package main

import (
	"fmt"
)

type RegexAST interface {
	compileWith(next RegexState) RegexState
}

type RegexASTRune rune
func (ast RegexASTRune) compileWith(next RegexState) RegexState {
	return RegexRuneState{
		rune: rune(ast),
		next: next,
	}
}
func (ast RegexASTRune) String() string {
	return string(rune(ast))
}

type RegexASTAny struct {}
func (ast RegexASTAny) compileWith(next RegexState) RegexState {
	return RegexAnyState{next}
}
func (ast RegexASTAny) String() string {
	return "."
}

type RegexASTConcat struct {
	first, second RegexAST
}
func (ast RegexASTConcat) compileWith(next RegexState) RegexState {
	return ast.first.compileWith(ast.second.compileWith(next))
}
func (ast RegexASTConcat) String() string {
	return fmt.Sprintf("Concat{%v, %v}", ast.first, ast.second)
}

type RegexASTOr struct {
	first, second RegexAST
}
func (ast RegexASTOr) compileWith(next RegexState) RegexState {
	return RegexGroupState{
		ast.first.compileWith(next),
		ast.second.compileWith(next),
	}
}

type RegexASTMaximise struct {
	content RegexAST
}
func (ast RegexASTMaximise) compileWith(next RegexState) RegexState {
	state := &RegexGroupState{
		nil,
		next,
	}
	state.first = ast.content.compileWith(state)
	return state
}

type RegexASTMinimise struct {
	content RegexAST
}
func (ast RegexASTMinimise) compileWith(next RegexState) RegexState {
	state := &RegexGroupState{
		next,
		nil,
	}
	state.second = ast.content.compileWith(state)
	return state
}

type RegexASTTry struct {
	content RegexAST
}
func (ast RegexASTTry) compileWith(next RegexState) RegexState {
	return RegexGroupState{
		ast.content.compileWith(next),
		next,
	}
}

type RegexASTMaybe struct {
	content RegexAST
}
func (ast RegexASTMaybe) compileWith(next RegexState) RegexState {
	return RegexGroupState {
		next,
		ast.content.compileWith(next),
	}
}