package main

type StringSegmentPathFilterAST struct {
	index string
}
func (ast StringSegmentPathFilterAST) compileWith(next PathFilterState) PathFilterState {
	return StringSegmentPathFilter {
		index: ast.index,
		next: next,
	}
}

type IntegerSegmentPathFilterAST struct {
	index int
}
func (ast IntegerSegmentPathFilterAST) compileWith(next PathFilterState) PathFilterState {
	return IntegerSegmentPathFilter {
		index: ast.index,
		next: next,
	}
}

type RepeatPathFilterAST struct {
	content PathFilterAST
}
func (ast RepeatPathFilterAST) compileWith(next PathFilterState) PathFilterState {
	nextGroup := &OrPathFilter{}
	repeatStart := ast.content.compileWith(nextGroup)
	nextGroup.filters = [2]PathFilterState{next, repeatStart}
	return nextGroup
}

type SequencePathFilterAST struct {
	first PathFilterAST
	second PathFilterAST
}
func (ast SequencePathFilterAST) compileWith(next PathFilterState) PathFilterState {
	next = ast.second.compileWith(next)
	next = ast.first.compileWith(next)
	return next
}

type AnySegmentPathFilterAST struct {}
func (ast AnySegmentPathFilterAST) compileWith(next PathFilterState) PathFilterState {
	return AnySegmentPathFilter{next: next}
}

type OrPathFilterAST struct {
	first PathFilterAST
	second PathFilterAST
}
func (ast OrPathFilterAST) compileWith(next PathFilterState) PathFilterState {
	return OrPathFilter {
		filters: [2]PathFilterState{
			ast.first.compileWith(next),
			ast.second.compileWith(next),
		},
	}
}

type NonePathFilterAST struct {}
func (ast NonePathFilterAST) compileWith(next PathFilterState) PathFilterState {
	return next
}

type PathFilterAST interface {
	compileWith(PathFilterState) PathFilterState
}

func compilePathFilterAST(ast PathFilterAST) PathFilter {
	return PathFilter{
		initial: ast.compileWith(NonePathFilter{}),
	}
}