From 1aa08f927c7043a643e847c434399fc76d053df0 Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Wed, 26 Apr 2023 14:41:25 +0100
Subject: Store stred programs as a flat list of commands with no nesting,
 using a new jump command to simulate command blocks

---
 main/parse.go | 64 +++++++++++++++++++++++++----------------------------------
 1 file changed, 27 insertions(+), 37 deletions(-)

(limited to 'main/parse.go')

diff --git a/main/parse.go b/main/parse.go
index 1972b66..ef50e81 100644
--- a/main/parse.go
+++ b/main/parse.go
@@ -57,18 +57,18 @@ func (p *parser) parseSubex() subex.SubexAST {
 	return subexAST
 }
 
-func (p *parser) parseBasicCommand(commandChar rune) Command {
+func (p *parser) parseBasicCommand(commands []Command, commandChar rune) []Command {
 	switch commandChar {
 		case 'p':
-			return PrintValueCommand{}
+			return append(commands, PrintValueCommand{})
 		case 'd':
-			return DeleteValueCommand{}
+			return append(commands, DeleteValueCommand{})
 		case 'D':
-			return DeletePathCommand{}
+			return append(commands, DeletePathCommand{})
 		case 'n':
-			return NextCommand{}
+			return append(commands, NextCommand{})
 		case 'N':
-			return AppendNextCommand{}
+			return append(commands, AppendNextCommand{})
 		case 's', 'S', 'f', 'F', 'l', 'L', 'a', 'A':
 			ast := p.parseSubex()
 			switch commandChar {
@@ -120,77 +120,67 @@ func (p *parser) parseBasicCommand(commandChar rune) Command {
 					}
 			}
 			subex := subex.CompileTransducer(ast)
-			var next Command
-			token := p.peek()
-			switch token.typ {
-				case TokenEOF, TokenRBrace:
-					next = NoopCommand{}
-				default:
-					next = p.parseCommand()
-			}
 			switch commandChar {
 				case 's', 'a':
-					return SubstituteValueCommand {subex, next}
+					return append(commands, SubstituteValueCommand {subex}, JumpCommand {len(commands) + 3})
 				case 'S', 'f', 'F', 'l', 'L', 'A':
-					return SubstitutePathCommand {subex, next}
+					return append(commands, SubstitutePathCommand {subex}, JumpCommand {len(commands) + 3})
 				default:
 					panic("Unreachable!?!?")
 			}
 		case 'o':
-			return NoopCommand{}
+			return append(commands, NoopCommand{})
 		case 'x':
-			return SwapXRegCommand{}
+			return append(commands, SwapXRegCommand{})
 		case 'X':
-			return AppendXRegCommand{}
+			return append(commands, AppendXRegCommand{})
 		case 'y':
-			return SwapYRegCommand{}
+			return append(commands, SwapYRegCommand{})
 		case 'Y':
-			return AppendYRegCommand{}
+			return append(commands, AppendYRegCommand{})
 		case 'z':
-			return SwapZRegCommand{}
+			return append(commands, SwapZRegCommand{})
 		case 'Z':
-			return AppendZRegCommand{}
+			return append(commands, AppendZRegCommand{})
 		case 'k':
-			return SwapPathCommand{}
+			return append(commands, SwapPathCommand{})
 		case 'K':
-			return AppendPathCommand{}
+			return append(commands, AppendPathCommand{})
 		default:
 			panic("Invalid command")
 	}
 }
 
-func (p *parser) parseCommand() Command {
+func (p *parser) parseCommand(commands []Command) []Command {
 	token := p.next()
 	switch token.typ {
 		case TokenLBrace:
-			commands := p.parseCommands()
+			jumpToBlockCommand := &JumpCommand{0}
+			commands = append(commands, JumpCommand {len(commands) + 2}, jumpToBlockCommand)
+			commands = p.parseCommands(commands)
 			if p.next().typ != TokenRBrace {
 				panic("Missing matching }")
 			}
-			return SequenceCommand {commands}
+			jumpToBlockCommand.destination = len(commands)
+			return commands
 		case TokenCommand:
 			commandChar, _, err := strings.NewReader(token.val).ReadRune()
 			if err != nil {
 				panic("Error reading a command character!?")
 			}
-			return p.parseBasicCommand(commandChar)
+			return p.parseBasicCommand(commands, commandChar)
 		default:
 			panic("Invalid token, expected command")
 	}
 }
 
-func (p *parser) parseCommands() []Command {
-	var commands []Command
+func (p *parser) parseCommands(commands []Command) []Command {
 	for {
 		nextToken := p.peek()
 		if nextToken.typ == TokenEOF || nextToken.typ == TokenRBrace {
 			return commands
 		}
-		commands = append(commands, p.parseCommand())
-		endToken := p.peek()
-		if endToken.typ == TokenEOF || endToken.typ == TokenRBrace {
-			return commands
-		}
+		commands = p.parseCommand(commands)
 	}
 }
 
@@ -198,5 +188,5 @@ func Parse(tokens chan Token) []Command {
 	p := parser {
 		tokenStream: tokens,
 	}
-	return p.parseCommands()
+	return p.parseCommands(nil)
 }
-- 
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