[pkg/ottl] Convert Statement to an interface (#14869)

* Convert Statement to an interface

* update documentation

* add changelog entry

* Add unit tests

* adjust routing processor if statements

* Reorder return values

* Switch from interface to struct

.chloggen/ottl-eval-interface.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: pkg/ottl
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Changed Statement to be an interface with an `Execute` function.
+
+# One or more tracking issues related to the change
+issues: [14869]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

pkg/ottl/grammar.go

@@ -151,13 +151,6 @@ type Field struct {
 	MapKey *string `parser:"( '[' @String ']' )?"`
 }
 
-// Statement holds a top level Statement for processing telemetry data. A Statement is a combination of a function
-// invocation and the expression to match telemetry for invoking the function.
-type Statement[K any] struct {
-	Function  ExprFunc[K]
-	Condition boolExpressionEvaluator[K]
-}
-
 // byteSlice type for capturing byte slices
 type byteSlice []byte
 

pkg/ottl/parser.go

@@ -27,6 +27,25 @@ type Parser[K any] struct {
 	telemetrySettings component.TelemetrySettings
 }
 
+// Statement holds a top level statement for processing telemetry data.
+type Statement[K any] struct {
+	function  ExprFunc[K]
+	condition boolExpressionEvaluator[K]
+}
+
+// Execute is a function that will execute the statement's function if the statement's condition is met.
+// Returns true if the function was run, returns false otherwise.
+// If the statement contains no condition, the function will run and true will be returned.
+// In addition, the functions return value is always returned.
+func (s *Statement[K]) Execute(ctx K) (any, bool) {
+	condition := s.condition(ctx)
+	var result any
+	if condition {
+		result = s.function(ctx)
+	}
+	return result, condition
+}
+
 func NewParser[K any](functions map[string]interface{}, pathParser PathExpressionParser[K], enumParser EnumParser, telemetrySettings component.TelemetrySettings) Parser[K] {
 	return Parser[K]{
 		functions:         functions,
@@ -57,8 +76,8 @@ func (p *Parser[K]) ParseStatements(statements []string) ([]Statement[K], error)
 			continue
 		}
 		parsedStatements = append(parsedStatements, Statement[K]{
-			Function:  function,
-			Condition: expression,
+			function:  function,
+			condition: expression,
 		})
 	}
 

pkg/ottl/parser_test.go

@@ -841,3 +841,54 @@ func Test_parseStatement(t *testing.T) {
 		})
 	}
 }
+
+func Test_Execute(t *testing.T) {
+	tests := []struct {
+		name              string
+		condition         boolExpressionEvaluator[interface{}]
+		function          ExprFunc[interface{}]
+		expectedCondition bool
+		expectedResult    interface{}
+	}{
+		{
+			name:      "Condition matched",
+			condition: alwaysTrue[interface{}],
+			function: func(ctx interface{}) interface{} {
+				return 1
+			},
+			expectedCondition: true,
+			expectedResult:    1,
+		},
+		{
+			name:      "Condition not matched",
+			condition: alwaysFalse[interface{}],
+			function: func(ctx interface{}) interface{} {
+				return 1
+			},
+			expectedCondition: false,
+			expectedResult:    nil,
+		},
+		{
+			name:      "No result",
+			condition: alwaysTrue[interface{}],
+			function: func(ctx interface{}) interface{} {
+				return nil
+			},
+			expectedCondition: true,
+			expectedResult:    nil,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			statement := Statement[interface{}]{
+				condition: tt.condition,
+				function:  tt.function,
+			}
+
+			result, condition := statement.Execute(nil)
+
+			assert.Equal(t, tt.expectedCondition, condition)
+			assert.Equal(t, tt.expectedResult, result)
+		})
+	}
+}

processor/routingprocessor/logs.go

@@ -101,11 +101,10 @@ func (p *logProcessor) route(ctx context.Context, l plog.Logs) error {
 
 		matchCount := len(p.router.routes)
 		for key, route := range p.router.routes {
-			if !route.expression.Condition(ltx) {
+			if _, isMatch := route.expression.Execute(ltx); !isMatch {
 				matchCount--
 				continue
 			}
-			route.expression.Function(ltx)
 			p.group(key, groups, route.exporters, rlogs)
 		}
 

processor/routingprocessor/metrics.go

@@ -103,11 +103,10 @@ func (p *metricsProcessor) route(ctx context.Context, tm pmetric.Metrics) error
 
 		matchCount := len(p.router.routes)
 		for key, route := range p.router.routes {
-			if !route.expression.Condition(mtx) {
+			if _, isMatch := route.expression.Execute(mtx); !isMatch {
 				matchCount--
 				continue
 			}
-			route.expression.Function(mtx)
 			p.group(key, groups, route.exporters, rmetrics)
 		}
 

processor/routingprocessor/traces.go

@@ -101,11 +101,10 @@ func (p *tracesProcessor) route(ctx context.Context, t ptrace.Traces) error {
 
 		matchCount := len(p.router.routes)
 		for key, route := range p.router.routes {
-			if !route.expression.Condition(stx) {
+			if _, isMatch := route.expression.Execute(stx); !isMatch {
 				matchCount--
 				continue
 			}
-			route.expression.Function(stx)
 			p.group(key, groups, route.exporters, rspans)
 		}
 

processor/transformprocessor/internal/logs/processor.go

@@ -48,9 +48,7 @@ func (p *Processor) ProcessLogs(_ context.Context, td plog.Logs) (plog.Logs, err
 			for k := 0; k < logs.Len(); k++ {
 				ctx := ottllogs.NewTransformContext(logs.At(k), slogs.Scope(), rlogs.Resource())
 				for _, statement := range p.statements {
-					if statement.Condition(ctx) {
-						statement.Function(ctx)
-					}
+					statement.Execute(ctx)
 				}
 			}
 		}

processor/transformprocessor/internal/metrics/processor.go

@@ -96,8 +96,6 @@ func (p *Processor) handleSummaryDataPoints(dps pmetric.SummaryDataPointSlice, m
 
 func (p *Processor) callFunctions(ctx ottldatapoints.TransformContext) {
 	for _, statement := range p.statements {
-		if statement.Condition(ctx) {
-			statement.Function(ctx)
-		}
+		statement.Execute(ctx)
 	}
 }

processor/transformprocessor/internal/traces/processor.go

@@ -48,9 +48,7 @@ func (p *Processor) ProcessTraces(_ context.Context, td ptrace.Traces) (ptrace.T
 			for k := 0; k < spans.Len(); k++ {
 				ctx := ottltraces.NewTransformContext(spans.At(k), sspan.Scope(), rspans.Resource())
 				for _, statement := range p.statements {
-					if statement.Condition(ctx) {
-						statement.Function(ctx)
-					}
+					statement.Execute(ctx)
 				}
 			}
 		}