CODEWITHSUNDEEP
javascriptnode.jsparsingjison
user228534
user228534

Reputation:

How can I pass additional input to `parse` in jison?

I want to parse a string, but this string may contain references to variables that are resolved at run time. Ideally, I'd like to pass in a hash of these variables and their values as the second argument to the parse function.

Currently, I'm running sed -i '' 's/parse: function parse(input) {/parse: function parse(input, in_data) { data = in_data;/' grammar.js after building my grammar.js from grammar.jison, but that seems like a less than optimal solution. What is the recommended way to do this?

In my jison grammar, I have something like: 

start : 'IS' string {$$ = is($2);} ;

and in the module section:

function is(a) {
    data.attrs && data.attrs.indexOf(a) >= 0;
}

I want the data hash to be passed in at run time, so something like:

parse = require("./grammar").parse;
parse("is 'something'", {attrs: ['something', 'else']})

Upvotes: 0

Views: 357

Answers (1)

Louis
Louis

Reputation: 151441

What you are trying to do should be achievable with this directive:

%parse-param data

In my .jison file, I put this directive just after my %start directive and just before the %% line. The name after %parse-param is the name of a parameter that the parser should expect. This directive above will make it so that there will be a data variable available inside your parser that will take for value the 2nd parameter passed to parse. So when you do:

parse = require("./grammar").parse;
parse("is 'something'", {attrs: ['something', 'else']})

then data should have the value {attrs: ['something', 'else']}.

Upvotes: 1

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