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[usernamealreadyis]

Matching Order

Sometimes you want to make sure that individual parts of your query get executed in the right order. This is important for example if you use references in your query and need to make sure that the branches of the tree where those references are generated get visited before the branches that use them. Basically that means some parts of your code check have to be evaluated first. For example if you need to know the name of a certain object before checking whether this object gets used in the body of a function definition. For this, you can use the match_first special argument, which accepts a list of strings and makes sure that the corresponding key/value pairs in the match query will get checked in the order you provided. This is important if you work with references and want to make sure that the branch which stores the reference will get executed before the branch that makes use of it. An example:

$ : {match_first: [foo]}
foo:
  $store:
    node_type: functiondef
  name: my_function
bar:
  $ref: {name : my_function}