issues 280: Support ON UPDATE ddl statements

[gleonid]

What problem does this PR solve?

"CREATE TABLE child ( id INT, parent_id INT, INDEX par_ind (parent_id), FOREIGN KEY (parent_id) REFERENCES parent(id) ON UPDATE CASCADE)" fails to parse even though grammar looks like it should b able to

What is changed and how it works?

1. Added a unit test for above (see changes to ast/ddl_test.go)
2. refactored slightly grammar definition to explicitly enumerate all 4 possible combinations:
   ReferDef: "REFERENCES" TableName '(' IndexColNameList ')' OnDeleteOpt OnUpdateOpt is replaced with

 ReferDef:
       "REFERENCES" TableName '(' IndexColNameList ')' OnDeleteUpdateOpt
...
OnDeleteUpdateOpt:
    OnDelete OnUpdate
    {
        $$ = OnDeleteUpdateDef{ $1.(*ast.OnDeleteOpt), $2.(*ast.OnUpdateOpt) }
       }
|   OnUpdate
    {
        $$ = OnDeleteUpdateDef{ &ast.OnDeleteOpt{}, $1.(*ast.OnUpdateOpt) }
    } %prec lowerThanOn
|   OnDelete
    {
        $$ = OnDeleteUpdateDef{ $1.(*ast.OnDeleteOpt), &ast.OnUpdateOpt{} }
    } %prec lowerThanOn
|   {
               $$ = OnDeleteUpdateDef{ &ast.OnDeleteOpt{}, &ast.OnUpdateOpt{} }
       } %prec lowerThanOn

Check List

Tests

• Unit test
  added

Code changes

• Has exported function/method change
  no
• Has exported variable/fields change
  no
• Has interface methods change
  no

Side effects

• Possible performance regression
  performance test was not performed
• Breaking backward compatibility
  existing tests pass

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #331 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #331   +/-   ##
=======================================
  Coverage   53.38%   53.38%           
=======================================
  Files          31       31           
  Lines        6519     6519           
=======================================
  Hits         3480     3480           
  Misses       2700     2700           
  Partials      339      339

Impacted Files	Coverage Δ
parser.go	70.58% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8395edb...5ead50a. Read the comment docs.

[gleonid]

I have signed "You have signed the CLA for pingcap/parser" on May 20th 2019 13:03 EST, yet it still shows as not signed in checklist above

[tiancaiamao]

LGTM
PTAL @winkyao

[gleonid]

@winkyao
Please decide faith of this PR

I can resolve conflict on parser.go (generated file), but most likely it will become a conflict again as soon as any change to grammar is made (another PR merged).

I have parser.go as a separate commit, specifically for purpose to simplify rebasing.
I am happy to do at any point, or you can do it as easily.

Please let me know how you'd like to proceed

[winkyao]

LGTM

[winkyao]

@gleonid Could you resolve the conflicts?

[winkyao]

These changes are approved, thanks for your contribution

[gleonid]

@gleonid Could you resolve the conflicts?

@winkyao
conflict has been resolved
unfortunately approval is required again

[winkyao]

The CI is failed with error:

----------------------------------------------------------------------
FAIL: write_test.go:1747: testSuite4.TestQualifiedDelete

write_test.go:1768:
    c.Assert(err, NotNil)
... value = nil

@crazycs520 will help to fix ci.

[kennytm]

@winkyao The integration test error will be fixed by pingcap/tidb#11184.

[gleonid]

conflict is resolved but now approval is required again