eslint/babel-eslint-parser/src/convert/convertAST.js
import { types as t, traverse } from "@babel/core";
function convertNodes(ast, code) {
const astTransformVisitor = {
noScope: true,
enter(path) {
const { node } = path;
if (node.innerComments) {
delete node.innerComments;
}
if (node.trailingComments) {
delete node.trailingComments;
}
if (node.leadingComments) {
delete node.leadingComments;
}
},
exit(path) {
const { node } = path;
// Used internally by @babel/parser.
if (node.extra) {
delete node.extra;
}
if (node?.loc.identifierName) {
delete node.loc.identifierName;
}
if (path.isTypeParameter()) {
node.type = "Identifier";
node.typeAnnotation = node.bound;
delete node.bound;
}
// flow: prevent "no-undef"
// for "Component" in: "let x: React.Component"
if (path.isQualifiedTypeIdentifier()) {
delete node.id;
}
// for "b" in: "var a: { b: Foo }"
if (path.isObjectTypeProperty()) {
delete node.key;
}
// for "indexer" in: "var a: {[indexer: string]: number}"
if (path.isObjectTypeIndexer()) {
delete node.id;
}
// for "param" in: "var a: { func(param: Foo): Bar };"
if (path.isFunctionTypeParam()) {
delete node.name;
}
// modules
if (path.isImportDeclaration()) {
delete node.isType;
}
// template string range fixes
if (path.isTemplateLiteral()) {
for (let i = 0; i < node.quasis.length; i++) {
const q = node.quasis[i];
q.range[0] -= 1;
if (q.tail) {
q.range[1] += 1;
} else {
q.range[1] += 2;
}
q.loc.start.column -= 1;
if (q.tail) {
q.loc.end.column += 1;
} else {
q.loc.end.column += 2;
}
}
}
},
};
const state = { source: code };
// Monkey patch visitor keys in order to be able to traverse the estree nodes
t.VISITOR_KEYS.Property = t.VISITOR_KEYS.ObjectProperty;
t.VISITOR_KEYS.MethodDefinition = [
"key",
"value",
"decorators",
"returnType",
"typeParameters",
];
traverse(ast, astTransformVisitor, null, state);
// These can be safely deleted because they are not defined in the original visitor keys.
delete t.VISITOR_KEYS.Property;
delete t.VISITOR_KEYS.MethodDefinition;
}
function convertProgramNode(ast) {
ast.type = "Program";
ast.sourceType = ast.program.sourceType;
ast.body = ast.program.body;
delete ast.program;
delete ast.errors;
if (ast.comments.length) {
const lastComment = ast.comments[ast.comments.length - 1];
if (ast.tokens.length) {
const lastToken = ast.tokens[ast.tokens.length - 1];
if (lastComment.end > lastToken.end) {
// If there is a comment after the last token, the program ends at the
// last token and not the comment
ast.range[1] = lastToken.end;
ast.loc.end.line = lastToken.loc.end.line;
ast.loc.end.column = lastToken.loc.end.column;
}
}
} else {
if (!ast.tokens.length) {
ast.loc.start.line = 1;
ast.loc.end.line = 1;
}
}
if (ast.body && ast.body.length > 0) {
ast.loc.start.line = ast.body[0].loc.start.line;
ast.range[0] = ast.body[0].start;
}
}
export default function convertAST(ast, code) {
convertNodes(ast, code);
convertProgramNode(ast);
}