Usando o dardo para criar uma biblioteca javascript
O problema
Atualmente, estou trabalhando em uma biblioteca JavaScript e, para reduzir a quantidade de bugs, pensei que minha biblioteca poderia se beneficiar do uso do mecanismo de digitação estática do Dart. Primeiro, porque minha biblioteca não fazia interoperabilidade nem com HTML nem com outras bibliotecas JavaScript, apenas coisas simples de manipulação de objetos javascript. No entanto, não encontrei nenhuma informação na rede mostrando como é possível construir uma biblioteca JS usando dardo. Então, eu tentei fazer isso sozinho, criei o arquivo dardo inicial:
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;
}
Compilei no JavaScript usando dart2js para ver como estou indo:
// 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
E é isso, joguei fora o Dart porque não sabia o que fazer com o arquivo JS gerado, também estava com medo do tempo potencialmente alto necessário para manter a interface da biblioteca resultante limpa e semelhante à que estou usando com JavaScript.
As questões)Como exponho as definições de classe criadas no Dart e depois as uso em JavaScript?Você acha que vale a pena entrar no Dart quando quase todos os usuários em potencial da biblioteca usarão a versão JS? (O uso do dardo já não é bom para mim devido à diferença no tamanho da comunidade, isso significa que menos pessoas acharão fácil contribuir com a minha biblioteca)Na sua opinião, o que devo fazer?