out-of-your-element/matrix/kstate.js

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// @ts-check
const assert = require("assert")
/** Mutates the input. */
function kstateStripConditionals(kstate) {
for (const [k, content] of Object.entries(kstate)) {
// conditional for whether a key is even part of the kstate (doing this declaratively on json is hard, so represent it as a property instead.)
if ("$if" in content) {
if (content.$if) delete content.$if
else delete kstate[k]
}
}
return kstate
}
function kstateToState(kstate) {
const events = []
kstateStripConditionals(kstate)
for (const [k, content] of Object.entries(kstate)) {
const [type, state_key] = k.split("/")
assert.ok(typeof type === "string")
assert.ok(typeof state_key === "string")
events.push({type, state_key, content})
}
return events
}
/**
* @param {import("../types").Event.BaseStateEvent[]} events
* @returns {any}
*/
function stateToKState(events) {
const kstate = {}
for (const event of events) {
kstate[event.type + "/" + event.state_key] = event.content
}
return kstate
}
function diffKState(actual, target) {
const diff = {}
// go through each key that it should have
for (const key of Object.keys(target)) {
if (key in actual) {
// diff
try {
assert.deepEqual(actual[key], target[key])
} catch (e) {
// they differ. reassign the target
diff[key] = target[key]
}
} else {
// not present, needs to be added
diff[key] = target[key]
}
// keys that are missing in "actual" will not be deleted on "target" (no action)
}
return diff
}
module.exports.kstateStripConditionals = kstateStripConditionals
module.exports.kstateToState = kstateToState
module.exports.stateToKState = stateToKState
module.exports.diffKState = diffKState