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vincentdchan · 2017-11-07T11:35:46Z

Q	A
Fixed Issues?	No
Patch: Bug Fix?	No
Major: Breaking Change?	No
Minor: New Feature?	parsing pattern matching expression
Tests Added + Pass?	Yes
Documentation PR	No
Any Dependency Changes?	No
License	MIT

This PR is implementing the proposal tc39/proposal-pattern-matching.
The parser can distinguish between function call of match and match expression.
Nested matching is supported.
Descriptions of new ASTs have been added to spec.md .
You can test transform plugin in REPL: https://deploy-preview-1421--babel.netlify.com/repl/build/5932/, activate stage-0 preset before you code.
Details in README.md

Example:

var test = {
    a: [1,2,3],
    b: {
      bb: "ok"
    },
    c: [[1,2], [3,4]],
}

// nested
assert.equal(match(test) {
  {c:[[1,2], [d, 4]]}: d, // match 3, and bind d to 3
  else: "foo"
}, 3);

var test = {
    a: 1,
    b: 2,
    c: {
      cc: "hello",
      ccc: " world",
    },
};

// rest matching
assert.equal(match(test) {
  {c: {cc, ...rest}}: cc + rest.ccc,  // match object, and bind rest property to `rest`
  else: "foo"
}, "hello world");

Progress:

a parser for match expression
a transform plugin
rest identifier feature

define AST in types.js add a parsing plugin add basic test and fix a parsing bug

new AST of clause fix "else" parsing bug add a test case

fix a bug about string literal add test of match function call

babel-bot · 2017-11-07T11:43:48Z

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/7391/

hzoo · 2017-11-07T14:06:15Z

Thanks for the PR! Issue for babel is at babel/proposals#6

Just FYI @krzkaczor also had started a PR at babel/babylon#635 before we moved babylon back into this repo

vincentdchan · 2017-11-07T15:21:48Z

@hzoo Oh, I'll take a look at it, I'm sure some code and tests can be reused.

hzoo · 2017-11-09T19:53:16Z

Btw can ast test changes in https://deploy-preview-1421--babel.netlify.com/repl/build/5694/, from babel/website#1421

ah nvm need to make a syntax plugin and add it to stage-0 to test

hzoo · 2017-11-09T19:53:49Z

.vscode/settings.json

@@ -0,0 +1,3 @@
+{


can you commit these config files locally?

Okay, got it

remove vscode setting

vincentdchan · 2017-11-11T02:25:47Z

@hzoo got it.

xtuc · 2017-12-11T13:54:05Z

@titouancreach yes we will, we are currently busy with the Babel 7 release sorry

# Conflicts: # packages/babel-preset-stage-0/package.json # packages/babel-preset-stage-0/src/index.js

babakness · 2018-02-02T22:10:24Z

Please merge this!! Excited to try it out :-)

ricochet1k · 2018-02-27T16:58:27Z

packages/babel-plugin-proposal-pattern-matching/src/index.js

+              ID: id,
+            });
+          } else {
+            return template.expression(`(PATTERN[Symbol.match] &&


The proposal refers to Symbol.matches, not Symbol.match

@ricochet1k Thx. I am going to fix it.

vincentdchan · 2018-02-28T04:20:11Z

@babakness It's coming soon! I am working on it.

vincentdchan · 2018-02-28T07:34:30Z

@hzoo @xtuc It's complete!

xtuc · 2018-03-02T07:55:18Z

packages/babel-plugin-proposal-pattern-matching/src/index.js

+
+    switch (pattern.type) {
+      case "NumericLiteral":
+      case "BigIntLiteral":


Since BigInt is not implemented in Babel, I think we should already include it here. It sounds like extra maintenance if it change.

Also it's not testable?

We'll need to create a issue to track that tho.

So should we keep it?

I would suggest to remove it, but let's wait for more thoughts on this.

xtuc · 2018-03-02T07:56:51Z

packages/babel-plugin-proposal-pattern-matching/src/index.js

+            BODY
+          }()`)({
+            BODY: bodyExpr,
+          }),


I like templates but this one could be clearer using t.* builders IMO

xtuc · 2018-03-02T07:58:13Z

.../babel-plugin-proposal-pattern-matching/test/fixtures/stupid-fixture-nesting-folder/array.js

+  },
+  [1, 2, 3, 4]: 3,
+  [1, 2, 3, 4, 5]: 4
+}, 666);


Why is this feature called stupid-fixture-nesting-folder? That isn't stupid?

Oh! I just copy the folder from another plugin, I'll remove it. Of cause it isn't stupid.

xtuc · 2018-03-02T08:06:02Z

...babel-plugin-proposal-pattern-matching/test/fixtures/stupid-fixture-nesting-folder/errors.js

+      2: "3"
+    }
+} catch (e) {
+  assert.equal(e.toString(), "Error: No patterns are matched");


FYI tc39/proposal-pattern-matching#64

@zkat: [...] the new spec throws a MatchError when no clauses were able to match [...]

vincentdchan · 2018-03-04T06:42:11Z

There are still two issues here:

tc39/proposal-pattern-matching#64
case of BigIntLiteral

This PR lasted four months. 😂😂😂

xtuc · 2018-03-05T18:58:18Z

This PR lasted four months.

I didn't finish my last review, sorry. And sorry if that takes so long, thanks!

zkat · 2018-03-25T22:31:04Z

nudge: this spec looks pretty different now. See https://github.com/tc39/proposal-pattern-matching

xtuc · 2018-03-26T07:39:54Z

Thanks for the update @zkat, we can see the changes in the PR here tc39/proposal-pattern-matching#65.

Sorry for the delai @vincentdchan, TC39 was missing a champion on this proposal and @zkat took over championing now (thanks 😄 )

vincentdchan · 2018-03-26T09:10:00Z

@xtuc OK. I have communicated with @zkat privately, and I will still work on this PR. But it takes time to implement the new proposal.

xtuc · 2018-03-26T11:19:19Z

@vincentdchan sounds good to me, thanks for your work on this!

zloirock · 2018-03-26T22:32:18Z

I added Symbol.{patternMatch, patternValue} for this proposal to core-js@3.

xtuc · 2018-03-27T06:12:54Z

Btw @vincentdchan we could close this PR and open a new one if you want to avoid the old comments here, might be easier to follow?

vincentdchan · 2018-03-27T06:50:24Z

Closed! Move to #7633

vincentdchan added 9 commits November 7, 2017 18:25

do the basic parsing of pattern matching

e6d5842

define AST in types.js add a parsing plugin add basic test and fix a parsing bug

use new match pattern

89b87a0

new AST of clause fix "else" parsing bug add a test case

add tests and fix bug

088ca57

fix a bug about string literal add test of match function call

add spec of new AST

434b126

change file for merge

d401a73

Merge remote-tracking branch 'origin/master' into pattern-matching

226d326

lint

e97a1de

add errors tests

9b81d07

add patternMatching item to plugin list

7867944

xtuc added Spec: Pattern Matching PR: New Feature 🚀 A type of pull request used for our changelog categories labels Nov 7, 2017

better error message for no clauses

63c0465

hzoo reviewed Nov 9, 2017

View reviewed changes

add syntax plugin for pattern matching

5802d25

remove vscode setting

vincentdchan force-pushed the pattern-matching branch 4 times, most recently from 994c02c to 5802d25 Compare November 11, 2017 02:22

vincentdchan and others added 3 commits November 13, 2017 19:22

add transform plugin(not finished)

50b4cdc

Merge branch 'master' into pattern-matching

a0126c8

Merge branch 'master' into pattern-matching

386279b

vincentdchan force-pushed the pattern-matching branch 2 times, most recently from 380cca0 to e7a325d Compare November 13, 2017 14:35

vincentdchan changed the title ~~Babylon: parsing part of pattern matching~~ tc39-proposal-pattern-matching Nov 13, 2017

add pattern-matching fixtures layout(stupid fixture)

6dd6f3b

vincentdchan force-pushed the pattern-matching branch from c7d905b to aea4697 Compare December 15, 2017 03:59

Merge branch 'master' into pattern-matching

64f7964

# Conflicts: # packages/babel-preset-stage-0/package.json # packages/babel-preset-stage-0/src/index.js

vincentdchan added 3 commits February 3, 2018 22:51

Merge remote-tracking branch 'origin/master' into pattern-matching

38bedd2

use cloneNode

9f14284

fix babylon

f10a871

ricochet1k reviewed Feb 27, 2018

View reviewed changes

vincentdchan added 4 commits February 28, 2018 10:49

stage

04082c4

Merge branch 'master' into pattern-matching

66c1185

fix Symbol.match to Symbol.matches

19019c1

add babylon test

7a3c83a

update definitions

63307a4

xtuc reviewed Mar 2, 2018

View reviewed changes

modify the template to generator. Rename the folder.

26d83d1

vincentdchan mentioned this pull request Mar 27, 2018

[WIP] tc39/pattern-matching #7633

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vincentdchan closed this Mar 27, 2018

lock bot added the outdated A closed issue/PR that is archived due to age. Recommended to make a new issue label Oct 5, 2019

lock bot locked as resolved and limited conversation to collaborators Oct 5, 2019

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zkat commented Mar 25, 2018

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