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Custom parser mappings

Some codebases use non-standard file extensions for files that are actually XML, JSON, YAML, or other structured formats. For example, a project might use .mst files for XML-based templates or .cfg files for JSON configuration. By default, the Moderne CLI parses these as plain text, which means recipes cannot inspect or transform their structure.

The build.parsers configuration lets you tell the CLI which parser to use for files matching specific glob patterns. Once configured, these files will be parsed into the appropriate Lossless Semantic Tree (LST) type, enabling recipes to work with their full structure.

In this guide, you will learn how to add, view, and remove custom parser mappings using the CLI or moderne.yml configuration.

Adding parser mappings via the CLI​

To map file extensions to a parser type, use mod config build parsers add followed by the parser type and one or more glob patterns:

mod config build parsers add xml "**/*.mst" "**/*.xbind"

You can add mappings for multiple parser types:

mod config build parsers add json "**/*.cfg"
mod config build parsers add yaml "**/*.conf"

If you add patterns for a parser type that already has mappings, the new patterns are merged with the existing ones.

Supported parser types​

The following parser types are available:

  • json
  • xml
  • yaml
  • properties
  • proto
  • toml
  • docker
  • hcl
  • plaintext
  • groovy
  • gradle
info

File extensions for compiled language types (Java, Kotlin, etc.) are managed by their respective build tool steps and cannot be customized here.

Configuring parser mappings in moderne.yml​

You can also define parser mappings directly in the moderne.yml file. This is useful when you want to commit the configuration to source control or manage it alongside other build settings.

build:
  parsers:
    - type: xml
      inclusion: |-
        **/*.mst
        **/*.xbind
    - type: json
      inclusion: |-
        **/*.cfg

See the layered configuration guide for details on global vs. local configuration files.

Viewing configured mappings​

To see what parser mappings are currently configured:

mod config build parsers show

Removing parser mappings​

To remove mappings for a specific parser type:

mod config build parsers delete xml

To remove all custom parser mappings:

mod config build parsers delete

Using local and saved configuration​

Like other CLI configuration, parser mappings support the --local and --save flags:

# Apply mappings to repositories in a specific directory (not committed to source control)
mod config build parsers add xml "**/*.mst" --local ./working-set

# Apply mappings and save them so they can be committed to source control
mod config build parsers add xml "**/*.mst" --local ./working-set --save

For more details on how these flags work, see the layered configuration guide.