[pkg/telemetryquerylanguage] Add split function to TQL (#13430)

* Add split function to TQL

* Change to factory function

* Add test case for empty string and delimiter

* Fix import group

pkg/telemetryquerylanguage/functions/tqlotel/README.md

@@ -5,6 +5,7 @@ The following functions are intended to be used in implementations of the Teleme
 Factory Functions
 - [SpanID](#spanid)
 - [TraceID](#traceid)
+- [Split](#split)
 
 Functions
 - [delete_key](#delete_key)
@@ -15,6 +16,7 @@ Functions
 - [replace_all_matches](#replace_all_matches)
 - [replace_all_patterns](#replace_all_patterns)
 
+
 ## SpanID
 
 `SpanID(bytes)`
@@ -147,3 +149,17 @@ If one or more sections of `target` match `regex` they will get replaced with `r
 Examples:
 
 - `replace_all_patterns(attributes, "/account/\\d{4}", "/account/{accountId}")`
+
+## Split
+
+`Split(target, delimiter)`
+
+The `Split` factory function separates a string by the delimiter, and returns an array of substrings.
+
+`target` is a string. `delimiter` is a string.
+
+If the `target` is not a string or does not exist, the `Split` factory function will return `nil`.
+
+Examples:
+
+- ```Split("A|B|C", "|")```

pkg/telemetryquerylanguage/functions/tqlotel/func_split.go

@@ -0,0 +1,32 @@
+// Copyright  The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tqlotel // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/functions/tqlotel"
+
+import (
+	"strings"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/tql"
+)
+
+func Split(target tql.Getter, delimiter string) (tql.ExprFunc, error) {
+	return func(ctx tql.TransformContext) interface{} {
+		if val := target.Get(ctx); val != nil {
+			if valStr, ok := val.(string); ok {
+				return strings.Split(valStr, delimiter)
+			}
+		}
+		return nil
+	}, nil
+}

pkg/telemetryquerylanguage/functions/tqlotel/func_split_test.go

@@ -0,0 +1,94 @@
+// Copyright  The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tqlotel
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/tql"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/tql/tqltest"
+)
+
+func Test_split(t *testing.T) {
+	tests := []struct {
+		name      string
+		target    tql.Getter
+		delimiter string
+		expected  interface{}
+	}{
+		{
+			name: "split string",
+			target: &tql.StandardGetSetter{
+				Getter: func(ctx tql.TransformContext) interface{} {
+					return "A|B|C"
+				},
+			},
+			delimiter: "|",
+			expected:  []string{"A", "B", "C"},
+		},
+		{
+			name: "split empty string",
+			target: &tql.StandardGetSetter{
+				Getter: func(ctx tql.TransformContext) interface{} {
+					return ""
+				},
+			},
+			delimiter: "|",
+			expected:  []string{""},
+		},
+		{
+			name: "split empty delimiter",
+			target: &tql.StandardGetSetter{
+				Getter: func(ctx tql.TransformContext) interface{} {
+					return "A|B|C"
+				},
+			},
+			delimiter: "",
+			expected:  []string{"A", "|", "B", "|", "C"},
+		},
+		{
+			name: "split empty string and empty delimiter",
+			target: &tql.StandardGetSetter{
+				Getter: func(ctx tql.TransformContext) interface{} {
+					return ""
+				},
+			},
+			delimiter: "",
+			expected:  []string{},
+		},
+		{
+			name: "split non-string",
+			target: &tql.StandardGetSetter{
+				Getter: func(ctx tql.TransformContext) interface{} {
+					return 123
+				},
+			},
+			delimiter: "|",
+			expected:  nil,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := tqltest.TestTransformContext{}
+
+			exprFunc, _ := Split(tt.target, tt.delimiter)
+			actual := exprFunc(ctx)
+
+			assert.Equal(t, tt.expected, actual)
+		})
+	}
+}

unreleased/tql_split_function.yaml

@@ -0,0 +1,16 @@
+# 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: telemetryquerylanguage
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add split factory function to separate a string by the delimiter, and returns an array of substrings.
+
+# One or more tracking issues related to the change
+issues: [11790]
+
+# (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: