# Parsing OCL Documents

As we saw in the Parsing Constraints and Queries topic, the OCL parser provides an `OCLHelper` API for parsing constraints embedded in models. OCL also permits constraints to be specified in a text document, as an adjunct to the model. In this case, the concrete syntax for context declarations indicates the context of constraints, equivalent to their placement in models.

As an example, consider the following Complete OCL document: "

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> The import on the first line is an extension supported by the Complete OCL editor for use with the Pivot meta-model. The import is ignored by the parsers for the Ecore or UML bindings, which assume that the relevant metamodels have been registered in either the global EPackage.Registry or the local EPackage.Registry passed to the EnvironmentFactory..

### The OCL Input

The `OCLInput` class encapsulates an OCL document. An input can be created from a string or an input stream.

Given an `OCLInput`, simply ask an `OCL` to parse it: "

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### Accessing the Constraints

The `OCL` returns the list of constraints if they were successfully parsed. They are retained by the OCL (available via the `getConstraints()` method at any time), and in particular, any definitions of additional operations or attributes are available for subsequent constraint parsing. Any number of OCL documents may be parsed by the same `OCL` instance, combined also with constraints parsed by `OCLHelpers`. All of these constraints are retained by the `OCL` environment.

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The source for these examples may be found in the org.eclipse.ocl.ecore.tests plugin in model/parsingDocumentsExample.ocl and in src/org/eclipse/ocl/ecore/tests/DocumentationExamples.java.