Contract documents

parcel_core::ContractDoc represents a parsed YAML or JSON contract. Related types are in parcel_core::document.

ContractDoc::parse

pub fn parse(source: &str) -> Result<ContractDoc, Diagnostic>;

source is document text, not a filename. Returns the parsed document or a diagnostic for invalid syntax or document structure. Column and expression checking happens during check_contract or compile.

use parcel_core::ContractDoc;

let source = std::fs::read_to_string("orders.yaml")?;
let doc = ContractDoc::parse(&source)?;
println!("{} v{}", doc.contract, doc.version);

The example is intended inside a function returning Result; both file errors and Diagnostic implement standard error reporting.

ContractDoc::parse_all

pub fn parse_all(source: &str) -> Result<ContractDoc, Vec<Diagnostic>>;

Returns every structural problem at once instead of the first: unknown or misspelled fields, a missing space after a colon, a rule without its op or on_fail, and values of the wrong kind. Each diagnostic carries the line it is about and, where parcel has one, a suggested fix in help. parse returns the first of these.

Public fields

Field	Type	Meaning
contract	String	Contract name.
version	Version	Semantic version (parcel_core::Version).
owner	Option<String>	Owner of the data; selects the owner-specific functions available to the contract.
inherits	Option<String>	Parent contract name.
binding	Option<Binding>	Data location; may be inherited.
residency	Option<crate::Residency>	Optional data-placement requirements.
expose	Option<Vec<ExposeColumn>>	Output columns; may be inherited.
rules	Vec<Rule>	Rules in document order.
extensions	Option<Extensions>	Types for custom namespace fields.
enrich	Option<Vec<Enricher>>	Calculations producing custom row fields.
dataset_other	Option<Vec<DatasetProducer>>	Constants or aggregates producing custom dataset fields.

Data location and columns

Type	Public fields or variants	Methods
Binding	source: Source, partitioned_by: Vec<String>	—
Source	Parquet(String), Iceberg(IcebergTable)	—
IcebergTable	namespace: Vec<String>, table: String	parse(s: &str) -> Result<IcebergTable, String> validates a dotted table identifier.
ExposeColumn	name: String, type_name: String	—
Extensions	row, ctx, dataset: each BTreeMap<String, String> mapping field names to type names.	default() creates empty maps.
Enricher	field: String, expr: String	—
DatasetProducer	field: String, value: Option<serde_json::Value>, expr: Option<String>	—

Rules

Rule has six variants, each wrapping its matching document type:

Variant	Wrapped type and public fields
Decide	DecideRule { id: String, expr: String }
Admit	AdmitRule { id: String, expr: String }
Assert	AssertRule { id: String, expr: String, on_fail: AssertOnFail }
Transform	TransformRule { id: String, column: String, expr: String }
Guarantee	GuaranteeRule { id: String, expr: String, on_fail: GuaranteeOnFail }
Shape	ShapeRule { id: String, operator: String, column: Option<String>, params: serde_json::Map<String, serde_json::Value>, unless: Option<String> }

Every rule type also has message: Option<String>, and Rule::message() returns it. AssertOnFail variants are Drop, Deny, and Report. GuaranteeOnFail variants are Deny and Annotate.

impl Rule {
    pub fn id(&self) -> &str;
    pub fn op_name(&self) -> &'static str;
}

id borrows the rule’s identifier. op_name returns its operation name, such as "assert". For each operation’s behavior and examples, see Rules.

json_schema

pub fn json_schema() -> serde_json::Value;

Returns the JSON Schema describing contract document structure, for editor and tooling integration.