[PATCH 13/22] Replace hand-made linked list of ui_out_hdr by vector and iterator

Simon Marchi
2016-11-24T15:28:12Z

Instead of keeping pointers to first, last and current ui_out_hdr in
ui_out_table, we can use an std::vector and an iterator. Direct random
access of to vector helps make get_next_header a bit nicer by avoiding
iterating on all the headers. append_header_to_list is also a bit
simpler.

Also, using unique_ptr inside the vector allows expressing the ownership
of the ui_out_hdr objects by the ui_out_table object, and it simplifies
the destruction.

gdb/ChangeLog:

* ui-out.c (struct ui_out_hdr) <next>: Remove.
(struct ui_out_table) <header_first, header_last, header_next>: Remove.
<headers, headers_iterator>: New fields.
(ui_out_table_body): Update for the new data structure.
(ui_out_begin): Likewise.
(clear_header_list): Likewise.
(append_header_to_list): Likewise.
(get_next_header): Likewise.
(ui_out_query_field): Likewise.
(ui_out_new): Likewise.
---
gdb/ui-out.c | 100 ++++++++++++++++++++++++++---------------------------------
1 file changed, 44 insertions(+), 56 deletions(-)

diff --git a/gdb/ui-out.c b/gdb/ui-out.c
index a40ac0a..8e44698 100644
--- a/gdb/ui-out.c
+++ b/gdb/ui-out.c
@@ -38,7 +38,6 @@ struct ui_out_hdr
enum ui_align alignment;
char *col_name;
char *colhdr;
- struct ui_out_hdr *next;
};

struct ui_out_level
@@ -75,14 +74,11 @@ struct ui_out_table
call). */
std::string id;

- /* Points to the first table header (if any). */
- struct ui_out_hdr *header_first;
+ /* Pointers to the column headers. */
+ std::vector<std::unique_ptr<ui_out_hdr>> headers;

- /* Points to the last table header (if any). */
- struct ui_out_hdr *header_last;
-
- /* Points to header of NEXT column to format. */
- struct ui_out_hdr *header_next;
+ /* Iterator over the headers vector, used when printing successive fields. */
+ std::vector<std::unique_ptr<ui_out_hdr>>::const_iterator headers_iterator;

};

@@ -224,13 +220,12 @@ after a table_begin and before a table_end."));
internal_error (__FILE__, __LINE__,
_("extra table_body call not allowed; there must be \
only one table_body after a table_begin and before a table_end."));
- if (uiout->table.header_next->colno != uiout->table.columns)
+ if (uiout->table.headers.size () != uiout->table.columns)
internal_error (__FILE__, __LINE__,
_("number of headers differ from number of table \
columns."));

uiout->table.body_flag = 1;
- uiout->table.header_next = uiout->table.header_first;

uo_table_body (uiout);
}
@@ -314,7 +309,7 @@ specified after table_body."));
got a new table row. Put the header pointer back to the start. */
if (uiout->table.body_flag
&& uiout->table.entry_level == new_level)
- uiout->table.header_next = uiout->table.header_first;
+ uiout->table.headers_iterator = uiout->table.headers.begin ();

uo_begin (uiout, type, new_level, id);
}
@@ -699,18 +694,14 @@ uo_redirect (struct ui_out *uiout, struct ui_file *outstream)
static void
clear_header_list (struct ui_out *uiout)
{
- while (uiout->table.header_first != NULL)
+ for (auto &it : uiout->table.headers)
{
- uiout->table.header_next = uiout->table.header_first;
- uiout->table.header_first = uiout->table.header_first->next;
- xfree (uiout->table.header_next->colhdr);
- xfree (uiout->table.header_next->col_name);
- delete uiout->table.header_next;
+ xfree (it->colhdr);
+ xfree (it->col_name);
}

- gdb_assert (uiout->table.header_first == NULL);
- uiout->table.header_last = NULL;
- uiout->table.header_next = NULL;
+ uiout->table.headers.clear ();
+ uiout->table.headers_iterator = uiout->table.headers.end ();
}

static void
@@ -720,9 +711,8 @@ append_header_to_list (struct ui_out *uiout,
const char *col_name,
const char *colhdr)
{
- struct ui_out_hdr *temphdr;
+ std::unique_ptr<ui_out_hdr> temphdr (new ui_out_hdr ());

- temphdr = new ui_out_hdr ();
temphdr->width = width;
temphdr->alignment = alignment;
/* We have to copy the column title as the original may be an
@@ -739,20 +729,9 @@ append_header_to_list (struct ui_out *uiout,
else
temphdr->col_name = NULL;

- temphdr->next = NULL;
- if (uiout->table.header_first == NULL)
- {
- temphdr->colno = 1;
- uiout->table.header_first = temphdr;
- uiout->table.header_last = temphdr;
- }
- else
- {
- temphdr->colno = uiout->table.header_last->colno + 1;
- uiout->table.header_last->next = temphdr;
- uiout->table.header_last = temphdr;
- }
- uiout->table.header_next = uiout->table.header_last;
+ temphdr->colno = uiout->table.headers.size () + 1;
+
+ uiout->table.headers.push_back (std::move (temphdr));
}

/* Extract the format information for the NEXT header and advance
@@ -766,14 +745,19 @@ get_next_header (struct ui_out *uiout,
char **colhdr)
{
/* There may be no headers at all or we may have used all columns. */
- if (uiout->table.header_next == NULL)
+ if (uiout->table.headers_iterator == uiout->table.headers.end ())
return 0;
- *colno = uiout->table.header_next->colno;
- *width = uiout->table.header_next->width;
- *alignment = uiout->table.header_next->alignment;
- *colhdr = uiout->table.header_next->colhdr;
+
+ ui_out_hdr *hdr = uiout->table.headers_iterator->get ();
+
+ *colno = hdr->colno;
+ *width = hdr->width;
+ *alignment = hdr->alignment;
+ *colhdr = hdr->colhdr;
+
/* Advance the header pointer to the next entry. */
- uiout->table.header_next = uiout->table.header_next->next;
+ uiout->table.headers_iterator++;
+
return 1;
}

@@ -834,21 +818,26 @@ int
ui_out_query_field (struct ui_out *uiout, int colno,
int *width, int *alignment, char **col_name)
{
- struct ui_out_hdr *hdr;
-
if (!uiout->table.flag)
return 0;

- for (hdr = uiout->table.header_first; hdr; hdr = hdr->next)
- if (hdr->colno == colno)
- {
- *width = hdr->width;
- *alignment = hdr->alignment;
- *col_name = hdr->col_name;
- return 1;
- }
+ /* Column numbers are 1-based, so convert to 0-based index. */
+ int index = colno - 1;
+
+ if (index >= 0 && index < uiout->table.headers.size ())
+ {
+ ui_out_hdr *hdr = uiout->table.headers[index].get ();
+
+ gdb_assert (colno == hdr->colno);

- return 0;
+ *width = hdr->width;
+ *alignment = hdr->alignment;
+ *col_name = hdr->col_name;
+
+ return 1;
+ }
+ else
+ return 0;
}

/* Initialize private members at startup. */
@@ -872,8 +861,7 @@ ui_out_new (const struct ui_out_impl *impl, void *data,
current->field_count = 0;
uiout->levels.push_back (std::move (current));

- uiout->table.header_first = NULL;
- uiout->table.header_last = NULL;
- uiout->table.header_next = NULL;
+ uiout->table.headers_iterator = uiout->table.headers.end ();
+
return uiout;
}
--
2.10.0