Skip to content

CQL Engine Evaluation API

Jump to bottom Edit New page
Anton Vasetenkov edited this page Mar 31, 2026 · 6 revisions

Note

This page is being moved to Src/java/engine/evaluation-api.md in #1713.

CqlEngine.evaluate() allows you to execute CQL libraries and expressions/functions within those libraries.

The API comes with a DSL-style builder to configure the evaluation parameters. The overall structure of the evaluate { ... } block is as follows:

val evaluationResults = engine.evaluate {
    library(...) {
        expressions(...)
    }
}

Multi-lib and multi-expression evaluation

The evaluate { ... } block can have multiple library(...) { ... } sub-blocks, which executes multiple libraries in a single evaluation call. expressions(...) can also be repeated inside library blocks, in which case all specified expressions/functions will be evaluated.

Full-library evaluation

If expressions(...) is never executed within a library block or if library(...) doesn't have a block, all expressions in that library will be evaluated. You can mix and match full-library evaluations with specific expression evaluations in the same evaluate { ... } block.

Evaluating specific expressions from a library

In the following example, only expr1, expr2, and expr3 from Lib1 will be evaluated:

library("Lib1") {
  expressions("expr1")
  expressions("expr2", EvaluationExpressionRef("expr3"))
}

Running functions

The API supports evaluating functions (define function func1(...): ...) within CQL libraries with given parameters.

In the following example, Lib1.func1 is called with parameters 1 and 2:

library("Lib1") {
  expressions(EvaluationFunctionRef("func1", /*signature*/ null, /*args*/ listOf(1, 2)))
}

Function signature can be provided to disambiguate overloaded functions. It is optional if there is no ambiguity.

Accessing evaluation results

EvaluationResults contains results for all evaluated libraries, grouped by library identifier. In a single-lib case, you can use evaluationResults.onlyResultOrThrow to get the single EvaluationResult.

EvaluationResult contains results for all evaluated expressions/functions within a library. The results can be accessed using the brackets operator [...] with the expression name or EvaluationExpressionRef/EvaluationFunctionRef as the key:

val evaluationResult = evaluationResults.onlyResultOrThrow
val exprValue = evaluationResult["expr1"]?.value
val funcValue = evaluationResult[evaluationFunctionRef]?.value

EvaluationResult also provides the expressionResults computed map of expression names to their results. Modifications to this map do not persist in the EvaluationResult instance.

Full example

val evaluationResults = engine.evaluate {
    // Evaluates all expressions from the referenced library
    library(versionedIdentifier)

    // Repeat when multiple libraries need to be evaluated
    library("Library1") // Short for library(VersionedIdentifier().apply { id = "Library1" })

    // Evaluate specific expressions and functions.
    library("Library2") {
        // Use expressions(...) to pass in evaluation expression refs
        expressions(EvaluationExpressionRef("expr1"), EvaluationExpressionRef("expr2"), ...)

        // Same as above
        expressions("expr1", "expr2", ...)

        // Evaluate func1 with parameters (1, 2)
        expressions(EvaluationFunctionRef("func1", /*signature*/ null, /*args*/ listOf(1, 2)))
    }

    // Additional params
    contextParameter = "Patient" to pat1
    parameters = mapOf(...)
    debugMap = DebugMap()
    evaluationDateTime = ZonedDateTime.of(2025, 12, 31, 0, 0, 0, 0, ZoneOffset.UTC)
}

// Get results for library using versionedIdentifier
val libraryResults = evaluationResults.results[versionedIdentifier]
// Or use shorthand in the single-lib case (returns non-nullable EvaluationResult):
// val libraryResults = evaluationResults.onlyResultOrThrow

// Use the brackets operator [...] to get the results for expressions and
// function evaluations from EvaluationResult
val exprValue = libraryResults?["expr1"]?.value
val funcValue = libraryResults?[evaluationFunctionRef]?.value
Add a custom footer
Add a custom sidebar

Clone this wiki locally