{
  "name": "geometry_overlay_within",
  "type": "function",
    "description": "Performs a spatial join of type WITHIN. This returns an array of results of an expression evaluated on features from an other layer that are WITHIN the current feature, or, if no expression if provided, simply returns whether at least one feature from the other layer is WITHIN the current feature.",
    "arguments": [
    {
      "arg": "layer",
      "description": "the other layer"
    },
    {
      "arg": "expression",
      "description": "an optional expression to evaluate on the features from the other layer (if not set, the function will just return a boolean indicating whether there is at least one match)",
      "optional": true
    },
    {
      "arg": "filter",
      "description": "an optional expression to filter the matching features (if not set, all features will be returned)",
      "optional": true
    },
    {
      "arg": "limit",
      "description": "an optional integer to limit the number of matching features (if not set, all features will be returned)",
      "optional": true
    }
  ],
  "examples": [
    {
      "expression": "geometry_overlay_within('regions')",
      "returns": "True"
    },
    {
      "expression": "geometry_overlay_within('regions', name)",
      "returns": "['South Africa', 'Africa', 'World']"
    },
    {
      "expression": "geometry_overlay_within('regions', name, name != 'World')",
      "returns": "['South Africa', 'Africa']"
    },
    {
      "expression": "geometry_overlay_within('regions', name, limit:=1)",
      "returns": "['South Africa']"
    }
  ]
}