Verwenden von Dart zum Erstellen einer Javascript-Bibliothek
Das Problem
Zur Zeit arbeite ich an einer JavaScript-Bibliothek und um die Anzahl der Fehler zu verringern, dachte ich, dass meine Bibliothek von der Verwendung des statischen Schreibmechanismus von Dart profitieren könnte. Erstens, weil meine Bibliothek weder mit HTML noch mit anderen JavaScript-Bibliotheken interoperiert hat, nur mit reinem JavaScript-Objektmanipulationsmaterial. Allerdings habe ich im Netz keine Informationen gefunden, die zeigen, wie es möglich ist, eine JS-Bibliothek mit Dart zu erstellen. Also habe ich versucht, das selbst zu machen und eine erste Dart-Datei erstellt:
library Repo;
class Type {
final String name;
final TypeCategory category;
Type(String name, TypeCategory category) : name = name, category = category {
category.types[name] = this;
}
}
class TypeCategory {
final String name;
final Map<String, Type> types = new Map();
TypeCategory(this.name);
}
class Branch {
}
class Descriptor {
}
class TableDescriptor extends Descriptor {
TableDescriptor.ctor() {
}
}
class Repo {
Descriptor descriptor(String name) {
}
Branch branch(String name) {
}
void Merge() {
}
}
main() {
return Repo;
}
Kompiliere es mit dart2js in JavaScript, um zu sehen, wie es mir geht:
// Generated by dart2js, the Dart to JavaScript compiler version: 1.3.6.
// The code supports the following hooks:
// dartPrint(message):
// if this function is defined it is called instead of the Dart [print]
// method.
//
// dartMainRunner(main, args):
// if this function is defined, the Dart [main] method will not be invoked
// directly. Instead, a closure that will invoke [main], and its arguments
// [args] is passed to [dartMainRunner].
(function($) {
function dart(){ this.x = 0 }var A = new dart;
delete A.x;
var B = new dart;
delete B.x;
var C = new dart;
delete C.x;
var D = new dart;
delete D.x;
var E = new dart;
delete E.x;
var F = new dart;
delete F.x;
var G = new dart;
delete G.x;
var H = new dart;
delete H.x;
var J = new dart;
delete J.x;
var K = new dart;
delete K.x;
var L = new dart;
delete L.x;
var M = new dart;
delete M.x;
var N = new dart;
delete N.x;
var O = new dart;
delete O.x;
var P = new dart;
delete P.x;
var Q = new dart;
delete Q.x;
var R = new dart;
delete R.x;
var S = new dart;
delete S.x;
var T = new dart;
delete T.x;
var U = new dart;
delete U.x;
var V = new dart;
delete V.x;
var W = new dart;
delete W.x;
var X = new dart;
delete X.x;
var Y = new dart;
delete Y.x;
var Z = new dart;
delete Z.x;
function Isolate() {}
init();
$ = Isolate.$isolateProperties;
var $$ = {};
(function (reflectionData) {
"use strict";
function map(x){x={x:x};delete x.x;return x}
function processStatics(descriptor) {
for (var property in descriptor) {
if (!hasOwnProperty.call(descriptor, property)) continue;
if (property === "^") continue;
var element = descriptor[property];
var firstChar = property.substring(0, 1);
var previousProperty;
if (firstChar === "+") {
mangledGlobalNames[previousProperty] = property.substring(1);
var flag = descriptor[property];
if (flag > 0) descriptor[previousProperty].$reflectable = flag;
if (element && element.length) init.typeInformation[previousProperty] = element;
} else if (firstChar === "@") {
property = property.substring(1);
$[property]["@"] = element;
} else if (firstChar === "*") {
globalObject[previousProperty].$defaultValues = element;
var optionalMethods = descriptor.$methodsWithOptionalArguments;
if (!optionalMethods) {
descriptor.$methodsWithOptionalArguments = optionalMethods = {}
}
optionalMethods[property] = previousProperty;
} else if (typeof element === "function") {
globalObject[previousProperty = property] = element;
functions.push(property);
init.globalFunctions[property] = element;
} else if (element.constructor === Array) {
addStubs(globalObject, element, property, true, descriptor, functions);
} else {
previousProperty = property;
var newDesc = {};
var previousProp;
for (var prop in element) {
if (!hasOwnProperty.call(element, prop)) continue;
firstChar = prop.substring(0, 1);
if (prop === "static") {
processStatics(init.statics[property] = element[prop]);
} else if (firstChar === "+") {
mangledNames[previousProp] = prop.substring(1);
var flag = element[prop];
if (flag > 0) element[previousProp].$reflectable = flag;
} else if (firstChar === "@" && prop !== "@") {
newDesc[prop.substring(1)]["@"] = element[prop];
} else if (firstChar === "*") {
newDesc[previousProp].$defaultValues = element[prop];
var optionalMethods = newDesc.$methodsWithOptionalArguments;
if (!optionalMethods) {
newDesc.$methodsWithOptionalArguments = optionalMethods={}
}
optionalMethods[prop] = previousProp;
} else {
var elem = element[prop];
if (prop !== "^" && elem != null && elem.constructor === Array && prop !== "<>") {
addStubs(newDesc, elem, prop, false, element, []);
} else {
newDesc[previousProp = prop] = elem;
}
}
}
$$[property] = [globalObject, newDesc];
classes.push(property);
}
}
}
function addStubs(descriptor, array, name, isStatic, originalDescriptor, functions) {
var f, funcs = [originalDescriptor[name] = descriptor[name] = f = array[0]];
f.$stubName = name;
functions.push(name);
for (var index = 0; index < array.length; index += 2) {
f = array[index + 1];
if (typeof f != "function") break;
f.$stubName = array[index + 2];
funcs.push(f);
if (f.$stubName) {
originalDescriptor[f.$stubName] = descriptor[f.$stubName] = f;
functions.push(f.$stubName);
}
}
for (var i = 0; i < funcs.length; index++, i++) {
funcs[i].$callName = array[index + 1];
}
var getterStubName = array[++index];
array = array.slice(++index);
var requiredParameterInfo = array[0];
var requiredParameterCount = requiredParameterInfo >> 1;
var isAccessor = (requiredParameterInfo & 1) === 1;
var isSetter = requiredParameterInfo === 3;
var isGetter = requiredParameterInfo === 1;
var optionalParameterInfo = array[1];
var optionalParameterCount = optionalParameterInfo >> 1;
var optionalParametersAreNamed = (optionalParameterInfo & 1) === 1;
var isIntercepted = requiredParameterCount + optionalParameterCount != funcs[0].length;
var functionTypeIndex = array[2];
var unmangledNameIndex = 2 * optionalParameterCount + requiredParameterCount + 3;
var isReflectable = array.length > unmangledNameIndex;
if (getterStubName) {
f = tearOff(funcs, array, isStatic, name, isIntercepted);
f.getterStub = true;
if (isStatic) init.globalFunctions[name] = f;
originalDescriptor[getterStubName] = descriptor[getterStubName] = f;
funcs.push(f);
if (getterStubName) functions.push(getterStubName);
f.$stubName = getterStubName;
f.$callName = null;
if (isIntercepted) init.interceptedNames[getterStubName] = true;
}
if (isReflectable) {
for (var i = 0; i < funcs.length; i++) {
funcs[i].$reflectable = 1;
funcs[i].$reflectionInfo = array;
}
var mangledNames = isStatic ? init.mangledGlobalNames : init.mangledNames;
var unmangledName = array[unmangledNameIndex];
var reflectionName = unmangledName;
if (getterStubName) mangledNames[getterStubName] = reflectionName;
if (isSetter) {
reflectionName += "=";
} else if (!isGetter) {
reflectionName += ":" + requiredParameterCount + ":" + optionalParameterCount;
}
mangledNames[name] = reflectionName;
funcs[0].$reflectionName = reflectionName;
funcs[0].$metadataIndex = unmangledNameIndex + 1;
if (optionalParameterCount) descriptor[unmangledName + "*"] = funcs[0];
}
}
function tearOffGetterNoCsp(funcs, reflectionInfo, name, isIntercepted) {
return isIntercepted
? new Function("funcs", "reflectionInfo", "name", "H", "c",
"return function tearOff_" + name + (functionCounter++)+ "(x) {" +
"if (c === null) c = H.closureFromTearOff(" +
"this, funcs, reflectionInfo, false, [x], name);" +
"return new c(this, funcs[0], x, name);" +
"}")(funcs, reflectionInfo, name, H, null)
: new Function("funcs", "reflectionInfo", "name", "H", "c",
"return function tearOff_" + name + (functionCounter++)+ "() {" +
"if (c === null) c = H.closureFromTearOff(" +
"this, funcs, reflectionInfo, false, [], name);" +
"return new c(this, funcs[0], null, name);" +
"}")(funcs, reflectionInfo, name, H, null)
}
function tearOffGetterCsp(funcs, reflectionInfo, name, isIntercepted) {
var cache = null;
return isIntercepted
? function(x) {
if (cache === null) cache = H.closureFromTearOff(this, funcs, reflectionInfo, false, [x], name);
return new cache(this, funcs[0], x, name)
}
: function() {
if (cache === null) cache = H.closureFromTearOff(this, funcs, reflectionInfo, false, [], name);
return new cache(this, funcs[0], null, name)
}
}
function tearOff(funcs, reflectionInfo, isStatic, name, isIntercepted) {
var cache;
return isStatic
? function() {
if (cache === void 0) cache = H.closureFromTearOff(this, funcs, reflectionInfo, true, [], name).prototype;
return cache;
}
: tearOffGetter(funcs, reflectionInfo, name, isIntercepted);
}
var functionCounter = 0;
var tearOffGetter = (typeof dart_precompiled == "function")
? tearOffGetterCsp : tearOffGetterNoCsp;
if (!init.libraries) init.libraries = [];
if (!init.mangledNames) init.mangledNames = map();
if (!init.mangledGlobalNames) init.mangledGlobalNames = map();
if (!init.statics) init.statics = map();
if (!init.typeInformation) init.typeInformation = map();
if (!init.globalFunctions) init.globalFunctions = map();
if (!init.interceptedNames) init.interceptedNames = map();
var libraries = init.libraries;
var mangledNames = init.mangledNames;
var mangledGlobalNames = init.mangledGlobalNames;
var hasOwnProperty = Object.prototype.hasOwnProperty;
var length = reflectionData.length;
for (var i = 0; i < length; i++) {
var data = reflectionData[i];
var name = data[0];
var uri = data[1];
var metadata = data[2];
var globalObject = data[3];
var descriptor = data[4];
var isRoot = !!data[5];
var fields = descriptor && descriptor["^"];
var classes = [];
var functions = [];
processStatics(descriptor);
libraries.push([name, uri, classes, functions, metadata, fields, isRoot,
globalObject]);
}
})
([
["Repo", "repo.dart", , F, {
"^": "",
main: function() {
return C.Type_Jeh;
}
},
1],
["_js_helper", "dart:_js_helper", , H, {
"^": "",
createRuntimeType: function($name) {
return new H.TypeImpl($name, null);
},
TypeImpl: {
"^": "Object;_typeName,_unmangledName"
}
}],
["dart.core", "dart:core", , P, {
"^": "",
Null: {
"^": "Object;"
},
Object: {
"^": ";"
}
}],
]);
Isolate.$finishClasses($$, $, null);
$$ = null;
// Runtime type support
// getInterceptor methods
C.Type_Jeh = H.createRuntimeType('Repo');
$.libraries_to_load = {};
$.Closure_functionCounter = 0;
$.BoundClosure_selfFieldNameCache = null;
$.BoundClosure_receiverFieldNameCache = null;
init.functionAliases = {};
;
init.metadata = [];
$ = null;
Isolate = Isolate.$finishIsolateConstructor(Isolate);
$ = new Isolate();
function convertToFastObject(properties) {
function MyClass() {};
MyClass.prototype = properties;
new MyClass();
return properties;
}
A = convertToFastObject(A);
B = convertToFastObject(B);
C = convertToFastObject(C);
D = convertToFastObject(D);
E = convertToFastObject(E);
F = convertToFastObject(F);
G = convertToFastObject(G);
H = convertToFastObject(H);
J = convertToFastObject(J);
K = convertToFastObject(K);
L = convertToFastObject(L);
M = convertToFastObject(M);
N = convertToFastObject(N);
O = convertToFastObject(O);
P = convertToFastObject(P);
Q = convertToFastObject(Q);
R = convertToFastObject(R);
S = convertToFastObject(S);
T = convertToFastObject(T);
U = convertToFastObject(U);
V = convertToFastObject(V);
W = convertToFastObject(W);
X = convertToFastObject(X);
Y = convertToFastObject(Y);
Z = convertToFastObject(Z);
// BEGIN invoke [main].
;(function (callback) {
if (typeof document === "undefined") {
callback(null);
return;
}
if (document.currentScript) {
callback(document.currentScript);
return;
}
var scripts = document.scripts;
function onLoad(event) {
for (var i = 0; i < scripts.length; ++i) {
scripts[i].removeEventListener("load", onLoad, false);
}
callback(event.target);
}
for (var i = 0; i < scripts.length; ++i) {
scripts[i].addEventListener("load", onLoad, false);
}
})(function(currentScript) {
init.currentScript = currentScript;
if (typeof dartMainRunner === "function") {
dartMainRunner(F.main, []);
} else {
F.main([]);
}
});
// END invoke [main].
function init() {
Isolate.$isolateProperties = {};
function generateAccessor(fieldDescriptor, accessors, cls) {
var fieldInformation = fieldDescriptor.split("-");
var field = fieldInformation[0];
var len = field.length;
var code = field.charCodeAt(len - 1);
var reflectable;
if (fieldInformation.length > 1)
reflectable = true;
else
reflectable = false;
code = code >= 60 && code <= 64 ? code - 59 : code >= 123 && code <= 126 ? code - 117 : code >= 37 && code <= 43 ? code - 27 : 0;
if (code) {
var getterCode = code & 3;
var setterCode = code >> 2;
var accessorName = field = field.substring(0, len - 1);
var divider = field.indexOf(":");
if (divider > 0) {
accessorName = field.substring(0, divider);
field = field.substring(divider + 1);
}
if (getterCode) {
var args = getterCode & 2 ? "receiver" : "";
var receiver = getterCode & 1 ? "this" : "receiver";
var body = "return " + receiver + "." + field;
var property = cls + ".prototype.get$" + accessorName + "=";
var fn = "function(" + args + "){" + body + "}";
if (reflectable)
accessors.push(property + "$reflectable(" + fn + ");\n");
else
accessors.push(property + fn + ";\n");
}
if (setterCode) {
var args = setterCode & 2 ? "receiver, value" : "value";
var receiver = setterCode & 1 ? "this" : "receiver";
var body = receiver + "." + field + " = value";
var property = cls + ".prototype.set$" + accessorName + "=";
var fn = "function(" + args + "){" + body + "}";
if (reflectable)
accessors.push(property + "$reflectable(" + fn + ");\n");
else
accessors.push(property + fn + ";\n");
}
}
return field;
}
Isolate.$isolateProperties.$generateAccessor = generateAccessor;
function defineClass(name, cls, fields) {
var accessors = [];
var str = "function " + cls + "(";
var body = "";
for (var i = 0; i < fields.length; i++) {
if (i != 0)
str += ", ";
var field = generateAccessor(fields[i], accessors, cls);
var parameter = "parameter_" + field;
str += parameter;
body += "this." + field + " = " + parameter + ";\n";
}
str += ") {\n" + body + "}\n";
str += cls + ".builtin$cls=\"" + name + "\";\n";
str += "$desc=$collectedClasses." + cls + ";\n";
str += "if($desc instanceof Array) $desc = $desc[1];\n";
str += cls + ".prototype = $desc;\n";
if (typeof defineClass.name != "string") {
str += cls + ".name=\"" + cls + "\";\n";
}
str += accessors.join("");
return str;
}
var inheritFrom = function() {
function tmp() {
}
var hasOwnProperty = Object.prototype.hasOwnProperty;
return function(constructor, superConstructor) {
tmp.prototype = superConstructor.prototype;
var object = new tmp();
var properties = constructor.prototype;
for (var member in properties)
if (hasOwnProperty.call(properties, member))
object[member] = properties[member];
object.constructor = constructor;
constructor.prototype = object;
return object;
};
}();
Isolate.$finishClasses = function(collectedClasses, isolateProperties, existingIsolateProperties) {
var pendingClasses = {};
if (!init.allClasses)
init.allClasses = {};
var allClasses = init.allClasses;
var hasOwnProperty = Object.prototype.hasOwnProperty;
if (typeof dart_precompiled == "function") {
var constructors = dart_precompiled(collectedClasses);
} else {
var combinedConstructorFunction = "function $reflectable(fn){fn.$reflectable=1;return fn};\n" + "var $desc;\n";
var constructorsList = [];
}
for (var cls in collectedClasses) {
if (hasOwnProperty.call(collectedClasses, cls)) {
var desc = collectedClasses[cls];
if (desc instanceof Array)
desc = desc[1];
var classData = desc["^"], supr, name = cls, fields = classData;
if (typeof classData == "string") {
var split = classData.split("/");
if (split.length == 2) {
name = split[0];
fields = split[1];
}
}
var s = fields.split(";");
fields = s[1] == "" ? [] : s[1].split(",");
supr = s[0];
split = supr.split(":");
if (split.length == 2) {
supr = split[0];
var functionSignature = split[1];
if (functionSignature)
desc.$signature = function(s) {
return function() {
return init.metadata[s];
};
}(functionSignature);
}
if (typeof dart_precompiled != "function") {
combinedConstructorFunction += defineClass(name, cls, fields);
constructorsList.push(cls);
}
if (supr)
pendingClasses[cls] = supr;
}
}
if (typeof dart_precompiled != "function") {
combinedConstructorFunction += "return [\n " + constructorsList.join(",\n ") + "\n]";
var constructors = new Function("$collectedClasses", combinedConstructorFunction)(collectedClasses);
combinedConstructorFunction = null;
}
for (var i = 0; i < constructors.length; i++) {
var constructor = constructors[i];
var cls = constructor.name;
var desc = collectedClasses[cls];
var globalObject = isolateProperties;
if (desc instanceof Array) {
globalObject = desc[0] || isolateProperties;
desc = desc[1];
}
allClasses[cls] = constructor;
globalObject[cls] = constructor;
}
constructors = null;
var finishedClasses = {};
init.interceptorsByTag = Object.create(null);
init.leafTags = {};
function finishClass(cls) {
var hasOwnProperty = Object.prototype.hasOwnProperty;
if (hasOwnProperty.call(finishedClasses, cls))
return;
finishedClasses[cls] = true;
var superclass = pendingClasses[cls];
if (!superclass || typeof superclass != "string")
return;
finishClass(superclass);
var constructor = allClasses[cls];
var superConstructor = allClasses[superclass];
if (!superConstructor)
superConstructor = existingIsolateProperties[superclass];
var prototype = inheritFrom(constructor, superConstructor);
}
for (var cls in pendingClasses)
finishClass(cls);
};
Isolate.$lazy = function(prototype, staticName, fieldName, getterName, lazyValue) {
var sentinelUndefined = {};
var sentinelInProgress = {};
prototype[fieldName] = sentinelUndefined;
prototype[getterName] = function() {
var result = $[fieldName];
try {
if (result === sentinelUndefined) {
$[fieldName] = sentinelInProgress;
try {
result = $[fieldName] = lazyValue();
} finally {
if (result === sentinelUndefined) {
if ($[fieldName] === sentinelInProgress) {
$[fieldName] = null;
}
}
}
} else {
if (result === sentinelInProgress)
H.throwCyclicInit(staticName);
}
return result;
} finally {
$[getterName] = function() {
return this[fieldName];
};
}
};
};
Isolate.$finishIsolateConstructor = function(oldIsolate) {
var isolateProperties = oldIsolate.$isolateProperties;
function Isolate() {
var hasOwnProperty = Object.prototype.hasOwnProperty;
for (var staticName in isolateProperties)
if (hasOwnProperty.call(isolateProperties, staticName))
this[staticName] = isolateProperties[staticName];
function ForceEfficientMap() {
}
ForceEfficientMap.prototype = this;
new ForceEfficientMap();
}
Isolate.prototype = oldIsolate.prototype;
Isolate.prototype.constructor = Isolate;
Isolate.$isolateProperties = isolateProperties;
Isolate.$finishClasses = oldIsolate.$finishClasses;
return Isolate;
};
}
})()
//# sourceMappingURL=out.js.map
//@ sourceMappingURL=out.js.map
Und das war es auch schon, ich habe Dart weggeworfen, weil ich nicht wusste, was ich mit der generierten JS-Datei anfangen sollte. Außerdem hatte ich Angst davor, dass möglicherweise viel Zeit erforderlich ist, um die resultierende Bibliotheksschnittstelle sauber zu halten, und zwar ähnlich wie die, die ich verwende mit JavaScript.
Die Fragen)Wie mache ich in Dart erstellte Klassendefinitionen verfügbar und verwende sie später in JavaScript?Denken Sie, dass es sich lohnt, in Dart einzusteigen, wenn fast alle potenziellen Bibliotheksbenutzer stattdessen die JS-Version verwenden? (Die Verwendung von Dart ist aufgrund der unterschiedlichen Community-Größe ohnehin nicht gut für mich. Dies bedeutet, dass es weniger Menschen leicht fällt, einen Beitrag zu meiner Bibliothek zu leisten.)Was soll ich Ihrer Meinung nach tun?