Joeri Exelmans
8eec5b9239
big part of the code base still needs to be 'ported' to the updated type constructors.
38 lines
1.5 KiB
JavaScript
38 lines
1.5 KiB
JavaScript
import { getParams, getSymbol } from "../type_constructor.js";
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import { compareBools, compareSymbols } from "./primitives.js";
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import { compareLists } from "./structures.js";
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const __compareTypes = state => typeX => typeY => {
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// tagX and tagY: just something unique & deterministic that can serve as JS map key
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const tagX = state.nextTag++;
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const tagY = state.nextTag++;
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state.tagsX.add(tagX);
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state.tagsY.add(tagY);
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state.comparing.set(tagX, tagY);
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return compareSymbols(getSymbol(typeX))(getSymbol(typeY))
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|| compareLists
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(paramOfX => paramOfY => {
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const pX = paramOfX(tagX);
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const pY = paramOfY(tagY);
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return compareBools(state.tagsX.has(pX))(state.tagsY.has(pY))
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|| (() => {
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if (state.tagsX.has(pX)) {
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// both sub-types have been visited already in an enclosing call
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// if they were being compared in the same enclosing call, we assume they are equal!
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// (we cannot compare them, that would result in endless recursion)
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return compareSymbols(state.comparing.get(pX))(pY);
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}
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// none have been visited -> recursively compare
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return __compareTypes(state)(pX)(pY);
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})();
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})
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(getParams(typeX))
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(getParams(typeY));
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};
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export const compareTypes = typeX => typeY => __compareTypes({
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tagsX: new Set(),
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tagsY: new Set(),
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comparing: new Map(),
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nextTag: 0,
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})(typeX)(typeY);
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