---
name: "CQL::Visitor"
section: "3pm"
platform: "linux"
package: "libcql-parser-perl"
version: "1.13-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/CQL::Visitor"
---

# CQL::Visitor(3pm)

visit nodes in a CQL parse tree

## NAME

CQL::Visitor - visit nodes in a CQL parse tree

## SYNOPSIS

```
    package MyVisitor;
    use base qw( CQL::Visitor );
    sub term {
        my ($self,$node) = @_;
        # do something to the node
    }
    # later on

    my $parser = CQL::Parser->new();
    my $root = $parser->parse($cql);
    my $visitor = MyVisitor->new();
    $vistor->visit($root);
```

## DESCRIPTION

CQL::Visitor provides a simple interface for visiting nodes in your parse tree. It could be useful if you want to do something like change a query like this:

```
    dc.title=foo and dc.creator=bar
    into
    title=foo and creator=bar
```

Or some similar procedure. You simply create a new subclass of CQL::Visitor and override the appropriate method, such as **term()**. Every term that is encountered during the traversal will be handed off to your **term()** method.

Note: at the moment only **term()** is supported because that's what was needed, but if you need other ones feel free to add them, or ask for them.

## METHODS

### new()

### visit()

Call this to traverse your parse tree, starting at the root.

### term()

Your subclass should override this, and do something meaningful with the CQL::TermNode object.