pegjs / website Goto Github PK

test syntax input don't show line numbers.
When there is an error I need to count lines.

The documentation says that parsers can also support their own custom options. How do I enable this? I'm generating the parser from the commandline, and I'm using the generated code. I'd like to pass context to the "parse" function.

The following grammar entered into the online version:

start = { return { item: 'abc' }; }

produces output [] for an empty input, instead of correct { item: 'abc' }.

The following grammars don't have this problem:

start = { return { item: 0 }; }

start = { return { index: 'abc' }; }

Debugging points to a bug in the jsDump library. I need to look whether this is fixed in a newer version. If not, I need to report it/fix it.

Originally reported in the Google Group.

Use source code of JSON Formatter extension for Google Chrome. (Assigned to me)

The “Download parser” button just doesn’t do anything in IE 9-11. I didn’t try any lower version.

To make prototyping of production scale parsers easier, there should be two tabs on the left side:

1. PEG.js source code
2. JS code (+ library selection from CDN)
   (Assigned to me)

I'd be very great if we could show line numbers in the Grammar writing section (<textarea>) at http://pegjs.majda.cz/online.

When we write grammar directly into the online editor and if any error occurs in the grammar it shows respective line number. But to find the line number we need to copy the code in the text editor and check the line number where exactly the error is. I feel it's not easy to debug there.

PS: I'd like take this up but need prior discussion before implementing.

So, it's been years since I've started using /online and I wanted to see some changes, but they never came. Here're some things that came to my head first:

• Burn the jQuery. Replace it with React
• Get rid of EJS on server
• Restyle website to conform to modern flat design: remove rounded corners, remove extraneous borders, create consistent color scheme, change to darker background etc
• Use CodeMirror for output
• Add a button to switch between CM and treeview for output
• Display stack trace
• Display errors on CM gutters in code and output
• Put execution into webworker, so that infinite loops do not destroy code in Chrome
• Add a combobox to select examples from the list
• Collapse options (parser variable, result cache) to take less space, they're almost never used
• Store previous code in localstorage
• Fix incorrect CM config (2/4 spaces depending on action)
• Add lodash into scope

Which of these do you think you will never let into master?

According to 0.9.0 changelog

line(), column() and offset() were removed and replaced by location()

however the documentation on the website still shows

line(), column() and offset() as available in predicates

emphasis added for clarity.

The predicate is a piece of JavaScript code that is executed as if it was inside a function. It gets the match results of labeled expressions in preceding expression as its arguments. It should return some JavaScript value using the return statement. If the returned value evaluates to true in boolean context, just return undefined and do not advance the parser position; otherwise consider the match failed.

The code inside the predicate can access all variables and functions defined in the initializer at the beginning of the grammar.

The code inside the predicate can also access location information using the location function. It returns an object like this:

{
start: { offset: 23, line: 5, column: 6 },
end: { offset: 23, line: 5, column: 6 }
}
The start and end properties both refer to the current parse position. The offset property contains an offset as a zero-based index and line and column properties contain a line and a column as one-based indices.

The code inside the predicate can also access the parser object using the parser variable and options passed to the parser using the options variable.

The code inside the predicate can also access the current parse position using the offset function. It returns a zero-based character index into the input string. The code can also access the current line and column using the line and column functions. Both return one-based indexes.

The code inside the predicate can also access options passed to the parser using the options variable.

Note that curly braces in the predicate code must be balanced.

When loading the online version in IE 11, the grammar area is initially very small vertically. It only gets its normal size upon window resize.

Everything works in IE 10.

Is there any plans into merging this functionality in the main lib? Seems really helpful.

https://github.com/casetext/pegjs-import

Thanks for the lib, BTW.

start = { var a = {}; a.a = a; return a; }

Consider this a wishlist feature request to provide an option in the web interface to produce a parser with '--trace' enabled and to show the resulting trace output for debugging purposes.

Implement a build system that will allow us to avoid the vendor directory with minified versions of various libraries.

After this is implemented, the website should have just one JavaScript and CSS file and its dependencies should not be included in the repository.

People get confused and try to use master-only features in the online version (see e.g. here).

Since this problem will surely re-occur in the future (i.e. releasing 0.8.0 won't solve it), I need to explicitly state somewhere that the online version uses the latest released version of PEG.js (currently 0.7.0), not master. Creating master-based online version and allowing to switch between this one and the latest-released-version-based one could also be useful.

Similar issue exists also for the documentation.

It would be neat if the online editor persisted the latest user input across visits, like the babel.js REPL - sometimes I want to go back to the idea code I was working on earlier, and at the moment I need to save the code somewhere locally or start from scratch.

It should be pretty trivial with localStorage. I'll happily submit a PR if you think it's a good idea.