Validating nomnoml diagrams?

[javierluraschi]

Currently there is no way to validate if a nomnoml diagram is valid, say [hello] (valid), vs [hello (invalid).

However, we can use the mlverse/duktape package as a workaround as follows:

remotes::install_github("mlverse/duktape")

Then define the following function:

nomnoml_validate <- function(diagram = "[test]") {
    duktape::eval(
        paste(c(
            readLines(system.file("htmlwidgets/lib/dagre/dagre.min.js", package = "nomnoml")),
            readLines(system.file("htmlwidgets/lib/lodash/lodash.js", package = "nomnoml")),
            readLines(system.file("htmlwidgets/lib/nomnoml/nomnoml.js", package = "nomnoml")),
            paste0("nomnoml.parse('", diagram, "')")
        ), collapse = "\n")
    )
}

And validate nomnoml syntax as follows:

nomnoml_validate("[hello]")

vs

nomnoml_validate("[hello")

 Error in duktape::rcpp_eval(paste(c(readLines(system.file("htmlwidgets/lib/dagre/dagre.min.js",  : 
  Error: Parse error on line 1:
[hello
------^
Expecting 'SEP', '|', ']', got 'EOF' 

[andrie]

This is great, thank you!

I tried your code, and it works great for the example provided, but I can't get it to work for multi-line diagrams, e.g:

nomnoml_validate("[hello]
                [world]")

results in:

Error in rcpp_eval(code) : SyntaxError: unterminated string (line 19004) 

However, I was able to get the same idea to work using V8 instead of duktape:

nomnoml_validate <- function(diagram = "[test]") {
  ct <- v8()
  ct$source(system.file("htmlwidgets/lib/dagre/dagre.min.js", package = "nomnoml"))
  ct$source(system.file("htmlwidgets/lib/lodash/lodash.js",   package = "nomnoml"))
  ct$source(system.file("htmlwidgets/lib/nomnoml/nomnoml.js", package = "nomnoml"))
  ct$assign("diagram", diagram)
  ct$eval("nomnoml.parse(diagram)"),
}

An invalid diagram:

> nomnoml_validate("[hello")
<std::runtime_error in context_eval(join(src), private$context, serialize): Error: Parse error on line 1:
[hello
------^
Expecting 'SEP', '|', ']', got 'EOF'>

A valid multi-line diagram:

> nomnoml_validate("[hello]
+                 [world]")
[1] "[object Object]"

Is there any disadvantage to use V8 compared to duktape?

[andrie]

I implemented this in #21