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Replace node src getter with substring. #43

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Replace node src getter with substring. #43

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3c7ccd7
Replace getter property with string reference.
aliceofhartley Feb 17, 2026
0e6d899
Update comment.
aliceofhartley Feb 17, 2026
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23 changes: 8 additions & 15 deletions src/flast.js
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Original file line number Diff line number Diff line change
Expand Up @@ -38,15 +38,6 @@ const generateFlatASTDefaultOptions = {
},
};

/**
* Return a function which retrieves a node's source on demand
* @param {string} src
* @returns {function(number, number): string}
*/
function createSrcClosure(src) {
return function(start, end) {return src.slice(start, end);};
}

/**
* @param {string} inputCode
* @param {object} opts Optional changes to behavior. See generateFlatASTDefaultOptions for available options.
Expand Down Expand Up @@ -96,13 +87,13 @@ function generateRootNode(inputCode, opts = {}) {
let rootNode;
try {
rootNode = parseCode(inputCode, parseOpts);
if (opts.includeSrc) rootNode.srcClosure = createSrcClosure(inputCode);
if (opts.includeSrc) rootNode.src = inputCode;
} catch (e) {
// If any parse error occurs and alternateSourceTypeOnFailure is set, try 'script' mode
if (opts.alternateSourceTypeOnFailure) {
try {
rootNode = parseCode(inputCode, {...parseOpts, sourceType: 'script'});
if (opts.includeSrc) rootNode.srcClosure = createSrcClosure(inputCode);
if (opts.includeSrc) rootNode.src = inputCode;
} catch (e2) {
logger.debug('Failed to parse as module and script:', e, e2);
}
Expand Down Expand Up @@ -171,10 +162,12 @@ function extractNodesFromRoot(rootNode, opts) {
node.lineage.push(node.scope.scopeId);
}
}
// Add a getter for the node's source code
if (opts.includeSrc && !node.src) Object.defineProperty(node, 'src', {
get() {return rootNode.srcClosure(node.start, node.end);},
});
// Avoid using a getter with a closure around source here, as the
// memory requirement for a function per node is far greater than using
// a string reference for sufficiently large AST Trees
// (~2.4 nodes for 3 Gib).
if (opts.includeSrc && !node.src)
node.src = rootNode.src.substring(node.start,node.end);
}
if (opts.detailed) {
const identifiers = typeMap.Identifier || [];
Expand Down