详细介绍：为IvorySQL增添PACKAGE语法帮助

认识语法帮助

当使用psql工具登录数据库时，\h command可以查看语法帮助。比如查看create database语法：

psql (17.6)
Type "help" for help.
ivorysql=# \h create database
Command:     CREATE DATABASE
Description: create a new database
Syntax:
CREATE DATABASE name
[ WITH ] [ OWNER [=] user_name ]
[ TEMPLATE [=] template ]
[ ENCODING [=] encoding ]
[ STRATEGY [=] strategy ]
[ LOCALE [=] locale ]
[ LC_COLLATE [=] lc_collate ]
[ LC_CTYPE [=] lc_ctype ]
[ BUILTIN_LOCALE [=] builtin_locale ]
[ ICU_LOCALE [=] icu_locale ]
[ ICU_RULES [=] icu_rules ]
[ LOCALE_PROVIDER [=] locale_provider ]
[ COLLATION_VERSION = collation_version ]
[ TABLESPACE [=] tablespace_name ]
[ ALLOW_CONNECTIONS [=] allowconn ]
[ CONNECTION LIMIT [=] connlimit ]
[ IS_TEMPLATE [=] istemplate ]
[ OID [=] oid ]
URL: https://www.postgresql.org/docs/17/sql-createdatabase.html
ivorysql=#

这也算是个小技巧，不需要死记太多的sql语法，使用时直接查看就行。不仅打印出了对应sql的语法，还打印出了该语法对应的官方文档URL。

语法帮助原理分析

主要是@SOURCE_ROOT/src/bin/psql/help.c中helpSQL函数实现查看语法的功能。

从Makefile看还得依赖sql_help.c, sql_help.h一起编译完成。而从meson.build看是make的时候才生成这两个文件的，并且是使用create_help.pl读取文档目录@SOURCE_ROOT@/doc/src/sgml/ref中的所有语法文档生成的。

sql_help = custom_target('psql_help',output: ['sql_help.c', 'sql_help.h'],depfile: 'sql_help.dep',command: [perl, files('create_help.pl'),'--docdir', '@SOURCE_ROOT@/doc/src/sgml/ref','--depfile', '@DEPFILE@','--outdir', '@OUTDIR@','--basename', 'sql_help',],
)
generated_sources += sql_help.to_list()
psql_sources += sql_help

可以看到doc/src/sgml/ref目录下确实包含了其他所有对象的create的sgml文件，并没有create_package的文件。

ls doc/src/sgml/ref/create*
doc/src/sgml/ref/create_access_method.sgml  doc/src/sgml/ref/create_extension.sgml             doc/src/sgml/ref/create_operator.sgml     doc/src/sgml/ref/create_server.sgml        doc/src/sgml/ref/create_tsdictionary.sgml
doc/src/sgml/ref/create_aggregate.sgml      doc/src/sgml/ref/create_foreign_data_wrapper.sgml  doc/src/sgml/ref/create_opfamily.sgml     doc/src/sgml/ref/create_statistics.sgml    doc/src/sgml/ref/create_tsparser.sgml
doc/src/sgml/ref/create_cast.sgml           doc/src/sgml/ref/create_foreign_table.sgml         doc/src/sgml/ref/create_policy.sgml       doc/src/sgml/ref/create_subscription.sgml  doc/src/sgml/ref/create_tstemplate.sgml
doc/src/sgml/ref/create_collation.sgml      doc/src/sgml/ref/create_function.sgml              doc/src/sgml/ref/create_procedure.sgml    doc/src/sgml/ref/create_table_as.sgml      doc/src/sgml/ref/create_type.sgml
doc/src/sgml/ref/create_conversion.sgml     doc/src/sgml/ref/create_group.sgml                 doc/src/sgml/ref/create_publication.sgml  doc/src/sgml/ref/create_table.sgml         doc/src/sgml/ref/create_user_mapping.sgml
doc/src/sgml/ref/create_database.sgml       doc/src/sgml/ref/create_index.sgml                 doc/src/sgml/ref/create_role.sgml         doc/src/sgml/ref/create_tablespace.sgml    doc/src/sgml/ref/create_user.sgml
doc/src/sgml/ref/createdb.sgml              doc/src/sgml/ref/create_language.sgml              doc/src/sgml/ref/create_rule.sgml         doc/src/sgml/ref/create_transform.sgml     doc/src/sgml/ref/createuser.sgml
doc/src/sgml/ref/create_domain.sgml         doc/src/sgml/ref/create_materialized_view.sgml     doc/src/sgml/ref/create_schema.sgml       doc/src/sgml/ref/create_trigger.sgml       doc/src/sgml/ref/create_view.sgml
doc/src/sgml/ref/create_event_trigger.sgml  doc/src/sgml/ref/create_opclass.sgml               doc/src/sgml/ref/create_sequence.sgml     doc/src/sgml/ref/create_tsconfig.sgml

增添create package语法帮助

仿照create_table.sgml或其他文件，生成create_package.sgml和create_package_body.sgml文件。

从create_help.pl可知：
cmd取自sgml文件中refname标签，help取自synopsis标签，docbook_id取自refentry id标签。

因此create_package.sgml为：

CREATE PACKAGECREATE PACKAGE7SQL - Language StatementsCREATE PACKAGEdefine a new package

CREATE [ OR REPLACE ] PACKAGE [schema.] package_name  [invoker_rights_clause] [IS | AS]item_list[, item_list ...]
END [package_name]
invoker_rights_clause:AUTHID [CURRENT_USER | DEFINER]
item_list:
[function_declaration    |procedure_declaration   |type_definition         |cursor_declaration      |item_declaration
]
function_declaration:FUNCTION function_name [ (parameter_declaration[, ...]) ] RETURN datatype;
procedure_declaration:PROCEDURE procedure_name [ (parameter_declaration[, ...]) ]
type_definition:record_type_definition      |ref_cursor_type_definition
cursor_declaration:CURSOR name  [(cur_param_decl[, ...])] RETURN rowtype;
item_declaration:cursor_declaration             |cursor_variable_declaration    |record_variable_declaration    |variable_declaration           |
record_type_definition:TYPE record_type IS RECORD  ( variable_declaration [, variable_declaration]... ) ;
ref_cursor_type_definition:TYPE type IS REF CURSOR [ RETURN type%ROWTYPE ];
cursor_variable_declaration:curvar curtype;
record_variable_declaration:recvar { record_type | rowtype_attribute | record_type%TYPE };
variable_declaration:varname datatype [ [ NOT NULL ] := expr ]
parameter_declaration:parameter_name [IN] datatype [[:= | DEFAULT] expr]

create_package_body.sgml为：

CREATE PACKAGE BODYCREATE PACKAGE BODY7SQL - Language StatementsCREATE PACKAGE BODYdefine a new package body

CREATE [ OR REPLACE ] PACKAGE BODY [schema.] package_name [IS | AS][item_list[, item_list ...]] |item_list_2 [, item_list_2 ...][initialize_section]
END [ package_name ];
initialize_section:BEGIN statement[, ...]
item_list:
[function_declaration    |procedure_declaration   |type_definition         |cursor_declaration      |item_declaration
]
item_list_2:
[function_declarationfunction_definitionprocedure_declarationprocedure_definitioncursor_definition
]
function_definition:FUNCTION function_name [ (parameter_declaration[, ...]) ] RETURN datatype  [IS | AS][declare_section] body;
procedure_definition:PROCEDURE procedure_name [ (parameter_declaration[, ...]) ] [IS | AS][declare_section] body;
cursor_definition:CURSOR name [ (cur_param_decl[, ...]) ] RETURN rowtype IS select_statement;
body:BEGIN statement[, ...] END [name];
statement:[<>] pl_statments[, ...];

当然还需对helpSQL函数做些修改，当查询的语法帮助为create package(body)时，展示IvorySQL对应的官方文档URL。

for (i = 0; QL_HELP[i].cmd; i++)
{
if (pg_strncasecmp(topic, QL_HELP[i].cmd, len) == 0 ||
strcmp(topic, "*") == 0)
{
PQExpBufferData buffer;
char       *url;
initPQExpBuffer(&buffer);
QL_HELP[i].syntaxfunc(&buffer);
if (pg_strncasecmp(QL_HELP[i].docbook_id, "sql-createpackage",17) == 0)
url = "https://www.ivorysql.org/en/docs/compatibillity_features/package \n"
"DETAIL: https://docs.ivorysql.org/en/ivorysql-doc/v4.6/v4.6/28";
else
url = psprintf("https://www.postgresql.org/docs/%s/%s.html",
strstr(PG_VERSION, "devel") ? "devel" : PG_MAJORVERSION,
QL_HELP[i].docbook_id);
/* # of newlines in format must match constant above! */
fprintf(output, _("Command:     %s\n"
"Description: %s\n"
"Syntax:\n%s\n\n"
"URL: %s\n\n"),
QL_HELP[i].cmd,
_(QL_HELP[i].help),
buffer.data,
url);
if (pg_strncasecmp(QL_HELP[i].docbook_id, "sql-createpackage",17))
free(url);
termPQExpBuffer(&buffer);
/* If we have an exact match, exit.  Fixes \h SELECT */
if (pg_strcasecmp(topic, QL_HELP[i].cmd) == 0)
break;
}
}

重新编译安装psql工具后，已经可以查看create package的语法帮助了。

\h create package

psql (17.6)
Type "help" for help.
ivorysql=# \h create package
Command:     CREATE PACKAGE
Description: define a new package
Syntax:
CREATE [ OR REPLACE ] PACKAGE [schema.] package_name  [invoker_rights_clause] [IS | AS]
item_list[, item_list ...]
END [package_name]
invoker_rights_clause:
AUTHID [CURRENT_USER | DEFINER]
item_list:
[
function_declaration    |
procedure_declaration   |
type_definition         |
cursor_declaration      |
item_declaration
]
function_declaration:
FUNCTION function_name [ (parameter_declaration[, ...]) ] RETURN datatype;
procedure_declaration:
PROCEDURE procedure_name [ (parameter_declaration[, ...]) ]
type_definition:
record_type_definition      |
ref_cursor_type_definition
cursor_declaration:
CURSOR name  [(cur_param_decl[, ...])] RETURN rowtype;
item_declaration:
cursor_declaration             |
cursor_variable_declaration    |
record_variable_declaration    |
variable_declaration           |
record_type_definition:
TYPE record_type IS RECORD  ( variable_declaration [, variable_declaration]... ) ;
ref_cursor_type_definition:
TYPE type IS REF CURSOR [ RETURN type%ROWTYPE ];
cursor_variable_declaration:
curvar curtype;
record_variable_declaration:
recvar { record_type | rowtype_attribute | record_type%TYPE };
variable_declaration:
varname datatype [ [ NOT NULL ] := expr ]
parameter_declaration:
parameter_name [IN] datatype [[:= | DEFAULT] expr]
URL: https://www.ivorysql.org/en/docs/compatibillity_features/package 
DETAIL: https://docs.ivorysql.org/en/ivorysql-doc/v4.6/v4.6/28
ivorysql=#

\h create package body

psql (17.6)
Type "help" for help.
ivorysql=# \h create package body
Command:     CREATE PACKAGE BODY
Description: define a new package body
Syntax:
CREATE [ OR REPLACE ] PACKAGE BODY [schema.] package_name [IS | AS]
[item_list[, item_list ...]] |
item_list_2 [, item_list_2 ...]
[initialize_section]
END [ package_name ];
initialize_section:
BEGIN statement[, ...]
item_list:
[
function_declaration    |
procedure_declaration   |
type_definition         |
cursor_declaration      |
item_declaration
]
item_list_2:
[
function_declaration
function_definition
procedure_declaration
procedure_definition
cursor_definition
]
function_definition:
FUNCTION function_name [ (parameter_declaration[, ...]) ] RETURN datatype  [IS | AS]
[declare_section] body;
procedure_definition:
PROCEDURE procedure_name [ (parameter_declaration[, ...]) ] [IS | AS]
[declare_section] body;
cursor_definition:
CURSOR name [ (cur_param_decl[, ...]) ] RETURN rowtype IS select_statement;
body:
BEGIN statement[, ...] END [name];
statement:
[<<LABEL>>] pl_statments[, ...];URL: https://www.ivorysql.org/en/docs/compatibillity_features/package DETAIL: https://docs.ivorysql.org/en/ivorysql-doc/v4.6/v4.6/28ivorysql=#

小结

psql的语法帮助文档挺好用的，本次给IvorySQL-4.6适配create package(body)语法帮助文档算是比较系统的了解了下语法帮助文档的原理。

引用：

[1]
helpSQL:
https://github.com/IvorySQL/IvorySQL/blob/IvorySQL_4.6/src/bin/psql/help.c#L575

[2]
URL: https://www.ivorysql.org/en/docs/Compatibillity_Features/package