Completions ignore maxOccurs restriction

[fflaten]

Completions does not filter elements based on maxOccurs when triggering completion above the existing elements. See example below.

The schema validation will fail as expected when the duplicate exists, but we should not get the suggestion in the first place.

Example:

# repro.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified">

  <xs:element name="Demo">
    <xs:complexType>
      <xs:all>
        <xs:element name="Hello" type="xs:string" minOccurs="0" />
        <xs:element name="World" type="xs:string" minOccurs="0" maxOccurs="1" />
      </xs:all>
    </xs:complexType>
  </xs:element>
</xs:schema>

# issue.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Demo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:noNamespaceSchemaLocation="repro.xsd">
    <!-- Trigger completions above Hello: Will get completion for both Hello and World -->
    <Hello></Hello>
    <!-- Trigger completions above World: Will get completion World -->
    <World></World>
    <!-- Trigger completions below World: No completions as expected -->
</Demo>

[fflaten]

Similarly when triggering completion inside a complex type using xs:sequence, I wouldn't expect to get completions for elements already present below the cursor.

E.g. in the schema above modified to xs:sequence, when triggering completion before , it should not return anything as there's no elements allowed above Hello in the sequence.

In general, can we make completions more aware of the context for the current node or are they both included by design?

[mickaelistria]

Those proposals make sense; and PR that adds them would be happily considered for inclusion.