fediversity.eu/node_modules/sucrase/dist/esm/util/getImportExportSpecifierInfo.js

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2024-03-26 16:28:28 +01:00
import {TokenType as tt} from "../parser/tokenizer/types";
/**
* Determine information about this named import or named export specifier.
*
* This syntax is the `a` from statements like these:
* import {A} from "./foo";
* export {A};
* export {A} from "./foo";
*
* As it turns out, we can exactly characterize the syntax meaning by simply
* counting the number of tokens, which can be from 1 to 4:
* {A}
* {type A}
* {A as B}
* {type A as B}
*
* In the type case, we never actually need the names in practice, so don't get
* them.
*
* TODO: There's some redundancy with the type detection here and the isType
* flag that's already present on tokens in TS mode. This function could
* potentially be simplified and/or pushed to the call sites to avoid the object
* allocation.
*/
export default function getImportExportSpecifierInfo(
tokens,
index = tokens.currentIndex(),
) {
let endIndex = index + 1;
if (isSpecifierEnd(tokens, endIndex)) {
// import {A}
const name = tokens.identifierNameAtIndex(index);
return {
isType: false,
leftName: name,
rightName: name,
endIndex,
};
}
endIndex++;
if (isSpecifierEnd(tokens, endIndex)) {
// import {type A}
return {
isType: true,
leftName: null,
rightName: null,
endIndex,
};
}
endIndex++;
if (isSpecifierEnd(tokens, endIndex)) {
// import {A as B}
return {
isType: false,
leftName: tokens.identifierNameAtIndex(index),
rightName: tokens.identifierNameAtIndex(index + 2),
endIndex,
};
}
endIndex++;
if (isSpecifierEnd(tokens, endIndex)) {
// import {type A as B}
return {
isType: true,
leftName: null,
rightName: null,
endIndex,
};
}
throw new Error(`Unexpected import/export specifier at ${index}`);
}
function isSpecifierEnd(tokens, index) {
const token = tokens.tokens[index];
return token.type === tt.braceR || token.type === tt.comma;
}