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get-reference-origin.cjs
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get-reference-origin.cjs
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/*::
type ReferenceOriginImport = { kind: "import", source: string, name: string };
type ReferenceOriginParam = {
kind: "param",
index: number,
functionNode: Node,
};
type ReferenceOrigin =
| ReferenceOriginImport
| ReferenceOriginParam
| { kind: "import *", source: string }
| {
kind: "property",
base: ReferenceOriginImport | ReferenceOriginParam,
path: string,
name: string,
};
*/
// Given a node and a context, returns a description of where its value comes
// from.
// It resolves imports, parameters of exported functions and property accesses.
// See the ReferenceOrigin type for more information.
module.exports = function getReferenceOrigin(
node,
scope,
) /*: ?ReferenceOrigin */ {
if (node.type === "Identifier") {
const variable = getVariableDefinition(node.name, scope);
if (!variable) return null;
const definition = variable.definition;
const defNode = definition.node;
if (definition.type === "ImportBinding") {
if (defNode.type === "ImportSpecifier") {
return {
kind: "import",
source: definition.parent.source.value,
name: defNode.imported.name,
};
}
if (defNode.type === "ImportNamespaceSpecifier") {
return {
kind: "import *",
source: definition.parent.source.value,
};
}
}
if (definition.type === "Variable" && defNode.init) {
const origin = getReferenceOrigin(defNode.init, variable.scope);
return origin && patternToProperty(definition.name, origin);
}
if (definition.type === "Parameter") {
return patternToProperty(definition.name, {
kind: "param",
index: definition.index,
functionNode: definition.node,
});
}
}
if (node.type === "MemberExpression" && !node.computed) {
const origin = getReferenceOrigin(node.object, scope);
return origin && addProperty(origin, node.property.name);
}
return null;
};
function getVariableDefinition(name, scope) {
let currentScope = scope;
do {
const variable = currentScope.set.get(name);
if (variable && variable.defs[0]) {
return { scope: currentScope, definition: variable.defs[0] };
}
} while ((currentScope = currentScope.upper));
}
function patternToProperty(id, base) {
const path = getPatternPath(id);
return path && path.reduce(addProperty, base);
}
// Adds a property to a given origin. If it was a namespace import it becomes
// a named import, so that `import * as x from "foo"; x.bar` and
// `import { bar } from "foo"` have the same origin.
function addProperty(origin, name) {
if (origin.kind === "import *") {
return {
kind: "import",
source: origin.source,
name,
};
}
if (origin.kind === "property") {
return {
kind: "property",
base: origin.base,
path: origin.path + "." + name,
name,
};
}
return {
kind: "property",
base: origin,
path: name,
name,
};
}
// if "node" is c of { a: { b: c } }, the result is ["a","b"]
function getPatternPath(node) {
let current = node;
const path = [];
// Unshift keys to path while going up
do {
const property = current.parent;
if (
property.type === "ArrayPattern" ||
property.type === "AssignmentPattern" ||
property.computed
) {
// These nodes are not supported.
return null;
}
if (property.type === "Property") {
path.unshift(property.key.name);
} else {
// The destructuring pattern is finished
break;
}
} while ((current = current.parent.parent));
return path;
}