Function mergeObjectShapes

packages/core/sdk/src/shape-inference.ts:85–126

(left: InferredShape, right: InferredShape)

};

const mergeObjectShapes = (left: InferredShape, right: InferredShape): InferredShape => {
  // A map-shaped observation absorbs struct-shaped ones: once keys look like
  // data, later struct keys are data too.
  if (left.additionalProperties !== undefined || right.additionalProperties !== undefined) {
    const values = [
      left.additionalProperties,
      right.additionalProperties,
      ...Object.values(left.properties ?? {}),
      ...Object.values(right.properties ?? {}),
    ].filter((shape): shape is InferredShape => shape !== undefined);
    return {
      type: "object",
      additionalProperties:
        values.length === 0 ? UNKNOWN : values.reduce((a, b) => mergeShapes(a, b)),
    };
  }

  const leftProps = left.properties ?? {};
  const rightProps = right.properties ?? {};
  const keys = [...new Set([...Object.keys(leftProps), ...Object.keys(rightProps)])].sort();
  if (keys.length > MAX_OBJECT_KEYS) {
    const values = keys
      .slice(0, MAX_ARRAY_SAMPLE)
      .map((key) => leftProps[key] ?? rightProps[key])
      .filter((shape): shape is InferredShape => shape !== undefined);
    return {
      type: "object",
      additionalProperties:
        values.length === 0 ? UNKNOWN : values.reduce((a, b) => mergeShapes(a, b)),
    };
  }

  const properties: Record<string, InferredShape> = {};
  for (const key of keys) {
    const a = leftProps[key];
    const b = rightProps[key];
    properties[key] = a !== undefined && b !== undefined ? mergeShapes(a, b) : (a ?? b ?? UNKNOWN);
  }
  const leftRequired = new Set(left.required ?? []);
  const required = (right.required ?? []).filter((key) => leftRequired.has(key)).sort();
  return { type: "object", properties, required };
};

/**
 * Merge two observed shapes into the narrowest shape matching both.