Have 'thread|frame apply' style their output.

'thread|frame apply CMD' launches CMD so that CMD output goes to a string_file.
This patch ensures that string_file for such CMD output contains
style escape sequences that 'thread|frame apply' will later on
output on the real terminal, so as to have CMD output properly styled.

The idea is to have the class ui_file having overridable methods
to indicate that the output to this ui_file should be done using
'terminal' behaviour such as styling.
Then these methods are overriden in string_file so that a specially
constructed string_file will get output with style escape sequences.

After this patch, the output of CMD by thread|frame apply CMD is styled
similarly as when CMD is launched directly.
Note that string_file (term_out true) could also support wrapping,
but this is not done (yet?).

Tested on debian/amd64.

gdb/ChangeLog
2019-04-27  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	Support style in 'frame|thread apply'

	* gdbcmd.h (execute_command_to_string): New term_out parameter.
	* record.c (record_start, record_stop): Update callers of
	execute_command_to_string with false.
	* ui-file.h (class ui_file): New term_out and can_emit_style_escape
	methods.
	(class string_file): New constructor with term_out parameter.
	Override methods term_out and can_emit_style_escape.  New member
	term_out.
	(class stdio_file): Override can_emit_style_escape.
	(class tee_file): Override term_out and can_emit_style_escape.
	* utils.h (can_emit_style_escape): Remove.
	* utils.c (can_emit_style_escape): Likewise.
	Update all callers of can_emit_style_escape (SOMESTREAM) to
	SOMESTREAM->can_emit_style_escape.
	* source-cache.c (source_cache::get_source_lines): Likewise.
	* stack.c (frame_apply_command_count): Call execute_command_to_string
	passing the term_out characteristic of the current gdb_stdout.
	* thread.c (thr_try_catch_cmd): Likewise.
	* top.c (execute_command_to_string): pass term_out parameter
	to construct the string_file for the command output.
	* ui-file.c (term_cli_styling): New function (most code moved
	from utils.c can_emit_style_escape).
	(string_file::string_file, string_file::can_emit_style_escape,
	stdio_file::can_emit_style_escape, tee_file::term_out,
	tee_file::can_emit_style_escape): New functions.

1 files changed, 27 insertions, 1 deletions

diff --git a/gdb/ui-file.h b/gdb/ui-file.h
index 6e6ca1c..56f0c0f 100644
--- a/gdb/ui-file.h
+++ b/gdb/ui-file.h
@@ -70,6 +70,17 @@ public:
   virtual bool isatty ()
   { return false; }
 
+  /* true indicates terminal output behaviour such as cli_styling.
+     This default implementation indicates to do terminal output
+     behaviour if the UI_FILE is a tty.  A derived class can override
+     TERM_OUT to have cli_styling behaviour without being a tty.  */
+  virtual bool term_out ()
+  { return isatty (); }
+
+  /* true if ANSI escapes can be used on STREAM.  */
+  virtual bool can_emit_style_escape ()
+  { return false; }
+
   virtual void flush ()
   {}
 };
@@ -109,7 +120,13 @@ extern int gdb_console_fputs (const char *, FILE *);
 class string_file : public ui_file
 {
 public:
-  string_file () {}
+  /* Construct a string_file to collect 'raw' output, i.e. without
+     'terminal' behaviour such as cli_styling.  */
+  string_file () : m_term_out (false) {};
+  /* If TERM_OUT, construct a string_file with terminal output behaviour
+     such as cli_styling)
+     else collect 'raw' output like the previous constructor.  */
+  explicit string_file (bool term_out) : m_term_out (term_out) {};
   ~string_file () override;
 
   /* Override ui_file methods.  */
@@ -119,6 +136,9 @@ public:
   long read (char *buf, long length_buf) override
   { gdb_assert_not_reached ("a string_file is not readable"); }
 
+  bool term_out () override;
+  bool can_emit_style_escape () override;
+
   /* string_file-specific public API.  */
 
   /* Accesses the std::string containing the entire output collected
@@ -145,6 +165,8 @@ public:
 private:
   /* The internal buffer.  */
   std::string m_string;
+
+  bool m_term_out;
 };
 
 /* A ui_file implementation that maps directly onto <stdio.h>'s FILE.
@@ -183,6 +205,8 @@ public:
 
   bool isatty () override;
 
+  bool can_emit_style_escape () override;
+
 private:
   /* Sets the internal stream to FILE, and saves the FILE's file
      descriptor in M_FD.  */
@@ -255,6 +279,8 @@ public:
   void puts (const char *) override;
 
   bool isatty () override;
+  bool term_out () override;
+  bool can_emit_style_escape () override;
   void flush () override;
 
 private: