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 := &GroupPathFilter{}
	repeatStart := ast.content.compileWith(nextGroup)
	nextGroup.filters = []PathFilterState{next, repeatStart}
	return nextGroup
}

type SequencePathFilterAST struct {
	sequence []PathFilterAST
}
func (ast SequencePathFilterAST) compileWith(next PathFilterState) PathFilterState {
	for i := len(ast.sequence) - 1; i >= 0; i -= 1 {
		next = ast.sequence[i].compileWith(next)
	}
	return next
}

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

type PathFilterAST interface {
	compileWith(PathFilterState) PathFilterState
}

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