From fba426b3910f16c8abc6f819da3138f03e5f0b1a Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Sun, 19 Feb 2023 08:59:16 +0000
Subject: Introduces subex processing

Doesn't integrate it at all yet
---
 subex/main.go | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 subex/main.go

(limited to 'subex/main.go')

diff --git a/subex/main.go b/subex/main.go
new file mode 100644
index 0000000..3ae0618
--- /dev/null
+++ b/subex/main.go
@@ -0,0 +1,114 @@
+package subex
+
+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 {
+		fmt.Printf("Running with %d states\n", len(states))
+		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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