add class scoped_push to automatically restore variable on function exit

This commit is contained in:
Cheer Xiao 2013-02-22 22:34:30 +08:00 committed by Peter Ammon
parent bbab6b2fdc
commit 76f715c486
2 changed files with 63 additions and 49 deletions

View file

@ -444,6 +444,49 @@ public:
~scoped_lock();
};
/**
A scoped manager to save the current value of some variable, and optionally
set it to a new value. On destruction it restores the variable to its old
value.
This can be handy when there are multiple code paths to exit a block.
*/
template <typename T>
class scoped_push
{
T &ref;
T saved_value;
bool restored;
public:
scoped_push(T &r):
ref(r), restored(false)
{
saved_value = ref;
}
scoped_push(T &r, T new_value):
ref(r), restored(false)
{
saved_value = ref;
ref = new_value;
}
~scoped_push()
{
if (!restored)
restore();
}
void restore()
{
ref = saved_value;
restored = true;
}
};
/* Wrapper around wcstok */
class wcstokenizer
{

View file

@ -731,12 +731,6 @@ int parser_t::eval_args(const wchar_t *line, std::vector<completion_t> &args)
if (this->parser_type != PARSER_TYPE_GENERAL)
eflags |= EXPAND_SKIP_CMDSUBST;
/*
eval_args may be called while evaulating another command, so we
save the previous tokenizer and restore it on exit
*/
tokenizer_t * const previous_tokenizer = current_tokenizer;
const int previous_pos = current_tokenizer_pos;
int do_loop=1;
CHECK(line, 1);
@ -747,8 +741,13 @@ int parser_t::eval_args(const wchar_t *line, std::vector<completion_t> &args)
proc_push_interactive(0);
tokenizer_t tok(line, (show_errors ? 0 : TOK_SQUASH_ERRORS));
current_tokenizer = &tok;
current_tokenizer_pos = 0;
/*
eval_args may be called while evaulating another command, so we
save the previous tokenizer and restore it on exit
*/
scoped_push<tokenizer_t*> tokenizer_push(current_tokenizer, &tok);
scoped_push<int> tokenizer_pos_push(current_tokenizer_pos, 0);
error_code=0;
@ -802,9 +801,6 @@ int parser_t::eval_args(const wchar_t *line, std::vector<completion_t> &args)
if (show_errors)
this->print_errors_stderr();
current_tokenizer=previous_tokenizer;
current_tokenizer_pos = previous_pos;
if (this->parser_type == PARSER_TYPE_GENERAL)
proc_pop_interactive();
@ -1652,9 +1648,7 @@ int parser_t::parse_job(process_t *p,
bool allow_bogus_command = false; // If we are an elseif that will not be executed, or an AND or OR that will have been short circuited, don't complain about non-existent commands
block_t *prev_block = current_block;
int prev_tokenizer_pos = current_tokenizer_pos;
current_tokenizer_pos = tok_get_pos(tok);
scoped_push<int> tokenizer_pos_push(current_tokenizer_pos, tok_get_pos(tok));
while (args.empty())
{
@ -1677,7 +1671,6 @@ int parser_t::parse_job(process_t *p,
ILLEGAL_CMD_ERR_MSG,
tok_last(tok));
current_tokenizer_pos = prev_tokenizer_pos;
return 0;
}
break;
@ -1690,7 +1683,6 @@ int parser_t::parse_job(process_t *p,
TOK_ERR_MSG,
tok_last(tok));
current_tokenizer_pos = prev_tokenizer_pos;
return 0;
}
@ -1712,7 +1704,6 @@ int parser_t::parse_job(process_t *p,
tok_get_desc(tok_last_type(tok)));
}
current_tokenizer_pos = prev_tokenizer_pos;
return 0;
}
@ -1723,7 +1714,6 @@ int parser_t::parse_job(process_t *p,
CMD_ERR_MSG,
tok_get_desc(tok_last_type(tok)));
current_tokenizer_pos = prev_tokenizer_pos;
return 0;
}
}
@ -1746,7 +1736,6 @@ int parser_t::parse_job(process_t *p,
error(SYNTAX_ERROR,
tok_get_pos(tok),
EXEC_ERR_MSG);
current_tokenizer_pos = prev_tokenizer_pos;
return 0;
}
@ -1801,7 +1790,7 @@ int parser_t::parse_job(process_t *p,
use_function = 0;
use_builtin=0;
p->type=INTERNAL_EXEC;
current_tokenizer_pos = prev_tokenizer_pos;
tokenizer_pos_push.restore();
}
}
}
@ -2231,7 +2220,6 @@ int parser_t::parse_job(process_t *p,
parser_t::pop_block();
}
}
current_tokenizer_pos = prev_tokenizer_pos;
return !error_code;
}
@ -2333,7 +2321,7 @@ void parser_t::eval_job(tokenizer_t *tok)
profile_item_t *profile_item = NULL;
bool skip = false;
int job_begin_pos, prev_tokenizer_pos;
int job_begin_pos;
const bool do_profile = profile;
if (do_profile)
@ -2422,10 +2410,8 @@ void parser_t::eval_job(tokenizer_t *tok)
int was_builtin = 0;
if (j->first_process->type==INTERNAL_BUILTIN && !j->first_process->next)
was_builtin = 1;
prev_tokenizer_pos = current_tokenizer_pos;
current_tokenizer_pos = job_begin_pos;
scoped_push<int> tokenizer_pos_push(current_tokenizer_pos, job_begin_pos);
exec(*this, j);
current_tokenizer_pos = prev_tokenizer_pos;
/* Only external commands require a new fishd barrier */
if (!was_builtin)
@ -2563,14 +2549,12 @@ int parser_t::eval(const wcstring &cmdStr, const io_chain_t &io, enum block_type
const wchar_t * const cmd = cmdStr.c_str();
size_t forbid_count;
int code;
tokenizer_t *previous_tokenizer=current_tokenizer;
block_t *start_current_block = current_block;
/* Record the current chain so we can put it back later */
const io_chain_t prev_io = block_io;
block_io = io;
scoped_push<io_chain_t> block_io_push(block_io, io);
std::vector<wcstring> prev_forbidden = forbidden_function;
scoped_push<std::vector<wcstring> > forbidden_function_push(forbidden_function);
if (block_type == SUBST)
{
@ -2581,8 +2565,6 @@ int parser_t::eval(const wcstring &cmdStr, const io_chain_t &io, enum block_type
forbid_count = forbidden_function.size();
block_io = io;
job_reap(0);
debug(4, L"eval: %ls", cmd);
@ -2609,7 +2591,7 @@ int parser_t::eval(const wcstring &cmdStr, const io_chain_t &io, enum block_type
this->push_block(new scope_block_t(block_type));
current_tokenizer = new tokenizer_t(cmd, 0);
scoped_push<tokenizer_t*> tokenizer_push(current_tokenizer, new tokenizer_t(cmd, 0));
error_code = 0;
@ -2667,9 +2649,6 @@ int parser_t::eval(const wcstring &cmdStr, const io_chain_t &io, enum block_type
/*
Restore previous eval state
*/
forbidden_function = prev_forbidden;
current_tokenizer=previous_tokenizer;
block_io = prev_io;
eval_level--;
code=error_code;
@ -2834,16 +2813,15 @@ int parser_t::parser_test_argument(const wchar_t *arg, wcstring *out, const wcha
int parser_t::test_args(const wchar_t * buff, wcstring *out, const wchar_t *prefix)
{
tokenizer_t *const previous_tokenizer = current_tokenizer;
const int previous_pos = current_tokenizer_pos;
int do_loop = 1;
int err = 0;
CHECK(buff, 1);
tokenizer_t tok(buff, 0);
current_tokenizer = &tok;
scoped_push<tokenizer_t*> tokenizer_push(current_tokenizer, &tok);
scoped_push<int> tokenizer_pos_push(current_tokenizer_pos);
for (; do_loop && tok_has_next(&tok); tok_next(&tok))
{
current_tokenizer_pos = tok_get_pos(&tok);
@ -2893,9 +2871,6 @@ int parser_t::test_args(const wchar_t * buff, wcstring *out, const wchar_t *pre
}
}
current_tokenizer = previous_tokenizer;
current_tokenizer_pos = previous_pos;
error_code=0;
return err;
@ -2923,9 +2898,6 @@ int parser_t::test(const wchar_t *buff, int *block_level, wcstring *out, const w
int err=0;
int unfinished = 0;
tokenizer_t * const previous_tokenizer=current_tokenizer;
const int previous_pos=current_tokenizer_pos;
// These are very nearly stacks, but sometimes we have to inspect non-top elements (e.g. return)
std::vector<struct block_info_t> block_infos;
int indentation_sum = 0; //sum of indentation in block_infos
@ -2973,7 +2945,9 @@ int parser_t::test(const wchar_t *buff, int *block_level, wcstring *out, const w
}
tokenizer_t tok(buff, 0);
current_tokenizer = &tok;
scoped_push<tokenizer_t*> tokenizer_push(current_tokenizer, &tok);
scoped_push<int> tokenizer_pos_push(current_tokenizer_pos);
for (;; tok_next(&tok))
{
@ -3714,9 +3688,6 @@ int parser_t::test(const wchar_t *buff, int *block_level, wcstring *out, const w
Cleanup
*/
current_tokenizer=previous_tokenizer;
current_tokenizer_pos = previous_pos;
error_code=0;