@mapbox/mapbox-gl-style-spec
Version:
a specification for mapbox gl styles
68 lines (51 loc) • 2.14 kB
text/typescript
import {array, ValueType, NumberType} from '../types';
import RuntimeError from '../runtime_error';
import type {Expression, SerializedExpression} from '../expression';
import type ParsingContext from '../parsing_context';
import type EvaluationContext from '../evaluation_context';
import type {Type, ArrayType} from '../types';
import type {Value} from '../values';
class At implements Expression {
type: Type;
index: Expression;
input: Expression;
constructor(type: Type, index: Expression, input: Expression) {
this.type = type;
this.index = index;
this.input = input;
}
static parse(args: ReadonlyArray<unknown>, context: ParsingContext): At | null | void {
if (args.length !== 3)
return context.error(`Expected 2 arguments, but found ${args.length - 1} instead.`);
const index = context.parse(args[1], 1, NumberType);
const input = context.parse(args[2], 2, array(context.expectedType || ValueType));
if (!index || !input) return null;
const t = input.type as ArrayType;
return new At(t.itemType, index, input);
}
evaluate(ctx: EvaluationContext): Value {
const index = (this.index.evaluate(ctx) as number);
const array = (this.input.evaluate(ctx) as Array<Value>);
if (index < 0) {
throw new RuntimeError(`Array index out of bounds: ${index} < 0.`);
}
if (index >= array.length) {
throw new RuntimeError(`Array index out of bounds: ${index} > ${array.length - 1}.`);
}
if (index !== Math.floor(index)) {
throw new RuntimeError(`Array index must be an integer, but found ${index} instead. Use at-interpolated to retrieve interpolated result with a fractional index.`);
}
return array[index];
}
eachChild(fn: (_: Expression) => void) {
fn(this.index);
fn(this.input);
}
outputDefined(): boolean {
return false;
}
serialize(): SerializedExpression {
return ["at", this.index.serialize(), this.input.serialize()];
}
}
export default At;