code refactoring a java script compiler

Question

I was trying to understand a JavaScript package compiler and redesigned the basic structure. Every time a string is compiled it is added to the SrcTable array. and thrown at the output. however, to get the output the SrcTable has to be declared global. but the example from which i am building this code has that variable declared as local. I would like to understand:- 1.Why can i not declare the variable as local in here? 2. What do i need to change to make it work as local?

the srcTable is in the preprocessors.compiler variable.

function resolveRequest(request) {
  var match = request.match(/^\s*import\s+(.*)$/),
    imports = {};

  if (match) {
    match[1].replace(/\s*([\w.\-$]+)(?:\s+as\s+([\w.\-$]+))?,?/g, function(_, from, as) {
      imports = {
        from: from,
        as: as || from
      };
    });
  }
  return imports;
}

var preprocessors = {
  import: "var importExpr = /^(\\s*)(import\\s+[^=+*\"'\\r\\n;\\/]+|from\\s+[^=+\"'\\r\\n;\\/ ]+\\s+import\\s+[^=+\"'\\r\\n;\\/]+)(;|\\/|$)/gm;" +
    "function replace(raw, p1, p2, p3) {" +
    "  return p1 + 'jsio(\"' + p2 + '\")' + p3;" +
    "};" +
    "exports = function(src) {" +
    "  return src.replace(importExpr, replace);" +
    "};",
  compiler: "srcTable = [];" + // this array needs to be local
    "        exports = function (src) {" +
    "          var jsioNormal = " + /^(.*)jsio\s*\(\s*(['"].+?['"])\s*(,\s*\{[^}]+\})?\)/gm + "\n;" +
    "          var match = jsioNormal.exec(src);\n" +
    "          if(match) {" +
    "            var request = eval(match[2]);\n" +
    "            jsio(request, ['import', 'compiler']);\n" +
    "          } \n" +
    "          srcTable.push(src);"+
    "          return '';\n" +
    "        };" +
    "        exports.compile = function(request) {" +
    "          jsio(request, ['import', 'compiler']);" +
    "        };" + 
    "        exports.generateSrc = function (callback) {"+
    "          callback(srcTable);"+
    "        };"
};

function _require(previousCtx, request, p) {
  var p = p || ['import'];
  var request = resolveRequest(request);
  var src = eval(request.from);

  p.forEach(function(name, index) {
    var args = name == 'import' ? [] : null;
    var preprocessor = jsio('import preprocessors.' + name, args);

    src = preprocessor(src);
  });

  var code = "(function (__) { with (__) {" + src + "}});";
  var fn = eval(code);
  var context = makeContext();
  fn(context);
  previousCtx[request.as] = context.exports;
  return context.exports;
}

function makeContext() {
  return {
    jsio: function(request, p) {
      return _require(this, request, p);
    },
    exports: {}
  };
}

var jsio = makeContext().jsio;

var example = {
  app: "import example.calculator as calculator;" +
    "   calculator.add(2, 3);",

  calculator: "import example.print as print;" +
    "          exports = {" +
    "            add: function (a, b) {" +
    "              print(a+b);" +
    "            }" +
    "          }",

  print: "exports = function(res) {" +
    "       console.log(res);" +
    "     }"
};

var compiler = jsio('import preprocessors.compiler;');
compiler.compile('import example.app;');
compiler.generateSrc(function(src) {
  console.log(src);
});

Answer 1

since the code is being compiled with the java-script with context, so, the function that is evaluating the code, needs to be cached, otherwise compiling the same code every time, will recreate the instance. so the solution is

function resolveRequest(request) {
  var match = request.match(/^\s*import\s+(.*)$/),
    imports = {};

  if (match) {
    match[1].replace(/\s*([\w.\-$]+)(?:\s+as\s+([\w.\-$]+))?,?/g, function(_, from, as) {
      imports = {
        from: from,
        as: as || from
      };
    });
  }
  return imports;
}

var preprocessors = {
  import: "var importExpr = /^(\\s*)(import\\s+[^=+*\"'\\r\\n;\\/]+|from\\s+[^=+\"'\\r\\n;\\/ ]+\\s+import\\s+[^=+\"'\\r\\n;\\/]+)(;|\\/|$)/gm;" +
    "function replace(raw, p1, p2, p3) {" +
    "  return p1 + 'jsio(\"' + p2 + '\")' + p3;" +
    "};" +
    "exports = function(src) {" +
    "  return src.replace(importExpr, replace);" +
    "};",
  compiler: "var srcTable = [];\n" +
    "        exports = function (src) {\n" +
    "          var jsioNormal = " + /^(.*)jsio\s*\(\s*(['"].+?['"])\s*(,\s*\{[^}]+\})?\)/gm + "\n;" +
    "          var match = jsioNormal.exec(src);\n" +
    "          if(match) {\n" +
    "            var request = eval(match[2]);\n" +
    "            jsio(request, ['import', 'compiler']);\n" +
    "          } \n" +
    "          srcTable.push(src);\n" +
    "          return '';\n" +
    "        };\n" +
    "        exports.compile = function(request) {\n" +
    "          jsio(request, ['import', 'compiler']);\n" +
    "        };\n" +
    "        exports.generateSrc = function (callback) {\n" +
    "          callback(srcTable);\n" +
    "        };\n"
};

var _cache_context = [];

function _require(previousCtx, request, p) {
  var p = p || ['import'];
  var request = resolveRequest(request);
  var src = loadModule(request).src;

  p.forEach(function(name, index) {
    var args = name == 'import' ? [] : null;
    var preprocessor = jsio('import preprocessors.' + name, args);
    src = preprocessor(src);
  });

  if (src) {
    if (!_cache_context[request.from]) {
      var code = "(function (__) { with (__) {\n" + src + "\n}});";
      var fn = eval(code);
      var context = makeContext();
      fn(context);
      _cache_context[request.from] = context.exports;
    }
    previousCtx[request.as] = _cache_context[request.from];
    return previousCtx[request.as];
  }
}

function loadModule(request){
 var src = eval(request.from);

 return {
   src: src,
   path: request.from
 } 
}

function makeContext() {
  return {
    jsio: function(request, p) {
      return _require(this, request, p);
    },
    exports: {}
  };
}

var jsio = makeContext().jsio;

var example = {
  app: "import example.calculator as calculator;" +
    "   calculator.add(2, 3);",

  calculator: "import example.print as print;" +
    "          exports = {" +
    "            add: function (a, b) {" +
    "              print(a+b);" +
    "            }" +
    "          }",

  print: "exports = function(res) {" +
    "       console.log(res);" +
    "     }"
};

var compiler = jsio('import preprocessors.compiler;');
compiler.compile('import example.app;');
compiler.generateSrc(function(src) {
  console.log(src);
});