(function()()

in benchmarks/wasm-misc/embenchen/src/wasm_zlib.c.js [412:541]

• 87 lines of code
• 18 McCabe index (conditional complexity)

(function(){
  var JSfuncs = {
    // Helpers for cwrap -- it can't refer to Runtime directly because it might
    // be renamed by closure, instead it calls JSfuncs['stackSave'].body to find
    // out what the minified function name is.
    'stackSave': function() {
      Runtime.stackSave()
    },
    'stackRestore': function() {
      Runtime.stackRestore()
    },
    // type conversion from js to c
    'arrayToC' : function(arr) {
      var ret = Runtime.stackAlloc(arr.length);
      writeArrayToMemory(arr, ret);
      return ret;
    },
    'stringToC' : function(str) {
      var ret = 0;
      if (str !== null && str !== undefined && str !== 0) { // null string
        // at most 4 bytes per UTF-8 code point, +1 for the trailing '\0'
        var len = (str.length << 2) + 1;
        ret = Runtime.stackAlloc(len);
        stringToUTF8(str, ret, len);
      }
      return ret;
    }
  };
  // For fast lookup of conversion functions
  var toC = {'string' : JSfuncs['stringToC'], 'array' : JSfuncs['arrayToC']};

  // C calling interface.
  ccall = function ccallFunc(ident, returnType, argTypes, args, opts) {
    var func = getCFunc(ident);
    var cArgs = [];
    var stack = 0;
    if (args) {
      for (var i = 0; i < args.length; i++) {
        var converter = toC[argTypes[i]];
        if (converter) {
          if (stack === 0) stack = Runtime.stackSave();
          cArgs[i] = converter(args[i]);
        } else {
          cArgs[i] = args[i];
        }
      }
    }
    var ret = func.apply(null, cArgs);
    if (returnType === 'string') ret = Pointer_stringify(ret);
    if (stack !== 0) {
      if (opts && opts.async) {
        EmterpreterAsync.asyncFinalizers.push(function() {
          Runtime.stackRestore(stack);
        });
        return;
      }
      Runtime.stackRestore(stack);
    }
    return ret;
  }

  var sourceRegex = /^function\s*[a-zA-Z$_0-9]*\s*\(([^)]*)\)\s*{\s*([^*]*?)[\s;]*(?:return\s*(.*?)[;\s]*)?}$/;
  function parseJSFunc(jsfunc) {
    // Match the body and the return value of a javascript function source
    var parsed = jsfunc.toString().match(sourceRegex).slice(1);
    return {arguments : parsed[0], body : parsed[1], returnValue: parsed[2]}
  }

  // sources of useful functions. we create this lazily as it can trigger a source decompression on this entire file
  var JSsource = null;
  function ensureJSsource() {
    if (!JSsource) {
      JSsource = {};
      for (var fun in JSfuncs) {
        if (JSfuncs.hasOwnProperty(fun)) {
          // Elements of toCsource are arrays of three items:
          // the code, and the return value
          JSsource[fun] = parseJSFunc(JSfuncs[fun]);
        }
      }
    }
  }

  cwrap = function cwrap(ident, returnType, argTypes) {
    argTypes = argTypes || [];
    var cfunc = getCFunc(ident);
    // When the function takes numbers and returns a number, we can just return
    // the original function
    var numericArgs = argTypes.every(function(type){ return type === 'number'});
    var numericRet = (returnType !== 'string');
    if ( numericRet && numericArgs) {
      return cfunc;
    }
    // Creation of the arguments list (["$1","$2",...,"$nargs"])
    var argNames = argTypes.map(function(x,i){return '$'+i});
    var funcstr = "(function(" + argNames.join(',') + ") {";
    var nargs = argTypes.length;
    if (!numericArgs) {
      // Generate the code needed to convert the arguments from javascript
      // values to pointers
      ensureJSsource();
      funcstr += 'var stack = ' + JSsource['stackSave'].body + ';';
      for (var i = 0; i < nargs; i++) {
        var arg = argNames[i], type = argTypes[i];
        if (type === 'number') continue;
        var convertCode = JSsource[type + 'ToC']; // [code, return]
        funcstr += 'var ' + convertCode.arguments + ' = ' + arg + ';';
        funcstr += convertCode.body + ';';
        funcstr += arg + '=(' + convertCode.returnValue + ');';
      }
    }

    // When the code is compressed, the name of cfunc is not literally 'cfunc' anymore
    var cfuncname = parseJSFunc(function(){return cfunc}).returnValue;
    // Call the function
    funcstr += 'var ret = ' + cfuncname + '(' + argNames.join(',') + ');';
    if (!numericRet) { // Return type can only by 'string' or 'number'
      // Convert the result to a string
      var strgfy = parseJSFunc(function(){return Pointer_stringify}).returnValue;
      funcstr += 'ret = ' + strgfy + '(ret);';
    }
    if (!numericArgs) {
      // If we had a stack, restore it
      ensureJSsource();
      funcstr += JSsource['stackRestore'].body.replace('()', '(stack)') + ';';
    }
    funcstr += 'return ret})';
    return eval(funcstr);
  };
})();