[RFA] completion in command definition

commit de170acae27af8a9899a01f32475b7095031e46a
Author: Jerome Guitton <guitton@adacore.com>
Date:   Tue Jan 10 15:15:53 2017 +0100

    Command abbreviation in define
    
    When defining a new macro, "command" is not recognized as an alias for
    "commands":
    
     (gdb) define breakmain
     Type commands for definition of "breakmain".
     End with a line saying just "end".
     >break main
     >command
     >echo "IN MAIN\n"
     >end
     (gdb)
    
    There is a special case for while-stepping, where 'ws' and 'stepping' are
    recognized explicitely. Instead of adding more special cases, this change
    uses cli-decode.
    
    gdb/ChangeLog:
    	* cli/cli-decode.c (find_command_name_length): Make it extern.
    	* cli/cli-decode.h (find_command_name_length): Declare.
    	* cli/cli-script.c (command_name_equals, line_first_arg):
    	New functions.
    	(process_next_line): Use cli-decode to parse command names.
    	(build_command_line): Make args a constant pointer.
    
    gdb/testsuite/ChangeLog:
    
    	* gdb.base/define.exp: Add test for command abbreviations
    	in define.

diff --git a/gdb/cli/cli-decode.c b/gdb/cli/cli-decode.c
index d3be93c..9312177 100644
--- a/gdb/cli/cli-decode.c
+++ b/gdb/cli/cli-decode.c
@@ -1255,7 +1255,9 @@  find_cmd (const char *command, int len, struct cmd_list_element *clist,
   return found;
 }
 
-static int
+/* Return the length of command name in TEXT.  */
+
+int
 find_command_name_length (const char *text)
 {
   const char *p = text;
diff --git a/gdb/cli/cli-decode.h b/gdb/cli/cli-decode.h
index e5ab839..66159fd 100644
--- a/gdb/cli/cli-decode.h
+++ b/gdb/cli/cli-decode.h
@@ -253,4 +253,6 @@  extern const char * const auto_boolean_enums[];
 
 extern int cli_user_command_p (struct cmd_list_element *);
 
+extern int find_command_name_length (const char *);
+
 #endif /* !defined (CLI_DECODE_H) */
diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index 6f44d52..9615037 100644
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -143,7 +143,7 @@  multi_line_command_p (enum command_control_type type)
    control commands (if/while).  */
 
 static struct command_line *
-build_command_line (enum command_control_type type, char *args)
+build_command_line (enum command_control_type type, const char *args)
 {
   struct command_line *cmd;
 
@@ -904,6 +904,27 @@  read_next_line (void)
   return command_line_input (prompt_ptr, from_tty, "commands");
 }
 
+/* Return non-zero if CMD's name is NAME.  */
+
+static bool
+command_name_equals (struct cmd_list_element *cmd, const char *name)
+{
+  return (cmd != NULL
+	  && cmd != CMD_LIST_AMBIGUOUS
+	  && strcmp (cmd->name, name) == 0);
+}
+
+/* Given an input line P, skip the command and return a pointer to the
+   first argument.  */
+
+static const char *
+line_first_arg (const char *p)
+{
+  const char *first_arg = p + find_command_name_length (p);
+
+  return skip_spaces_const (first_arg); 
+}
+
 /* Process one input line.  If the command is an "end", return such an
    indication to the caller.  If PARSE_COMMANDS is true, strip leading
    whitespace (trailing whitespace is always stripped) in the line,
@@ -938,9 +959,14 @@  process_next_line (char *p, struct command_line **command, int parse_commands,
      We also permit whitespace before end and after.  */
   if (p_end - p_start == 3 && startswith (p_start, "end"))
     return end_command;
-  
+
   if (parse_commands)
     {
+      /* Resolve command abbreviations (e.g. 'ws' for 'while-stepping').  */
+      const char *cmd_name = p;
+      struct cmd_list_element *cmd =
+	lookup_cmd_1 (&cmd_name, cmdlist, NULL, 1);
+
       /* If commands are parsed, we skip initial spaces.  Otherwise,
 	 which is the case for Python commands and documentation
 	 (see the 'document' command), spaces are preserved.  */
@@ -958,9 +984,7 @@  process_next_line (char *p, struct command_line **command, int parse_commands,
 
       /* Check for while, if, break, continue, etc and build a new
 	 command line structure for them.  */
-      if ((p_end - p >= 14 && startswith (p, "while-stepping"))
-	  || (p_end - p >= 8 && startswith (p, "stepping"))
-	  || (p_end - p >= 2 && startswith (p, "ws")))
+      if (command_name_equals (cmd, "while-stepping"))
 	{
 	  /* Because validate_actionline and encode_action lookup
 	     command's line as command, we need the line to
@@ -975,40 +999,25 @@  process_next_line (char *p, struct command_line **command, int parse_commands,
 	     not.  */
 	  *command = build_command_line (while_stepping_control, p);
 	}
-      else if (p_end - p > 5 && startswith (p, "while"))
+      else if (command_name_equals (cmd, "while"))
 	{
-	  char *first_arg;
-
-	  first_arg = p + 5;
-	  while (first_arg < p_end && isspace (*first_arg))
-	    first_arg++;
-	  *command = build_command_line (while_control, first_arg);
+	  *command = build_command_line (while_control, line_first_arg (p));
 	}
-      else if (p_end - p > 2 && startswith (p, "if"))
+      else if (command_name_equals (cmd, "if"))
 	{
-	  char *first_arg;
-
-	  first_arg = p + 2;
-	  while (first_arg < p_end && isspace (*first_arg))
-	    first_arg++;
-	  *command = build_command_line (if_control, first_arg);
+	  *command = build_command_line (if_control, line_first_arg (p));
 	}
-      else if (p_end - p >= 8 && startswith (p, "commands"))
+      else if (command_name_equals (cmd, "commands"))
 	{
-	  char *first_arg;
-
-	  first_arg = p + 8;
-	  while (first_arg < p_end && isspace (*first_arg))
-	    first_arg++;
-	  *command = build_command_line (commands_control, first_arg);
+	  *command = build_command_line (commands_control, line_first_arg (p));
 	}
-      else if (p_end - p == 6 && startswith (p, "python"))
+      else if (command_name_equals (cmd, "python"))
 	{
 	  /* Note that we ignore the inline "python command" form
 	     here.  */
 	  *command = build_command_line (python_control, "");
 	}
-      else if (p_end - p == 6 && startswith (p, "compile"))
+      else if (command_name_equals (cmd, "compile"))
 	{
 	  /* Note that we ignore the inline "compile command" form
 	     here.  */
@@ -1016,7 +1025,7 @@  process_next_line (char *p, struct command_line **command, int parse_commands,
 	  (*command)->control_u.compile.scope = COMPILE_I_INVALID_SCOPE;
 	}
 
-      else if (p_end - p == 5 && startswith (p, "guile"))
+      else if (command_name_equals (cmd, "guile"))
 	{
 	  /* Note that we ignore the inline "guile command" form here.  */
 	  *command = build_command_line (guile_control, "");
diff --git a/gdb/testsuite/gdb.base/define.exp b/gdb/testsuite/gdb.base/define.exp
index 59203ec..91aadd7 100644
--- a/gdb/testsuite/gdb.base/define.exp
+++ b/gdb/testsuite/gdb.base/define.exp
@@ -147,6 +147,34 @@  gdb_test_multiple "define ifnospace" "define user command: ifnospace" \
 
 gdb_test "ifnospace" ".*hi there.*" "test ifnospace is parsed correctly"
 
+# Verify that the command parser properly handles command abbreviations.
+with_test_prefix "command abbreviations in define" {
+  set test "define user command: breakmain"
+  gdb_test_multiple "define breakmain" "$test" {
+      -re "Type commands for definition of \"breakmain\".\r\nEnd with a line saying just \"end\".\r\n>$" {
+	  pass "$test"
+	  set test "send body of breakmain"
+	  gdb_test_multiple "break main\ncommand\necho\nend\nend" "$test"  {
+	      -re "$gdb_prompt $"\
+		  {pass "$test"}
+	  }
+      }
+  }
+
+  gdb_test "breakmain" ".*Breakpoint .*" "run user command"
+
+  # If GDB fails to interpret properly the abbrev "command", the last "end"
+  # will be missing. Issue it to avoid a desync that would break the other
+  # tests in this file.
+  gdb_test "end" ".*This command cannot be used at the top level.*" "additional end command"
+
+  gdb_test "info break \$bpnum" \
+    "Num     Type\[ \]+Disp Enb Address\[ \]+What.*
+\[0-9\]+\[\t \]+breakpoint     keep y.* in main at .*
+\[\t \]+echo.*" "info break shows echo command"
+}
+
+
 # Verify that the command parser doesn't require a space after an 'while'
 # command in a user defined function.
 #