Add abs, round, floor, ceil operators (#11653)

* Add abs, round, floor, ceil operators

Port of https://github.com/mapbox/mapbox-gl-js/pull/6496

* [ios, macos] Simplified abs, ceiling, floor expressions

* [ios, macos] Added rounding expression function

* [android] - binding integration for round, ceil, floor and abs expressions

* Update mapbox-gl-js to include non-integer rounding test

* Drop extra braces

* mapbox-gl-js -> master

* Update style-spec docs -> PropertyFactory.java

1 files changed, 1 insertions, 0 deletions

diff --git a/platform/darwin/docs/guides/Predicates and Expressions.md b/platform/darwin/docs/guides/Predicates and Expressions.md
index 13204b09a6..1b8714811d 100644
--- a/platform/darwin/docs/guides/Predicates and Expressions.md
+++ b/platform/darwin/docs/guides/Predicates and Expressions.md
@@ -196,6 +196,7 @@ Initializer parameter | Format string syntax | Description
 `mgl_interpolate:withCurveType:parameters:stops:` | `mgl_interpolate:withCurveType:parameters:stops:(x, 'linear', nil, %@)` | Produces continuous, smooth results by interpolating between pairs of input and output values (“stops”). Compared to the `mgl_interpolateWithCurveType:parameters:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
 `mgl_step:from:stops:` | `mgl_step:from:stops:(x, 11, %@)` | Produces discrete, stepped results by evaluating a piecewise-constant function defined by pairs of input and output values ("stops"). Compared to the `mgl_stepWithMinimum:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
 `mgl_join:` | `mgl_join({'Old', 'MacDonald'})` | Returns the result of concatenating together all the elements of an array in order. Compared to the `stringByAppendingString:` custom function, this function takes only one argument, which is an aggregate expression containing the strings to concatenate.
+`mgl_round:` | `mgl_round(1.5)` | Returns the number rounded to the nearest integer. If the number is halfway between two integers, this function rounds it away from zero.
 `mgl_coalesce:` | `mgl_coalesce({x, y, z})` | Returns the first non-`nil` value from an array of expressions.
 `MGL_LET` | `MGL_LET('age', uppercase('old'), 'name', uppercase('MacDonald'), mgl_join({$age, $name}))` | Any number of variable names interspersed with their assigned `NSExpression` values, followed by an `NSExpression` that may contain references to those variables. Compared to the `mgl_expressionWithContext:` custom function, this function takes the variable names and values inline before the expression that contains references to those variables.
 `MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')` | Evaluates the first expression and returns the value that matches the initial condition. After the first expression condition a pair of matching/return value should be added and a default value.