path: root/main/main.go

package main

import (
	"os"
	"bufio"
	"fmt"
	"strings"
	"unicode/utf8"
)

type PathSegment interface {}
type Path []PathSegment

type TerminalValue int
const (
	ArrayBegin TerminalValue = iota
	ArrayEnd
	MapBegin
	MapEnd
)
type ValueNull struct {}
type ValueBool bool
type ValueNumber float64
type ValueString string

type WalkValue interface {}

type WalkItem struct {
	value WalkValue
	path Path
}

type Program []Command

type ProgramState struct {
	space []WalkItem
	in chan WalkItem
	out chan WalkItem
	program []Command
}

//const eof rune = -1
type RuneReader struct {
	input string
	pos, width int
}
func (l *RuneReader) next() rune {
	if l.pos >= len(l.input) {
		l.width = 0
		return eof
	}
	var r rune
	r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
	l.pos += l.width
	return r
}
func (l *RuneReader) accept(chars string) bool {
	r := l.next()
	for _, char := range chars {
		if char == r {
			return true
		}
	}
	l.rewind()
	return false
}
func (l *RuneReader) rewind() {
	l.pos -= l.width
}

func parseReplacement(l *RuneReader) (output []TransducerOutput) {
	loop: for {
		r := l.next()
		switch r {
			case eof:
				panic("Missing closing \"")
			case '"':
				break loop
			case '$':
				slot := l.next()
				if slot == eof {
					panic("Missing slot character")
				}
				output = append(output, TransducerReplacementLoad(slot))
			default:
				output = append(output, TransducerReplacementRune(r))
		}
	}
	return output
}

func parseRegex(l *RuneReader, minPower int) RegexAST {
	var lhs RegexAST
	r := l.next()
	switch r {
		case eof:
			return nil
		case ')', '*', '-', '|':
			l.rewind()
			return nil
		case '(':
			lhs = parseRegex(l, 0)
			if !l.accept(")") {
				panic("Missing matching )")
			}
		case '.':
			lhs = RegexASTAny{}
		default:
			lhs = RegexASTRune(r)
	}
	loop: for {
		if minPower <= 0 {
			next := parseRegex(l, 1)
			if next != nil {
				lhs = RegexASTConcat{lhs, next}
				continue loop
			}
		}
		r := l.next()
		switch {
			case r == '*' && minPower <= 4:
				lhs = RegexASTMaximise{lhs}
			case r == '-' && minPower <= 4:
				lhs = RegexASTMinimise{lhs}
			case r == '|' && minPower <= 2:
				rhs := parseRegex(l, 3)
				if rhs == nil {
					panic("Missing regex after |")
				}
				lhs = RegexASTOr{lhs, rhs}
			default:
				l.rewind()
				break loop
		}
	}
	return lhs
}

func parseSubex(l *RuneReader, minPower int) TransducerAST {
	var lhs TransducerAST
	r := l.next()
	switch r {
		case eof:
			return nil
		case '(':
			lhs = parseSubex(l, 0)
			if !l.accept(")") {
				panic("Missing matching )")
			}
		case ')', '*', '-', '|':
			l.rewind()
			return nil
		case '$':
			slot := l.next()
			if slot == eof {
				panic("Missing slot character")
			}
			match := parseRegex(l, 100)
			if match == nil {
				panic("Missing regex for store")
			}
			lhs = TransducerASTStore{
				match: match,
				slot: slot,
			}
		case '"':
			replacement := parseReplacement(l)
			lhs = TransducerASTOutput{replacement}
		case '.':
			lhs = TransducerASTCopyAny{}
		default:
			lhs = TransducerASTCopyRune(r)
	}
	loop: for {
		if minPower <= 0 {
			next := parseSubex(l, 1)
			if next != nil {
				lhs = TransducerASTConcat{lhs, next}
				continue loop
			}
		}
		r := l.next()
		switch {
			case r == '*' && minPower <= 4:
				lhs = TransducerASTMaximise{lhs}
			case r == '-' && minPower <= 4:
				lhs = TransducerASTMinimise{lhs}
			case r == '|' && minPower <= 2:
				rhs := parseSubex(l, 3)
				if rhs == nil {
					panic("Missing subex after |")
				}
				lhs = TransducerASTOr{lhs, rhs}
			default:
				l.rewind()
				break loop
		}
	}
	return lhs
}

func parse(input string) TransducerAST {
	l := RuneReader {
		input: input,
		pos: 0,
		width: 0,
	}
	return parseSubex(&l, 0)
}

type TransducerOutput interface {
	build(Store) string
}

type TransducerReplacementRune rune
func (replacement TransducerReplacementRune) build(store Store) string {
	return string(replacement)
}

type TransducerReplacementLoad rune
func (replacement TransducerReplacementLoad) build(store Store) string {
	return store[rune(replacement)]
}

type RegexState interface {
	eat(char rune) []RegexState
	accepting() bool
}

type RegexNoneState struct {}
func (state RegexNoneState) eat(char rune) []RegexState {
	return nil
}
func (state RegexNoneState) accepting() bool {
	return true
}

type RegexAnyState struct {
	next RegexState
}
func (state RegexAnyState) eat(char rune) []RegexState {
	return []RegexState{state.next}
}
func (state RegexAnyState) accepting() bool {
	return false
}

type RegexRuneState struct {
	rune rune
	next RegexState
}
func (state RegexRuneState) eat(char rune) []RegexState {
	if char == state.rune {
		return []RegexState{state.next}
	}
	return nil
}
func (state RegexRuneState) accepting() bool {
	return false
}

type RegexGroupState struct {
	first, second RegexState
}
func (state RegexGroupState) eat(char rune) []RegexState {
	return append(state.first.eat(char), state.second.eat(char)...)
}
func (state RegexGroupState) accepting() bool {
	return state.first.accepting() || state.second.accepting()
}

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 Store map[rune]string
func (store Store) clone() Store {
	newStore := make(Store)
	for key, val := range store {
		newStore[key] = val
	}
	return newStore
}

type TransducerState interface {
	eat(store Store, char rune) []TransducerStatePair
	accepting(store Store) []string
}

type TransducerGroupState struct {
	first, second TransducerState
}
func (state TransducerGroupState) eat(store Store, char rune) []TransducerStatePair {
	otherStore := store.clone()
	return append(state.first.eat(store, char), state.second.eat(otherStore, char)...)
}
func (state TransducerGroupState) accepting(store Store) []string {
	return append(state.first.accepting(store), state.second.accepting(store)...)
}

type TransducerStoreState struct {
	match RegexState
	slot rune
	next TransducerState
	input string
}
func (state TransducerStoreState) eat(store Store, char rune) []TransducerStatePair {
	var nextStates []TransducerStatePair
	if state.match.accepting() {
		store[state.slot] = state.input
		nextStates = state.next.eat(store, char)
	}
	nextRegexStates := state.match.eat(char)
	for _, regexState := range nextRegexStates {
		nextStates = append(nextStates, TransducerStatePair {
			state: TransducerStoreState {
				match: regexState,
				slot: state.slot,
				next: state.next,
				input: state.input + string(char),
			},
			output: "",
			store: store.clone(),
		})
	}
	return nextStates
}
func (state TransducerStoreState) accepting(store Store) []string {
	if state.match.accepting() {
		return state.next.accepting(store)
	}
	return nil
}

type TransducerOutputState struct {
	content []TransducerOutput
	next TransducerState
}
func (state TransducerOutputState) build(store Store) string {
	var builder strings.Builder
	for _, part := range state.content {
		builder.WriteString(part.build(store))
	}
	return builder.String()
}
func (state TransducerOutputState) eat(store Store, char rune) []TransducerStatePair {
	content := state.build(store)
	nextStates := state.next.eat(store, char)
	for i := range nextStates {
		nextStates[i].output = content + nextStates[i].output
	}
	return nextStates
}
func (state TransducerOutputState) accepting(store Store) []string {
	content := state.build(store)
	outputs := state.next.accepting(store)
	for i := range outputs {
		outputs[i] = content + outputs[i]
	}
	return outputs
}

type TransducerNoneState struct {}
func (state TransducerNoneState) eat(store Store, char rune) []TransducerStatePair {
	return nil
}
func (state TransducerNoneState) accepting(store Store) []string {
	return []string{""}
}

type TransducerCopyRuneState struct {
	rune rune
	next TransducerState
}
func (state TransducerCopyRuneState) eat(store Store, char rune) []TransducerStatePair {
	if char == state.rune {
		return []TransducerStatePair{{
			state: state.next,
			output: string(char),
			store: store,
		}}
	}
	return nil
}
func (state TransducerCopyRuneState) accepting(store Store) []string {
	return nil
}

type TransducerCopyAnyState struct {
	next TransducerState
}
func (state TransducerCopyAnyState) eat(store Store, char rune) []TransducerStatePair {
	return []TransducerStatePair{{
		state: state.next,
		output: string(char),
		store: store,
	}}
}
func (state TransducerCopyAnyState) accepting(store Store) []string {
	return nil
}

type TransducerAST interface {
	compileWithNext(next TransducerState) TransducerState
}

type TransducerASTConcat struct {
	first, second TransducerAST
}
func (ast TransducerASTConcat) compileWithNext(next TransducerState) TransducerState {
	return ast.first.compileWithNext(ast.second.compileWithNext(next))
}
func (ast TransducerASTConcat) String() string {
	return fmt.Sprintf("(%v)(%v)", ast.first, ast.second)
}

type TransducerASTStore struct {
	match RegexAST
	slot rune
}
func (ast TransducerASTStore) compileWithNext(next TransducerState) TransducerState {
	return TransducerStoreState {
		match: ast.match.compileWith(RegexNoneState{}),
		slot: ast.slot,
		next: next,
	}
}
func (ast TransducerASTStore) String() string {
	return fmt.Sprintf("$%c(%v)", ast.slot, ast.match)
}

type TransducerASTOr struct {
	first, second TransducerAST
}
func (ast TransducerASTOr) compileWithNext(next TransducerState) TransducerState {
	return TransducerGroupState {
		ast.first.compileWithNext(next),
		ast.second.compileWithNext(next),
	}
}

type TransducerASTMaximise struct {
	content TransducerAST
}
func (ast TransducerASTMaximise) compileWithNext(next TransducerState) TransducerState {
	state := &TransducerGroupState {
		nil,
		next,
	}
	state.first = ast.content.compileWithNext(state)
	return state
}
func (ast TransducerASTMaximise) String() string {
	return fmt.Sprintf("(%v)*", ast.content)
}

type TransducerASTMinimise struct {
	content TransducerAST
}
func (ast TransducerASTMinimise) compileWithNext(next TransducerState) TransducerState {
	state := &TransducerGroupState {
		next,
		nil,
	}
	state.second = ast.content.compileWithNext(state)
	return state
}
func (ast TransducerASTMinimise) String() string {
	return fmt.Sprintf("(%v)-", ast.content)
}

type TransducerASTRepeat struct {
	content TransducerAST
	min, max int
}
func (ast TransducerASTRepeat) compileWithNext(next TransducerState) TransducerState {
	for i := ast.min; i < ast.max; i += 1 {
		next = TransducerGroupState {
			ast.content.compileWithNext(next),
			next,
		}
	}
	for i := 0; i < ast.min; i += 1 {
		next = ast.content.compileWithNext(next)
	}
	return next
}

type TransducerASTCopyRune rune
func (ast TransducerASTCopyRune) compileWithNext(next TransducerState) TransducerState {
	return TransducerCopyRuneState{
		rune: rune(ast),
		next: next,
	}
}

type TransducerASTCopyAny struct {}
func (ast TransducerASTCopyAny) compileWithNext(next TransducerState) TransducerState {
	return TransducerCopyAnyState{next}
}
func (ast TransducerASTCopyAny) String() string {
	return "."
}

type TransducerASTOutput struct {
	replacement []TransducerOutput
}
func (ast TransducerASTOutput) compileWithNext(next TransducerState) TransducerState {
	return TransducerOutputState{
		content: ast.replacement,
		next: next,
	}
}

func compileTransducer(transducerAst TransducerAST) TransducerState {
	return transducerAst.compileWithNext(TransducerNoneState{})
}

type TransducerStatePair struct {
	store Store
	state TransducerState
	output string
}
func (pair TransducerStatePair) eat(char rune) []TransducerStatePair {
	states := pair.state.eat(pair.store, char)
	for i := range states {
		states[i].output = pair.output + states[i].output
	}
	return states
}
func (pair TransducerStatePair) accepting() []string {
	return pair.state.accepting(pair.store)
}

func runTransducer(transducer TransducerState, input string) (output string, err bool) {
	states := []TransducerStatePair{{
		state: transducer,
		output: "",
		store: make(Store),
	}}
	for _, char := range input {
		var newStates []TransducerStatePair
		for _, state := range states {
			newStates = append(newStates, state.eat(char)...)
		}
		states = newStates
	}
	for _, state := range states {
		outputEnds := state.accepting()
		for _, outputEnd := range outputEnds {
			return state.output + outputEnd, false
		}
	}
	return "", true
}

func main() {
	if len(os.Args) != 3 {
		panic("Expected: program [input] [subex]")
	}
	input := os.Args[1]
	program := os.Args[2]
	ast := parse(program)
	transducer := compileTransducer(ast)
	output, err := runTransducer(transducer, input)
	if err {
		output = input
	}
	fmt.Println(output)
}

func mainISH() {
	quiet := false
	var input string
	hasInput := false
	
	for i := 1; i < len(os.Args); i += 1 {
		switch os.Args[i] {
			case "-n":
				quiet = true
				continue
		}
		if i < len(os.Args) - 1 {
			panic("Unexpected arguments after program")
		}
		input = os.Args[i]
		hasInput = true
	}
	if !hasInput {
		panic("Missing program")
	}

	tokens := Lex(input)
	program := Parse(tokens)

	stdin := bufio.NewReader(os.Stdin)
	dataStream := Json(stdin)

	state := ProgramState {
		in: dataStream,
		out: make(chan WalkItem),
		program: program,
	}
	
	go func () {
		for walkItem := range dataStream {
			state.space = []WalkItem{walkItem}
			for _, cmd := range state.program {
				cmd.exec(&state)
			}
			if !quiet {
				for _, item := range state.space {
					state.out <- item
				}
			}
		}
		close(state.out)
	}()
	
	JsonOut(state.out)
}