[pkg/ottl] Add isList OTTL Function (#32392)

Description:
Add isList OTTL function that returns true if the target is a slice and
returns false if it is not

Link to tracking Issue:
#27870

Testing: Added tests

Documentation: Updated readme and added changelog entry

---------

Co-authored-by: Tyler Helmuth <[email protected]>

.chloggen/ottl-islist.yaml

@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# 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: Add `IsList` OTTL Function
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [27870]
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

pkg/ottl/e2e/e2e_test.go

@@ -382,6 +382,12 @@ func Test_e2e_converters(t *testing.T) {
 				tCtx.GetLogRecord().Attributes().PutStr("test", "pass")
 			},
 		},
+		{
+			statement: `set(attributes["test"], "pass") where IsList(attributes["foo"]["slice"])`,
+			want: func(tCtx ottllog.TransformContext) {
+				tCtx.GetLogRecord().Attributes().PutStr("test", "pass")
+			},
+		},
 		{
 			statement: `set(attributes["test"], "pass") where IsMatch("aa123bb", "\\d{3}")`,
 			want: func(tCtx ottllog.TransformContext) {

pkg/ottl/ottlfuncs/README.md

@@ -392,6 +392,7 @@ Available Converters:
 - [IsInt](#isint)
 - [IsMap](#ismap)
 - [IsMatch](#ismatch)
+- [IsList](#islist)
 - [IsString](#isstring)
 - [Len](#len)
 - [Log](#log)
@@ -708,6 +709,22 @@ Examples:
 
 - `IsMatch("string", ".*ring")`
 
+### IsList
+
+`IsList(value)`
+
+The `IsList` Converter returns true if the given value is a list.
+
+The `value` is either a path expression to a telemetry field to retrieve or a literal.
+
+If `value` is a `list`, `pcommon.ValueTypeSlice`. `pcommon.Slice`, or any other list type, then returns `true`, otherwise returns `false`.
+
+Examples:
+
+- `IsList(body)`
+
+- `IsList(attributes["maybe a slice"])`
+
 ### IsString
 
 `IsString(value)`

pkg/ottl/ottlfuncs/func_is_list.go

@@ -0,0 +1,53 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+	"context"
+	"fmt"
+
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/plog"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+type IsListArguments[K any] struct {
+	Target ottl.Getter[K]
+}
+
+func NewIsListFactory[K any]() ottl.Factory[K] {
+	return ottl.NewFactory("IsList", &IsListArguments[K]{}, createIsListFunction[K])
+}
+
+func createIsListFunction[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+	args, ok := oArgs.(*IsListArguments[K])
+
+	if !ok {
+		return nil, fmt.Errorf("IsListFactory args must be of type *IsListArguments[K]")
+	}
+
+	return isList(args.Target), nil
+}
+
+func isList[K any](target ottl.Getter[K]) ottl.ExprFunc[K] {
+	return func(ctx context.Context, tCtx K) (any, error) {
+		val, err := target.Get(ctx, tCtx)
+		if err != nil {
+			return false, err
+		}
+
+		switch valType := val.(type) {
+		case pcommon.Value:
+			return valType.Type() == pcommon.ValueTypeSlice, nil
+
+		case pcommon.Slice, plog.LogRecordSlice, plog.ResourceLogsSlice, plog.ScopeLogsSlice, pmetric.ExemplarSlice, pmetric.ExponentialHistogramDataPointSlice, pmetric.HistogramDataPointSlice, pmetric.MetricSlice, pmetric.NumberDataPointSlice, pmetric.ResourceMetricsSlice, pmetric.ScopeMetricsSlice, pmetric.SummaryDataPointSlice, pmetric.SummaryDataPointValueAtQuantileSlice, ptrace.ResourceSpansSlice, ptrace.ScopeSpansSlice, ptrace.SpanEventSlice, ptrace.SpanLinkSlice, ptrace.SpanSlice, []string, []bool, []int64, []float64, [][]byte, []any:
+			return true, nil
+		}
+
+		return false, nil
+	}
+}

pkg/ottl/ottlfuncs/func_is_list_test.go

@@ -0,0 +1,189 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/plog"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+func Test_IsList(t *testing.T) {
+	tests := []struct {
+		name     string
+		value    any
+		expected bool
+	}{
+		{
+			name:     "map",
+			value:    make(map[string]any, 0),
+			expected: false,
+		},
+		{
+			name:     "ValueTypeMap",
+			value:    pcommon.NewValueMap(),
+			expected: false,
+		},
+		{
+			name:     "not map",
+			value:    "not a map",
+			expected: false,
+		},
+		{
+			name:     "ValueTypeSlice",
+			value:    pcommon.NewValueSlice(),
+			expected: true,
+		},
+		{
+			name:     "nil",
+			value:    nil,
+			expected: false,
+		},
+		{
+			name:     "plog.LogRecordSlice",
+			value:    plog.NewLogRecordSlice(),
+			expected: true,
+		},
+		{
+			name:     "plog.ResourceLogsSlice",
+			value:    plog.NewResourceLogsSlice(),
+			expected: true,
+		},
+		{
+			name:     "plog.ScopeLogsSlice",
+			value:    plog.NewScopeLogsSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.ExemplarSlice",
+			value:    pmetric.NewExemplarSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.ExponentialHistogramDataPointSlice",
+			value:    pmetric.NewExponentialHistogramDataPointSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.HistogramDataPointSlice",
+			value:    pmetric.NewHistogramDataPointSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.MetricSlice",
+			value:    pmetric.NewMetricSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.NumberDataPointSlice",
+			value:    pmetric.NewNumberDataPointSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.ResourceMetricsSlice",
+			value:    pmetric.NewResourceMetricsSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.ScopeMetricsSlice",
+			value:    pmetric.NewScopeMetricsSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.SummaryDataPointSlice",
+			value:    pmetric.NewSummaryDataPointSlice(),
+			expected: true,
+		},
+		{
+			name:     "pmetric.SummaryDataPointValueAtQuantileSlice",
+			value:    pmetric.NewSummaryDataPointValueAtQuantileSlice(),
+			expected: true,
+		},
+		{
+			name:     "ptrace.ResourceSpansSlice",
+			value:    ptrace.NewResourceSpansSlice(),
+			expected: true,
+		},
+		{
+			name:     "ptrace.ScopeSpansSlice",
+			value:    ptrace.NewScopeSpansSlice(),
+			expected: true,
+		},
+		{
+			name:     "ptrace.SpanEventSlice",
+			value:    ptrace.NewSpanEventSlice(),
+			expected: true,
+		},
+		{
+			name:     "ptrace.SpanLinkSlice",
+			value:    ptrace.NewSpanLinkSlice(),
+			expected: true,
+		},
+		{
+			name:     "ptrace.SpanSlice",
+			value:    ptrace.NewSpanSlice(),
+			expected: true,
+		},
+		{
+			name:     "[]string",
+			value:    []string{},
+			expected: true,
+		},
+		{
+			name:     "[]bool",
+			value:    []bool{},
+			expected: true,
+		},
+		{
+			name:     "[]int64",
+			value:    []int64{},
+			expected: true,
+		},
+		{
+			name:     "[]float64",
+			value:    []float64{},
+			expected: true,
+		},
+		{
+			name:     "[][]byte",
+			value:    [][]byte{},
+			expected: true,
+		},
+		{
+			name:     "[]any",
+			value:    []any{},
+			expected: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			exprFunc := isList[any](&ottl.StandardGetSetter[any]{
+				Getter: func(context.Context, any) (any, error) {
+					return tt.value, nil
+				},
+			})
+			result, err := exprFunc(context.Background(), nil)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func Test_IsList_Error(t *testing.T) {
+	exprFunc := isList[any](&ottl.StandardGetSetter[any]{
+		Getter: func(context.Context, any) (any, error) {
+			return nil, ottl.TypeError("")
+		},
+	})
+	result, err := exprFunc(context.Background(), nil)
+	assert.Equal(t, false, result)
+	assert.IsType(t, ottl.TypeError(""), err)
+}

pkg/ottl/ottlfuncs/functions.go

@@ -47,6 +47,7 @@ func converters[K any]() []ottl.Factory[K] {
 		NewIntFactory[K](),
 		NewIsBoolFactory[K](),
 		NewIsDoubleFactory[K](),
+		NewIsListFactory[K](),
 		NewIsIntFactory[K](),
 		NewIsMapFactory[K](),
 		NewIsMatchFactory[K](),