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Simplify DnD for fileInputs, fix #2142 (Firefox 57+)

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- Simplified dragHover "plugin" by counting children instead of storing them.
  Counting children fixes Firefox 57+ bug (to be found or filed) that causes
  text object of input element to produce drag events
- Removed multimethod since it's no longer used anywhere
- Firefox 57+ appears not to trigger a change event when the `files` field is modified,
  which prevented uploads from occuring. This commit triggers a change event manually
  and doesn't impact the functioning of other browsers.
This commit is contained in:
Alan Dipert
2018-10-08 21:24:18 -07:00
parent b25cb0f2d5
commit fcd09e2bae
7 changed files with 178 additions and 673 deletions
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196
srcjs/utils.js
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@@ -326,199 +326,3 @@ exports.compareVersion = function(a, op, b) {
else if (op === "<") return (diff < 0);
else throw `Unknown operator: ${op}`;
};
// multimethod: Creates functions — "multimethods" — that are polymorphic on one
// or more of their arguments.
//
// Multimethods can take any number of arguments. Arguments are passed to an
// applicable function or "method", returning its result. By default, if no
// method was applicable, an exception is thrown.
//
// Methods are searched in the order that they were added, and the first
// applicable method found is the one used.
//
// A method is applicable when the "dispatch value" associated with it
// corresponds to the value returned by the dispatch function. The dispatch
// function defaults to the value of the first argument passed to the
// multimethod.
//
// The correspondence between the value returned by the dispatch function and
// any method's dispatch value is determined by the test function, which is
// user-definable and defaults to `equal` or deep equality.
//
// # Chainable Functions
//
// The function returned by `multimethod()` exposes functions as properties.
// These functions generally return the multimethod, and so can be chained.
//
// - dispatch([function newDispatch]): Sets the dispatch function. The dispatch
// function can take any number of arguments, but must return a dispatch
// value. The default dispatch function returns the first argument passed to
// the multimethod.
//
// - test([function newTest]): Sets the test function. The test function takes
// two arguments: the dispatch value produced by the dispatch function, and
// the dispatch value associated with some method. It must return a boolean
// indicating whether or not to select the method. The default test function
// is `equal`.
//
// - when(object dispatchVal, function method): Adds a new dispatch value/method
// combination.
//
// - whenAny(array<object> dispatchVals, function method): Like `when`, but
// associates the method with every dispatch value in the `dispatchVals`
// array.
//
// - else(function newDefaultMethod): Sets the default function. This function
// is invoked when no methods apply. If left unset, the multimethod will throw
// an exception when no methods are applicable.
//
// - clone(): Returns a new, functionally-equivalent multimethod. This is a way
// to extend an existing multimethod in a local context — such as inside a
// function — without modifying the original. NOTE: The array of methods is
// copied, but the dispatch values themselves are not.
//
// # Self-reference
//
// The multimethod function can be obtained inside its method bodies without
// referring to it by name.
//
// This makes it possible for one method to call another, or to pass the
// multimethod to other functions as a callback from within methods.
//
// The mechanism is: the multimethod itself is bound as `this` to methods when
// they are called. Since arrow functions cannot be bound to objects, **self-reference
// is only possible within methods created using the `function` keyword**.
//
// # Tail recursion
//
// A method can call itself in a way that will not overflow the stack by using
// `this.recur`.
//
// `this.recur` is a function available in methods created using `function`.
// When the return value of a call to `this.recur` is returned by a method, the
// arguments that were supplied to `this.recur` are used to call the
// multimethod.
//
// # Examples
//
// Handling events:
//
// var handle = multimethod()
// .dispatch(e => [e.target.tagName.toLowerCase(), e.type])
// .when(["h1", "click"], e => "you clicked on an h1")
// .when(["p", "mouseover"], e => "you moused over a p"})
// .else(e => {
// let tag = e.target.tagName.toLowerCase();
// return `you did ${e.type} to an ${tag}`;
// });
//
// $(document).on("click mouseover mouseup mousedown", e => console.log(handle(e)))
//
// Self-calls:
//
// var demoSelfCall = multimethod()
// .when(0, function(n) {
// this(1);
// })
// .when(1, function(n) {
// doSomething(this);
// })
// .when(2, _ => console.log("tada"));
//
// Using (abusing?) the test function:
//
// var fizzBuzz = multimethod()
// .test((x, divs) => divs.map(d => x % d === 0).every(Boolean))
// .when([3, 5], x => "FizzBuzz")
// .when([3], x => "Fizz")
// .when([5], x => "Buzz")
// .else(x => x);
//
// for(let i = 0; i <= 100; i++) console.log(fizzBuzz(i));
//
// Getting carried away with tail recursion:
//
// var factorial = multimethod()
// .when(0, () => 1)
// .when(1, (_, prod = 1) => prod)
// .else(function(n, prod = 1) {
// return this.recur(n-1, n*prod);
// });
//
// var fibonacci = multimethod()
// .when(0, (_, a = 0) => a)
// .else(function(n, a = 0, b = 1) {
// return this.recur(n-1, b, a+b);
// });
function multimethod(dispatch = (firstArg) => firstArg,
test = equal,
defaultMethod = null,
methods = []) {
var trampolining = false;
function Sentinel (args) { this.args = args; }
function trampoline(f) {
return (...args) => {
trampolining = true;
var ret = f.apply(invoke, args);
while (ret instanceof Sentinel)
ret = f.apply(invoke, ret.args);
trampolining = false;
return ret;
};
}
let invoke = trampoline((...args) => {
var dispatchVal = dispatch.apply(null, args);
for (let i = 0; i < methods.length; i++) {
let [methodVal, methodFn] = methods[i];
if (test(dispatchVal, methodVal)) {
return methodFn.apply(invoke, args);
}
}
if (defaultMethod) {
return defaultMethod.apply(invoke, args);
} else {
throw new Error(`No method for dispatch value ${dispatchVal}`);
}
});
invoke.recur = (...args) => {
if (!trampolining) throw new Error("recur can only be called inside a method");
return new Sentinel(args);
};
invoke.dispatch = (newDispatch) => {
dispatch = newDispatch;
return invoke;
};
invoke.test = (newTest) => {
test = newTest;
return invoke;
};
invoke.when = (dispatchVal, methodFn) => {
methods = methods.concat([[dispatchVal, methodFn]]);
return invoke;
};
invoke.whenAny = (dispatchVals, methodFn) => {
return dispatchVals.reduce((self, val) => invoke.when(val, methodFn), invoke);
};
invoke.else = (newDefaultMethod = null) => {
defaultMethod = newDefaultMethod;
return invoke;
};
invoke.clone = () => {
return multimethod(dispatch, test, defaultMethod, methods.slice());
};
return invoke;
}