@maplibre/maplibre-gl-style-spec/src/expression/expression.ts

a specification for maplibre styles

import type {Type} from './types';
import type {ParsingContext} from './parsing_context';
import type {EvaluationContext} from './evaluation_context';

/**
 * Expression
 */
export interface Expression {
    readonly type: Type;
    evaluate(ctx: EvaluationContext): any;
    eachChild(fn: (a: Expression) => void): void;
    /**
     * Statically analyze the expression, attempting to enumerate possible outputs. Returns
     * false if the complete set of outputs is statically undecidable, otherwise true.
     */
    outputDefined(): boolean;
}

export type ExpressionParser = (args: ReadonlyArray<unknown>, context: ParsingContext) => Expression;
export type ExpressionRegistration = {
    new (...args: any): Expression;
} & {
    readonly parse: ExpressionParser;
};
export type ExpressionRegistry = {[_: string]: ExpressionRegistration};