From 53e5f3cf290c7591f459743845dd24391d72796c Mon Sep 17 00:00:00 2001 From: Andrew Stubbs Date: Fri, 2 Dec 2005 11:44:19 +0000 Subject: 2005-12-02 Andrew Stubbs * value.c (init_if_undefined_command): New function. (_initialize_values): Add command init-if-undefined. * NEWS (Changes since GDB 6.3): Rename to 'Changes in GDB 6.4'. (Changes since GDB 6.4): New section. Mention new command init-if-undefined. doc/ * gdb.texinfo (Convenience variables): Add init-if-undefined command. --- gdb/value.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) (limited to 'gdb/value.c') diff --git a/gdb/value.c b/gdb/value.c index 097d941..82746ae 100644 --- a/gdb/value.c +++ b/gdb/value.c @@ -727,6 +727,39 @@ show_values (char *num_exp, int from_tty) static struct internalvar *internalvars; +/* If the variable does not already exist create it and give it the value given. + If no value is given then the default is zero. */ +static void +init_if_undefined_command (char* args, int from_tty) +{ + struct internalvar* intvar; + + /* Parse the expression - this is taken from set_command(). */ + struct expression *expr = parse_expression (args); + register struct cleanup *old_chain = + make_cleanup (free_current_contents, &expr); + + /* Validate the expression. + Was the expression an assignment? + Or even an expression at all? */ + if (expr->nelts == 0 || expr->elts[0].opcode != BINOP_ASSIGN) + error (_("Init-if-undefined requires an assignment expression.")); + + /* Extract the variable from the parsed expression. + In the case of an assign the lvalue will be in elts[1] and elts[2]. */ + if (expr->elts[1].opcode != OP_INTERNALVAR) + error (_("The first parameter to init-if-undefined should be a GDB variable.")); + intvar = expr->elts[2].internalvar; + + /* Only evaluate the expression if the lvalue is void. + This may still fail if the expresssion is invalid. */ + if (TYPE_CODE (value_type (intvar->value)) == TYPE_CODE_VOID) + evaluate_expression (expr); + + do_cleanups (old_chain); +} + + /* Look up an internal variable with name NAME. NAME should not normally include a dollar sign. @@ -1639,4 +1672,11 @@ A few convenience variables are given values automatically:\n\ add_cmd ("values", no_class, show_values, _("Elements of value history around item number IDX (or last ten)."), &showlist); + + add_com ("init-if-undefined", class_vars, init_if_undefined_command, _("\ +Initialize a convenience variable if necessary.\n\ +init-if-undefined VARIABLE = EXPRESSION\n\ +Set an internal VARIABLE to the result of the EXPRESSION if it does not\n\ +exist or does not contain a value. The EXPRESSION is not evaluated if the\n\ +VARIABLE is already initialized.")); } -- cgit v1.1