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author | Florian Dold <florian.dold@gmail.com> | 2019-12-14 19:09:01 +0100 |
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committer | Florian Dold <florian.dold@gmail.com> | 2019-12-14 19:09:01 +0100 |
commit | a0b5aba71c6e1a9fc5fba83fea0cfb1f9fe0b9f2 (patch) | |
tree | 848b76c72190f469523dd5db1d07b7b22fd21eaa /src/util/codec.ts | |
parent | 47b2b841357dd723be0144ff4ae9eab51bba37a0 (diff) | |
download | wallet-core-a0b5aba71c6e1a9fc5fba83fea0cfb1f9fe0b9f2.tar.xz |
allow specifying common base type for unions
Diffstat (limited to 'src/util/codec.ts')
-rw-r--r-- | src/util/codec.ts | 48 |
1 files changed, 34 insertions, 14 deletions
diff --git a/src/util/codec.ts b/src/util/codec.ts index 7dcf493a2..0215ce797 100644 --- a/src/util/codec.ts +++ b/src/util/codec.ts @@ -118,10 +118,10 @@ class ObjectCodecBuilder<T, TC> { } } -class UnionCodecBuilder<T, D extends keyof T, TC> { +class UnionCodecBuilder<T, D extends keyof T, B, TC> { private alternatives = new Map<any, Alternative>(); - constructor(private discriminator: D) {} + constructor(private discriminator: D, private baseCodec?: Codec<B>) {} /** * Define a property for the object. @@ -129,7 +129,7 @@ class UnionCodecBuilder<T, D extends keyof T, TC> { alternative<V>( tagValue: T[D], codec: Codec<V>, - ): UnionCodecBuilder<T, D, TC | V> { + ): UnionCodecBuilder<T, D, B, TC | V> { this.alternatives.set(tagValue, { codec, tagValue }); return this as any; } @@ -140,21 +140,36 @@ class UnionCodecBuilder<T, D extends keyof T, TC> { * @param objectDisplayName name of the object that this codec operates on, * used in error messages. */ - build<R extends TC>(objectDisplayName: string): Codec<R> { + build<R extends TC & B>(objectDisplayName: string): Codec<R> { const alternatives = this.alternatives; const discriminator = this.discriminator; + const baseCodec = this.baseCodec; return { decode(x: any, c?: Context): R { const d = x[discriminator]; if (d === undefined) { - throw new DecodingError(`expected tag for ${objectDisplayName} at ${renderContext(c)}.${discriminator}`); + throw new DecodingError( + `expected tag for ${objectDisplayName} at ${renderContext( + c, + )}.${discriminator}`, + ); } const alt = alternatives.get(d); if (!alt) { - throw new DecodingError(`unknown tag for ${objectDisplayName} ${d} at ${renderContext(c)}.${discriminator}`); + throw new DecodingError( + `unknown tag for ${objectDisplayName} ${d} at ${renderContext( + c, + )}.${discriminator}`, + ); } - return alt.codec.decode(x); - } + const altDecoded = alt.codec.decode(x); + if (baseCodec) { + const baseDecoded = baseCodec.decode(x, c); + return { ...baseDecoded, ...altDecoded }; + } else { + return altDecoded; + } + }, }; } } @@ -180,10 +195,12 @@ export function stringConstCodec<V extends string>(s: V): Codec<V> { if (x === s) { return x; } - throw new DecodingError(`expected string constant "${s}" at ${renderContext(c)}`); - } - } -}; + throw new DecodingError( + `expected string constant "${s}" at ${renderContext(c)}`, + ); + }, + }; +} /** * Return a codec for a value that must be a number. @@ -234,8 +251,11 @@ export function mapCodec<T>(innerCodec: Codec<T>): Codec<{ [x: string]: T }> { } export class UnionCodecPreBuilder<T> { - discriminateOn<D extends keyof T>(discriminator: D): UnionCodecBuilder<T, D, never> { - return new UnionCodecBuilder<T, D, never>(discriminator); + discriminateOn<D extends keyof T, B>( + discriminator: D, + baseCodec?: Codec<B>, + ): UnionCodecBuilder<T, D, B, never> { + return new UnionCodecBuilder<T, D, B, never>(discriminator, baseCodec); } } |