Add support for unit in NumberFormat

src/style-spec/expression/definitions/number_format.js

@@ -28,8 +28,9 @@ declare class Intl$NumberFormat {
 }
 
 type NumberFormatOptions = {
-    style?: 'decimal' | 'currency' | 'percent';
+    style?: 'decimal' | 'currency' | 'percent' | 'unit';
     currency?: null | string;
+    unit?: null | string;
     minimumFractionDigits?: null | string;
     maximumFractionDigits?: null | string;
 };
@@ -39,18 +40,21 @@ export default class NumberFormat implements Expression {
     number: Expression;
     locale: Expression | null;   // BCP 47 language tag
     currency: Expression | null; // ISO 4217 currency code, required if style=currency
+    unit: Expression | null;     // Simple units sanctioned for use in ECMAScript, required if style=unit. https://tc39.es/proposal-unified-intl-numberformat/section6/locales-currencies-tz_proposed_out.html#sec-issanctionedsimpleunitidentifier
     minFractionDigits: Expression | null; // Default 0
     maxFractionDigits: Expression | null; // Default 3
 
     constructor(number: Expression,
                 locale: Expression | null,
                 currency: Expression | null,
+                unit: Expression | null,
                 minFractionDigits: Expression | null,
                 maxFractionDigits: Expression | null) {
         this.type = StringType;
         this.number = number;
         this.locale = locale;
         this.currency = currency;
+        this.unit = unit;
         this.minFractionDigits = minFractionDigits;
         this.maxFractionDigits = maxFractionDigits;
     }
@@ -78,6 +82,12 @@ export default class NumberFormat implements Expression {
             if (!currency) return null;
         }
 
+        let unit = null;
+        if (options['unit']) {
+            unit = context.parse(options['unit'], 1, StringType);
+            if (!unit) return null;
+        }
+
         let minFractionDigits = null;
         if (options['min-fraction-digits']) {
             minFractionDigits = context.parse(options['min-fraction-digits'], 1, NumberType);
@@ -90,14 +100,18 @@ export default class NumberFormat implements Expression {
             if (!maxFractionDigits) return null;
         }
 
-        return new NumberFormat(number, locale, currency, minFractionDigits, maxFractionDigits);
+        return new NumberFormat(number, locale, currency, unit, minFractionDigits, maxFractionDigits);
     }
 
     evaluate(ctx: EvaluationContext): string {
         return new Intl.NumberFormat(this.locale ? this.locale.evaluate(ctx) : [],
             {
-                style: this.currency ? "currency" : "decimal",
+                style:
+                    (this.currency && "currency") ||
+                    (this.unit && "unit") ||
+                    "decimal",
                 currency: this.currency ? this.currency.evaluate(ctx) : undefined,
+                unit: this.unit ? this.unit.evaluate(ctx) : undefined,
                 minimumFractionDigits: this.minFractionDigits ? this.minFractionDigits.evaluate(ctx) : undefined,
                 maximumFractionDigits: this.maxFractionDigits ? this.maxFractionDigits.evaluate(ctx) : undefined,
             }).format(this.number.evaluate(ctx));
@@ -111,6 +125,9 @@ export default class NumberFormat implements Expression {
         if (this.currency) {
             fn(this.currency);
         }
+        if (this.unit) {
+            fn(this.unit);
+        }
         if (this.minFractionDigits) {
             fn(this.minFractionDigits);
         }
@@ -131,6 +148,9 @@ export default class NumberFormat implements Expression {
         if (this.currency) {
             options['currency'] = this.currency.serialize();
         }
+        if (this.unit) {
+            options['unit'] = this.unit.serialize();
+        }
         if (this.minFractionDigits) {
             options['min-fraction-digits'] = this.minFractionDigits.serialize();
         }

src/style-spec/reference/v8.json

@@ -3046,7 +3046,7 @@
         }
       },
       "number-format": {
-        "doc": "Converts the input number into a string representation using the providing formatting rules. If set, the `locale` argument specifies the locale to use, as a BCP 47 language tag. If set, the `currency` argument specifies an ISO 4217 code to use for currency-style formatting. If set, the `min-fraction-digits` and `max-fraction-digits` arguments specify the minimum and maximum number of fractional digits to include.",
+        "doc": "Converts the input number into a string representation using the providing formatting rules. If set, the `locale` argument specifies the locale to use, as a BCP 47 language tag. If set, the `currency` argument specifies an ISO 4217 code to use for currency-style formatting. If set, the `unit` argument specifies a [simple ECMAScript unit](https://tc39.es/proposal-unified-intl-numberformat/section6/locales-currencies-tz_proposed_out.html#sec-issanctionedsimpleunitidentifier) to use for unit-style formatting. If set, the `min-fraction-digits` and `max-fraction-digits` arguments specify the minimum and maximum number of fractional digits to include.",
         "group": "Types",
         "sdk-support": {
           "basic functionality": {

test/integration/expression-tests/number-format/unit/test.json

@@ -0,0 +1,31 @@
+{
+  "expression": [
+    "number-format",
+    123456.789,
+    {
+        "locale": ["get", "locale"],
+        "unit": ["get", "unit"]
+    }
+  ],
+  "inputs": [
+    [{}, {"properties": {"locale": "en-US", "unit": "hectare"}}],
+    [{}, {"properties": {"locale": "en-US", "unit": "acre"}}]
+  ],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": false,
+      "isZoomConstant": true,
+      "type": "string"
+    },
+    "outputs": ["123,456.789 ha", "123,456.789 ac"],
+    "serialized": [
+      "number-format",
+      123456.789,
+      {
+          "locale": ["string", ["get", "locale"]],
+          "unit": ["string", ["get", "unit"]]
+      }
+    ]
+  }
+}