@maplibre/maplibre-gl-style-spec/src/validate/validate_variable_anchor_offset_collection.ts

a specification for maplibre styles

import {ValidationError} from '../error/validation_error';
import {getType} from '../util/get_type';
import {validateArray} from './validate_array';
import {validateEnum} from './validate_enum';

export function validateVariableAnchorOffsetCollection(options): ValidationError[] {
    const key = options.key;
    const value = options.value;
    const type = getType(value);
    const styleSpec = options.styleSpec;

    if (type !== 'array' || value.length < 1 || value.length % 2 !== 0) {
        return [
            new ValidationError(
                key,
                value,
                'variableAnchorOffsetCollection requires a non-empty array of even length'
            )
        ];
    }

    let errors = [];

    for (let i = 0; i < value.length; i += 2) {
        // Elements in even positions should be values from text-anchor enum
        errors = errors.concat(
            validateEnum({
                key: `${key}[${i}]`,
                value: value[i],
                valueSpec: styleSpec['layout_symbol']['text-anchor']
            })
        );

        // Elements in odd positions should be points (2-element numeric arrays)
        errors = errors.concat(
            validateArray({
                key: `${key}[${i + 1}]`,
                value: value[i + 1],
                valueSpec: {
                    length: 2,
                    value: 'number'
                },
                validateSpec: options.validateSpec,
                style: options.style,
                styleSpec
            })
        );
    }

    return errors;
}