[RFA 1/8] Add helper functions check_for_flags and check_for_flags_vqcs

[Philippe Waroquiers <philippe dot waroquiers at skynet dot be>]

Add helper functions check_for_flags and check_for_flags_vqcs
check_for_flags helper function allows to look for a set of flags at
the start of a string.

check_for_flags_vqcs is a specialised helper function to handle
the flags vqcs, that are used in the new command 'frame apply'
and in the command 'thread apply.

Modify number_or_range_parser::get_number to differentiate a
- followed by digits from a - followed by a flag (i.e. an alpha).
That is needed for the addition of the optional -FLAGS... argument to
thread apply ID... [-FLAGS...] COMMAND

The error message for 'thread apply -$unknownconvvar p 1'
is now the more clear:
  Convenience variable must have integer value.
  Invalid thread ID: -$unknownconvvar p 1
instead of previously:
  negative value
---
 gdb/cli/cli-utils.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 gdb/cli/cli-utils.h |  30 ++++++++++++++
 2 files changed, 138 insertions(+), 2 deletions(-)

diff --git a/gdb/cli/cli-utils.c b/gdb/cli/cli-utils.c
index c55b5035e4..de2220c21a 100644
--- a/gdb/cli/cli-utils.c
+++ b/gdb/cli/cli-utils.c
@@ -169,7 +169,10 @@ number_or_range_parser::get_number ()
       /* Default case: state->m_cur_tok is pointing either to a solo
 	 number, or to the first number of a range.  */
       m_last_retval = get_number_trailer (&m_cur_tok, '-');
-      if (*m_cur_tok == '-')
+      /* If get_number_trailer has found a -, it might be the start
+	 of flags.  So, do not parse a range if the - is followed by
+	 an alpha.  */
+      if (*m_cur_tok == '-' && !isalpha (*(m_cur_tok + 1)))
 	{
 	  const char **temp;
 
@@ -196,7 +199,17 @@ number_or_range_parser::get_number ()
 	}
     }
   else
-    error (_("negative value"));
+    {
+      if (isdigit (*(m_cur_tok + 1)))
+	error (_("negative value"));
+      if (*(m_cur_tok + 1) == '$')
+	{
+	  // Convenience variable.
+	  m_last_retval = ::get_number (&m_cur_tok);
+	  if (m_last_retval < 0)
+	    error (_("negative value"));
+	}
+    }
   m_finished = *m_cur_tok == '\0';
   return m_last_retval;
 }
@@ -304,3 +317,96 @@ check_for_argument (const char **str, const char *arg, int arg_len)
     }
   return 0;
 }
+
+/* See documentation in cli-utils.h.  */
+
+int
+check_for_flags (const char **str, const char *flags,
+		 int *flags_counts)
+{
+  const char *p = *str;
+  bool all_valid = true;
+
+  /* First set the flags_counts to 0.  */
+  memset (flags_counts, 0, sizeof (flags_counts[0]) * strlen (flags));
+
+  if (*p != '-')
+    return 0;
+
+  p++;
+  /* If - is followed by anything else than an alpha (including \0),
+     then we do not have flags.  This also cover the case of a command
+     that accepts optional flags followed by a negative integer.
+     In such a case, we will not handle a negative integer as invalid
+     flags : rather let the caller handler the negative integer.  */
+  if (!isalpha (*p))
+    return 0;
+
+  /* We have a set of flags :
+     Scan and validate the flags, and update flags_counts for valid flags.  */
+  while (*p != '\0' && !isspace (*p))
+    {
+      const char *f = flags;
+      bool valid = false;
+
+      while (*f != '\0')
+	{
+	  valid = *f == *p;
+	  if (valid)
+	    {
+	      flags_counts[f - flags]++;
+	      break;
+	    }
+	  f++;
+	}
+      all_valid = all_valid && valid;
+      p++;
+    }
+
+  /* Skip the space(s). */
+  p = skip_spaces (p);
+
+  if (all_valid)
+    {
+      *str = p;
+      return 1;
+    }
+  else
+    return -1;
+}
+
+/* See documentation in cli-utils.h.  */
+
+int
+check_for_flags_vqcs (const char *which_command, const char **str,
+		      int *print_what_v, int max_v,
+		      bool *cont, bool *silent)
+{
+  const char *flags = "vqcs";
+  int flags_counts[strlen (flags)];
+  int res;
+
+  *cont = false;
+  *silent = false;
+
+  res = check_for_flags (str, flags, flags_counts);
+  if (res == 0)
+    return 0;
+  if (res == -1)
+    error (_("%s only accepts flags %s"), which_command, flags);
+  gdb_assert (res == 1);
+
+  *print_what_v = *print_what_v + flags_counts[0] - flags_counts[1];
+  if (*print_what_v < 0)
+    *print_what_v = 0;
+  if (*print_what_v > max_v)
+    *print_what_v = max_v;
+
+  *cont = flags_counts[2] > 0;
+  *silent = flags_counts[3] > 0;
+  if (*cont && *silent)
+    error (_("%s: flags c and s are mutually exclusive"),
+	   which_command);
+
+  return res;
+}
diff --git a/gdb/cli/cli-utils.h b/gdb/cli/cli-utils.h
index e34ee0df37..7b94b82844 100644
--- a/gdb/cli/cli-utils.h
+++ b/gdb/cli/cli-utils.h
@@ -173,4 +173,34 @@ check_for_argument (char **str, const char *arg, int arg_len)
 			     arg, arg_len);
 }
 
+/* A helper function that looks for a set of flags at the start of a
+   string.  The possible flags are given as a null terminated string.
+   The flags must also either be at the end of the string,
+   or be followed by whitespace.  Returns 1 if it finds only valid flags,
+   0 if no flags are found, -1 if invalid flags are found.
+   FLAGS_COUNTS must be an int array of length equal to strlen (flags).
+   Sets *FLAGS_COUNTS to the number of times the corresponding flag
+   was found in *STR.
+   If only valid flags are found, it updates *STR.  Note that a negative
+   integer (e.g. -123) will not be considered as an invalid set of flags.  */
+extern int check_for_flags (const char **str, const char *flags,
+			    int *flags_counts);
+
+/* A helper function that uses check_for_flags to handle the flags vqcs :
+     A flag v increases *print_what_v.
+     A flag q decreases *print_what_v.
+     A flag c sets *cont to true, otherwise to false.
+     A flag s sets *silent to true, otherwise to false.
+   The caller must initialise *PRINT_WHAT_V to the default verbosity.
+   MAX_V gives the maximum verbosity : the value returned in *PRINT_WHAT_V
+   will always be >= 0 and <= MAX_V.
+   WHICH_COMMAND is used in the error message in case invalid flags are found.
+
+   Returns 1 and updates *STR if it finds only valid flags.
+   Returns 0 if no flags are found.
+   Raises an error if invalid flags are found.
+*/
+extern int check_for_flags_vqcs (const char *which_command, const char **str,
+				 int *print_what_v, int max_v,
+				 bool *cont, bool *silent);
 #endif /* CLI_UTILS_H */
-- 
2.11.0