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cs_mast_s_exists

function cs_mast_s_exists(tree: CsMastTree, signature: string): boolean

O(1) lookup — returns true if the given CS-MAST-S signature string exists in the tree.

Parameters​

tree​

Type: CsMastTree

A tree returned by cs_mast_init. The internal _signatureMap is used for the lookup.

signature​

Type: string

A full CS-MAST-S PHC signature string, e.g.:

$v=1$hash=sha256,lang=js,prsr=-babel/parser,scat=lit_val$a3f2b1...

Must include the complete config section and the 64-char hash portion. Partial strings or hash-only strings return false.

Return Value​

true if signature exactly matches any key in tree._signatureMap, false otherwise.

Returns false immediately for empty string.

Complexity​

O(1) amortized — backed by a JavaScript Map (hash table). The spec mandates constant-time implementation.

No Side Effects​

The call does not modify tree._signatureMap or any node in the tree.

Examples​

Typical SAST use case​

import { cs_mast_init, cs_mast_s_exists } from '@shriyanss/cs-mast';

// Known signature of a dangerous pattern (fingerprinted offline)
const TRACKING_SIG =
  '$v=1$hash=sha256,lang=js,prsr=-babel/parser,scat=lit_val_decl$<known-hex>';

const tree = cs_mast_init(targetSource, config);

if (cs_mast_s_exists(tree, TRACKING_SIG)) {
  console.warn('Known tracking pattern detected');
}

Self-lookup (always true)​

const tree = cs_mast_init('const x = 1;', config);
// Any signature built from this tree will be found
for (const sig of tree._signatureMap.keys()) {
  console.assert(cs_mast_s_exists(tree, sig) === true);
}

Cross-tree lookup​

const configA = { hash: 'sha256', lang: 'js', prsr: '@babel/parser', scat: ['lit', 'val'], sinc: [] };
const treeA = cs_mast_init('const x = 1;', configA);
const treeB = cs_mast_init('const y = 1;', configA);

// Same config + same NumericLiteral value (1) → same signature
// Both trees share the NumericLiteral signature
const litSig = [...treeA._signatureMap.keys()].find(s => s.includes('sha256'));
console.log(cs_mast_s_exists(treeB, litSig!)); // likely true for the literal