import type { ExprValue } from '../types/expr-value';
import { ExpressionDef } from '../types/expression-def';
import type { FieldSpace } from '../types/field-space';
export declare class ExprCoalesce extends ExpressionDef {
    readonly expr: ExpressionDef;
    readonly altExpr: ExpressionDef;
    elementType: string;
    legalChildTypes: import("../../../model").TypeDesc[];
    constructor(expr: ExpressionDef, altExpr: ExpressionDef);
    getExpression(fs: FieldSpace): ExprValue;
}