Re: pg_scanner - patch no.1 - Mailing list pgadmin-hackers

Just an FYI - I'm not ignoring your patches; I was away at PGConf.EU
last week and am very busy at the moment. They are on my TODO list
though.

Thanks.

On Sun, Oct 21, 2012 at 9:08 AM, Vladimir Kokovic
<vladimir.kokovic@gmail.com> wrote:
> Hi,
>
> This patch is my try to add lexical scanner for PostgreSQL SQL
> commands in Pgadmin source tree(prerequisite for patches no.2 and 3).
>
> The main reason why that is done is to scan and parse a SQL command in
> the same way
>  like PostgreSQL server, but for limited number of parse functions.
>
> All scanner special cases are covered: TYPECAST(::), COLON_EQUALS(:=),
> DOT_DOT(..) and $foo$.
>
> Currently, three parsers implemented:
>
> 1. parse SQL command string for commands separated by ';'
>       returns single linked list of commands
>       struct myScannerNode *get_all_commands_cpp(const struct
> myScannerNode *head);
>
> 2. parse RULE SQL command and substitute source schema with target schema
>       returns CREATE RULE SQL command with new schema name
>       char *parse_rule_cpp(const struct myScannerNode *head, const
> char *rulename, const char *targetschema, const char *tablename);
>
> 3. parse TRIGGER SQL command and substitute source schema with target
> schema (pgadmin/utils/pasteTables.cpp)
>       returns CREATE TRIGGER SQL command with new schema name
>       char *parse_trigger_cpp(const struct myScannerNode *head, const
> char *targetschema);
>
>
> For all parsers 'scan_SQL_cpp' method is prerequisite which scan SQL
> command for tokens:
>         returns single linked list of scan results (tokens)
>         struct myScannerNode *scan_SQL_cpp(const char *command);
>
> If some error occurred during scan process, variable
> 'pgadmin_scanner_last_error' contains diagnostic message.
>
>
> *** This code snippet is from my pgadmin/frm/frmQuery.cpp ***
>
> /*
>  * The scanner returns extra data about scanned tokens in this union type.
>  * Note that this is a subset of the fields used in YYSTYPE of the bison
>  * parsers built atop the scanner.
>  */
> typedef union core_YYSTYPE
> {
>         int                     ival;                   /* for integer literals */
>         char       *str;                        /* for identifiers and non-integer literals */
>         const char *keyword;            /* canonical spelling of keywords */
> } core_YYSTYPE;
>
>
> /*
>         my token data struct
> */
> struct myScannerData {
>         int loc;
>         int token;
>         core_YYSTYPE val;
> };
>
>
> /*
>         my single linked list for scan results
> */
> struct myScannerNode {
>         struct myScannerData data;
>         struct myScannerNode *next;
> };
>
>
> //command offest from the beginning of SQL command string for each SQL command
> wxArrayInt locs;
>
> //SQL commands (queries)
> wxArrayString   queries;
>
> //this is the first step which must be executed
> //scan_SQL_cpp returns single linked list of scan results (tokens)
>
> struct myScannerNode *head = scan_SQL_cpp(query.ToUTF8());
> if (head)
> {
> //parse scan results
> //get_all_commands_cpp returns single linked list of commands
>         struct myScannerNode *result = get_all_commands_cpp(head);
>
>         struct myScannerNode *current = result;
>         if (current)
>         {
>                 do
>                 {
>                         wxString x = wxString(current->data.val.str, wxConvUTF8);
>                         queries.Add(x);
>                         locs.Add(current->data.loc);
>                         current = current->next;
>                 } while (current != result);
>                 destroylist(result);
>         }
>         destroylist(head);
> }
>
>
>
> *** This code snippet is from my pgadmin/utils/pasteTables.cpp ***
>
>         struct myScannerNode *head =
> scan_SQL_cpp(definition.mb_str(*srcrule->GetConnection()->GetConv()));
>         if (head)
>         {
>                 char *rule = parse_rule_cpp(
>                         head, qtname.ToAscii(), targetschema->GetIdentifier().ToAscii(),
> newtablename.ToAscii());
>                 if (rule)
>                 {
>                         newdefinition = wxString(rule, *targetschema->GetConnection()->GetConv());
>                         free(rule);
>                 }
>                 destroylist_cpp(head);
>         }
>
>
> Best regards
> Vladimir Kokovic
> Belgrade, Serbia, 21.October 2012
>
>
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