js-slang
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Javascript-based implementations of Source, written in Typescript
71 lines • 2.86 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.transformBabelASTToESTreeCompliantAST = void 0;
/**
* Transforms an AST generated by the Babel parser into one
* that is compliant with the ESTree types. While the Babel
* parser-generated AST is mostly compliant with the ESTree
* specifications due to the use of the 'estree' plugin, not
* everything is compliant with the ESTree types.
*
* @param program The AST to be transformed.
*/
const transformBabelASTToESTreeCompliantAST = (program) => {
renameFilenameAttributeToSource(program);
};
exports.transformBabelASTToESTreeCompliantAST = transformBabelASTToESTreeCompliantAST;
/**
* Renames the 'filename' attribute on AST nodes to 'source'.
* This is because the Babel parser tags AST nodes with the
* 'filename' attribute when the name of the file in which
* the AST was generated from is given. However, by the ESTree
* types that js-slang uses, this attribute should be named
* 'source' instead of 'filename'. As a workaround, we
* recursively walk the AST generated by the Babel parser and
* replace all instances of the 'filename' attribute with
* 'source'.
*
* Note that we do not use acorn-walk here as a precondition
* of acorn-walk is that the AST is compliant with the ESTree
* specifications. Since the reason why we are transforming
* the AST generated by the Babel parser is because it is not
* entirely compliant with the ESTree specifications in the
* first place, we avoid the use of acorn-walk.
*
* @param node The node to be transformed.
*/
const renameFilenameAttributeToSource = (node) => {
// Rename all 'filename' attributes to 'source'.
if (node.hasOwnProperty('filename')) {
node.source = node.filename;
delete node.filename;
}
// Iterate over all property values of the AST node.
Object.values(node).forEach(value => {
// If the value is null or undefined, do nothing.
if (value === null || value === undefined) {
return;
}
// If the value is an array, check if any of its elements
// are objects (i.e., AST nodes) which we should recurse on.
if (Array.isArray(value)) {
value.forEach(element => {
if (element === null || element === undefined) {
return;
}
if (typeof element !== 'object') {
return;
}
renameFilenameAttributeToSource(element);
});
}
// If the value is a primitive type, do nothing.
if (typeof value !== 'object') {
return;
}
// Otherwise, the value is an object (i.e., AST node) which
// we recurse on.
renameFilenameAttributeToSource(value);
});
};
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