
those existing stylesheets. This led to the need for extra-special syntactic
cleverness.

[mathematical expressions]: https://www.w3.org/TR/css-values-4/#math
[`round()`]: ../modules/math#round
[`abs()`]: ../modules/math#abs
[`min()`]: ../modules/math#min
[`max()`]: ../modules/math#max

If a call to `round()`, `abs()`, `min()`, or `max()` is a valid calculation
expression, it will be parsed as a calculation. But as soon as any part of the
call contains a SassScript feature that isn't supported in a calculation, like
the [modulo operator], it's parsed as a call to the appropriate Sass math
function instead.

Since calculations are simplified to numbers when possible anyway, the only
substantive difference is that the Sass functions only support units that can be
combined at build time, so `min(12px % 10, 10%)` will throw an error.

[modulo operator]: /documentation/operators/numeric/

{% headsUp %}
Other calculations don't allow unitless numbers to be added to, subtracted
from, or compared to numbers with units. [`min()`], [`max()`], [`abs()`] and
[single-argument `round()`] are different, though: for backwards-compatibility
with the global Sass legacy functions which allow unit/unitless mixing for
historical reasons, these units can be mixed as long as they're contained
directly within a `min()`, `max()`, `abs()`, or single-argument `round()`
calculation.

For instance, `min(5 + 10px, 20px)` will result in `15px`. However
`sqrt(5 + 10px)` will throw an error, as `sqrt(5 + 10px)` was never a global
Sass function, and these are incompatible units.

[single-argument `round()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/round
[`abs()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/abs
[`min()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/min
[`max()`]: https://developer.mozilla.org/en-US/docs/Web/CSS/max
{% endheadsUp %}

#### `min()` and `max()`

{% compatibility 'dart: ">=1.11.0 <1.42.0"', 'libsass: false', 'ruby: false', 'feature: "min and max syntax"' %}
{% compatibility 'dart: ">=1.11.0 <1.42.0"', 'libsass: false', 'ruby: false', 'feature: "Special function syntax"' %}
LibSass, Ruby Sass, and versions of Dart Sass prior to 1.11.0 *always* parse
`min()` and `max()` as Sass functions. To create a plain CSS `min()` or
`max()` call for those implementations, you can write something like
`unquote("min(#{$padding}, env(safe-area-inset-left))")` instead.

CSS added support for [`min()` and `max()` functions] in Values and Units
Level 4, from where they were quickly adopted by Safari [to support the iPhoneX].
Since we already supported `min()` and `max()` as legacy Sass functions, we
had to implement logic for backwards-compatibility and for support as CSS
functions.

Versions of Dart Sass between 1.11.0 and 1.40.0, and between 1.40.1
and 1.42.0 parse `min()` and `max()` functions as [special functions] if
they're valid plain CSS, but parse them as Sass functions if they contain Sass
features other than interpolation, like variables or function calls.
Versions of Dart Sass between 1.11.0 and 1.40.0, and between 1.40.1 and 1.42.0
parse `min()` and `max()` functions as [special functions] if they're valid
plain CSS, but parse them as Sass functions if they contain Sass features
other than interpolation, like variables or function calls.

Dart Sass 1.41.0 parses `min()` and `max()` functions as calculations, but
doesn't allow unitless numbers to be combined with numbers with units. This
was backwards-incompatible with the global `min()` and `max()` functions, so
that behavior was reverted.

[`min()` and `max()` functions]: https://www.w3.org/TR/css-values-4/#math
[to support the iPhoneX]: https://webkit.org/blog/7929/designing-websites-for-iphone-x/
[special functions]: /documentation/syntax/special-functions/
[special functions]: /documentation/syntax/special-functions
{% endcompatibility %}

CSS added support for [`min()` and `max()` functions] in Values and Units Level
4, from where they were quickly adopted by Safari [to support the iPhoneX]. But
Sass supported its own [`min()`] and [`max()`] functions long before this, and
it needed to be backwards-compatible with all those existing stylesheets. This
led to the need for extra-special syntactic cleverness.

[`min()` and `max()` functions]: https://drafts.csswg.org/css-values-4/#calc-notation
[to support the iPhoneX]: https://webkit.org/blog/7929/designing-websites-for-iphone-x/
[`min()`]: /documentation/modules/math#min
[`max()`]: /documentation/modules/math#max

If a `min()` or `max()` function call is a valid calculation expression, it will
be parsed as a calculation. But as soon as any part of the call contains a
SassScript feature that isn't supported in a calculation, like the [modulo
operator], it's parsed as a call to Sass's core `min()` or `max()` function
instead.

Since calculations are simplified to numbers when possible anyway, the only
substantive difference is that the Sass functions only support units that can be
combined at build time, so `min(12px % 10, 10%)` will throw an error.

[modulo operator]: /documentation/operators/numeric

{% headsUp %}
Other calculations don't allow unitless numbers to be added to, subtracted
from, or compared to numbers with units. `min()` and `max()` are different,
though: for backwards-compatibility with the global Sass `min()` and `max()`
functions which allow unit/unitless mixing for historical reasons, these units
can be mixed as long as they're contained directly within a `min()` or `max()`
calculation.
{% endheadsUp %}

{% codeExample 'min-max' %}
$padding: 12px;

Expand All @@ -285,7 +225,6 @@ combined at build time, so `min(12px % 10, 10%)` will throw an error.
padding-left: max($padding % 10, 20px);
padding-right: max($padding % 10, 20px);
}

===
$padding: 12px

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// SassScript function calls.
padding-left: max($padding % 10, 20px)
padding-right: max($padding % 10, 20px)

===
.post {
padding-left: max(12px, env(safe-area-inset-left));
padding-right: max(12px, env(safe-area-inset-right));
}

.sidebar {
padding-left: 20px;
padding-right: 20px;
}
{% endcodeExample %}

#### `round()`

{% compatibility 'dart: "1.65.0"', 'libsass: false', 'ruby: false', 'feature: "min and max syntax"' %}
LibSass, Ruby Sass, and versions of Dart Sass prior to 1.65.0 *always* parse
`round()` as a Sass function. To create a plain CSS calculation for those
implementations, you can write something like
`round(#{$strategy, $number, $step})` instead.
{% endcompatibility %}

The [`round(<strategy>, number, step)`] function accepts an optional rounding
strategy, a value to be rounded and a rounding interval `step`. `strategy`
should be `nearest`, `up`, `down`, or `to-zero`.

[`round(<strategy>, number, step)`]: https://developer.mozilla.org/en-US/docs/Web/CSS/round#parameter

{% codeExample 'round' %}
$number: 12.5px;
$step: 15px;

.post-image {
// Since these round() calls are valid calculation expressions, they're
// parsed as calculations.
padding-left: round(nearest, $number, $step);
padding-right: round($number + 10px);
padding-bottom: round($number + 10px, $step + 10%);
}

===
$number: 12.5px
$step: 15px

.post-image
// Since these round() calls are valid calculation expressions, they're
// parsed as calculations.
padding-left: round(nearest, $number, $step)
padding-right: round($number + 10px)
padding-bottom: round($number + 10px, $step + 10%)

===
.post-image {
padding-left: 15px;
padding-right: 23px;
padding-bottom: round(22.5px, 15px + 10%);
}
{% endcodeExample %}

#### `abs()`

{% compatibility 'dart: "1.65.0"', 'libsass: false', 'ruby: false', 'feature: "min and max syntax"' %}
LibSass, Ruby Sass, and versions of Dart Sass prior to 1.65.0 *always* parse
`abs()` as a Sass function. To create a plain CSS calculation for those
implementations, you can write something like `abs(#{$number})` instead.
{% endcompatibility %}

{% headsUp %}
The global `abs()` function compatibiliy with [% unit parameters is deprecated].
In the future, this will emit a CSS abs() function to be resolved by the browser.

[% unit parameters is deprecated]: /documentation/breaking-changes/abs-percent/
{% endheadsUp %}

The [`abs(value)`] takes in a single expressiona as a parameter and returns the
absolute value of `$value`. If `$value` is negative, this returns `-$value`, and if
`$value` is positive, it returns `$value` as-is.

[`abs(value)`]: https://developer.mozilla.org/en-US/docs/Web/CSS/abs

{% codeExample 'abs' %}
.post-image {
// Since these abs() calls are valid calculation expressions, they're
// parsed as calculations.
padding-left: abs(10px);
padding-right: math.abs(-7.5%);
padding-top: abs(1 + 1px);
}

===
.post-image
// Since these abs() calls are valid calculation expressions, they're
// parsed as calculations.
padding-left: abs(-10px)
padding-right: math.abs(-7.5%)
padding-top: abs(1 + 1px)

===
.post-image {
padding-left: 10px;
padding-right: 7.5%;
padding-top: 2px;
}

{% endcodeExample %}

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