Implement FHIRPath's skip() and take() functions.

PiperOrigin-RevId: 313840420
google · Jun 15, 2020 · 30409c0 · 30409c0
1 parent 1e9dc2c
commit 30409c0
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Showing 2 changed files with 104 additions and 2 deletions.
diff --git a/cc/google/fhir/fhir_path/fhir_path.cc b/cc/google/fhir/fhir_path/fhir_path.cc
@@ -14,6 +14,8 @@
 
 #include "google/fhir/fhir_path/fhir_path.h"
 
+#include <algorithm>
+#include <iterator>
 #include <utility>
 
 #include "google/protobuf/any.pb.h"
@@ -1307,6 +1309,60 @@ class TailFunction : public ZeroParameterFunctionNode {
  const Descriptor* ReturnType() const override { return child_->ReturnType(); }
 };
 
+class SkipFunction : public SingleValueFunctionNode {
+ public:
+ explicit SkipFunction(
+ const std::shared_ptr<ExpressionNode>& child,
+ const std::vector<std::shared_ptr<ExpressionNode>>& params)
+ : SingleValueFunctionNode(child, params) {}
+
+ Status EvaluateWithParam(
+ WorkSpace* work_space, const WorkspaceMessage& param,
+ std::vector<WorkspaceMessage>* results) const override {
+ std::vector<WorkspaceMessage> child_results;
+ FHIR_RETURN_IF_ERROR(child_->Evaluate(work_space, &child_results));
+ FHIR_ASSIGN_OR_RETURN(
+ int num,
+ ToSystemInteger(work_space->GetPrimitiveHandler(), *param.Message()));
+
+ auto start = child_results.begin();
+ std::advance(start, std::min(num < 0 ? 0 : static_cast<size_t>(num),
+ child_results.size()));
+ results->insert(results->begin(), start, child_results.end());
+
+ return absl::OkStatus();
+ }
+
+ const Descriptor* ReturnType() const override { return child_->ReturnType(); }
+};
+
+class TakeFunction : public SingleValueFunctionNode {
+ public:
+ explicit TakeFunction(
+ const std::shared_ptr<ExpressionNode>& child,
+ const std::vector<std::shared_ptr<ExpressionNode>>& params)
+ : SingleValueFunctionNode(child, params) {}
+
+ Status EvaluateWithParam(
+ WorkSpace* work_space, const WorkspaceMessage& param,
+ std::vector<WorkspaceMessage>* results) const override {
+ std::vector<WorkspaceMessage> child_results;
+ FHIR_RETURN_IF_ERROR(child_->Evaluate(work_space, &child_results));
+ FHIR_ASSIGN_OR_RETURN(
+ int num,
+ ToSystemInteger(work_space->GetPrimitiveHandler(), *param.Message()));
+
+ auto end = child_results.begin();
+ std::advance(end, std::min(num < 0 ? 0 : static_cast<size_t>(num),
+ child_results.size()));
+ results->insert(results->begin(), child_results.begin(), end);
+
+ return absl::OkStatus();
+ }
+
+ const Descriptor* ReturnType() const override { return child_->ReturnType(); }
+};
+
 // Implements the FHIRPath .trace() function.
 class TraceFunction : public SingleValueFunctionNode {
  public:
@@ -3604,8 +3660,8 @@ class FhirPathCompilerVisitor : public FhirPathBaseVisitor {
  {"repeat", UnimplementedFunction},
  {"single", FunctionNode::Create<SingleFunction>},
  {"last", FunctionNode::Create<LastFunction>},
- {"skip", UnimplementedFunction},
- {"take", UnimplementedFunction},
+ {"skip", FunctionNode::Create<SkipFunction>},
+ {"take", FunctionNode::Create<TakeFunction>},
  {"exclude", UnimplementedFunction},
  {"union", UnimplementedFunction},
  {"convertsToBoolean", UnimplementedFunction},

diff --git a/cc/google/fhir/fhir_path/fhir_path_test.cc b/cc/google/fhir/fhir_path/fhir_path_test.cc
@@ -818,6 +818,52 @@ FHIR_VERSION_TEST(FhirPathTest, TestFunctionTail, {
  EXPECT_THAT(Evaluate("true.combine(true).tail()"), EvalsToTrue());
 })
 
+FHIR_VERSION_TEST(FhirPathTest, TestFunctionSkip, {
+ EXPECT_THAT(Evaluate("{}.skip(-1)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("{}.skip(0)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("{}.skip(1)"), EvalsToEmpty());
+
+ EXPECT_THAT(Evaluate("(true).skip(-1)"), EvalsToTrue());
+ EXPECT_THAT(Evaluate("(true).skip(0)"), EvalsToTrue());
+ EXPECT_THAT(Evaluate("(true).skip(1)"), EvalsToEmpty());
+
+ EXPECT_THAT(Evaluate("true.combine(true).skip(-1) = true.combine(true)"),
+ EvalsToTrue());
+ EXPECT_THAT(Evaluate("true.combine(true).skip(0) = true.combine(true)"),
+ EvalsToTrue());
+ EXPECT_THAT(Evaluate("true.combine(true).skip(1)"), EvalsToTrue());
+ EXPECT_THAT(Evaluate("true.combine(true).skip(2)"), EvalsToEmpty());
+
+ EXPECT_THAT(Evaluate("(true).skip()"),
+ HasStatusCode(StatusCode::kInvalidArgument));
+ EXPECT_THAT(Evaluate("(true).skip('1')"),
+ HasStatusCode(StatusCode::kInvalidArgument));
+})
+
+FHIR_VERSION_TEST(FhirPathTest, TestFunctionTake, {
+ EXPECT_THAT(Evaluate("{}.take(-1)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("{}.take(0)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("{}.take(1)"), EvalsToEmpty());
+
+ EXPECT_THAT(Evaluate("(true).take(-1)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("(true).take(0)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("(true).take(1)"), EvalsToTrue());
+ EXPECT_THAT(Evaluate("(true).take(2)"), EvalsToTrue());
+
+ EXPECT_THAT(Evaluate("true.combine(true).take(-1)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("true.combine(true).take(0)"), EvalsToEmpty());
+ EXPECT_THAT(Evaluate("true.combine(true).take(1)"), EvalsToTrue());
+ EXPECT_THAT(Evaluate("true.combine(true).take(2) = true.combine(true)"),
+ EvalsToTrue());
+ EXPECT_THAT(Evaluate("true.combine(true).take(3) = true.combine(true)"),
+ EvalsToTrue());
+
+ EXPECT_THAT(Evaluate("(true).take()"),
+ HasStatusCode(StatusCode::kInvalidArgument));
+ EXPECT_THAT(Evaluate("(true).take('1')"),
+ HasStatusCode(StatusCode::kInvalidArgument));
+})
+
 FHIR_VERSION_TEST(FhirPathTest, TestFunctionOfTypePrimitives, {
  EXPECT_THAT(Evaluate("{}.ofType(Boolean)"), EvalsToEmpty());