From dae74317d84471f6a859117fcbba1cf546be8ea1 Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Wed, 19 Apr 2023 15:19:42 +0100
Subject: Adds parsing substitute commands, though executing them currently
 does nothing

---
 main/parse.go | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

(limited to 'main/parse.go')

diff --git a/main/parse.go b/main/parse.go
index 73c7913..bf2f0ac 100644
--- a/main/parse.go
+++ b/main/parse.go
@@ -5,6 +5,7 @@ import (
 	"strconv"
 	"fmt"
 	"main/walk"
+	"main/subex"
 )
 
 type parser struct {
@@ -202,6 +203,25 @@ func (p *parser) parseLiterals() (items []walk.WalkItem) {
 	return items
 }
 
+func (p *parser) parseSubex() subex.SubexState {
+	delim := p.next()
+	if delim.typ != TokenSubstituteDelimiter {
+		panic("Missing substitute delimiter")
+	}
+	subexProgramToken := p.next()
+	if subexProgramToken.typ != TokenSubex {
+		panic("Missing subex from substitution")
+	}
+	reader := subex.NewStringRuneReader(subexProgramToken.val)
+	subexAST := subex.Parse(reader)
+	subex := subex.CompileTransducer(subexAST)
+	delim = p.next()
+	if delim.typ != TokenSubstituteDelimiter {
+		panic("Missing end substitute delimiter")
+	}
+	return subex
+}
+
 func (p *parser) parseBasicCommand(commandChar rune) Command {
 	switch commandChar {
 		case 'p':
@@ -212,6 +232,9 @@ func (p *parser) parseBasicCommand(commandChar rune) Command {
 			return NextCommand{}
 		case 'N':
 			return AppendNextCommand{}
+		case 's':
+			subex := p.parseSubex()
+			return SubstituteCommand {subex: subex}
 		case 'i':
 			items := p.parseLiterals()
 			return PrintLiteralsCommand {items: items}
-- 
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