[lldb] Fix indentation when printing stop hooks (#165945)

This commit aggregates the following changes:
1. Fix the format (i.e., indentation) when printing stop hooks via `target
   stop-hook list`.
2. Add `IndentScope Stream::MakeIndentScope()` to make managing (and restoring!)
   of the indentation level on `Stream` instances more ergonomic and less error
   prone.
3. Simplify printing of stop hooks using the new `IndentScope`.

Author: yln

lldb/include/lldb/Utility/Stream.h

@@ -300,6 +300,12 @@ class Stream {
   ///     The current indentation level.
   unsigned GetIndentLevel() const;
 
+  /// Set the current indentation level.
+  ///
+  /// \param[in] level
+  ///     The new indentation level.
+  void SetIndentLevel(unsigned level);
+
   /// Indent the current line in the stream.
   ///
   /// Indent the current line using the current indentation level and print an
@@ -315,6 +321,20 @@ class Stream {
   /// Increment the current indentation level.
   void IndentMore(unsigned amount = 2);
 
+  struct IndentScope {
+    IndentScope(Stream &stream)
+        : m_stream(stream), m_original_indent_level(stream.GetIndentLevel()) {}
+    ~IndentScope() { m_stream.SetIndentLevel(m_original_indent_level); }
+
+  private:
+    Stream &m_stream;
+    unsigned m_original_indent_level;
+  };
+
+  /// Create an indentation scope that restores the original indent level when
+  /// the object goes out of scope (RAII).
+  IndentScope MakeIndentScope(unsigned indent_amount = 2);
+
   /// Output an offset value.
   ///
   /// Put an offset \a uval out to the stream using the printf format in \a
@@ -364,12 +384,6 @@ class Stream {
   ///     address and pointer values.
   void SetAddressByteSize(uint32_t addr_size);
 
-  /// Set the current indentation level.
-  ///
-  /// \param[in] level
-  ///     The new indentation level.
-  void SetIndentLevel(unsigned level);
-
   /// Output a SLEB128 number to the stream.
   ///
   /// Put an SLEB128 \a uval out to the stream using the printf format in \a

lldb/source/Target/Target.cpp

@@ -3962,9 +3962,7 @@ void Target::StopHook::GetDescription(Stream &s,
     return;
   }
 
-  unsigned indent_level = s.GetIndentLevel();
-
-  s.SetIndentLevel(indent_level + 2);
+  auto indent_scope = s.MakeIndentScope();
 
   s.Printf("Hook: %" PRIu64 "\n", GetID());
   if (m_active)
@@ -3978,19 +3976,17 @@ void Target::StopHook::GetDescription(Stream &s,
   if (m_specifier_sp) {
     s.Indent();
     s.PutCString("Specifier:\n");
-    s.SetIndentLevel(indent_level + 4);
+    auto indent_scope = s.MakeIndentScope();
     m_specifier_sp->GetDescription(&s, level);
-    s.SetIndentLevel(indent_level + 2);
   }
 
   if (m_thread_spec_up) {
     StreamString tmp;
     s.Indent("Thread:\n");
     m_thread_spec_up->GetDescription(&tmp, level);
-    s.SetIndentLevel(indent_level + 4);
+    auto indent_scope = s.MakeIndentScope();
     s.Indent(tmp.GetString());
     s.PutCString("\n");
-    s.SetIndentLevel(indent_level + 2);
   }
   GetSubclassDescription(s, level);
 }
@@ -4003,14 +3999,13 @@ void Target::StopHookCommandLine::GetSubclassDescription(
       s.PutCString(m_commands.GetStringAtIndex(0));
     return;
   }
-  s.Indent("Commands: \n");
-  s.SetIndentLevel(s.GetIndentLevel() + 4);
+  s.Indent("Commands:\n");
+  auto indent_scope = s.MakeIndentScope(4);
   uint32_t num_commands = m_commands.GetSize();
   for (uint32_t i = 0; i < num_commands; i++) {
     s.Indent(m_commands.GetStringAtIndex(i));
     s.PutCString("\n");
   }
-  s.SetIndentLevel(s.GetIndentLevel() - 4);
 }
 
 // Target::StopHookCommandLine
@@ -4145,7 +4140,7 @@ void Target::StopHookScripted::GetSubclassDescription(
     return;
 
   s.Indent("Args:\n");
-  s.SetIndentLevel(s.GetIndentLevel() + 4);
+  auto indent_scope = s.MakeIndentScope(4);
 
   auto print_one_element = [&s](llvm::StringRef key,
                                 StructuredData::Object *object) {
@@ -4155,8 +4150,6 @@ void Target::StopHookScripted::GetSubclassDescription(
   };
 
   as_dict->ForEach(print_one_element);
-
-  s.SetIndentLevel(s.GetIndentLevel() - 4);
 }
 
 static constexpr OptionEnumValueElement g_dynamic_value_types[] = {

lldb/source/Utility/Stream.cpp

@@ -202,6 +202,14 @@ void Stream::IndentLess(unsigned amount) {
     m_indent_level = 0;
 }
 
+// Create an indentation scope that restores the original indent level when the
+// object goes out of scope (RAII).
+Stream::IndentScope Stream::MakeIndentScope(unsigned indent_amount) {
+  IndentScope indent_scope(*this);
+  IndentMore(indent_amount);
+  return indent_scope;
+}
+
 // Get the address size in bytes
 uint32_t Stream::GetAddressByteSize() const { return m_addr_size; }
 

lldb/test/Shell/ExecControl/StopHook/stop-hook-list-format.test

@@ -0,0 +1,36 @@
+# Test format (e.g., indentation) when printing the list of stop hooks.
+#
+# RUN: %lldb -b -s %s | FileCheck %s --match-full-lines --strict-whitespace
+
+# Create some stop hooks
+target stop-hook add -o 'print "Hello"' --auto-continue true --at-initial-stop true
+target stop-hook add -o 'print "world,"' -o 'print "nice"' --file 'my_file'
+target stop-hook add -o 'print "weather!"'  --classname 'MyClass' --thread-name 'my_thread'
+
+# Print hooks
+target stop-hook list
+
+# CHECK:(lldb) target stop-hook list
+# CHECK:Hook: 1
+# CHECK:  State: enabled
+# CHECK:  AutoContinue on
+# CHECK:  Commands:
+# CHECK:      print "Hello"
+# CHECK-EMPTY:
+# CHECK:Hook: 2
+# CHECK:  State: enabled
+# CHECK:  Specifier:
+# CHECK:    File: my_file.
+# CHECK:  Commands:
+# CHECK:      print "world,"
+# CHECK:      print "nice"
+# CHECK-EMPTY:
+# CHECK:Hook: 3
+# CHECK:  State: enabled
+# CHECK:  Specifier:
+# CHECK:    Class name: MyClass.
+# CHECK:  Thread:
+# CHECK:    thread name: "my_thread" 
+# CHECK:  Commands:
+# CHECK:      print "weather!"
+# CHECK-EMPTY: