I'm starting to use excellent PEG.JS JavaScript parser generator
to implement Qt's qmake project file parser (*.pro).
It looks bash script, with variable assignments and function calls.
First of all, i need to parse all assignments to some kind of Dictionary,
and use it in external code.
I can't undestand how to access internal parser state from the external function.
I.e.: i need to parse my pro-file, and save state into client code-accessible variable, e.g. JavaScript Dictionary.
But i can't achieve this!
Grammar (right now understood only assignment statement like TEMPLATE = app):
{
var SystemVariablesDict = {};
}
Start = Statement*
Statement = Whitespace GenericAssignmentStatement Whitespace
GenericAssignmentStatement = TemplateAssignmentStatement
// TEMPLATE = app|lib|subdirs|aux|vcapp|vclib
SystemTemplateVariableName = "TEMPLATE"
SystemTemplateVariableValue = "app" / "lib" / "subdirs" / "aux" / "vcapp" / "vclib"
TemplateAssignmentStatement = lvalue:SystemTemplateVariableName
AssignmentOperator rvalue:SystemTemplateVariableValue
{
// [REF 1] !!! Assignment to the global state variable !!!
SystemVariablesDict[lvalue] = rvalue;
return undefined;
}
AssignmentOperator = Whitespace "=" Whitespace
Word = w:Character+ { return w.join(""); }
Character = c:[a-zA-Z0-9]
Whitespace = [ \t\r\n]*
(The grammar above was successfully compiled in the qmake-project-parser.js)
The parser usage code (frontend.js file):
var pegjs = require("./qmake-project-parser.js");
var parserOutput = pegjs.parse("TEMPLATE = app");
console.log("PEG.js parser output:");
console.log(parserOutput);
console.log("System variables dict:");
console.log(pegjs.SystemVariablesDict);
And the output:
C:\Projects\qmake-project-parser>node frontend.js
PEG.js parser output:
[ [ [], undefined, [] ] ]
System variables dict:
**undefined**
The question is: why undefined was outputed, however the REF 1 rule was successfully applied?
What am i doing wrong?
Thanks!
P.S. I'm new to JavaScript, so be patient to my silly mistakes please :)