From ce2db2bc333ed938ec93d5ad0838f8cb720c4865 Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Sat, 24 Dec 2022 10:03:56 +0000
Subject: Remove the redundant regex implementation

---
 main/parse.go      | 51 ------------------------------
 main/regexast.go   | 92 ------------------------------------------------------
 main/regexstate.go | 48 ----------------------------
 3 files changed, 191 deletions(-)
 delete mode 100644 main/regexast.go
 delete mode 100644 main/regexstate.go

diff --git a/main/parse.go b/main/parse.go
index 18941f2..59104c1 100644
--- a/main/parse.go
+++ b/main/parse.go
@@ -21,57 +21,6 @@ func parseReplacement(l *RuneReader) (output []TransducerOutput) {
 	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 <= 4:
-				lhs = RegexASTTry{lhs}
-			case r == '?' && minPower <= 4:
-				lhs = RegexASTMaybe{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) SubexAST {
 	var lhs SubexAST
 	r := l.next()
diff --git a/main/regexast.go b/main/regexast.go
deleted file mode 100644
index a5a60c4..0000000
--- a/main/regexast.go
+++ /dev/null
@@ -1,92 +0,0 @@
-package main
-
-import (
-	"fmt"
-)
-
-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 RegexASTTry struct {
-	content RegexAST
-}
-func (ast RegexASTTry) compileWith(next RegexState) RegexState {
-	return RegexGroupState{
-		ast.content.compileWith(next),
-		next,
-	}
-}
-
-type RegexASTMaybe struct {
-	content RegexAST
-}
-func (ast RegexASTMaybe) compileWith(next RegexState) RegexState {
-	return RegexGroupState {
-		next,
-		ast.content.compileWith(next),
-	}
-}
diff --git a/main/regexstate.go b/main/regexstate.go
deleted file mode 100644
index 16d5581..0000000
--- a/main/regexstate.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package main
-
-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()
-}
-- 
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