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package main
import (
"os"
"fmt"
"io"
)
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 Store map[rune]string
func (store Store) clone() Store {
newStore := make(Store)
for key, val := range store {
newStore[key] = val
}
return newStore
}
func (store Store) withValue(key rune, value string) Store {
newStore := store.clone()
newStore[key] = value
return newStore
}
func compileTransducer(transducerAst SubexAST) SubexState {
return transducerAst.compileWith(SubexNoneState{})
}
type SubexBranch struct {
store Store
state SubexState
output string
}
func (pair SubexBranch) eat(char rune) []SubexBranch {
states := pair.state.eat(pair.store, char)
for i := range states {
states[i].output = pair.output + states[i].output
}
return states
}
func (pair SubexBranch) accepting() []string {
return pair.state.accepting(pair.store)
}
func equalStates(left SubexBranch, right SubexBranch) bool {
// Only care about if they are the same pointer
return left.state == right.state
}
func pruneStates(states []SubexBranch) (newStates []SubexBranch) {
outer: for _, state := range states {
for _, newState := range newStates {
if equalStates(state, newState) {
continue outer
}
}
newStates = append(newStates, state)
}
return newStates
}
func runTransducer(transducer SubexState, input string) (output string, err bool) {
states := []SubexBranch{{
state: transducer,
output: "",
store: make(Store),
}}
for _, char := range input {
var newStates []SubexBranch
for _, state := range states {
newStates = append(newStates, state.eat(char)...)
}
states = pruneStates(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) != 2 {
panic("Expected: program [subex]")
}
inputBytes, inputErr := io.ReadAll(os.Stdin)
input := string(inputBytes)
if inputErr != nil {
fmt.Println("Error reading")
}
program := os.Args[1]
ast := parse(program)
transducer := compileTransducer(ast)
output, err := runTransducer(transducer, input)
if err {
output = input
}
fmt.Print(output)
}
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