support DROP FUNCTION syntax

[zidaye]

close #753
refer to :https://www.postgresql.org/docs/current/sql-dropfunction.html

[coveralls]

Pull Request Test Coverage Report for Build 3764235521

• 95 of 111 (85.59%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.008%) to 86.328%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser.rs	24	31	77.42%
src/ast/mod.rs	13	22	59.09%

Totals
Change from base Build 3720056662:	-0.008%
Covered Lines:	12856
Relevant Lines:	14892

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💛 - Coveralls

[AugustoFKL]

@zidaye maybe an enum here would be better (or an option with a boolean inside).

Here you allow the state "cascade + restrict", which doesn't make sense at all.

[zidaye]

@AugustoFKL done.

[alamb]

Thank you for the contribution @zidaye

I have some suggestions, but overall this PR is looking close

[alamb]

It might be possible to use https://github.com/sqlparser-rs/sqlparser-rs/blob/d420001c37eeb38aac26a85dd5661755d6ef4228/src/ast/ddl.rs#LL602C16-L602C16

[zidaye]

I will change it later, thanks for your suggestion

[zidaye]

It might be possible to use https://github.com/sqlparser-rs/sqlparser-rs/blob/d420001c37eeb38aac26a85dd5661755d6ef4228/src/ast/ddl.rs#LL602C16-L602C16

done

[alamb]

What do you think about reusing the CreateFunctionArg structure used in CREATE FUNCTION

sqlparser-rs/src/ast/mod.rs

Lines 1410 to 1417 in d420001

	CreateFunction {
	or_replace: bool,
	temporary: bool,
	name: ObjectName,
	args: Option<Vec<CreateFunctionArg>>,
	return_type: Option<DataType>,
	/// Optional parameters.
	params: CreateFunctionBody,

?

I can also see the argument for using a separate struct. If we stay with a separate struct, I suggest we name if DropFunctionArg to mirror the CreateFunctionArg

[zidaye]

I'll try to combine these structures later

[zidaye]

What do you think about reusing the CreateFunctionArg structure used in CREATE FUNCTION

sqlparser-rs/src/ast/mod.rs

Lines 1410 to 1417 in d420001

	CreateFunction {
	or_replace: bool,
	temporary: bool,
	name: ObjectName,
	args: Option<Vec<CreateFunctionArg>>,
	return_type: Option<DataType>,
	/// Optional parameters.
	params: CreateFunctionBody,

?

I can also see the argument for using a separate struct. If we stay with a separate struct, I suggest we name if DropFunctionArg to mirror the CreateFunctionArg

sorry for my late reply。I've reconsidered your suggestion, and I think the structure might be acceptable. The DropFunctionDesc contains the function name and function parameters. The CreateFunctionArg only describes function parameters. Also, CreateFunctionArg has been reused and renamed OperateFunctionArg

[alamb]

marking as draft -- please mark as ready for review when you have made the changes you plan. Thank you

[alamb]

Thank you @zidaye