/**
 * The CST root is always a {@link CST.Message}.
 *
 * ```ts
 * import type { CST } from 'messageformat/cst';
 * ```
 *
 * @module
 */
import type { MessageSyntaxError } from '../errors.ts';
export type Message = SimpleMessage | ComplexMessage | SelectMessage;
export interface SimpleMessage {
    type: 'simple';
    declarations?: never;
    pattern: Pattern;
    errors: MessageSyntaxError[];
}
export interface ComplexMessage {
    type: 'complex';
    declarations: Declaration[];
    pattern: Pattern;
    errors: MessageSyntaxError[];
}
export interface SelectMessage {
    type: 'select';
    declarations: Declaration[];
    match: Syntax<'.match'>;
    selectors: VariableRef[];
    variants: Variant[];
    errors: MessageSyntaxError[];
}
export type Declaration = InputDeclaration | LocalDeclaration | Junk;
export interface InputDeclaration {
    type: 'input';
    start: number;
    end: number;
    keyword: Syntax<'.input'>;
    value: Expression | Junk;
}
export interface LocalDeclaration {
    type: 'local';
    start: number;
    end: number;
    keyword: Syntax<'.local'>;
    target: VariableRef | Junk;
    equals?: Syntax<'='>;
    value: Expression | Junk;
}
export interface Variant {
    start: number;
    end: number;
    keys: Array<Literal | CatchallKey>;
    value: Pattern;
}
export interface CatchallKey {
    type: '*';
    /** position of the `*` */
    start: number;
    end: number;
}
export interface Pattern {
    start: number;
    end: number;
    body: Array<Text | Expression>;
    braces?: [Syntax<'{{'>] | [Syntax<'{{'>, Syntax<'}}'>];
}
export interface Text {
    type: 'text';
    start: number;
    end: number;
    value: string;
}
export interface Expression {
    type: 'expression';
    start: number;
    end: number;
    braces: [Syntax<'{'>] | [Syntax<'{'>, Syntax<'}'>];
    arg?: Literal | VariableRef;
    functionRef?: FunctionRef | Junk;
    markup?: Markup;
    attributes: Attribute[];
}
export interface Junk {
    type: 'junk';
    start: number;
    end: number;
    source: string;
    name?: never;
}
export interface Literal {
    type: 'literal';
    quoted: boolean;
    start: number;
    end: number;
    open?: Syntax<'|'>;
    value: string;
    close?: Syntax<'|'>;
}
export interface VariableRef {
    type: 'variable';
    start: number;
    end: number;
    open: Syntax<'$'>;
    name: string;
}
export interface FunctionRef {
    type: 'function';
    start: number;
    end: number;
    open: Syntax<':'>;
    name: Identifier;
    options: Option[];
}
export interface Markup {
    type: 'markup';
    start: number;
    end: number;
    open: Syntax<'#' | '/'>;
    name: Identifier;
    options: Option[];
    close?: Syntax<'/'>;
}
export interface Option {
    /** position at the start of the name */
    start: number;
    end: number;
    name: Identifier;
    equals?: Syntax<'='>;
    value: Literal | VariableRef;
}
export interface Attribute {
    /** position at the start of the name */
    start: number;
    end: number;
    open: Syntax<'@'>;
    name: Identifier;
    equals?: Syntax<'='>;
    value?: Literal;
}
export type Identifier = [name: Syntax<string>] | [namespace: Syntax<string>, separator: Syntax<':'>] | [namespace: Syntax<string>, separator: Syntax<':'>, name: Syntax<string>];
export interface Syntax<T extends string> {
    start: number;
    end: number;
    value: T;
}