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Support defaults in Flow's type parameter declarations

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The primary goal of this commit is to add the ability to parse type parameter
declarations with defaults, like `type Foo<T = string> = T`. While I was in the
code, I fixed a few small things, like

* Type parameter declarations need 1 or more type parameters.
* The existential type `*` is not a valid type parameter.
* The existential type `*` is a primary type
* The param list for type parameter declarations now consists of
  `TypeParameter` nodes
This commit is contained in:
Gabe Levi
2016-04-27 15:00:54 -04:00
parent b926e401c6
commit fe5193a40a
38 changed files with 3457 additions and 133 deletions
Download Patch File Download Diff File Expand all files Collapse all files

59
src/plugins/flow.js
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@@ -190,30 +190,48 @@ pp.flowParseTypeAlias = function (node) {
// Type annotations
pp.flowParseTypeParameter = function () {
let node = this.startNode();
let variance;
if (this.match(tt.plusMin)) {
if (this.state.value === "+") {
variance = "plus";
} else if (this.state.value === "-") {
variance = "minus";
}
this.eat(tt.plusMin);
}
let ident = this.flowParseTypeAnnotatableIdentifier(false, false);
node.name = ident.name;
node.variance = variance;
node.bound = ident.typeAnnotation;
if (this.match(tt.eq)) {
this.eat(tt.eq);
node.default = this.flowParseType ();
}
return this.finishNode(node, "TypeParameter");
};
pp.flowParseTypeParameterDeclaration = function () {
let node = this.startNode();
node.params = [];
this.expectRelational("<");
while (!this.isRelational(">")) {
node.params.push(this.flowParseExistentialTypeParam() || this.flowParseTypeAnnotatableIdentifier());
do {
node.params.push(this.flowParseTypeParameter());
if (!this.isRelational(">")) {
this.expect(tt.comma);
}
}
} while (!this.isRelational(">"));
this.expectRelational(">");
return this.finishNode(node, "TypeParameterDeclaration");
};
pp.flowParseExistentialTypeParam = function () {
if (this.match(tt.star)) {
let node = this.startNode();
this.next();
return this.finishNode(node, "ExistentialTypeParam");
}
};
pp.flowParseTypeParameterInstantiation = function () {
let node = this.startNode(), oldInType = this.state.inType;
node.params = [];
@@ -222,7 +240,7 @@ pp.flowParseTypeParameterInstantiation = function () {
this.expectRelational("<");
while (!this.isRelational(">")) {
node.params.push(this.flowParseExistentialTypeParam() || this.flowParseType());
node.params.push(this.flowParseType());
if (!this.isRelational(">")) {
this.expect(tt.comma);
}
@@ -558,6 +576,10 @@ pp.flowParsePrimaryType = function () {
this.next();
return this.finishNode(node, "ThisTypeAnnotation");
case tt.star:
this.next();
return this.finishNode(node, "ExistentialTypeParam");
default:
if (this.state.type.keyword === "typeof") {
return this.flowParseTypeofType();
@@ -624,23 +646,10 @@ pp.flowParseTypeAnnotation = function () {
};
pp.flowParseTypeAnnotatableIdentifier = function (requireTypeAnnotation, canBeOptionalParam) {
let variance;
if (this.match(tt.plusMin)) {
if (this.state.value === "+") {
variance = "plus";
} else if (this.state.value === "-") {
variance = "minus";
}
this.eat(tt.plusMin);
}
let ident = this.parseIdentifier();
let isOptionalParam = false;
if (variance) {
ident.variance = variance;
}
if (canBeOptionalParam && this.eat(tt.question)) {
this.expect(tt.question);
isOptionalParam = true;