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author | Florian Dold <florian.dold@gmail.com> | 2017-03-24 16:20:31 +0100 |
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committer | Florian Dold <florian.dold@gmail.com> | 2017-03-24 16:20:31 +0100 |
commit | 970230da068570385a03483dec0559049f3ac458 (patch) | |
tree | afb204951b3edb6c80facc975600e42d6a25a58e /src | |
parent | f721c1ee827ed61136922e5ccf112d9007c5bfac (diff) | |
download | wallet-core-970230da068570385a03483dec0559049f3ac458.tar.xz |
Add support for conditionals in DB queries
Diffstat (limited to 'src')
-rw-r--r-- | src/query.ts | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/src/query.ts b/src/query.ts index 30633b0af..89d4133b3 100644 --- a/src/query.ts +++ b/src/query.ts @@ -76,10 +76,87 @@ export interface QueryStream<T> { map<S>(f: (x:T) => S): QueryStream<S>; flatMap<S>(f: (x: T) => S[]): QueryStream<S>; toArray(): Promise<T[]>; + first(): QueryValue<T>; then(onfulfill: any, onreject: any): any; } + +/** + * Query result that consists of at most one value. + */ +export interface QueryValue<T> { + map<S>(f: (x: T) => S): QueryValue<S>; + cond<R>(f: (x: T) => boolean, onTrue: (r: QueryRoot) => R, onFalse: (r: QueryRoot) => R): Promise<void>; +} + + +abstract class BaseQueryValue<T> implements QueryValue<T> { + root: QueryRoot; + + constructor(root: QueryRoot) { + this.root = root; + } + + map<S>(f: (x: T) => S): QueryValue<S> { + return new MapQueryValue<T,S>(this, f); + } + + cond<R>(f: (x: T) => boolean, onTrue: (r: QueryRoot) => R, onFalse: (r: QueryRoot) => R): Promise<void> { + return new Promise((resolve, reject) => { + this.subscribeOne((v, tx) => { + if (f(v)) { + onTrue(this.root); + } else { + onFalse(this.root); + } + }); + resolve(); + }); + } + + abstract subscribeOne(f: SubscribeOneFn): void; +} + +class FirstQueryValue<T> extends BaseQueryValue<T> { + gotValue = false; + s: QueryStreamBase<T>; + constructor(stream: QueryStreamBase<T>) { + super(stream.root); + this.s = stream; + } + + subscribeOne(f: SubscribeOneFn): void { + this.s.subscribe((isDone, value, tx) => { + if (this.gotValue) { + return; + } + if (isDone) { + f(undefined, tx); + } else { + f(value, tx); + } + this.gotValue = true; + }); + } +} + +class MapQueryValue<T,S> extends BaseQueryValue<S> { + mapFn: (x: T) => S; + v: BaseQueryValue<T>; + + constructor(v: BaseQueryValue<T>, mapFn: (x: T) => S) { + super(v.root); + this.v = v; + this.mapFn = mapFn; + } + + subscribeOne(f: SubscribeOneFn): void { + this.v.subscribeOne((v, tx) => this.mapFn(v)); + } +} + + export let AbortTransaction = Symbol("abort_transaction"); /** @@ -112,6 +189,10 @@ abstract class QueryStreamBase<T> implements QueryStream<T>, PromiseLike<void> { this.root = root; } + first(): QueryValue<T> { + return new FirstQueryValue(this); + } + then<R>(onfulfilled: (value: void) => R | PromiseLike<R>, onrejected: (reason: any) => R | PromiseLike<R>): PromiseLike<R> { return this.root.then(onfulfilled, onrejected); } @@ -183,6 +264,7 @@ abstract class QueryStreamBase<T> implements QueryStream<T>, PromiseLike<void> { type FilterFn = (e: any) => boolean; type SubscribeFn = (done: boolean, value: any, tx: IDBTransaction) => void; +type SubscribeOneFn = (value: any, tx: IDBTransaction) => void; interface FlatMapFn<T> { (v: T): T[]; |