mapbox-gl/src/style-spec/expression/is_constant.js

A WebGL interactive maps library

// @flow

import CompoundExpression from './compound_expression';

import type { Expression } from './expression.js';

function isFeatureConstant(e: Expression) {
    if (e instanceof CompoundExpression) {
        if (e.name === 'get' && e.args.length === 1) {
            return false;
        } else if (e.name === 'feature-state') {
            return false;
        } else if (e.name === 'has' && e.args.length === 1) {
            return false;
        } else if (
            e.name === 'properties' ||
            e.name === 'geometry-type' ||
            e.name === 'id'
        ) {
            return false;
        } else if (/^filter-/.test(e.name)) {
            return false;
        }
    }

    let result = true;
    e.eachChild(arg => {
        if (result && !isFeatureConstant(arg)) { result = false; }
    });
    return result;
}

function isStateConstant(e: Expression) {
    if (e instanceof CompoundExpression) {
        if (e.name === 'feature-state') {
            return false;
        }
    }
    let result = true;
    e.eachChild(arg => {
        if (result && !isStateConstant(arg)) { result = false; }
    });
    return result;
}

function isGlobalPropertyConstant(e: Expression, properties: Array<string>) {
    if (e instanceof CompoundExpression && properties.indexOf(e.name) >= 0) { return false; }
    let result = true;
    e.eachChild((arg) => {
        if (result && !isGlobalPropertyConstant(arg, properties)) { result = false; }
    });
    return result;
}

export { isFeatureConstant, isGlobalPropertyConstant, isStateConstant };