dope2/lib/versioning/static/merge.js

71 lines
2.2 KiB
JavaScript

import { emptySet, add, length, forEach, has, remove } from "../../structures/set.js";
import { getDepth, Slot } from "./value_slot.js";
import { compareSlot } from "./compare.js";
import { makeTypeParser } from "../../parser/type_parser.js";
import { newDynamic } from "../../primitives/dynamic.js";
const emptySetOfSlots = compareElems => emptySet(compareSlot(compareElems));
export const findLCA = compareElems => slotA => slotB => {
console.log('compareSlot...', slotA, slotB);
if (compareSlot(compareElems)(slotA)(slotB) === 0) {
return slotA;
}
if (getDepth(slotA) > getDepth(slotB)) {
// we can assume that slotA.variant === "write"
return findLCA(compareElems)(slotA.value.slot)(slotB);
}
else {
// we can assume that slotB.variant === "write"
return findLCA(compareElems)(slotA)(slotB.value.slot);
}
};
// returns
// {slotA} if slotA is younger
// {slotB} if slotB is younger
// {slotA, slotB} if they are concurrent (conflicting)
export const merge = compareElems => slotA => slotB => {
const lca = findLCA(compareElems)(slotA)(slotB);
const emptySet = emptySetOfSlots(compareElems);
if (compareSlot(compareElems)(lca)(slotA) === 0) {
return add(emptySet)(slotB);
}
if (compareSlot(compareElems)(lca)(slotB) === 0) {
return add(emptySet)(slotA);
}
const setWithA = add(emptySet)(slotA);
const setWithAandB = add(setWithA)(slotB);
return setWithAandB;
};
export const mergeN = compareElems => slots => {
let result = slots;
forEach(slots)(slotA => {
forEach(slots)(slotB => {
// compare all non-identical pairs
if (compareSlot(compareElems)(slotA)(slotB) !== 0) {
const m = merge(compareElems)(slotA)(slotB);
if (length(m) === 1) {
// if in the pair, one is an ancestor of the other,
// only keep the other
if (has(m)(slotA)) {
result = remove(result)(slotB);
}
}
}
});
});
return result;
};
const mkType = makeTypeParser({
extraBracketOperators: [
[':=', ['=:', Slot]],
],
});
export const ModuleStaticMerge = [
["merge" , newDynamic(merge)(mkType(":=a=: -> :=a=: -> {:=a=:}"))],
["mergeN", newDynamic(merge)(mkType("{:=a=:} -> {:=a=:}" ))],
];