Parser add var decl #55

katcipis · 2018-08-03T03:16:29Z

Closes #53

codecov-io · 2018-08-03T03:26:03Z

Codecov Report

Merging #55 into master will increase coverage by 1.48%.
The diff coverage is 96.82%.

@@            Coverage Diff            @@
##           master     #55      +/-   ##
=========================================
+ Coverage   63.61%   65.1%   +1.48%     
=========================================
  Files          19      19              
  Lines        1528    1576      +48     
=========================================
+ Hits          972    1026      +54     
+ Misses        507     502       -5     
+ Partials       49      48       -1

Impacted Files	Coverage Δ
parser/parser.go	`87.86% <96.82%> (+6.19%)`	⬆️

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katcipis · 2018-08-04T00:12:21Z

parser/parser.go

 )

 func init() {
 	unaryParsers = map[token.Type]parserfn{
 		token.Minus: parseUnary,
 		token.Plus:  parseUnary,
 	}
+	literalParsers = map[token.Type]parserfn{


@tiago4orion I moved everything to init for the sake of consistency and also because I wrote a bug before because a variable that could be initialized outside init used the unaryParsers variable but the variable was an empty map at the time since the initialization was not on the order that the variables appeared on the code. If everything was able to be initialized outside init it would be good, but if one needs to be inside init it seems better to all the other ones to be there as well.

i4ki · 2018-08-07T00:00:50Z

ast/node.go

+		Value Node
+	}
+
+	VarDecls []VarDecl


i4ki · 2018-08-07T00:04:58Z

ast/node.go

@@ -76,6 +83,8 @@ const (
 	NodeUnaryExpr
 	NodeMemberExpr
 	NodeCallExpr
+	NodeVarDecl


if(var a = 1) { console.log("hello"); } VM99:1 Uncaught SyntaxError: Unexpected token var

simple var decl is not permitted.

I don't get the point

abad/ast/node.go

Line 76 in a2703fa

exprBegin

You defined the NodeVarDecl and NodeVarDecls beetwen exprBegin and exprEnd.
Take a look:

abad/ast/node.go

Line 123 in a2703fa

func IsExpr(node Node) bool {

Just need to move it out of this section.

i4ki · 2018-08-07T00:05:50Z

ast/node.go

@@ -76,6 +83,8 @@ const (
 	NodeUnaryExpr
 	NodeMemberExpr
 	NodeCallExpr
+	NodeVarDecl
+	NodeVarDecls


if(var a = 1, b = 2, c =3) console.log("ok") VM85:1 Uncaught SyntaxError: Unexpected token var

I don't tried to use var statements as expressions, they are being accepted right now as a bug ? I just added the var parser on the node parser, I did not realized that the parseNode function is the expression parser (it is the main entrypoint no ?)

see my other comment. Sorry for not being clear.

i4ki · 2018-08-07T00:08:51Z

parser/parser.go

@@ -126,10 +125,10 @@ func (p *Parser) parseNode() (n ast.Node, eof bool, err error) {
 	// parsers should not leave tokens not processed
 	// in the lookahead buffer.
 	if len(p.lookahead) != 0 {
-		panic(fmt.Sprintf(
+		return nil, false, fmt.Errorf(


why not panic? (just asking for the motivation)

the error the a test was giving was a lot harder to understand with panic, after using a error return the error was much easier to track. Since this is a bug inside the parser panic may be better but I forgot the code like this.

i4ki · 2018-08-07T00:10:21Z

parser/parser.go

+	return _parseVarDecls(p)
+}
+
+func _parseVarDecls(p *Parser) (ast.VarDecls, error) {


This is because I wanted to recursively build the vardecls from other vardecls but to use the function on the parserfn maps it needs to return an ast.Node. If I allow VarDecls to be built from ast.Node I would allow all sort of odd stuff to happen like var decls with other things inside (function declarations for example).

I'm complaining mostly about the name hehe

i4ki · 2018-08-07T00:12:23Z

parser/parser.go

+
+func _parseVarDecls(p *Parser) (ast.VarDecls, error) {
+
+	if !p.scry(2) {


Why lookahead of 2?

var a; // no lookahead
var a = 1; // no lookahead

At this point I had just "var". I dropped it since it is not necessary anymore. Now I need at least two tokens to see if it is:

identifier + semicolon

identifier + assignment (=)

How could this be written differently ?

ident := p.next() if ident.Type() != token.Ident { return nil, p.errorf(ident, "expected IDENT") } tok := p.next() if tok.Type() == token.Semicolon { return ast.NewVarDecls(ast.NewVarDecl(ident.Value, ast.NewUndefined())), nil } if tok.Type != token.Assign { return nil, fmt.Errorf("parser: var decl: expected assignment token [=] got [%s]", tok) } // parse assignment ...

i4ki · 2018-08-07T00:28:15Z

parser/parser_test.go

+			fail: true,
+		},
+		{
+			name: "InvalidMemberAccess",


Shouldn't this test be together with memberexpr tests?

Not sure, they are just as about member expression as they are about variable initialization. Actually the objective of these tests is to check that if the parser of the member access (the one that already has been tested isolated) fails the parser for variable statements checks that error and handles it properly, so it seemed like here would be the best place.

Do you are saying that this just test if errors are being checked ?

katcipis

Did not understood some things =/

katcipis · 2018-08-07T01:42:34Z

ast/node.go

@@ -76,6 +83,8 @@ const (
 	NodeUnaryExpr
 	NodeMemberExpr
 	NodeCallExpr
+	NodeVarDecl


I don't get the point

katcipis · 2018-08-07T01:44:41Z

ast/node.go

@@ -76,6 +83,8 @@ const (
 	NodeUnaryExpr
 	NodeMemberExpr
 	NodeCallExpr
+	NodeVarDecl
+	NodeVarDecls


I don't tried to use var statements as expressions, they are being accepted right now as a bug ? I just added the var parser on the node parser, I did not realized that the parseNode function is the expression parser (it is the main entrypoint no ?)

katcipis · 2018-08-07T01:47:17Z

parser/parser.go

@@ -126,10 +125,10 @@ func (p *Parser) parseNode() (n ast.Node, eof bool, err error) {
 	// parsers should not leave tokens not processed
 	// in the lookahead buffer.
 	if len(p.lookahead) != 0 {
-		panic(fmt.Sprintf(
+		return nil, false, fmt.Errorf(


the error the a test was giving was a lot harder to understand with panic, after using a error return the error was much easier to track. Since this is a bug inside the parser panic may be better but I forgot the code like this.

katcipis · 2018-08-07T01:48:37Z

parser/parser.go

+	return _parseVarDecls(p)
+}
+
+func _parseVarDecls(p *Parser) (ast.VarDecls, error) {


This is because I wanted to recursively build the vardecls from other vardecls but to use the function on the parserfn maps it needs to return an ast.Node. If I allow VarDecls to be built from ast.Node I would allow all sort of odd stuff to happen like var decls with other things inside (function declarations for example).

katcipis · 2018-08-07T01:50:00Z

parser/parser.go

+
+func _parseVarDecls(p *Parser) (ast.VarDecls, error) {
+
+	if !p.scry(2) {


At this point I had just "var". I dropped it since it is not necessary anymore. Now I need at least two tokens to see if it is:

identifier + semicolon

identifier + assignment (=)

How could this be written differently ?

katcipis · 2018-08-07T01:52:37Z

parser/parser_test.go

+			fail: true,
+		},
+		{
+			name: "InvalidMemberAccess",


Not sure, they are just as about member expression as they are about variable initialization. Actually the objective of these tests is to check that if the parser of the member access (the one that already has been tested isolated) fails the parser for variable statements checks that error and handles it properly, so it seemed like here would be the best place.

katcipis · 2018-08-07T02:11:31Z

parser/parser.go

+		return nil, fmt.Errorf("parser: var decl: invalid token[%s] expected comma", possibleSemiColon)
+	}
+
+	vars, err := _parseVarDecls(p)


I wanted to be able to do this recursion, it does not expect a "var" token and it can't return an ast.Node (not exactly can't but it don't seem like a good idea to me). The name is kinda lame but I was unable to think on something better until now. I thought about varAssigment since it parsers "a = value" not expecting the "var", but I imagine that the kind of node produced must be different since there is a difference on Javascript between declaring multiple variables starting with "var" and without (reference errors if the variable does not exist and it is not initialized).

http://es5.github.io/#x12.2

Spec call this section of declaration as VariableDeclarationList. What about parseDeclList ?

katcipis added 2 commits August 1, 2018 20:38

Initial def of var decl

c0b7351

add first working var decl

30fdd78

katcipis self-assigned this Aug 3, 2018

katcipis requested review from i4ki and ryukinix August 3, 2018 03:16

katcipis added 7 commits August 3, 2018 00:27

add error handling

e1abf8e

add var with literal expression

2502780

add var with literal expression

10bd1fa

add more error handling

8b0922d

add more error handling

ffbeb39

add var init to identifier

ac7059c

refactor node parsing

73202b9

katcipis commented Aug 4, 2018

View reviewed changes

katcipis added 3 commits August 6, 2018 13:54

add design for multiple vars in single statement

bef3fee

add multiple vars in single statement without identifier

bd1ada5

Fix formatting

d081cad

katcipis changed the title ~~WIP: Parser add var decl~~ Parser add var decl Aug 6, 2018

i4ki reviewed Aug 7, 2018

View reviewed changes

ast/node.go

Value Node

}

VarDecls []VarDecl

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i4ki suggested changes Aug 7, 2018

View reviewed changes

katcipis commented Aug 7, 2018

View reviewed changes

panic at error again

a2703fa

katcipis commented Aug 7, 2018

View reviewed changes

katcipis added 2 commits August 7, 2018 16:08

fix stupid mistakes

11bd5c1

fix stupid mistakes

aa035bc

katcipis merged commit f029e0d into master Aug 7, 2018

katcipis deleted the parserAddVarDecl branch August 7, 2018 19:24

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Parser add var decl #55

Parser add var decl #55

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		func _parseVarDecls(p *Parser) (ast.VarDecls, error) {

		if !p.scry(2) {

Parser add var decl #55

Parser add var decl #55

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