Shell: Move to Userland/Shell/

1 files changed, 2996 insertions, 0 deletions

diff --git a/Userland/Shell/AST.cpp b/Userland/Shell/AST.cpp
new file mode 100644
index 0000000000..992452f503
--- /dev/null
+++ b/Userland/Shell/AST.cpp
@@ -0,0 +1,2996 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "AST.h"
+#include "Shell.h"
+#include <AK/MemoryStream.h>
+#include <AK/ScopeGuard.h>
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
+#include <AK/URL.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/File.h>
+#include <signal.h>
+
+//#define EXECUTE_DEBUG
+
+void AK::Formatter<Shell::AST::Command>::format(FormatBuilder& builder, const Shell::AST::Command& value)
+{
+    if (m_sign_mode != FormatBuilder::SignMode::Default)
+        ASSERT_NOT_REACHED();
+    if (m_alternative_form)
+        ASSERT_NOT_REACHED();
+    if (m_zero_pad)
+        ASSERT_NOT_REACHED();
+    if (m_mode != Mode::Default && m_mode != Mode::String)
+        ASSERT_NOT_REACHED();
+    if (m_width.has_value())
+        ASSERT_NOT_REACHED();
+    if (m_precision.has_value())
+        ASSERT_NOT_REACHED();
+
+    if (value.argv.is_empty()) {
+        builder.put_literal("(ShellInternal)");
+    } else {
+        bool first = true;
+        for (auto& arg : value.argv) {
+            if (!first)
+                builder.put_literal(" ");
+            first = false;
+            builder.put_literal(arg);
+        }
+    }
+
+    for (auto& redir : value.redirections) {
+        builder.put_padding(' ', 1);
+        if (redir.is_path_redirection()) {
+            auto path_redir = (const Shell::AST::PathRedirection*)&redir;
+            builder.put_i64(path_redir->fd);
+            switch (path_redir->direction) {
+            case Shell::AST::PathRedirection::Read:
+                builder.put_literal("<");
+                break;
+            case Shell::AST::PathRedirection::Write:
+                builder.put_literal(">");
+                break;
+            case Shell::AST::PathRedirection::WriteAppend:
+                builder.put_literal(">>");
+                break;
+            case Shell::AST::PathRedirection::ReadWrite:
+                builder.put_literal("<>");
+                break;
+            }
+            builder.put_literal(path_redir->path);
+        } else if (redir.is_fd_redirection()) {
+            auto* fdredir = (const Shell::AST::FdRedirection*)&redir;
+            builder.put_i64(fdredir->new_fd);
+            builder.put_literal(">");
+            builder.put_i64(fdredir->old_fd);
+        } else if (redir.is_close_redirection()) {
+            auto close_redir = (const Shell::AST::CloseRedirection*)&redir;
+            builder.put_i64(close_redir->fd);
+            builder.put_literal(">&-");
+        } else {
+            ASSERT_NOT_REACHED();
+        }
+    }
+
+    if (!value.next_chain.is_empty()) {
+        for (auto& command : value.next_chain) {
+            switch (command.action) {
+            case Shell::AST::NodeWithAction::And:
+                builder.put_literal(" && ");
+                break;
+            case Shell::AST::NodeWithAction::Or:
+                builder.put_literal(" || ");
+                break;
+            case Shell::AST::NodeWithAction::Sequence:
+                builder.put_literal("; ");
+                break;
+            }
+
+            builder.put_literal("(");
+            builder.put_literal(command.node->class_name());
+            builder.put_literal("...)");
+        }
+    }
+    if (!value.should_wait)
+        builder.put_literal("&");
+}
+
+namespace Shell::AST {
+
+static inline void print_indented(const String& str, int indent)
+{
+    for (auto i = 0; i < indent; ++i)
+        dbgprintf("  ");
+    dbgprintf("%s\n", str.characters());
+}
+
+static inline Optional<Position> merge_positions(const Optional<Position>& left, const Optional<Position>& right)
+{
+    if (!left.has_value())
+        return right;
+
+    if (!right.has_value())
+        return left;
+
+    return Position {
+        .start_offset = left->start_offset,
+        .end_offset = right->end_offset,
+        .start_line = left->start_line,
+        .end_line = right->end_line,
+    };
+}
+
+static inline Vector<Command> join_commands(Vector<Command> left, Vector<Command> right)
+{
+    Command command;
+
+    auto last_in_left = left.take_last();
+    auto first_in_right = right.take_first();
+
+    command.argv.append(last_in_left.argv);
+    command.argv.append(first_in_right.argv);
+
+    command.redirections.append(last_in_left.redirections);
+    command.redirections.append(first_in_right.redirections);
+
+    command.should_wait = first_in_right.should_wait && last_in_left.should_wait;
+    command.is_pipe_source = first_in_right.is_pipe_source;
+    command.should_notify_if_in_background = first_in_right.should_notify_if_in_background || last_in_left.should_notify_if_in_background;
+
+    command.position = merge_positions(last_in_left.position, first_in_right.position);
+
+    Vector<Command> commands;
+    commands.append(left);
+    commands.append(command);
+    commands.append(right);
+
+    return commands;
+}
+
+void Node::for_each_entry(RefPtr<Shell> shell, Function<IterationDecision(NonnullRefPtr<Value>)> callback)
+{
+    auto value = run(shell)->resolve_without_cast(shell);
+    if (value->is_job()) {
+        callback(value);
+        return;
+    }
+
+    if (value->is_list_without_resolution()) {
+        auto list = value->resolve_without_cast(shell);
+        for (auto& element : static_cast<ListValue*>(list.ptr())->values()) {
+            if (callback(element) == IterationDecision::Break)
+                break;
+        }
+        return;
+    }
+
+    auto list = value->resolve_as_list(shell);
+    for (auto& element : list) {
+        if (callback(create<StringValue>(move(element))) == IterationDecision::Break)
+            break;
+    }
+}
+
+Vector<Command> Node::to_lazy_evaluated_commands(RefPtr<Shell> shell)
+{
+    if (would_execute()) {
+        // Wrap the node in a "should immediately execute next" command.
+        return {
+            Command { {}, {}, true, false, true, true, {}, { NodeWithAction(*this, NodeWithAction::Sequence) }, position() }
+        };
+    }
+
+    return run(shell)->resolve_as_commands(shell);
+}
+
+void Node::dump(int level) const
+{
+    print_indented(String::formatted("{} at {}:{} (from {}.{} to {}.{})",
+                       class_name().characters(),
+                       m_position.start_offset,
+                       m_position.end_offset,
+                       m_position.start_line.line_number,
+                       m_position.start_line.line_column,
+                       m_position.end_line.line_number,
+                       m_position.end_line.line_column),
+        level);
+}
+
+Node::Node(Position position)
+    : m_position(position)
+{
+}
+
+Vector<Line::CompletionSuggestion> Node::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (matching_node) {
+        if (matching_node->is_bareword()) {
+            auto* node = static_cast<BarewordLiteral*>(matching_node.ptr());
+            auto corrected_offset = find_offset_into_node(node->text(), offset - matching_node->position().start_offset);
+
+            if (corrected_offset > node->text().length())
+                return {};
+            auto& text = node->text();
+
+            // If the literal isn't an option, treat it as a path.
+            if (!(text.starts_with("-") || text == "--" || text == "-"))
+                return shell.complete_path("", text, corrected_offset);
+
+            // If the literal is an option, we have to know the program name
+            // should we have no way to get that, bail early.
+
+            if (!hit_test_result.closest_command_node)
+                return {};
+
+            auto program_name_node = hit_test_result.closest_command_node->leftmost_trivial_literal();
+            if (!program_name_node)
+                return {};
+
+            String program_name;
+            if (program_name_node->is_bareword())
+                program_name = static_cast<BarewordLiteral*>(program_name_node.ptr())->text();
+            else
+                program_name = static_cast<StringLiteral*>(program_name_node.ptr())->text();
+
+            return shell.complete_option(program_name, text, corrected_offset);
+        }
+        return {};
+    }
+    auto result = hit_test_position(offset);
+    if (!result.matching_node)
+        return {};
+    auto node = result.matching_node;
+    if (node->is_bareword() || node != result.closest_node_with_semantic_meaning)
+        node = result.closest_node_with_semantic_meaning;
+
+    if (!node)
+        return {};
+
+    return node->complete_for_editor(shell, offset, result);
+}
+
+Vector<Line::CompletionSuggestion> Node::complete_for_editor(Shell& shell, size_t offset)
+{
+    return Node::complete_for_editor(shell, offset, { nullptr, nullptr, nullptr });
+}
+
+Node::~Node()
+{
+}
+
+void And::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> And::run(RefPtr<Shell> shell)
+{
+    auto commands = m_left->to_lazy_evaluated_commands(shell);
+    commands.last().next_chain.append(NodeWithAction { *m_right, NodeWithAction::And });
+    return create<CommandSequenceValue>(move(commands));
+}
+
+void And::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    metadata.is_first_in_list = true;
+    m_left->highlight_in_editor(editor, shell, metadata);
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult And::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node) {
+        if (!result.closest_command_node)
+            result.closest_command_node = m_right;
+        return result;
+    }
+
+    result = m_right->hit_test_position(offset);
+    if (!result.closest_command_node)
+        result.closest_command_node = m_right;
+    return result;
+}
+
+And::And(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right, Position and_position)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+    , m_and_position(and_position)
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+And::~And()
+{
+}
+
+void ListConcatenate::dump(int level) const
+{
+    Node::dump(level);
+    for (auto& element : m_list)
+        element->dump(level + 1);
+}
+
+RefPtr<Value> ListConcatenate::run(RefPtr<Shell> shell)
+{
+    RefPtr<Value> result = nullptr;
+
+    for (auto& element : m_list) {
+        if (!result) {
+            result = create<ListValue>({ element->run(shell)->resolve_without_cast(shell) });
+            continue;
+        }
+        auto element_value = element->run(shell)->resolve_without_cast(shell);
+
+        if (result->is_command() || element_value->is_command()) {
+            auto joined_commands = join_commands(result->resolve_as_commands(shell), element_value->resolve_as_commands(shell));
+
+            if (joined_commands.size() == 1) {
+                auto& command = joined_commands[0];
+                command.position = position();
+                result = create<CommandValue>(command);
+            } else {
+                result = create<CommandSequenceValue>(move(joined_commands));
+            }
+        } else {
+            NonnullRefPtrVector<Value> values;
+
+            if (result->is_list_without_resolution()) {
+                values.append(static_cast<ListValue*>(result.ptr())->values());
+            } else {
+                for (auto& result : result->resolve_as_list(shell))
+                    values.append(create<StringValue>(result));
+            }
+
+            values.append(element_value);
+
+            result = create<ListValue>(move(values));
+        }
+    }
+    if (!result)
+        return create<ListValue>({});
+
+    return result;
+}
+
+void ListConcatenate::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    auto first = metadata.is_first_in_list;
+    metadata.is_first_in_list = false;
+
+    metadata.is_first_in_list = first;
+    for (auto& element : m_list) {
+        element->highlight_in_editor(editor, shell, metadata);
+        metadata.is_first_in_list = false;
+    }
+}
+
+HitTestResult ListConcatenate::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    bool first = true;
+    for (auto& element : m_list) {
+        auto result = element->hit_test_position(offset);
+        if (!result.closest_node_with_semantic_meaning && !first)
+            result.closest_node_with_semantic_meaning = this;
+        if (result.matching_node)
+            return result;
+        first = false;
+    }
+
+    return {};
+}
+
+RefPtr<Node> ListConcatenate::leftmost_trivial_literal() const
+{
+    if (m_list.is_empty())
+        return nullptr;
+
+    return m_list.first()->leftmost_trivial_literal();
+}
+
+ListConcatenate::ListConcatenate(Position position, Vector<NonnullRefPtr<Node>> list)
+    : Node(move(position))
+    , m_list(move(list))
+{
+    for (auto& element : m_list) {
+        if (element->is_syntax_error()) {
+            set_is_syntax_error(element->syntax_error_node());
+            break;
+        }
+    }
+}
+
+ListConcatenate::~ListConcatenate()
+{
+}
+
+void Background::dump(int level) const
+{
+    Node::dump(level);
+    m_command->dump(level + 1);
+}
+
+RefPtr<Value> Background::run(RefPtr<Shell> shell)
+{
+    auto commands = m_command->to_lazy_evaluated_commands(shell);
+    for (auto& command : commands)
+        command.should_wait = false;
+
+    return create<CommandSequenceValue>(move(commands));
+}
+
+void Background::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_command->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Background::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return m_command->hit_test_position(offset);
+}
+
+Background::Background(Position position, NonnullRefPtr<Node> command)
+    : Node(move(position))
+    , m_command(move(command))
+{
+    if (m_command->is_syntax_error())
+        set_is_syntax_error(m_command->syntax_error_node());
+}
+
+Background::~Background()
+{
+}
+
+void BarewordLiteral::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_text, level + 1);
+}
+
+RefPtr<Value> BarewordLiteral::run(RefPtr<Shell>)
+{
+    return create<StringValue>(m_text);
+}
+
+void BarewordLiteral::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    if (metadata.is_first_in_list) {
+        if (shell.is_runnable(m_text)) {
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Bold });
+        } else {
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Red) });
+        }
+
+        return;
+    }
+
+    if (m_text.starts_with('-')) {
+        if (m_text == "--") {
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Green) });
+            return;
+        }
+        if (m_text == "-")
+            return;
+
+        if (m_text.starts_with("--")) {
+            auto index = m_text.index_of("=").value_or(m_text.length() - 1) + 1;
+            editor.stylize({ m_position.start_offset, m_position.start_offset + index }, { Line::Style::Foreground(Line::Style::XtermColor::Cyan) });
+        } else {
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Cyan) });
+        }
+    }
+    if (Core::File::exists(m_text)) {
+        auto realpath = shell.resolve_path(m_text);
+        auto url = URL::create_with_file_protocol(realpath);
+        url.set_host(shell.hostname);
+        editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_string()) });
+    }
+}
+
+BarewordLiteral::BarewordLiteral(Position position, String text)
+    : Node(move(position))
+    , m_text(move(text))
+{
+}
+
+BarewordLiteral::~BarewordLiteral()
+{
+}
+
+void BraceExpansion::dump(int level) const
+{
+    Node::dump(level);
+    for (auto& entry : m_entries)
+        entry.dump(level + 1);
+}
+
+RefPtr<Value> BraceExpansion::run(RefPtr<Shell> shell)
+{
+    NonnullRefPtrVector<Value> values;
+    for (auto& entry : m_entries) {
+        auto value = entry.run(shell);
+        if (value)
+            values.append(value.release_nonnull());
+    }
+
+    return create<ListValue>(move(values));
+}
+
+HitTestResult BraceExpansion::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    for (auto& entry : m_entries) {
+        auto result = entry.hit_test_position(offset);
+        if (result.matching_node) {
+            if (!result.closest_command_node)
+                result.closest_command_node = &entry;
+            return result;
+        }
+    }
+
+    return {};
+}
+
+void BraceExpansion::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    for (auto& entry : m_entries) {
+        entry.highlight_in_editor(editor, shell, metadata);
+        metadata.is_first_in_list = false;
+    }
+}
+
+BraceExpansion::BraceExpansion(Position position, NonnullRefPtrVector<Node> entries)
+    : Node(move(position))
+    , m_entries(move(entries))
+{
+    for (auto& entry : m_entries) {
+        if (entry.is_syntax_error()) {
+            set_is_syntax_error(entry.syntax_error_node());
+            break;
+        }
+    }
+}
+
+BraceExpansion::~BraceExpansion()
+{
+}
+
+void CastToCommand::dump(int level) const
+{
+    Node::dump(level);
+    m_inner->dump(level + 1);
+}
+
+RefPtr<Value> CastToCommand::run(RefPtr<Shell> shell)
+{
+    if (m_inner->is_command())
+        return m_inner->run(shell);
+
+    auto value = m_inner->run(shell)->resolve_without_cast(shell);
+    if (value->is_command())
+        return value;
+
+    auto argv = value->resolve_as_list(shell);
+    return create<CommandValue>(move(argv), position());
+}
+
+void CastToCommand::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_inner->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult CastToCommand::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_inner->hit_test_position(offset);
+    if (!result.closest_node_with_semantic_meaning)
+        result.closest_node_with_semantic_meaning = this;
+    return result;
+}
+
+Vector<Line::CompletionSuggestion> CastToCommand::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node || !matching_node->is_bareword())
+        return {};
+
+    auto corrected_offset = offset - matching_node->position().start_offset;
+    auto* node = static_cast<BarewordLiteral*>(matching_node.ptr());
+
+    if (corrected_offset > node->text().length())
+        return {};
+
+    return shell.complete_program_name(node->text(), corrected_offset);
+}
+
+RefPtr<Node> CastToCommand::leftmost_trivial_literal() const
+{
+    return m_inner->leftmost_trivial_literal();
+}
+
+CastToCommand::CastToCommand(Position position, NonnullRefPtr<Node> inner)
+    : Node(move(position))
+    , m_inner(move(inner))
+{
+    if (m_inner->is_syntax_error())
+        set_is_syntax_error(m_inner->syntax_error_node());
+}
+
+CastToCommand::~CastToCommand()
+{
+}
+
+void CastToList::dump(int level) const
+{
+    Node::dump(level);
+    if (m_inner)
+        m_inner->dump(level + 1);
+    else
+        print_indented("(empty)", level + 1);
+}
+
+RefPtr<Value> CastToList::run(RefPtr<Shell> shell)
+{
+    if (!m_inner)
+        return create<ListValue>({});
+
+    auto inner_value = m_inner->run(shell)->resolve_without_cast(shell);
+
+    if (inner_value->is_command() || inner_value->is_list())
+        return inner_value;
+
+    auto values = inner_value->resolve_as_list(shell);
+    NonnullRefPtrVector<Value> cast_values;
+    for (auto& value : values)
+        cast_values.append(create<StringValue>(value));
+
+    return create<ListValue>(cast_values);
+}
+
+void CastToList::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    if (m_inner)
+        m_inner->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult CastToList::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    if (!m_inner)
+        return {};
+
+    return m_inner->hit_test_position(offset);
+}
+
+RefPtr<Node> CastToList::leftmost_trivial_literal() const
+{
+    return m_inner->leftmost_trivial_literal();
+}
+
+CastToList::CastToList(Position position, RefPtr<Node> inner)
+    : Node(move(position))
+    , m_inner(move(inner))
+{
+    if (m_inner && m_inner->is_syntax_error())
+        set_is_syntax_error(m_inner->syntax_error_node());
+}
+
+CastToList::~CastToList()
+{
+}
+
+void CloseFdRedirection::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String::format("%d -> Close", m_fd), level);
+}
+
+RefPtr<Value> CloseFdRedirection::run(RefPtr<Shell>)
+{
+    Command command;
+    command.position = position();
+    command.redirections.append(adopt(*new CloseRedirection(m_fd)));
+    return create<CommandValue>(move(command));
+}
+
+void CloseFdRedirection::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset - 1 }, { Line::Style::Foreground(0x87, 0x9b, 0xcd) }); // 25% Darkened Periwinkle
+    editor.stylize({ m_position.end_offset - 1, m_position.end_offset }, { Line::Style::Foreground(0xff, 0x7e, 0x00) });   // Amber
+}
+
+CloseFdRedirection::CloseFdRedirection(Position position, int fd)
+    : Node(move(position))
+    , m_fd(fd)
+{
+}
+
+CloseFdRedirection::~CloseFdRedirection()
+{
+}
+
+void CommandLiteral::dump(int level) const
+{
+    Node::dump(level);
+    print_indented("(Generated command literal)", level + 1);
+}
+
+RefPtr<Value> CommandLiteral::run(RefPtr<Shell>)
+{
+    return create<CommandValue>(m_command);
+}
+
+CommandLiteral::CommandLiteral(Position position, Command command)
+    : Node(move(position))
+    , m_command(move(command))
+{
+}
+
+CommandLiteral::~CommandLiteral()
+{
+}
+
+void Comment::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_text, level + 1);
+}
+
+RefPtr<Value> Comment::run(RefPtr<Shell>)
+{
+    return create<ListValue>({});
+}
+
+void Comment::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(150, 150, 150) }); // Light gray
+}
+
+Comment::Comment(Position position, String text)
+    : Node(move(position))
+    , m_text(move(text))
+{
+}
+
+Comment::~Comment()
+{
+}
+
+void ContinuationControl::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_kind == Continue ? "(Continue)" : "(Break)", level + 1);
+}
+
+RefPtr<Value> ContinuationControl::run(RefPtr<Shell> shell)
+{
+    if (m_kind == Break)
+        shell->raise_error(Shell::ShellError::InternalControlFlowBreak, {}, position());
+    else if (m_kind == Continue)
+        shell->raise_error(Shell::ShellError::InternalControlFlowContinue, {}, position());
+    else
+        ASSERT_NOT_REACHED();
+    return create<ListValue>({});
+}
+
+void ContinuationControl::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+}
+
+void DoubleQuotedString::dump(int level) const
+{
+    Node::dump(level);
+    m_inner->dump(level + 1);
+}
+
+RefPtr<Value> DoubleQuotedString::run(RefPtr<Shell> shell)
+{
+    StringBuilder builder;
+    auto values = m_inner->run(shell)->resolve_as_list(shell);
+
+    builder.join("", values);
+
+    return create<StringValue>(builder.to_string());
+}
+
+void DoubleQuotedString::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    Line::Style style { Line::Style::Foreground(Line::Style::XtermColor::Yellow) };
+    if (metadata.is_first_in_list)
+        style.unify_with({ Line::Style::Bold });
+
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, style);
+    metadata.is_first_in_list = false;
+    m_inner->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult DoubleQuotedString::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return m_inner->hit_test_position(offset);
+}
+
+DoubleQuotedString::DoubleQuotedString(Position position, RefPtr<Node> inner)
+    : Node(move(position))
+    , m_inner(move(inner))
+{
+    if (m_inner->is_syntax_error())
+        set_is_syntax_error(m_inner->syntax_error_node());
+}
+
+DoubleQuotedString::~DoubleQuotedString()
+{
+}
+
+void DynamicEvaluate::dump(int level) const
+{
+    Node::dump(level);
+    m_inner->dump(level + 1);
+}
+
+RefPtr<Value> DynamicEvaluate::run(RefPtr<Shell> shell)
+{
+    auto result = m_inner->run(shell)->resolve_without_cast(shell);
+    // Dynamic Evaluation behaves differently between strings and lists.
+    // Strings are treated as variables, and Lists are treated as commands.
+    if (result->is_string()) {
+        auto name_part = result->resolve_as_list(shell);
+        ASSERT(name_part.size() == 1);
+        return create<SimpleVariableValue>(name_part[0]);
+    }
+
+    // If it's anything else, we're just gonna cast it to a list.
+    auto list = result->resolve_as_list(shell);
+    return create<CommandValue>(move(list), position());
+}
+
+void DynamicEvaluate::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+    m_inner->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult DynamicEvaluate::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return m_inner->hit_test_position(offset);
+}
+
+DynamicEvaluate::DynamicEvaluate(Position position, NonnullRefPtr<Node> inner)
+    : Node(move(position))
+    , m_inner(move(inner))
+{
+    if (m_inner->is_syntax_error())
+        set_is_syntax_error(m_inner->syntax_error_node());
+}
+
+DynamicEvaluate::~DynamicEvaluate()
+{
+}
+
+void Fd2FdRedirection::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String::format("%d -> %d", m_old_fd, m_new_fd), level);
+}
+
+RefPtr<Value> Fd2FdRedirection::run(RefPtr<Shell>)
+{
+    Command command;
+    command.position = position();
+    command.redirections.append(FdRedirection::create(m_new_fd, m_old_fd, Rewiring::Close::None));
+    return create<CommandValue>(move(command));
+}
+
+void Fd2FdRedirection::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(0x87, 0x9b, 0xcd) }); // 25% Darkened Periwinkle
+}
+
+Fd2FdRedirection::Fd2FdRedirection(Position position, int src, int dst)
+    : Node(move(position))
+    , m_old_fd(src)
+    , m_new_fd(dst)
+{
+}
+
+Fd2FdRedirection::~Fd2FdRedirection()
+{
+}
+
+void FunctionDeclaration::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String::format("(name: %s)\n", m_name.name.characters()), level + 1);
+    print_indented("(argument namess)", level + 1);
+    for (auto& arg : m_arguments)
+        print_indented(String::format("(name: %s)\n", arg.name.characters()), level + 2);
+
+    print_indented("(body)", level + 1);
+    if (m_block)
+        m_block->dump(level + 2);
+    else
+        print_indented("(null)", level + 2);
+}
+
+RefPtr<Value> FunctionDeclaration::run(RefPtr<Shell> shell)
+{
+    Vector<String> args;
+    for (auto& arg : m_arguments)
+        args.append(arg.name);
+
+    shell->define_function(m_name.name, move(args), m_block);
+
+    return create<ListValue>({});
+}
+
+void FunctionDeclaration::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    editor.stylize({ m_name.position.start_offset, m_name.position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Blue) });
+
+    for (auto& arg : m_arguments)
+        editor.stylize({ arg.position.start_offset, arg.position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Blue), Line::Style::Italic });
+
+    metadata.is_first_in_list = true;
+    if (m_block)
+        m_block->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult FunctionDeclaration::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    if (!m_block)
+        return {};
+
+    auto result = m_block->hit_test_position(offset);
+    if (result.matching_node && result.matching_node->is_simple_variable())
+        result.closest_node_with_semantic_meaning = this;
+    return result;
+}
+
+Vector<Line::CompletionSuggestion> FunctionDeclaration::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node)
+        return {};
+
+    if (!matching_node->is_simple_variable())
+        return matching_node->complete_for_editor(shell, offset, hit_test_result);
+
+    auto corrected_offset = offset - matching_node->position().start_offset - 1; // Skip the first '$'
+    auto* node = static_cast<SimpleVariable*>(matching_node.ptr());
+
+    auto name = node->name().substring_view(0, corrected_offset);
+
+    Vector<Line::CompletionSuggestion> results;
+    for (auto& arg : m_arguments) {
+        if (arg.name.starts_with(name))
+            results.append(arg.name);
+    }
+
+    results.append(matching_node->complete_for_editor(shell, offset, hit_test_result));
+
+    return results;
+}
+
+FunctionDeclaration::FunctionDeclaration(Position position, NameWithPosition name, Vector<NameWithPosition> arguments, RefPtr<AST::Node> body)
+    : Node(move(position))
+    , m_name(move(name))
+    , m_arguments(arguments)
+    , m_block(move(body))
+{
+    if (m_block && m_block->is_syntax_error())
+        set_is_syntax_error(m_block->syntax_error_node());
+}
+
+FunctionDeclaration::~FunctionDeclaration()
+{
+}
+
+void ForLoop::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String::format("%s in\n", m_variable_name.characters()), level + 1);
+    if (m_iterated_expression)
+        m_iterated_expression->dump(level + 2);
+    else
+        print_indented("(ever)", level + 2);
+    print_indented("Running", level + 1);
+    if (m_block)
+        m_block->dump(level + 2);
+    else
+        print_indented("(null)", level + 2);
+}
+
+RefPtr<Value> ForLoop::run(RefPtr<Shell> shell)
+{
+    if (!m_block)
+        return create<ListValue>({});
+
+    size_t consecutive_interruptions = 0;
+    auto run = [&](auto& block_value) {
+        if (shell->has_error(Shell::ShellError::InternalControlFlowBreak)) {
+            shell->take_error();
+            return IterationDecision::Break;
+        }
+
+        if (shell->has_error(Shell::ShellError::InternalControlFlowContinue)) {
+            shell->take_error();
+            return IterationDecision::Continue;
+        }
+
+        if (block_value->is_job()) {
+            auto job = static_cast<JobValue*>(block_value.ptr())->job();
+            if (!job || job->is_running_in_background())
+                return IterationDecision::Continue;
+            shell->block_on_job(job);
+
+            if (job->signaled()) {
+                if (job->termination_signal() == SIGINT)
+                    ++consecutive_interruptions;
+                else
+                    return IterationDecision::Break;
+            } else {
+                consecutive_interruptions = 0;
+            }
+        }
+        return IterationDecision::Continue;
+    };
+
+    if (m_iterated_expression) {
+        m_iterated_expression->for_each_entry(shell, [&](auto value) {
+            if (consecutive_interruptions == 2)
+                return IterationDecision::Break;
+
+            RefPtr<Value> block_value;
+
+            {
+                auto frame = shell->push_frame(String::formatted("for ({})", this));
+                shell->set_local_variable(m_variable_name, value, true);
+
+                block_value = m_block->run(shell);
+            }
+            return run(block_value);
+        });
+    } else {
+        for (;;) {
+            if (consecutive_interruptions == 2)
+                break;
+
+            RefPtr<Value> block_value = m_block->run(shell);
+            if (run(block_value) == IterationDecision::Break)
+                break;
+        }
+    }
+
+    return create<ListValue>({});
+}
+
+void ForLoop::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    auto is_loop = m_iterated_expression.is_null();
+    editor.stylize({ m_position.start_offset, m_position.start_offset + (is_loop ? 4 : 3) }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+    if (!is_loop) {
+        if (m_in_kw_position.has_value())
+            editor.stylize({ m_in_kw_position.value().start_offset, m_in_kw_position.value().end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+
+        metadata.is_first_in_list = false;
+        m_iterated_expression->highlight_in_editor(editor, shell, metadata);
+    }
+
+    metadata.is_first_in_list = true;
+    if (m_block)
+        m_block->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult ForLoop::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    if (m_iterated_expression) {
+        if (auto result = m_iterated_expression->hit_test_position(offset); result.matching_node)
+            return result;
+    }
+
+    if (!m_block)
+        return {};
+
+    return m_block->hit_test_position(offset);
+}
+
+ForLoop::ForLoop(Position position, String variable_name, RefPtr<AST::Node> iterated_expr, RefPtr<AST::Node> block, Optional<Position> in_kw_position)
+    : Node(move(position))
+    , m_variable_name(move(variable_name))
+    , m_iterated_expression(move(iterated_expr))
+    , m_block(move(block))
+    , m_in_kw_position(move(in_kw_position))
+{
+    if (m_iterated_expression && m_iterated_expression->is_syntax_error())
+        set_is_syntax_error(m_iterated_expression->syntax_error_node());
+    else if (m_block && m_block->is_syntax_error())
+        set_is_syntax_error(m_block->syntax_error_node());
+}
+
+ForLoop::~ForLoop()
+{
+}
+
+void Glob::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_text, level + 1);
+}
+
+RefPtr<Value> Glob::run(RefPtr<Shell>)
+{
+    return create<GlobValue>(m_text, position());
+}
+
+void Glob::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata metadata)
+{
+    Line::Style style { Line::Style::Foreground(Line::Style::XtermColor::Cyan) };
+    if (metadata.is_first_in_list)
+        style.unify_with({ Line::Style::Bold });
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, move(style));
+}
+
+Glob::Glob(Position position, String text)
+    : Node(move(position))
+    , m_text(move(text))
+{
+}
+
+Glob::~Glob()
+{
+}
+
+void Execute::dump(int level) const
+{
+    Node::dump(level);
+    if (m_capture_stdout)
+        print_indented("(Capturing stdout)", level + 1);
+    m_command->dump(level + 1);
+}
+
+void Execute::for_each_entry(RefPtr<Shell> shell, Function<IterationDecision(NonnullRefPtr<Value>)> callback)
+{
+    if (m_command->would_execute())
+        return m_command->for_each_entry(shell, move(callback));
+
+    auto commands = shell->expand_aliases(m_command->run(shell)->resolve_as_commands(shell));
+
+    if (m_capture_stdout) {
+        int pipefd[2];
+        int rc = pipe(pipefd);
+        if (rc < 0) {
+            dbgln("Error: cannot pipe(): {}", strerror(errno));
+            return;
+        }
+        auto& last_in_commands = commands.last();
+
+        last_in_commands.redirections.prepend(FdRedirection::create(pipefd[1], STDOUT_FILENO, Rewiring::Close::Old));
+        last_in_commands.should_wait = false;
+        last_in_commands.should_notify_if_in_background = false;
+        last_in_commands.is_pipe_source = false;
+
+        Core::EventLoop loop;
+
+        auto notifier = Core::Notifier::construct(pipefd[0], Core::Notifier::Read);
+        DuplexMemoryStream stream;
+
+        enum {
+            Continue,
+            Break,
+            NothingLeft,
+        };
+        auto check_and_call = [&] {
+            auto ifs = shell->local_variable_or("IFS", "\n");
+
+            if (auto offset = stream.offset_of(ifs.bytes()); offset.has_value()) {
+                auto line_end = offset.value();
+                if (line_end == 0) {
+                    auto rc = stream.discard_or_error(ifs.length());
+                    ASSERT(rc);
+
+                    if (shell->options.inline_exec_keep_empty_segments)
+                        if (callback(create<StringValue>("")) == IterationDecision::Break) {
+                            loop.quit(Break);
+                            notifier->set_enabled(false);
+                            return Break;
+                        }
+                } else {
+                    auto entry = ByteBuffer::create_uninitialized(line_end + ifs.length());
+                    auto rc = stream.read_or_error(entry);
+                    ASSERT(rc);
+
+                    auto str = StringView(entry.data(), entry.size() - ifs.length());
+                    if (callback(create<StringValue>(str)) == IterationDecision::Break) {
+                        loop.quit(Break);
+                        notifier->set_enabled(false);
+                        return Break;
+                    }
+                }
+
+                return Continue;
+            }
+
+            return NothingLeft;
+        };
+
+        notifier->on_ready_to_read = [&] {
+            constexpr static auto buffer_size = 16;
+            u8 buffer[buffer_size];
+            size_t remaining_size = buffer_size;
+
+            for (;;) {
+                notifier->set_event_mask(Core::Notifier::None);
+                bool should_enable_notifier = false;
+
+                ScopeGuard notifier_enabler { [&] {
+                    if (should_enable_notifier)
+                        notifier->set_event_mask(Core::Notifier::Read);
+                } };
+
+                if (check_and_call() == Break) {
+                    loop.quit(Break);
+                    return;
+                }
+
+                auto read_size = read(pipefd[0], buffer, remaining_size);
+                if (read_size < 0) {
+                    int saved_errno = errno;
+                    if (saved_errno == EINTR) {
+                        should_enable_notifier = true;
+                        continue;
+                    }
+                    if (saved_errno == 0)
+                        continue;
+                    dbgln("read() failed: {}", strerror(saved_errno));
+                    break;
+                }
+                if (read_size == 0)
+                    break;
+
+                should_enable_notifier = true;
+                stream.write({ buffer, (size_t)read_size });
+            }
+
+            loop.quit(NothingLeft);
+        };
+
+        auto jobs = shell->run_commands(commands);
+        ScopeGuard kill_jobs_if_around { [&] {
+            for (auto& job : jobs) {
+                if (job.is_running_in_background() && !job.exited() && !job.signaled()) {
+                    job.set_should_announce_signal(false); // We're explicitly killing it here.
+                    shell->kill_job(&job, SIGTERM);
+                }
+            }
+        } };
+
+        auto exit_reason = loop.exec();
+
+        notifier->on_ready_to_read = nullptr;
+
+        if (close(pipefd[0]) < 0) {
+            dbgln("close() failed: {}", strerror(errno));
+        }
+
+        if (exit_reason != Break && !stream.eof()) {
+            auto action = Continue;
+            do {
+                action = check_and_call();
+                if (action == Break)
+                    return;
+            } while (action == Continue);
+
+            if (!stream.eof()) {
+                auto entry = ByteBuffer::create_uninitialized(stream.size());
+                auto rc = stream.read_or_error(entry);
+                ASSERT(rc);
+                callback(create<StringValue>(String::copy(entry)));
+            }
+        }
+
+        return;
+    }
+
+    auto jobs = shell->run_commands(commands);
+
+    if (!jobs.is_empty())
+        callback(create<JobValue>(&jobs.last()));
+}
+
+RefPtr<Value> Execute::run(RefPtr<Shell> shell)
+{
+    if (m_command->would_execute())
+        return m_command->run(shell);
+
+    NonnullRefPtrVector<Value> values;
+    for_each_entry(shell, [&](auto value) {
+        values.append(*value);
+        return IterationDecision::Continue;
+    });
+
+    if (values.size() == 1 && values.first().is_job())
+        return values.first();
+
+    return create<ListValue>(move(values));
+}
+
+void Execute::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    if (m_capture_stdout)
+        editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Green) });
+    metadata.is_first_in_list = true;
+    m_command->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Execute::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_command->hit_test_position(offset);
+    if (!result.closest_node_with_semantic_meaning)
+        result.closest_node_with_semantic_meaning = this;
+    if (!result.closest_command_node)
+        result.closest_command_node = m_command;
+    return result;
+}
+
+Vector<Line::CompletionSuggestion> Execute::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node || !matching_node->is_bareword())
+        return {};
+
+    auto corrected_offset = offset - matching_node->position().start_offset;
+    auto* node = static_cast<BarewordLiteral*>(matching_node.ptr());
+
+    if (corrected_offset > node->text().length())
+        return {};
+
+    return shell.complete_program_name(node->text(), corrected_offset);
+}
+
+Execute::Execute(Position position, NonnullRefPtr<Node> command, bool capture_stdout)
+    : Node(move(position))
+    , m_command(move(command))
+    , m_capture_stdout(capture_stdout)
+{
+    if (m_command->is_syntax_error())
+        set_is_syntax_error(m_command->syntax_error_node());
+}
+
+Execute::~Execute()
+{
+}
+
+void IfCond::dump(int level) const
+{
+    Node::dump(level);
+    print_indented("Condition", ++level);
+    m_condition->dump(level + 1);
+    print_indented("True Branch", level);
+    if (m_true_branch)
+        m_true_branch->dump(level + 1);
+    else
+        print_indented("(empty)", level + 1);
+    print_indented("False Branch", level);
+    if (m_false_branch)
+        m_false_branch->dump(level + 1);
+    else
+        print_indented("(empty)", level + 1);
+}
+
+RefPtr<Value> IfCond::run(RefPtr<Shell> shell)
+{
+    auto cond = m_condition->run(shell)->resolve_without_cast(shell);
+    // The condition could be a builtin, in which case it has already run and exited.
+    if (cond && cond->is_job()) {
+        auto cond_job_value = static_cast<const JobValue*>(cond.ptr());
+        auto cond_job = cond_job_value->job();
+
+        shell->block_on_job(cond_job);
+
+        if (cond_job->signaled())
+            return create<ListValue>({}); // Exit early.
+    }
+    if (shell->last_return_code == 0) {
+        if (m_true_branch)
+            return m_true_branch->run(shell);
+    } else {
+        if (m_false_branch)
+            return m_false_branch->run(shell);
+    }
+
+    return create<ListValue>({});
+}
+
+void IfCond::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    metadata.is_first_in_list = true;
+
+    editor.stylize({ m_position.start_offset, m_position.start_offset + 2 }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+    if (m_else_position.has_value())
+        editor.stylize({ m_else_position.value().start_offset, m_else_position.value().start_offset + 4 }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+
+    m_condition->highlight_in_editor(editor, shell, metadata);
+    if (m_true_branch)
+        m_true_branch->highlight_in_editor(editor, shell, metadata);
+    if (m_false_branch)
+        m_false_branch->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult IfCond::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    if (auto result = m_condition->hit_test_position(offset); result.matching_node)
+        return result;
+
+    if (m_true_branch) {
+        if (auto result = m_true_branch->hit_test_position(offset); result.matching_node)
+            return result;
+    }
+
+    if (m_false_branch) {
+        if (auto result = m_false_branch->hit_test_position(offset); result.matching_node)
+            return result;
+    }
+
+    return {};
+}
+
+IfCond::IfCond(Position position, Optional<Position> else_position, NonnullRefPtr<Node> condition, RefPtr<Node> true_branch, RefPtr<Node> false_branch)
+    : Node(move(position))
+    , m_condition(move(condition))
+    , m_true_branch(move(true_branch))
+    , m_false_branch(move(false_branch))
+    , m_else_position(move(else_position))
+{
+    if (m_condition->is_syntax_error())
+        set_is_syntax_error(m_condition->syntax_error_node());
+    else if (m_true_branch && m_true_branch->is_syntax_error())
+        set_is_syntax_error(m_true_branch->syntax_error_node());
+    else if (m_false_branch && m_false_branch->is_syntax_error())
+        set_is_syntax_error(m_false_branch->syntax_error_node());
+
+    m_condition = create<AST::Execute>(m_condition->position(), m_condition);
+
+    if (m_true_branch) {
+        auto true_branch = m_true_branch.release_nonnull();
+        m_true_branch = create<AST::Execute>(true_branch->position(), true_branch);
+    }
+
+    if (m_false_branch) {
+        auto false_branch = m_false_branch.release_nonnull();
+        m_false_branch = create<AST::Execute>(false_branch->position(), false_branch);
+    }
+}
+
+IfCond::~IfCond()
+{
+}
+
+void Join::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> Join::run(RefPtr<Shell> shell)
+{
+    auto left = m_left->to_lazy_evaluated_commands(shell);
+    auto right = m_right->to_lazy_evaluated_commands(shell);
+
+    return create<CommandSequenceValue>(join_commands(move(left), move(right)));
+}
+
+void Join::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+    if (m_left->is_list() || m_left->is_command())
+        metadata.is_first_in_list = false;
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Join::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node)
+        return result;
+
+    return m_right->hit_test_position(offset);
+}
+
+RefPtr<Node> Join::leftmost_trivial_literal() const
+{
+    if (auto value = m_left->leftmost_trivial_literal())
+        return value;
+    return m_right->leftmost_trivial_literal();
+}
+
+Join::Join(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+Join::~Join()
+{
+}
+
+void MatchExpr::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String::formatted("(expression: {})", m_expr_name.characters()), level + 1);
+    m_matched_expr->dump(level + 2);
+    print_indented(String::formatted("(named: {})", m_expr_name.characters()), level + 1);
+    print_indented("(entries)", level + 1);
+    for (auto& entry : m_entries) {
+        StringBuilder builder;
+        builder.append("(match");
+        if (entry.match_names.has_value()) {
+            builder.append(" to names (");
+            bool first = true;
+            for (auto& name : entry.match_names.value()) {
+                if (!first)
+                    builder.append(' ');
+                first = false;
+                builder.append(name);
+            }
+            builder.append("))");
+
+        } else {
+            builder.append(')');
+        }
+        print_indented(builder.string_view(), level + 2);
+        for (auto& node : entry.options)
+            node.dump(level + 3);
+        print_indented("(execute)", level + 2);
+        if (entry.body)
+            entry.body->dump(level + 3);
+        else
+            print_indented("(nothing)", level + 3);
+    }
+}
+
+RefPtr<Value> MatchExpr::run(RefPtr<Shell> shell)
+{
+    auto value = m_matched_expr->run(shell)->resolve_without_cast(shell);
+    auto list = value->resolve_as_list(shell);
+
+    auto list_matches = [&](auto&& pattern, auto& spans) {
+        if (pattern.size() != list.size())
+            return false;
+
+        for (size_t i = 0; i < pattern.size(); ++i) {
+            Vector<AK::MaskSpan> mask_spans;
+            if (!list[i].matches(pattern[i], mask_spans))
+                return false;
+            for (auto& span : mask_spans)
+                spans.append(list[i].substring(span.start, span.length));
+        }
+
+        return true;
+    };
+
+    auto resolve_pattern = [&](auto& option) {
+        Vector<String> pattern;
+        if (option.is_glob()) {
+            pattern.append(static_cast<const Glob*>(&option)->text());
+        } else if (option.is_bareword()) {
+            pattern.append(static_cast<const BarewordLiteral*>(&option)->text());
+        } else {
+            auto list = option.run(shell);
+            option.for_each_entry(shell, [&](auto&& value) {
+                pattern.append(value->resolve_as_list(nullptr)); // Note: 'nullptr' incurs special behaviour,
+                                                                 //       asking the node for a 'raw' value.
+                return IterationDecision::Continue;
+            });
+        }
+
+        return pattern;
+    };
+
+    auto frame = shell->push_frame(String::formatted("match ({})", this));
+    if (!m_expr_name.is_empty())
+        shell->set_local_variable(m_expr_name, value, true);
+
+    for (auto& entry : m_entries) {
+        for (auto& option : entry.options) {
+            Vector<String> spans;
+            if (list_matches(resolve_pattern(option), spans)) {
+                if (entry.body) {
+                    if (entry.match_names.has_value()) {
+                        size_t i = 0;
+                        for (auto& name : entry.match_names.value()) {
+                            if (spans.size() > i)
+                                shell->set_local_variable(name, create<AST::StringValue>(spans[i]), true);
+                            ++i;
+                        }
+                    }
+                    return entry.body->run(shell);
+                } else {
+                    return create<AST::ListValue>({});
+                }
+            }
+        }
+    }
+
+    shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, "Non-exhaustive match rules!", position());
+    return create<AST::ListValue>({});
+}
+
+void MatchExpr::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.start_offset + 5 }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+    if (m_as_position.has_value())
+        editor.stylize({ m_as_position.value().start_offset, m_as_position.value().end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+
+    metadata.is_first_in_list = false;
+    m_matched_expr->highlight_in_editor(editor, shell, metadata);
+
+    for (auto& entry : m_entries) {
+        metadata.is_first_in_list = false;
+        for (auto& option : entry.options)
+            option.highlight_in_editor(editor, shell, metadata);
+
+        metadata.is_first_in_list = true;
+        if (entry.body)
+            entry.body->highlight_in_editor(editor, shell, metadata);
+
+        for (auto& position : entry.pipe_positions)
+            editor.stylize({ position.start_offset, position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+
+        if (entry.match_as_position.has_value())
+            editor.stylize({ entry.match_as_position.value().start_offset, entry.match_as_position.value().end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+    }
+}
+
+HitTestResult MatchExpr::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_matched_expr->hit_test_position(offset);
+    if (result.matching_node)
+        return result;
+
+    for (auto& entry : m_entries) {
+        if (!entry.body)
+            continue;
+        auto result = entry.body->hit_test_position(offset);
+        if (result.matching_node)
+            return result;
+    }
+
+    return {};
+}
+
+MatchExpr::MatchExpr(Position position, NonnullRefPtr<Node> expr, String name, Optional<Position> as_position, Vector<MatchEntry> entries)
+    : Node(move(position))
+    , m_matched_expr(move(expr))
+    , m_expr_name(move(name))
+    , m_as_position(move(as_position))
+    , m_entries(move(entries))
+{
+    if (m_matched_expr->is_syntax_error()) {
+        set_is_syntax_error(m_matched_expr->syntax_error_node());
+    } else {
+        for (auto& entry : m_entries) {
+            if (!entry.body)
+                continue;
+            if (entry.body->is_syntax_error()) {
+                set_is_syntax_error(entry.body->syntax_error_node());
+                break;
+            }
+        }
+    }
+}
+
+MatchExpr::~MatchExpr()
+{
+}
+
+void Or::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> Or::run(RefPtr<Shell> shell)
+{
+    auto commands = m_left->to_lazy_evaluated_commands(shell);
+    commands.last().next_chain.empend(*m_right, NodeWithAction::Or);
+    return create<CommandSequenceValue>(move(commands));
+}
+
+void Or::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Or::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node) {
+        if (!result.closest_command_node)
+            result.closest_command_node = m_right;
+        return result;
+    }
+
+    result = m_right->hit_test_position(offset);
+    if (!result.closest_command_node)
+        result.closest_command_node = m_right;
+    return result;
+}
+
+Or::Or(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right, Position or_position)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+    , m_or_position(or_position)
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+Or::~Or()
+{
+}
+
+void Pipe::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> Pipe::run(RefPtr<Shell> shell)
+{
+    auto left = m_left->to_lazy_evaluated_commands(shell);
+    auto right = m_right->to_lazy_evaluated_commands(shell);
+
+    auto last_in_left = left.take_last();
+    auto first_in_right = right.take_first();
+
+    auto pipe_read_end = FdRedirection::create(-1, STDIN_FILENO, Rewiring::Close::Old);
+    auto pipe_write_end = FdRedirection::create(-1, STDOUT_FILENO, pipe_read_end, Rewiring::Close::RefreshOld);
+    first_in_right.redirections.append(pipe_read_end);
+    last_in_left.redirections.append(pipe_write_end);
+    last_in_left.should_wait = false;
+    last_in_left.is_pipe_source = true;
+
+    if (first_in_right.pipeline) {
+        last_in_left.pipeline = first_in_right.pipeline;
+    } else {
+        auto pipeline = create<Pipeline>();
+        last_in_left.pipeline = pipeline;
+        first_in_right.pipeline = pipeline;
+    }
+
+    Vector<Command> commands;
+    commands.append(left);
+    commands.append(last_in_left);
+    commands.append(first_in_right);
+    commands.append(right);
+
+    return create<CommandSequenceValue>(move(commands));
+}
+
+void Pipe::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Pipe::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node) {
+        if (!result.closest_command_node)
+            result.closest_command_node = m_right;
+        return result;
+    }
+
+    result = m_right->hit_test_position(offset);
+    if (!result.closest_command_node)
+        result.closest_command_node = m_right;
+    return result;
+}
+
+Pipe::Pipe(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+Pipe::~Pipe()
+{
+}
+
+PathRedirectionNode::PathRedirectionNode(Position position, int fd, NonnullRefPtr<Node> path)
+    : Node(move(position))
+    , m_fd(fd)
+    , m_path(move(path))
+{
+}
+
+void PathRedirectionNode::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(0x87, 0x9b, 0xcd) }); // 25% Darkened Periwinkle
+    metadata.is_first_in_list = false;
+    m_path->highlight_in_editor(editor, shell, metadata);
+    if (m_path->is_bareword()) {
+        auto path_text = m_path->run(nullptr)->resolve_as_list(nullptr);
+        ASSERT(path_text.size() == 1);
+        // Apply a URL to the path.
+        auto& position = m_path->position();
+        auto& path = path_text[0];
+        if (!path.starts_with('/'))
+            path = String::format("%s/%s", shell.cwd.characters(), path.characters());
+        auto url = URL::create_with_file_protocol(path);
+        url.set_host(shell.hostname);
+        editor.stylize({ position.start_offset, position.end_offset }, { Line::Style::Hyperlink(url.to_string()) });
+    }
+}
+
+HitTestResult PathRedirectionNode::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_path->hit_test_position(offset);
+    if (!result.closest_node_with_semantic_meaning)
+        result.closest_node_with_semantic_meaning = this;
+    return result;
+}
+
+Vector<Line::CompletionSuggestion> PathRedirectionNode::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node || !matching_node->is_bareword())
+        return {};
+
+    auto corrected_offset = offset - matching_node->position().start_offset;
+    auto* node = static_cast<BarewordLiteral*>(matching_node.ptr());
+
+    if (corrected_offset > node->text().length())
+        return {};
+
+    return shell.complete_path("", node->text(), corrected_offset);
+}
+
+PathRedirectionNode::~PathRedirectionNode()
+{
+}
+
+void Range::dump(int level) const
+{
+    Node::dump(level);
+    print_indented("(From)", level + 1);
+    m_start->dump(level + 2);
+    print_indented("(To)", level + 1);
+    m_end->dump(level + 2);
+}
+
+RefPtr<Value> Range::run(RefPtr<Shell> shell)
+{
+    auto interpolate = [position = position()](RefPtr<Value> start, RefPtr<Value> end, RefPtr<Shell> shell) -> NonnullRefPtrVector<Value> {
+        NonnullRefPtrVector<Value> values;
+
+        if (start->is_string() && end->is_string()) {
+            auto start_str = start->resolve_as_list(shell)[0];
+            auto end_str = end->resolve_as_list(shell)[0];
+
+            Utf8View start_view { start_str }, end_view { end_str };
+            if (start_view.validate() && end_view.validate()) {
+                if (start_view.length() == 1 && end_view.length() == 1) {
+                    // Interpolate between two code points.
+                    auto start_code_point = *start_view.begin();
+                    auto end_code_point = *end_view.begin();
+                    auto step = start_code_point > end_code_point ? -1 : 1;
+                    StringBuilder builder;
+                    for (u32 code_point = start_code_point; code_point != end_code_point; code_point += step) {
+                        builder.clear();
+                        builder.append_code_point(code_point);
+                        values.append(create<StringValue>(builder.to_string()));
+                    }
+                    // Append the ending code point too, most shells treat this as inclusive.
+                    builder.clear();
+                    builder.append_code_point(end_code_point);
+                    values.append(create<StringValue>(builder.to_string()));
+                } else {
+                    // Could be two numbers?
+                    auto start_int = start_str.to_int();
+                    auto end_int = end_str.to_int();
+                    if (start_int.has_value() && end_int.has_value()) {
+                        auto start = start_int.value();
+                        auto end = end_int.value();
+                        auto step = start > end ? -1 : 1;
+                        for (int value = start; value != end; value += step)
+                            values.append(create<StringValue>(String::number(value)));
+                        // Append the range end too, most shells treat this as inclusive.
+                        values.append(create<StringValue>(String::number(end)));
+                    } else {
+                        goto yield_start_end;
+                    }
+                }
+            } else {
+            yield_start_end:;
+                shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, String::formatted("Cannot interpolate between '{}' and '{}'!", start_str, end_str), position);
+                // We can't really interpolate between the two, so just yield both.
+                values.append(create<StringValue>(move(start_str)));
+                values.append(create<StringValue>(move(end_str)));
+            }
+
+            return values;
+        }
+
+        warnln("Shell: Cannot apply the requested interpolation");
+        return values;
+    };
+
+    auto start_value = m_start->run(shell);
+    auto end_value = m_end->run(shell);
+    if (!start_value || !end_value)
+        return create<ListValue>({});
+
+    return create<ListValue>(interpolate(*start_value, *end_value, shell));
+}
+
+void Range::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_start->highlight_in_editor(editor, shell, metadata);
+
+    // Highlight the '..'
+    editor.stylize({ m_start->position().end_offset, m_end->position().start_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Yellow) });
+
+    metadata.is_first_in_list = false;
+    m_end->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Range::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_start->hit_test_position(offset);
+    if (result.matching_node) {
+        if (!result.closest_command_node)
+            result.closest_command_node = m_start;
+        return result;
+    }
+
+    result = m_end->hit_test_position(offset);
+    if (!result.closest_command_node)
+        result.closest_command_node = m_end;
+    return result;
+}
+
+Range::Range(Position position, NonnullRefPtr<Node> start, NonnullRefPtr<Node> end)
+    : Node(move(position))
+    , m_start(move(start))
+    , m_end(move(end))
+{
+    if (m_start->is_syntax_error())
+        set_is_syntax_error(m_start->syntax_error_node());
+    else if (m_end->is_syntax_error())
+        set_is_syntax_error(m_end->syntax_error_node());
+}
+
+Range::~Range()
+{
+}
+
+void ReadRedirection::dump(int level) const
+{
+    Node::dump(level);
+    m_path->dump(level + 1);
+    print_indented(String::format("To %d", m_fd), level + 1);
+}
+
+RefPtr<Value> ReadRedirection::run(RefPtr<Shell> shell)
+{
+    Command command;
+    auto path_segments = m_path->run(shell)->resolve_as_list(shell);
+    StringBuilder builder;
+    builder.join(" ", path_segments);
+
+    command.redirections.append(PathRedirection::create(builder.to_string(), m_fd, PathRedirection::Read));
+    return create<CommandValue>(move(command));
+}
+
+ReadRedirection::ReadRedirection(Position position, int fd, NonnullRefPtr<Node> path)
+    : PathRedirectionNode(move(position), fd, move(path))
+{
+}
+
+ReadRedirection::~ReadRedirection()
+{
+}
+
+void ReadWriteRedirection::dump(int level) const
+{
+    Node::dump(level);
+    m_path->dump(level + 1);
+    print_indented(String::format("To/From %d", m_fd), level + 1);
+}
+
+RefPtr<Value> ReadWriteRedirection::run(RefPtr<Shell> shell)
+{
+    Command command;
+    auto path_segments = m_path->run(shell)->resolve_as_list(shell);
+    StringBuilder builder;
+    builder.join(" ", path_segments);
+
+    command.redirections.append(PathRedirection::create(builder.to_string(), m_fd, PathRedirection::ReadWrite));
+    return create<CommandValue>(move(command));
+}
+
+ReadWriteRedirection::ReadWriteRedirection(Position position, int fd, NonnullRefPtr<Node> path)
+    : PathRedirectionNode(move(position), fd, move(path))
+{
+}
+
+ReadWriteRedirection::~ReadWriteRedirection()
+{
+}
+
+void Sequence::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> Sequence::run(RefPtr<Shell> shell)
+{
+    auto left = m_left->to_lazy_evaluated_commands(shell);
+    // This could happen if a comment is next to a command.
+    if (left.size() == 1) {
+        auto& command = left.first();
+        if (command.argv.is_empty() && command.redirections.is_empty() && command.next_chain.is_empty())
+            return m_right->run(shell);
+    }
+
+    if (left.last().should_wait)
+        left.last().next_chain.append(NodeWithAction { *m_right, NodeWithAction::Sequence });
+    else
+        left.append(m_right->to_lazy_evaluated_commands(shell));
+
+    return create<CommandSequenceValue>(move(left));
+}
+
+void Sequence::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Sequence::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node) {
+        if (!result.closest_command_node)
+            result.closest_command_node = m_right;
+        return result;
+    }
+
+    result = m_right->hit_test_position(offset);
+    if (!result.closest_command_node)
+        result.closest_command_node = m_right;
+    return result;
+}
+
+Sequence::Sequence(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right, Position separator_position)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+    , m_separator_position(separator_position)
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+Sequence::~Sequence()
+{
+}
+
+void Subshell::dump(int level) const
+{
+    Node::dump(level);
+    if (m_block)
+        m_block->dump(level + 1);
+}
+
+RefPtr<Value> Subshell::run(RefPtr<Shell> shell)
+{
+    if (!m_block)
+        return create<ListValue>({});
+
+    return create<AST::CommandSequenceValue>(m_block->to_lazy_evaluated_commands(shell));
+}
+
+void Subshell::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    metadata.is_first_in_list = true;
+    if (m_block)
+        m_block->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult Subshell::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    if (m_block)
+        return m_block->hit_test_position(offset);
+
+    return {};
+}
+
+Subshell::Subshell(Position position, RefPtr<Node> block)
+    : Node(move(position))
+    , m_block(block)
+{
+    if (m_block && m_block->is_syntax_error())
+        set_is_syntax_error(m_block->syntax_error_node());
+}
+
+Subshell::~Subshell()
+{
+}
+
+void SimpleVariable::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_name, level + 1);
+}
+
+RefPtr<Value> SimpleVariable::run(RefPtr<Shell>)
+{
+    return create<SimpleVariableValue>(m_name);
+}
+
+void SimpleVariable::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata metadata)
+{
+    Line::Style style { Line::Style::Foreground(214, 112, 214) };
+    if (metadata.is_first_in_list)
+        style.unify_with({ Line::Style::Bold });
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, move(style));
+}
+
+HitTestResult SimpleVariable::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return { this, this, nullptr };
+}
+
+Vector<Line::CompletionSuggestion> SimpleVariable::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node)
+        return {};
+
+    if (matching_node != this)
+        return {};
+
+    auto corrected_offset = offset - matching_node->position().start_offset - 1;
+
+    if (corrected_offset > m_name.length() + 1)
+        return {};
+
+    return shell.complete_variable(m_name, corrected_offset);
+}
+
+SimpleVariable::SimpleVariable(Position position, String name)
+    : Node(move(position))
+    , m_name(move(name))
+{
+}
+
+SimpleVariable::~SimpleVariable()
+{
+}
+
+void SpecialVariable::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(String { &m_name, 1 }, level + 1);
+}
+
+RefPtr<Value> SpecialVariable::run(RefPtr<Shell>)
+{
+    return create<SpecialVariableValue>(m_name);
+}
+
+void SpecialVariable::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(214, 112, 214) });
+}
+
+Vector<Line::CompletionSuggestion> SpecialVariable::complete_for_editor(Shell&, size_t, const HitTestResult&)
+{
+    return {};
+}
+
+HitTestResult SpecialVariable::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return { this, this, nullptr };
+}
+
+SpecialVariable::SpecialVariable(Position position, char name)
+    : Node(move(position))
+    , m_name(name)
+{
+}
+
+SpecialVariable::~SpecialVariable()
+{
+}
+
+void Juxtaposition::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> Juxtaposition::run(RefPtr<Shell> shell)
+{
+    auto left_value = m_left->run(shell)->resolve_without_cast(shell);
+    auto right_value = m_right->run(shell)->resolve_without_cast(shell);
+
+    auto left = left_value->resolve_as_list(shell);
+    auto right = right_value->resolve_as_list(shell);
+
+    if (left_value->is_string() && right_value->is_string()) {
+
+        ASSERT(left.size() == 1);
+        ASSERT(right.size() == 1);
+
+        StringBuilder builder;
+        builder.append(left[0]);
+        builder.append(right[0]);
+
+        return create<StringValue>(builder.to_string());
+    }
+
+    // Otherwise, treat them as lists and create a list product.
+    if (left.is_empty() || right.is_empty())
+        return create<ListValue>({});
+
+    Vector<String> result;
+    result.ensure_capacity(left.size() * right.size());
+
+    StringBuilder builder;
+    for (auto& left_element : left) {
+        for (auto& right_element : right) {
+            builder.append(left_element);
+            builder.append(right_element);
+            result.append(builder.to_string());
+            builder.clear();
+        }
+    }
+
+    return create<ListValue>(move(result));
+}
+
+void Juxtaposition::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+
+    // '~/foo/bar' is special, we have to actually resolve the tilde
+    // since that resolution is a pure operation, we can just go ahead
+    // and do it to get the value :)
+    if (m_right->is_bareword() && m_left->is_tilde()) {
+        auto tilde_value = m_left->run(shell)->resolve_as_list(shell)[0];
+        auto bareword_value = m_right->run(shell)->resolve_as_list(shell)[0];
+
+        StringBuilder path_builder;
+        path_builder.append(tilde_value);
+        path_builder.append("/");
+        path_builder.append(bareword_value);
+        auto path = path_builder.to_string();
+
+        if (Core::File::exists(path)) {
+            auto realpath = shell.resolve_path(path);
+            auto url = URL::create_with_file_protocol(realpath);
+            url.set_host(shell.hostname);
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_string()) });
+        }
+
+    } else {
+        m_right->highlight_in_editor(editor, shell, metadata);
+    }
+}
+
+Vector<Line::CompletionSuggestion> Juxtaposition::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    // '~/foo/bar' is special, we have to actually resolve the tilde
+    // then complete the bareword with that path prefix.
+    if (m_right->is_bareword() && m_left->is_tilde()) {
+        auto tilde_value = m_left->run(shell)->resolve_as_list(shell)[0];
+
+        auto corrected_offset = offset - matching_node->position().start_offset;
+        auto* node = static_cast<BarewordLiteral*>(matching_node.ptr());
+
+        if (corrected_offset > node->text().length())
+            return {};
+
+        auto text = node->text().substring(1, node->text().length() - 1);
+
+        return shell.complete_path(tilde_value, text, corrected_offset - 1);
+    }
+
+    return Node::complete_for_editor(shell, offset, hit_test_result);
+}
+
+HitTestResult Juxtaposition::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (!result.closest_node_with_semantic_meaning)
+        result.closest_node_with_semantic_meaning = this;
+    if (result.matching_node)
+        return result;
+
+    result = m_right->hit_test_position(offset);
+    if (!result.closest_node_with_semantic_meaning)
+        result.closest_node_with_semantic_meaning = this;
+    return result;
+}
+
+Juxtaposition::Juxtaposition(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+Juxtaposition::~Juxtaposition()
+{
+}
+
+void StringLiteral::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_text, level + 1);
+}
+
+RefPtr<Value> StringLiteral::run(RefPtr<Shell>)
+{
+    return create<StringValue>(m_text);
+}
+
+void StringLiteral::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata metadata)
+{
+    if (m_text.is_empty())
+        return;
+
+    Line::Style style { Line::Style::Foreground(Line::Style::XtermColor::Yellow) };
+    if (metadata.is_first_in_list)
+        style.unify_with({ Line::Style::Bold });
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, move(style));
+}
+
+StringLiteral::StringLiteral(Position position, String text)
+    : Node(move(position))
+    , m_text(move(text))
+{
+}
+
+StringLiteral::~StringLiteral()
+{
+}
+
+void StringPartCompose::dump(int level) const
+{
+    Node::dump(level);
+    m_left->dump(level + 1);
+    m_right->dump(level + 1);
+}
+
+RefPtr<Value> StringPartCompose::run(RefPtr<Shell> shell)
+{
+    auto left = m_left->run(shell)->resolve_as_list(shell);
+    auto right = m_right->run(shell)->resolve_as_list(shell);
+
+    StringBuilder builder;
+    builder.join(" ", left);
+    builder.join(" ", right);
+
+    return create<StringValue>(builder.to_string());
+}
+
+void StringPartCompose::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    m_left->highlight_in_editor(editor, shell, metadata);
+    m_right->highlight_in_editor(editor, shell, metadata);
+}
+
+HitTestResult StringPartCompose::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    auto result = m_left->hit_test_position(offset);
+    if (result.matching_node)
+        return result;
+    return m_right->hit_test_position(offset);
+}
+
+StringPartCompose::StringPartCompose(Position position, NonnullRefPtr<Node> left, NonnullRefPtr<Node> right)
+    : Node(move(position))
+    , m_left(move(left))
+    , m_right(move(right))
+{
+    if (m_left->is_syntax_error())
+        set_is_syntax_error(m_left->syntax_error_node());
+    else if (m_right->is_syntax_error())
+        set_is_syntax_error(m_right->syntax_error_node());
+}
+
+StringPartCompose::~StringPartCompose()
+{
+}
+
+void SyntaxError::dump(int level) const
+{
+    Node::dump(level);
+    print_indented("(Error text)", level + 1);
+    print_indented(m_syntax_error_text, level + 2);
+    print_indented("(Can be recovered from)", level + 1);
+    print_indented(String::formatted("{}", m_is_continuable), level + 2);
+}
+
+RefPtr<Value> SyntaxError::run(RefPtr<Shell> shell)
+{
+    shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, m_syntax_error_text, position());
+    return create<StringValue>("");
+}
+
+void SyntaxError::highlight_in_editor(Line::Editor& editor, Shell&, HighlightMetadata)
+{
+    editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Red), Line::Style::Bold });
+}
+
+SyntaxError::SyntaxError(Position position, String error, bool is_continuable)
+    : Node(move(position))
+    , m_syntax_error_text(move(error))
+    , m_is_continuable(is_continuable)
+{
+    m_is_syntax_error = true;
+}
+
+const SyntaxError& SyntaxError::syntax_error_node() const
+{
+    return *this;
+}
+
+SyntaxError::~SyntaxError()
+{
+}
+
+void Tilde::dump(int level) const
+{
+    Node::dump(level);
+    print_indented(m_username, level + 1);
+}
+
+RefPtr<Value> Tilde::run(RefPtr<Shell>)
+{
+    return create<TildeValue>(m_username);
+}
+
+void Tilde::highlight_in_editor(Line::Editor&, Shell&, HighlightMetadata)
+{
+}
+
+HitTestResult Tilde::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    return { this, this, nullptr };
+}
+
+Vector<Line::CompletionSuggestion> Tilde::complete_for_editor(Shell& shell, size_t offset, const HitTestResult& hit_test_result)
+{
+    auto matching_node = hit_test_result.matching_node;
+    if (!matching_node)
+        return {};
+
+    if (matching_node != this)
+        return {};
+
+    auto corrected_offset = offset - matching_node->position().start_offset - 1;
+
+    if (corrected_offset > m_username.length() + 1)
+        return {};
+
+    return shell.complete_user(m_username, corrected_offset);
+}
+
+String Tilde::text() const
+{
+    StringBuilder builder;
+    builder.append('~');
+    builder.append(m_username);
+    return builder.to_string();
+}
+
+Tilde::Tilde(Position position, String username)
+    : Node(move(position))
+    , m_username(move(username))
+{
+}
+
+Tilde::~Tilde()
+{
+}
+
+void WriteAppendRedirection::dump(int level) const
+{
+    Node::dump(level);
+    m_path->dump(level + 1);
+    print_indented(String::format("From %d", m_fd), level + 1);
+}
+
+RefPtr<Value> WriteAppendRedirection::run(RefPtr<Shell> shell)
+{
+    Command command;
+    auto path_segments = m_path->run(shell)->resolve_as_list(shell);
+    StringBuilder builder;
+    builder.join(" ", path_segments);
+
+    command.redirections.append(PathRedirection::create(builder.to_string(), m_fd, PathRedirection::WriteAppend));
+    return create<CommandValue>(move(command));
+}
+
+WriteAppendRedirection::WriteAppendRedirection(Position position, int fd, NonnullRefPtr<Node> path)
+    : PathRedirectionNode(move(position), fd, move(path))
+{
+}
+
+WriteAppendRedirection::~WriteAppendRedirection()
+{
+}
+
+void WriteRedirection::dump(int level) const
+{
+    Node::dump(level);
+    m_path->dump(level + 1);
+    print_indented(String::format("From %d", m_fd), level + 1);
+}
+
+RefPtr<Value> WriteRedirection::run(RefPtr<Shell> shell)
+{
+    Command command;
+    auto path_segments = m_path->run(shell)->resolve_as_list(shell);
+    StringBuilder builder;
+    builder.join(" ", path_segments);
+
+    command.redirections.append(PathRedirection::create(builder.to_string(), m_fd, PathRedirection::Write));
+    return create<CommandValue>(move(command));
+}
+
+WriteRedirection::WriteRedirection(Position position, int fd, NonnullRefPtr<Node> path)
+    : PathRedirectionNode(move(position), fd, move(path))
+{
+}
+
+WriteRedirection::~WriteRedirection()
+{
+}
+
+void VariableDeclarations::dump(int level) const
+{
+    Node::dump(level);
+    for (auto& var : m_variables) {
+        print_indented("Set", level + 1);
+        var.name->dump(level + 2);
+        var.value->dump(level + 2);
+    }
+}
+
+RefPtr<Value> VariableDeclarations::run(RefPtr<Shell> shell)
+{
+    for (auto& var : m_variables) {
+        auto name_value = var.name->run(shell)->resolve_as_list(shell);
+        ASSERT(name_value.size() == 1);
+        auto name = name_value[0];
+        auto value = var.value->run(shell);
+        if (value->is_list()) {
+            auto parts = value->resolve_as_list(shell);
+            shell->set_local_variable(name, adopt(*new ListValue(move(parts))));
+        } else if (value->is_command()) {
+            shell->set_local_variable(name, value);
+        } else {
+            auto part = value->resolve_as_list(shell);
+            shell->set_local_variable(name, adopt(*new StringValue(part[0])));
+        }
+    }
+
+    return create<ListValue>({});
+}
+
+void VariableDeclarations::highlight_in_editor(Line::Editor& editor, Shell& shell, HighlightMetadata metadata)
+{
+    metadata.is_first_in_list = false;
+    for (auto& var : m_variables) {
+        var.name->highlight_in_editor(editor, shell, metadata);
+        // Highlight the '='.
+        editor.stylize({ var.name->position().end_offset - 1, var.name->position().end_offset }, { Line::Style::Foreground(Line::Style::XtermColor::Blue) });
+        var.value->highlight_in_editor(editor, shell, metadata);
+    }
+}
+
+HitTestResult VariableDeclarations::hit_test_position(size_t offset)
+{
+    if (!position().contains(offset))
+        return {};
+
+    for (auto decl : m_variables) {
+        auto result = decl.value->hit_test_position(offset);
+        if (result.matching_node)
+            return result;
+    }
+
+    return { nullptr, nullptr, nullptr };
+}
+
+VariableDeclarations::VariableDeclarations(Position position, Vector<Variable> variables)
+    : Node(move(position))
+    , m_variables(move(variables))
+{
+    for (auto& decl : m_variables) {
+        if (decl.name->is_syntax_error()) {
+            set_is_syntax_error(decl.name->syntax_error_node());
+            break;
+        }
+        if (decl.value->is_syntax_error()) {
+            set_is_syntax_error(decl.value->syntax_error_node());
+            break;
+        }
+    }
+}
+
+VariableDeclarations::~VariableDeclarations()
+{
+}
+
+Value::~Value()
+{
+}
+Vector<AST::Command> Value::resolve_as_commands(RefPtr<Shell> shell)
+{
+    Command command;
+    command.argv = resolve_as_list(shell);
+    return { command };
+}
+
+ListValue::ListValue(Vector<String> values)
+{
+    m_contained_values.ensure_capacity(values.size());
+    for (auto& str : values)
+        m_contained_values.append(adopt(*new StringValue(move(str))));
+}
+
+ListValue::~ListValue()
+{
+}
+
+Vector<String> ListValue::resolve_as_list(RefPtr<Shell> shell)
+{
+    Vector<String> values;
+    for (auto& value : m_contained_values)
+        values.append(value.resolve_as_list(shell));
+
+    return values;
+}
+
+NonnullRefPtr<Value> ListValue::resolve_without_cast(RefPtr<Shell> shell)
+{
+    NonnullRefPtrVector<Value> values;
+    for (auto& value : m_contained_values)
+        values.append(value.resolve_without_cast(shell));
+
+    return create<ListValue>(move(values));
+}
+
+CommandValue::~CommandValue()
+{
+}
+
+CommandSequenceValue::~CommandSequenceValue()
+{
+}
+
+Vector<String> CommandSequenceValue::resolve_as_list(RefPtr<Shell>)
+{
+    // TODO: Somehow raise an "error".
+    return {};
+}
+
+Vector<Command> CommandSequenceValue::resolve_as_commands(RefPtr<Shell>)
+{
+    return m_contained_values;
+}
+
+Vector<String> CommandValue::resolve_as_list(RefPtr<Shell>)
+{
+    // TODO: Somehow raise an "error".
+    return {};
+}
+
+Vector<Command> CommandValue::resolve_as_commands(RefPtr<Shell>)
+{
+    return { m_command };
+}
+
+JobValue::~JobValue()
+{
+}
+
+StringValue::~StringValue()
+{
+}
+Vector<String> StringValue::resolve_as_list(RefPtr<Shell>)
+{
+    if (is_list()) {
+        auto parts = StringView(m_string).split_view(m_split, m_keep_empty);
+        Vector<String> result;
+        result.ensure_capacity(parts.size());
+        for (auto& part : parts)
+            result.append(part);
+        return result;
+    }
+
+    return { m_string };
+}
+
+GlobValue::~GlobValue()
+{
+}
+Vector<String> GlobValue::resolve_as_list(RefPtr<Shell> shell)
+{
+    if (!shell)
+        return { m_glob };
+
+    auto results = shell->expand_globs(m_glob, shell->cwd);
+    if (results.is_empty())
+        shell->raise_error(Shell::ShellError::InvalidGlobError, "Glob did not match anything!", m_generation_position);
+    return results;
+}
+
+SimpleVariableValue::~SimpleVariableValue()
+{
+}
+Vector<String> SimpleVariableValue::resolve_as_list(RefPtr<Shell> shell)
+{
+    if (!shell)
+        return {};
+
+    if (auto value = resolve_without_cast(shell); value != this)
+        return value->resolve_as_list(shell);
+
+    char* env_value = getenv(m_name.characters());
+    if (env_value == nullptr)
+        return { "" };
+
+    Vector<String> res;
+    String str_env_value = String(env_value);
+    const auto& split_text = str_env_value.split_view(' ');
+    for (auto& part : split_text)
+        res.append(part);
+    return res;
+}
+
+NonnullRefPtr<Value> SimpleVariableValue::resolve_without_cast(RefPtr<Shell> shell)
+{
+    ASSERT(shell);
+
+    if (auto value = shell->lookup_local_variable(m_name))
+        return value.release_nonnull();
+    return *this;
+}
+
+SpecialVariableValue::~SpecialVariableValue()
+{
+}
+
+Vector<String> SpecialVariableValue::resolve_as_list(RefPtr<Shell> shell)
+{
+    if (!shell)
+        return {};
+
+    switch (m_name) {
+    case '?':
+        return { String::number(shell->last_return_code) };
+    case '$':
+        return { String::number(getpid()) };
+    case '*':
+        if (auto argv = shell->lookup_local_variable("ARGV"))
+            return argv->resolve_as_list(shell);
+        return {};
+    case '#':
+        if (auto argv = shell->lookup_local_variable("ARGV")) {
+            if (argv->is_list()) {
+                auto list_argv = static_cast<AST::ListValue*>(argv.ptr());
+                return { String::number(list_argv->values().size()) };
+            }
+            return { "1" };
+        }
+        return { "0" };
+    default:
+        return { "" };
+    }
+}
+
+TildeValue::~TildeValue()
+{
+}
+Vector<String> TildeValue::resolve_as_list(RefPtr<Shell> shell)
+{
+    StringBuilder builder;
+    builder.append("~");
+    builder.append(m_username);
+
+    if (!shell)
+        return { builder.to_string() };
+
+    return { shell->expand_tilde(builder.to_string()) };
+}
+
+Result<NonnullRefPtr<Rewiring>, String> CloseRedirection::apply() const
+{
+    return adopt(*new Rewiring(fd, fd, Rewiring::Close::ImmediatelyCloseNew));
+}
+
+CloseRedirection::~CloseRedirection()
+{
+}
+
+Result<NonnullRefPtr<Rewiring>, String> PathRedirection::apply() const
+{
+    auto check_fd_and_return = [my_fd = this->fd](int fd, const String& path) -> Result<NonnullRefPtr<Rewiring>, String> {
+        if (fd < 0) {
+            String error = strerror(errno);
+            dbgln("open() failed for '{}' with {}", path, error);
+            return error;
+        }
+        return adopt(*new Rewiring(fd, my_fd, Rewiring::Close::Old));
+    };
+    switch (direction) {
+    case AST::PathRedirection::WriteAppend:
+        return check_fd_and_return(open(path.characters(), O_WRONLY | O_CREAT | O_APPEND, 0666), path);
+
+    case AST::PathRedirection::Write:
+        return check_fd_and_return(open(path.characters(), O_WRONLY | O_CREAT | O_TRUNC, 0666), path);
+
+    case AST::PathRedirection::Read:
+        return check_fd_and_return(open(path.characters(), O_RDONLY), path);
+
+    case AST::PathRedirection::ReadWrite:
+        return check_fd_and_return(open(path.characters(), O_RDWR | O_CREAT, 0666), path);
+    }
+
+    ASSERT_NOT_REACHED();
+}
+
+PathRedirection::~PathRedirection()
+{
+}
+
+FdRedirection::~FdRedirection()
+{
+}
+
+Redirection::~Redirection()
+{
+}
+
+}