Method checkOptSelect

checker/checker.go:187–213

(e ast.Expr)

}

func (c *checker) checkOptSelect(e ast.Expr) {
	// Collect metadata related to the opt select call packaged by the parser.
	call := e.AsCall()
	if len(call.Args()) != 2 || call.IsMemberFunction() {
		t := ""
		if call.IsMemberFunction() {
			t = " member call with"
		}
		c.errors.notAnOptionalFieldSelectionCall(e.ID(), c.location(e),
			fmt.Sprintf(
				"incorrect signature.%s argument count: %d", t, len(call.Args())))
		return
	}

	operand := call.Args()[0]
	field := call.Args()[1]
	fieldName, isString := maybeUnwrapString(field)
	if !isString {
		c.errors.notAnOptionalFieldSelection(field.ID(), c.location(field), field)
		return
	}

	// Perform type-checking using the field selection logic.
	resultType := c.checkSelectField(e, operand, fieldName, true)
	c.setType(e, substitute(c.mappings, resultType, false))
	c.setReference(e, ast.NewFunctionReference("select_optional_field"))
}

func (c *checker) checkSelectField(e, operand ast.Expr, field string, optional bool) *types.Type {
	// Interpret as field selection, first traversing down the operand.