From 9ae167ac4aed6e505ac8855858767ea0c34b5f95 Mon Sep 17 00:00:00 2001
From: Sami Samhuri <sami@samhuri.net>
Date: Fri, 2 Jan 2026 16:15:49 -0800
Subject: [PATCH] Start ditching wordexp in Ruby

---
 ruby/shell/builtins.rb  |  8 +++-
 ruby/shell/repl.rb      | 82 ++++++++++++++++++++++++++++++++++++-----
 ruby/test/shell_test.rb |  4 +-
 3 files changed, 82 insertions(+), 12 deletions(-)

diff --git a/ruby/shell/builtins.rb b/ruby/shell/builtins.rb
index 4a39cd9..1259d57 100644
--- a/ruby/shell/builtins.rb
+++ b/ruby/shell/builtins.rb
@@ -51,7 +51,13 @@ module Shell
     end
 
     def builtin_cd(args)
-      Dir.chdir args.first
+      dir = args.first
+      if dir.nil?
+        Dir.chdir Dir.home
+      else
+        Dir.chdir dir
+      end
+      ENV["PWD"] = Dir.pwd
       0
     end
 
diff --git a/ruby/shell/repl.rb b/ruby/shell/repl.rb
index 94bf78c..2a95fe3 100644
--- a/ruby/shell/repl.rb
+++ b/ruby/shell/repl.rb
@@ -50,16 +50,21 @@ module Shell
       return 0 if line.strip.empty? # no input, no-op
 
       logger.verbose "Processing command: #{line.inspect}"
-      args = word_expander.expand(line)
-      cmd = args.shift
-      logger.verbose "Parsed command: #{cmd} #{args.inspect}"
-      if builtins.builtin?(cmd)
-        logger.verbose "Executing builtin #{cmd}"
-        builtins.exec(cmd, args)
-      else
-        logger.verbose "Shelling out for #{cmd}"
-        job_control.exec_command(cmd, args)
+      commands = parse_line(line)
+      result = nil
+      commands.each do |command|
+        args = word_expander.expand(command)
+        program = args.shift
+        logger.verbose "Parsed command: #{program} #{args.inspect}"
+        if builtins.builtin?(program)
+          logger.verbose "Executing builtin #{program}"
+          result = builtins.exec(program, args)
+        else
+          logger.verbose "Shelling out for #{program}"
+          result = job_control.exec_command(program, args)
+        end
       end
+      result
     rescue Errno => e
       warn "#{red("[ERROR]")} #{e.message}"
       -1
@@ -69,5 +74,64 @@ module Shell
     def prompt(pwd)
       "#{blue(pwd)}#{white("%")} #{CLEAR}"
     end
+
+    def parse_line(line)
+      commands = []
+      command = "".dup
+      state = :unquoted
+      line.each_char do |c|
+        case state
+        when :unquoted
+          case c
+          when ";"
+            commands << command
+            command = "".dup
+          when "'"
+            command << c
+            state = :single_quoted
+          when "\""
+            command << c
+            state = :double_quoted
+          when "\\"
+            command << c
+            state = :escaped
+          else
+            command << c
+          end
+
+        when :single_quoted
+          command << c
+          state = :unquoted if c == "'"
+
+        when :double_quoted
+          case c
+          when "\\"
+            state = :double_quoted_escape
+          else
+            command << c
+          end
+          state = :unquoted if c == "\""
+
+        when :double_quoted_escape
+          case c
+          when "\"", "\\", "$", "`"
+            # no-op
+          else
+            command << "\\" # POSIX behaviour, backslash remains
+          end
+          command << c
+          state = :double_quoted
+
+        when :escaped
+          command << c
+          state = :unquoted
+
+        else
+          raise "Unknown state #{state}"
+        end
+      end
+      commands << command
+      commands
+    end
   end
 end
diff --git a/ruby/test/shell_test.rb b/ruby/test/shell_test.rb
index 59daea6..275d428 100644
--- a/ruby/test/shell_test.rb
+++ b/ruby/test/shell_test.rb
@@ -108,11 +108,11 @@ class ShellTest < Minitest::Test
   #########################
 
   def test_builtin_cd_no_args
-    skip "cannot easily implement without sequencing with ; or &&"
+    assert_equal Dir.home, `#{A1_PATH} -c 'cd; echo $PWD'`.strip
   end
 
   def test_builtin_cd
-    skip "cannot easily implement without sequencing with ; or &&"
+    assert_equal File.join(Dir.pwd, "blah"), `#{A1_PATH} -c 'mkdir -p blah; cd blah; echo $PWD; cd ..; rm -rf blah'`.strip
   end
 
   def test_builtin_cd_dash