Function emitGoFlatDiscriminatedUnion

scripts/codegen/go.ts:1767–1984

* Emit a Go interface for a discriminated union (anyOf with const discriminator).

(
    typeName: string,
    discriminator: GoDiscriminatorInfo,
    ctx: GoCodegenCtx,
    description?: string,
    experimental = false
)

 * Emit a Go interface for a discriminated union (anyOf with const discriminator).
 */
function emitGoFlatDiscriminatedUnion(
    typeName: string,
    discriminator: GoDiscriminatorInfo,
    ctx: GoCodegenCtx,
    description?: string,
    experimental = false
): void {
    if (ctx.generatedNames.has(typeName)) return;
    ctx.generatedNames.add(typeName);

    const discriminatorProp = discriminator.property;
    const mapping = discriminator.mapping;
    const unionVariants = [...discriminator.variants].sort((left, right) => compareGoTypeNames(left.typeName, right.typeName));
    const discGoName = toGoFieldName(discriminatorProp);
    const discriminatorMethodName = goDiscriminatorMethodName(typeName, discriminatorProp, discGoName, unionVariants, ctx);
    let discEnumName: string | undefined;
    let discGoType = "bool";
    if (discriminator.valueKind === "string") {
        const discValues = [...mapping.keys()].filter((value): value is string => typeof value === "string");
        discEnumName = getOrCreateGoEnum(
            typeName + discGoName,
            discValues,
            ctx,
            `${discGoName} discriminator for ${typeName}.`,
            undefined,
            false,
            experimental
        );
        discGoType = discEnumName;
    }

    const unmarshalFuncName = goUnexportedFunctionName("unmarshal", typeName);
    const rawDataName = `Raw${typeName}${ctx.discriminatedUnionRawVariantSuffix ?? "Data"}`;
    const hasRawVariant = discriminator.valueKind === "string";
    const markerName = toGoUnexportedIdentifier(typeName);
    ctx.discriminatedUnions.set(typeName, { typeName, unmarshalFuncName });

    const lines: string[] = [];
    if (description) {
        pushGoCommentForContext(lines, description, ctx);
    }
    if (experimental) {
        pushGoExperimentalTypeComment(lines, typeName, ctx);
    }
    lines.push(`type ${typeName} interface {`);
    lines.push(`\t${markerName}()`);
    lines.push(`\t${discriminatorMethodName}() ${discGoType}`);
    lines.push(`}`);
    lines.push(``);

    const ambiguousGroupsByVariantTypeName = new Map<string, GoDiscriminatedUnionVariant[]>();
    for (const groupVariants of mapping.values()) {
        if (groupVariants.length <= 1) continue;
        const sortedGroupVariants = [...groupVariants].sort((left, right) => compareGoTypeNames(left.typeName, right.typeName));
        for (const variant of groupVariants) {
            ambiguousGroupsByVariantTypeName.set(variant.typeName, sortedGroupVariants);
        }
    }