From cfbe645715114234510bda068d2f30ffbe208eae Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Sat, 27 Aug 2022 18:11:10 +0100
Subject: Adds new filters

- Begin terminals
- End terminals
- All terminals
- Negate
- AND
---
 main/filter.go | 51 ++++++++++++++++++++++++++-------------------------
 main/lex.go    | 27 +++++++++++++++++++++++++++
 main/parse.go  | 50 ++++++++++++++++++++++++++++++++++----------------
 3 files changed, 87 insertions(+), 41 deletions(-)

diff --git a/main/filter.go b/main/filter.go
index 662fa7b..796f558 100644
--- a/main/filter.go
+++ b/main/filter.go
@@ -32,31 +32,6 @@ func (filter MapTerminalFilter) exec(space WalkItem) bool {
 	return terminal == MapBegin || terminal == MapEnd
 }
 
-type NonTerminalFilter struct {}
-func (filter NonTerminalFilter) exec(space WalkItem) bool {
-	_, isTerminal := space.value.(TerminalValue)
-	return !isTerminal
-}
-
-type RangeFilter struct {
-	start Filter
-	end Filter
-	active bool
-}
-func (filter *RangeFilter) exec(space WalkItem) bool {
-	if filter.active {
-		if filter.end.exec(space) {
-			filter.active = false
-		}
-		return true
-	} else {
-		if filter.start.exec(space) {
-			filter.active = true
-		}
-		return filter.active
-	}
-}
-
 type BeginTerminalFilter struct {}
 func (filter BeginTerminalFilter) exec(space WalkItem) bool {
 	terminal, isTerminal := space.value.(TerminalValue)
@@ -75,6 +50,32 @@ func (filter EndTerminalFilter) exec(space WalkItem) bool {
 	return terminal == ArrayEnd || terminal == MapEnd
 }
 
+type TerminalFilter struct {}
+func (filter TerminalFilter) exec(space WalkItem) bool {
+	_, isTerminal := space.value.(TerminalValue)
+	return isTerminal
+}
+
+type RootFilter struct {}
+func (filter RootFilter) exec(space WalkItem) bool {
+	return len(space.path) == 0
+}
+
+type AndFilter struct {
+	left Filter
+	right Filter
+}
+func (filter AndFilter) exec(space WalkItem) bool {
+	return filter.left.exec(space) && filter.right.exec(space)
+}
+
+type NotFilter struct {
+	content Filter
+}
+func (filter NotFilter) exec(space WalkItem) bool {
+	return !filter.content.exec(space)
+}
+
 type Filter interface {
 	exec(WalkItem) bool
 }
\ No newline at end of file
diff --git a/main/lex.go b/main/lex.go
index fdb3b59..91231ed 100644
--- a/main/lex.go
+++ b/main/lex.go
@@ -116,7 +116,13 @@ const (
 	TokenDot // .
 	TokenAst // *
 	TokenBar // |
+	TokenAnd // &&
+	TokenHat // ^
+	TokenDollar // $
 	TokenQuestion // ?
+	TokenHatDollar // ^$
+	TokenExclamation // !
+	TokenTilde // ~
 	TokenPatternStringIndex // A string index in a pattern
 	TokenPatternIntegerIndex // An integer index in a pattern
 )
@@ -205,6 +211,27 @@ func lexCommand(l *lexer) stateFunc {
 		case '}':
 			l.emit(TokenRBrace)
 			return lexCommandEnd
+		case '&':
+			if l.accept("&") {
+				l.emit(TokenAnd)
+				return lexCommand
+			}
+		case '^':
+			if l.accept("$") {
+				l.emit(TokenHatDollar)
+			} else {
+				l.emit(TokenHat)
+			}
+			return lexCommand
+		case '$':
+			l.emit(TokenDollar)
+			return lexCommand
+		case '!':
+			l.emit(TokenExclamation)
+			return lexCommand
+		case '~':
+			l.emit(TokenTilde)
+			return lexCommand
 	}
 	if isAlpha(r) {
 		l.emit(TokenCommand)
diff --git a/main/parse.go b/main/parse.go
index 492b58f..0767c0d 100644
--- a/main/parse.go
+++ b/main/parse.go
@@ -90,22 +90,36 @@ func (p *parser) parsePathPatternFilter(minPower int) PathFilterAST {
 	return lhs
 }
 
-// TODO: should only return a single filter
-func (p *parser) parseFilter() []Filter {
-	var filters []Filter
+func (p *parser) parseFilter(minPower int) Filter {
+	var lhs Filter
 	token := p.next()
 	switch token.typ {
 		case TokenHash, TokenAt, TokenDot:
 			p.rewind(token)
 			filterAst := p.parsePathPatternFilter(0)
-			filters = append(filters, compilePathFilterAST(filterAst))
-			token = p.next()
+			lhs = compilePathFilterAST(filterAst)
+		case TokenHat:
+			lhs = BeginTerminalFilter{}
+		case TokenDollar:
+			lhs = EndTerminalFilter{}
+		case TokenHatDollar:
+			lhs = TerminalFilter{}
+		case TokenTilde:
+			lhs = RootFilter{}
+		default:
+			panic("Expected filter")
 	}
-	if len(filters) == 0 {
-		panic("Missing filter")
+	loop: for {
+		token = p.next()
+		switch {
+			case token.typ == TokenAnd && 2 >= minPower:
+				lhs = AndFilter {lhs, p.parseFilter(3)}
+			default:
+				p.rewind(token)
+				break loop
+		}
 	}
-	p.rewind(token)
-	return filters
+	return lhs
 }
 
 func (p *parser) parseBasicCommand(commandChar rune) Command {
@@ -122,15 +136,19 @@ func (p *parser) parseBasicCommand(commandChar rune) Command {
 func (p *parser) parseCommand() Command {
 	token := p.next()
 	switch token.typ {
-		case TokenHash, TokenAt, TokenDot:
+		case TokenHash, TokenAt, TokenDot, TokenLParen, TokenHat, TokenDollar, TokenHatDollar, TokenTilde:
 			p.rewind(token)
-			filters := p.parseFilter()
+			filter := p.parseFilter(0)
+			notToken := p.next()
+			if notToken.typ == TokenExclamation {
+				filter = NotFilter {filter}
+			} else {
+				p.rewind(notToken)
+			}
 			command := p.parseCommand()
-			for _, filter := range filters {
-				command = FilteredCommand {
-					filter: filter,
-					command: command,
-				}
+			command = FilteredCommand {
+				filter: filter,
+				command: command,
 			}
 			return command
 		case TokenCommand:
-- 
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