planning

node_modules/@mapbox/mapbox-gl-style-spec/expression/definitions/length.js

@@ -0,0 +1,61 @@
+// @flow
+
+import {NumberType, toString} from '../types.js';
+
+import {typeOf} from '../values.js';
+import RuntimeError from '../runtime_error.js';
+
+import type {Expression, SerializedExpression} from '../expression.js';
+import type ParsingContext from '../parsing_context.js';
+import type EvaluationContext from '../evaluation_context.js';
+import type {Type} from '../types.js';
+
+class Length implements Expression {
+    type: Type;
+    input: Expression;
+
+    constructor(input: Expression) {
+        this.type = NumberType;
+        this.input = input;
+    }
+
+    static parse(args: $ReadOnlyArray<mixed>, context: ParsingContext): ?Length {
+        if (args.length !== 2)
+            return context.error(`Expected 1 argument, but found ${args.length - 1} instead.`);
+
+        const input = context.parse(args[1], 1);
+        if (!input) return null;
+
+        if (input.type.kind !== 'array' && input.type.kind !== 'string' && input.type.kind !== 'value')
+            return context.error(`Expected argument of type string or array, but found ${toString(input.type)} instead.`);
+
+        return new Length(input);
+    }
+
+    evaluate(ctx: EvaluationContext): any | number {
+        const input = this.input.evaluate(ctx);
+        if (typeof input === 'string') {
+            return input.length;
+        } else if (Array.isArray(input)) {
+            return input.length;
+        } else {
+            throw new RuntimeError(`Expected value to be of type string or array, but found ${toString(typeOf(input))} instead.`);
+        }
+    }
+
+    eachChild(fn: (_: Expression) => void) {
+        fn(this.input);
+    }
+
+    outputDefined(): boolean {
+        return false;
+    }
+
+    serialize(): SerializedExpression {
+        const serialized = ["length"];
+        this.eachChild(child => { serialized.push(child.serialize()); });
+        return serialized;
+    }
+}
+
+export default Length;