import { type ClassDef } from "../../layout/structures/class-def.ts";
import { type Coverage } from "../../layout/structures/coverage.ts";
import type { GlyphId, uint16 } from "../../types.ts";
import type { Reader } from "../binary/reader.ts";
import type { GsubLookup } from "./gsub.ts";
/** Sequence lookup record - applies a lookup at a position */
export interface SequenceLookupRecord {
    sequenceIndex: uint16;
    lookupListIndex: uint16;
}
/** Context substitution lookup (Type 5) */
export interface ContextSubstLookup extends GsubLookup {
    type: 5;
    subtables: ContextSubstSubtable[];
}
export type ContextSubstSubtable = ContextSubstFormat1 | ContextSubstFormat2 | ContextSubstFormat3;
/** Format 1: Simple glyph contexts */
export interface ContextSubstFormat1 {
    format: 1;
    coverage: Coverage;
    ruleSets: (ContextRule[] | null)[];
}
export interface ContextRule {
    glyphCount: uint16;
    inputSequence: GlyphId[];
    lookupRecords: SequenceLookupRecord[];
}
/** Format 2: Class-based contexts */
export interface ContextSubstFormat2 {
    format: 2;
    coverage: Coverage;
    classDef: ClassDef;
    classRuleSets: (ClassRule[] | null)[];
}
export interface ClassRule {
    glyphCount: uint16;
    inputClasses: uint16[];
    lookupRecords: SequenceLookupRecord[];
}
/** Format 3: Coverage-based contexts */
export interface ContextSubstFormat3 {
    format: 3;
    coverages: Coverage[];
    lookupRecords: SequenceLookupRecord[];
}
/** Chaining context substitution lookup (Type 6) */
export interface ChainingContextSubstLookup extends GsubLookup {
    type: 6;
    subtables: ChainingContextSubstSubtable[];
}
export type ChainingContextSubstSubtable = ChainingContextFormat1 | ChainingContextFormat2 | ChainingContextFormat3;
/** Format 1: Simple chaining context */
export interface ChainingContextFormat1 {
    format: 1;
    coverage: Coverage;
    chainRuleSets: (ChainRule[] | null)[];
}
export interface ChainRule {
    backtrackSequence: GlyphId[];
    inputSequence: GlyphId[];
    lookaheadSequence: GlyphId[];
    lookupRecords: SequenceLookupRecord[];
}
/** Format 2: Class-based chaining context */
export interface ChainingContextFormat2 {
    format: 2;
    coverage: Coverage;
    backtrackClassDef: ClassDef;
    inputClassDef: ClassDef;
    lookaheadClassDef: ClassDef;
    chainClassRuleSets: (ChainClassRule[] | null)[];
}
export interface ChainClassRule {
    backtrackClasses: uint16[];
    inputClasses: uint16[];
    lookaheadClasses: uint16[];
    lookupRecords: SequenceLookupRecord[];
}
/** Format 3: Coverage-based chaining context */
export interface ChainingContextFormat3 {
    format: 3;
    backtrackCoverages: Coverage[];
    inputCoverages: Coverage[];
    lookaheadCoverages: Coverage[];
    lookupRecords: SequenceLookupRecord[];
}
export declare function parseContextSubst(reader: Reader, subtableOffsets: number[]): ContextSubstSubtable[];
export declare function parseChainingContextSubst(reader: Reader, subtableOffsets: number[]): ChainingContextSubstSubtable[];