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Chris Tate
858328703b
The first Object.freeze, Object.seal or Object.preventExtensions of a typed function creates its property table from the function's dynamic box. The box had no name, so later `f.name` reads answered "". The box now carries the function's JS name, as a closure flowing into any checked-dynamic slot does. The runtime's own callers (published values, os and node constants, the private-range block list, Wasm exports) freeze data they built, and now call scr_dyn_freeze_data, the freeze for values that are not functions. Object.isFrozen, Object.isSealed and Object.isExtensible read a function's existing table and answer false, false and true when it has none. Fully typed programs therefore link no dynamic-tier object code for these calls again.
46 lines
1.5 KiB
JavaScript
46 lines
1.5 KiB
JavaScript
// Object.freeze, seal and preventExtensions on functions, and the queries:
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// they act on the function's own properties (name, length, prototype, and
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// the ones a program assigns), as in Node. A frozen function still calls,
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// and its properties still read.
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const createHasher = (block) => {
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const hash = (msg) => msg.length * block;
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hash.outputLen = 32;
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hash.blockLen = block;
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hash.create = () => hash(" ".repeat(block));
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return Object.freeze(hash);
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};
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const sha = createHasher(64);
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console.log(sha("abc"), sha.outputLen, sha.blockLen, sha.create(), sha.name, sha.length);
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console.log(Object.isFrozen(sha), Object.isSealed(sha), Object.isExtensible(sha));
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try {
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sha.extra = 1;
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} catch (error) {
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console.log(error.name, error.message);
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}
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try {
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sha.outputLen = 64;
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} catch (error) {
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console.log(error.name);
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}
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console.log(sha.outputLen, sha.extra);
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function plain(a, b) {
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return a + b;
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}
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console.log(Object.isFrozen(plain), Object.isSealed(plain), Object.isExtensible(plain));
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plain.tag = "t";
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Object.seal(plain);
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console.log(Object.isFrozen(plain), Object.isSealed(plain), Object.isExtensible(plain));
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plain.tag = "u";
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console.log(plain.tag, plain(1, 2), plain.name, plain.length);
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const stopped = () => 0;
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Object.preventExtensions(stopped);
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console.log(Object.isFrozen(stopped), Object.isSealed(stopped), Object.isExtensible(stopped));
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try {
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stopped.late = 1;
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} catch (error) {
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console.log(error.name, error.message);
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}
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console.log(stopped.name, stopped.length);
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