Avoid '?' shortcut as its easily confused with the conditional operator commonly found in other languages.

For each of the following two cases, an error is incorrectly reported as

Parsing error: mismatched input 'sub' expecting <EOF>

1. sub with non-void return

sub dostuff() as Object
end sub

2. print followed with elements separated by comma

sub dostuff()
  print "Restarting app", appStoreID
end sub

Description:

Use 'As Dynamic' or omit parameter types to avoid runtime "Type Mismatch" exceptions. Specifying explicit types requires parameter type validation at the caller, which is more verbose than checking within the function and also prone to omission.

Explanation:

This is a pattern adopted after encountering many runtime errors. Because BRS type coercion is incosistent, (example: invalid is ok for Object but not for Integer), we avoid type declarations in function definitions and resort to manual type checks where needed.

At some point, chaining objects with the . operator becomes dangerous and prone to runtime errors due to an intermedia object being invalid.

It'd be nice to warn against some threshold of chained operations, such as:

if m.object.child.child.child.field = true
...

https://forums.roku.com/viewtopic.php?t=106057

https://sdkdocs.roku.com/display/sdkdoc/Conditional+Compilation

We need to make sure that we are giving proper attribution for ESLint in the spots where we have forked their code. The same goes for any other code that we've pulled from other repos.

My application has the

"no-private-func": [ "error" ],

Rule enabled which is causing linting error when including third party libraries. I wanted to see if there is an option to add an exception to the generic rule.

The following valid syntax causes a parse error in wist

sub main()
  for each i in [1,2,3]
    print i
  end for
end sub

if the array is defined before the block, wist will parse it ok.

This is an open RFC to define what our initial set of default rules should be. Please comment below and I will aggregate them into a list here.

Best Practices

• no-print: warn : Disallow print statements
• no-stop: warn : Disallow stop statements
• function-return-statement: error : Require return statements for functions
• function-return-type: warn : Require return type for functions

Possible Errors

• no-private-func: warn : Disallow calls to private functions outside of current script scope
• no-unused-vars: warn : Disallow unused variables (including function parameters)

Style Issues

• no-void-func: warn : Disallow void functions
• no-shorthand-if: warn : Disallow shorthand if statements
• comma-separated-arrays: warn : Require array/associative array entries to be comma separated
• no-comma-separated-arrays: warn : Disallow array/associative array entries from being comma separated
• no-inferred-types: warn : Disallow type inference for variables
• camel-case-functions: warn : Require functions to conform to camel case

Dangling dot operators are valid syntax and the roku interpreter ends up ignoring the final dot. I dislike the language behavior here but it does run as valid syntax. Would be nice to have wist successfully parse this but also have a rule to warn against it since it almost surely was not intended by the developer.

Example behavior from the console

Brightscript Debugger> print m
<Component: roAssociativeArray> =
{
}

Brightscript Debugger> m.foo. = "hi"

Brightscript Debugger> print m
<Component: roAssociativeArray> =
{
    foo: "hi"
}

Brightscript Debugger> m.bar = "bye"

Brightscript Debugger> a = m.bar.

Brightscript Debugger> print a
bye

Brightscript Debugger> 

REM some comment here works fine, but a REM followed be a line break returns a parsing error. ' comments do not seem to be affected by this.

We should add a new rule for trailing commas?

Reference eslint implementation
https://eslint.org/docs/rules/comma-dangle

For example, the following function

function sampleFunction() as object
    if GetGlobalAA().user = invalid then
        user = {
            _name : "",
        }
        GetGlobalAA()["user"] = user
    end if
    return invalid
end function

would warn about the trailing comma , in the code block.

Original issue: willowtreeapps/brs-lang#41

'stop' is currently considered a parser error but should probably be a warning for users so they don't accidentally ship code with 'stop' keywords in them since that would halt script execution.

sub whatever()
  m.constants = {
    test: [
        "pkg:/images/1.png",
        "pkg:/images/2.png",
    ]
  }
end sub

produces : 7:0 error Parsing error: mismatched input 'sub' expecting <EOF>

We could leverage wist to find or enforce minimum firmware versions, something which is required for Roku app submission. The Roku SDK docs are pretty good at documenting which version recent features were introduced. They could be put into a rule or set of rules in order to verify.

Normally, when the ANTLR runtime encounters a parse error, it attempts to recover by removing tokens from the token stream until it finds a token that satisfies the current or enclosing context.

However, in our case, it seems that Wist is unable to recover from a parse error because it makes the assumption that the enclosing scope is always a componentContext or componentHeadContext. These are always followed by EOF which means that the runtime will continue to remove tokens from the stream until the end of the file.

It seems that the solution is to remove the component rule as well as the componentBody rule from componentHeadElement.

Sample

function test()
    dim value[99] ' error
end function

Using the '-c' flag always gives an "Invalid path to configuration file." error. It looks like handleConfiguration is being passed an object rather than a string argument.

function whatever() as LongInteger
    return 1
end function

Reports error Parsing error: mismatched input 'function' expecting <EOF>

Changing "LongInteger" to "Integer" eliminates the error. Note LongInteger should be a valid return type: https://sdkdocs.roku.com/display/sdkdoc/Expressions,+Variables,+and+Types#Expressions,Variables,andTypes-Types

setFocus() should not be called inside a SG node's init() function, since the node may be stealing focus from elsewhere in the app when it shouldn't

The shortened version of an 'If' statement causes Wist to crash.

Sample Code:

Sub Main(args As Dynamic)
    ' Check for Something
    if not myFunctionThatChecksSomething() return
End Sub

Call Stack Trace:

Cannot read property 'start' of undefined
TypeError: Cannot read property 'start' of undefined
    at checkThen (/Users/joffa/node_modules/@willowtreeapps/wist/lib/rules/no-shorthand-if.js:17:47)
    at Linter.ifSingleLineStatement:enter (/Users/joffa/node_modules/@willowtreeapps/wist/lib/rules/no-shorthand-if.js:25:17)
    at Linter.emit (events.js:182:13)
    at BrightScriptEventListener.enterIfSingleLineStatement (/Users/joffa/node_modules/@willowtreeapps/wist/parser/BrightScriptEventGenerator.js:84:22)
    at IfSingleLineStatementContext.enterRule (/Users/joffa/node_modules/@willowtreeapps/wist/parser/antlr/BrightScriptParser.js:4263:18)
    at ParseTreeWalker.enterRule (/Users/joffa/node_modules/antlr4/tree/Tree.js:207:6)
    at ParseTreeWalker.walk (/Users/joffa/node_modules/antlr4/tree/Tree.js:190:8)
    at ParseTreeWalker.walk (/Users/joffa/node_modules/antlr4/tree/Tree.js:193:9)
    at ParseTreeWalker.walk (/Users/joffa/node_modules/antlr4/tree/Tree.js:193:9)
    at ParseTreeWalker.walk (/Users/joffa/node_modules/antlr4/tree/Tree.js:193:9)

The following example returns a parsing error because of the trailing comma:

someArray = [
  1,
  2,
  3,
]

Here is the error:

[wist] Parsing error: no viable alternative at input 'subinit()\nsomeArray=[\n1,\n2,\n3,\n]'

The following example runs fine:

someArray = [
  1,
  2,
  3
]

boolean type coersion is inconsistent. A rule to detect this would be helpful.

Motivation:

Brightscript Debugger> a = invalid

Brightscript Debugger> if a: print "hi": end if
Type Mismatch. (runtime error &h18) in $LIVECOMPILE(8)

Brightscript Debugger> a = "true"

Brightscript Debugger> if a: print "hi": end if
Type Mismatch. (runtime error &h18) in $LIVECOMPILE(10)

Brightscript Debugger> a = true

Brightscript Debugger> if a: print "hi": end if
hi

Brightscript Debugger> a = 1

Brightscript Debugger> if a: print "hi": end if
hi

Improved style allows for invalid without crashes (though string vs. boolean still crashes)

Brightscript Debugger> a = invalid

Brightscript Debugger> if a = true: print "hi": end if

Brightscript Debugger> a = "true"

Brightscript Debugger> if a = true: print "hi": end if
Type Mismatch. (runtime error &h18) in $LIVECOMPILE(18)

Brightscript Debugger> a = 1

Brightscript Debugger> if a = true: print "hi": end if
hi

I think we can take advantage of wist's abstract syntax tree to implement a code formatting tool. This is currently on track to merge with the experimental WASM parser. The general specification that I have in mind right now is as follows.

Indentation

• The default indentation should be 4 spaces
• Logical blocks including function, sub, if, else if, while, etc... should increase indentation level

function myFunction()
    ' increase indent
    a  = 10
end function

Whitespace

The code formatter should manage whitespace before and after tokens in the tree. For example,

• There should not be whitespace before ., ,, (, ),:, [ and ]
• There should not be whitespace after ., }, (, [

vars["sample"] = test.doSomething("some string") 

Array and Associative array definitions should be placed on new lines with an increased indent inside the block.

val = [
    "foo",
    "bar",
    "baz"
]

Comments

• The content of comments should be preserved and written back unaltered
• Comments within a block should respect the current indentation level

' comment at 0 indent
function foo()
    'comment at 1 indent
    bar = 0
end function

function whatever() as somethingBad
    return 1
end function

reported as error Parsing error: mismatched input 'function' expecting <EOF>

In my file I had a "print" statement with a quoted string followed by a comma and a var (line 153):
print "something", something_else

this generated an appropriate error, however the rest of the file then generated a bunch of errors:

  153:24  error    Parsing error: mismatched input ',' expecting {COMMENT, NEWLINE, ':'}
  161:40  error    Parsing error: mismatched input 'as' expecting {COMMENT, NEWLINE, ':'}
  162:2   error    Parsing error: extraneous input 'overrides' expecting {<EOF>, FUNCTION, SUB, COMMENT, NEWLINE}
  165:2   error    Parsing error: extraneous input 'if' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  166:4   error    Parsing error: extraneous input 'overrides' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  167:2   error    Parsing error: extraneous input 'end' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  169:2   error    Parsing error: extraneous input 'if' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  170:4   error    Parsing error: extraneous input 'overrides' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  171:2   error    Parsing error: extraneous input 'end' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  173:2   error    Parsing error: extraneous input 'if' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  174:4   error    Parsing error: extraneous input 'overrides' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  175:2   error    Parsing error: extraneous input 'end' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  177:2   error    Parsing error: extraneous input 'print' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  179:2   error    Parsing error: extraneous input 'return' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  180:0   error    Parsing error: extraneous input 'end' expecting {FUNCTION, SUB, COMMENT, NEWLINE}
  180:7   error    Parsing error: missing IDENTIFIER at '\n'
  181:0   error    Parsing error: extraneous input '<EOF>' expecting {BOX, CREATEOBJECT, DIM, END, ENDSUB, EXIT, EXITWHILE, EVAL, FALSE, FOR, GETGLOBALAA, GETLASTRUNCOMPILEERROR, GETLASTRUNRUNTIMEERROR, GOTO, IF, INVALID, NEXT, NOT, PRINT, RETURN, RUN, STOP, STRING, TAB, TRUE, TYPE, WHILE, STRING_LITERAL, INT_LITERAL, FLOAT_LITERAL, IDENTIFIER, COMMENT, NEWLINE, CONDITIONAL_CONST, CONDITIONAL_ERROR, CONDITIONAL_IF, '?', '(', ':', '+', '-'}

Running wist on my 2013 Macbook, it takes ~14s for wist to lint a 200-line BRS file. This is a lot longer than I expected but I don't have much experience with antlr.

Does this seem in line with performance you guys are seeing? If not, any hints on where I should start to isolate bottlenecks?

The error:

Error: ENOENT: no such file or directory, open 'C:\Git_work\Roku-Sample-App\source\*.brs'
    at Object.fs.openSync (fs.js:646:18)
    at Object.fs.readFileSync (fs.js:551:33)
    at processFile (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\src\js\cli-engine.js:64:21)
    at executeOnFile (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\src\js\cli-engine.js:89:28)
    at patterns.forEach.filename (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\src\js\cli-engine.js:94:13)
    at Array.forEach (<anonymous>)
    at CLIEngine.executeOnFiles (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\src\js\cli-engine.js:93:18)
    at Object.execute (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\src\js\cli.js:61:35)
    at Object.<anonymous> (C:\Users\eg874k\AppData\Roaming\npm\node_modules\@willowtreeapps\wist\bin\wist.js:13:24)
    at Module._compile (module.js:635:30)

It's works fine on single file

We need unit tests.

• Add AVA to project
• Add unit test guidelines
• Add tests

Running wist --init returns

Invalid path to configuration file.

Something like a comment-based format to override rules.
Maybe ' bslint "rule-name": "severity"

As an example to turn off the rule no-print you would add the following comment:
' bslint "no-print": "off"

When wist encounters a character not in the supported character encoding, it completely bombs. It would be nice if wist would be able to recover a bit more gracefully, perhaps add a specific error message about that token.

Here's the sample brightscript file (note the question mark character at the end of the print statement).

sub PrintError()
    print "request failed �"
end sub

When I run this command: wist PrintError.brs, it fails with this output.

C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1
(function (exports, require, module, __filename, __dirname) { var Module=typeof Module!=="undefined"?Module:{};var Module={"locateFile":(function(url){const path=require("path");return path.resolve(_dirname)+"/"+url})};var moduleOverrides={};var key;for(key in Module){if(Module.hasOwnProperty(key)){moduleOverrides[key]=Module[key]}}Module["arguments"]=[];Module["thisProgram"]="./this.program";Module["quit"]=(function(status,toThrow){throw toThrow});Module["preRun"]=[];Module["postRun"]=[];var ENVIRONMENT_IS_WEB=false;var ENVIRONMENT_IS_WORKER=false;var ENVIRONMENT_IS_NODE=false;var ENVIRONMENT_IS_SHELL=false;if(Module["ENVIRONMENT"]){if(Module["ENVIRONMENT"]==="WEB"){ENVIRONMENT_IS_WEB=true}else if(Module["ENVIRONMENT"]==="WORKER"){ENVIRONMENT_IS_WORKER=true}else if(Module["ENVIRONMENT"]==="NODE"){ENVIRONMENT_IS_NODE=true}else if(Module["ENVIRONMENT"]==="SHELL"){ENVIRONMENT_IS_SHELL=true}else{throw new Error("
BindingError: String has UTF-16 code units that do not fit in 8 bits
at BindingError. (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1:102871)
at new BindingError (eval at createNamedFunction (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1:102577), :4:34)
at throwBindingError (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1:106396)
at Object.toWireType (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1:135594)
at Object.parseText (eval at new (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\dist\libwist.js:1:125751), :7:26)
at Linter.verify (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\src\js\linter.js:141:36)
at processText (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\src\js\cli-engine.js:49:23)
at processFile (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\src\js\cli-engine.js:65:18)
at executeOnFile (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\src\js\cli-engine.js:89:28)
at patterns.forEach.filename (C:\Users\MY_USER_NAME\AppData\Roaming\nvm\v10.11.0\node_modules@willowtreeapps\wist\src\js\cli-engine.js:94:13)

When constructing console strings from non-string objects, avoid '+' operator which requires objects to be converted to strings first, where many approaches are susceptible to crashes.

Example:

AA = {
    a: 34
    b:dsd
    count:54
}

Attempting to invoke AA.count() generates a runtime error

Reference forum topic: https://forums.roku.com/viewtopic.php?f=34&t=114773

Issue with node.children being null when using "no-private-func" rule.

Cannot read property '1' of null
TypeError: Cannot read property '1' of null
    at isFunctionInvocation (/usr/local/lib/node_modules/@willowtreeapps/wist/lib/rules/no-private-func.js:11:42)
    at Linter.expression:exit (/usr/local/lib/node_modules/@willowtreeapps/wist/lib/rules/no-private-func.js:37:22)
    at emitOne (events.js:96:13)
    at Linter.emit (events.js:191:7)
    at BrightScriptEventListener.exitExpression (/usr/local/lib/node_modules/@willowtreeapps/wist/parser/BrightScriptEventGenerator.js:261:22)
    at ExpressionContext.exitRule (/usr/local/lib/node_modules/@willowtreeapps/wist/parser/antlr/BrightScriptParser.js:5439:18)
    at ParseTreeWalker.exitRule (/usr/local/lib/node_modules/antlr4/tree/Tree.js:212:6)
    at ParseTreeWalker.walk (/usr/local/lib/node_modules/antlr4/tree/Tree.js:195:8)
    at ParseTreeWalker.walk (/usr/local/lib/node_modules/antlr4/tree/Tree.js:193:9)
    at ParseTreeWalker.walk (/usr/local/lib/node_modules/antlr4/tree/Tree.js:193:9)

Sample File:

function sampleFunction() as object
    if GetGlobalAA().user = invalid then
        user = {
            _name : "",
        }
        GetGlobalAA()["user"] = user
    end if
    return invalid
end function

The dangling comma in _name : "",

Maybe we can add new rules for trailing commas?
https://eslint.org/docs/rules/comma-dangle

Original issue: willowtreeapps/brs-lang#54

print and ? are not good practice and should be warnings

Hey,

I'm looking for some guidance on the best way to programmatically use wist. I've got some gulp tasks setup for building and deploying. I'd like to have another task that's used to lint code before that happens.

I can use exec however that seems a little dirty when the code is all JavaScript. Any ideas or best practice?

Thanks!

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Code sample to reproduce

sub buOptionalTests()
    res = optional.ifPresent(function(value) as Integer 'parse error
        return value + 1
     end function)
end sub

Running wist on my 2013 Macbook, it takes ~14s for wist to lint a 200-line BRS file. This is a lot longer than I expected but I don't have much experience with antlr.

Does this seem in line with performance you guys are seeing? If not, any hints on where I should start to isolate bottlenecks?

BSLint should generate a .bslintrc.json file in the cwd where bslint --init is executed. The config would include a set of recommended rules, with a secondary command line parameter that allows an override to a file path with a different set of default rules to use for initialization.

See https://sdkdocs.roku.com/display/sdkdoc/Expressions%2C+Variables%2C+and+Types#Expressions,Variables,andTypes-ExponentiationOperator

Currently have a parse error raised on an expression:

a = b^3

Sample to reproduce.

Function com_rostreamer_screen_CreateBaseScreen()
    imageCanvas.SetLayer(0, { color : "#000000" }) ' fails here
    return imageCanvas
End Function