[pkg/telemetryquerylanguage] Added Int factory function to TQL (#11810)

pkg/telemetryquerylanguage/functions/tqlcommon/README.md

@@ -4,6 +4,7 @@ The following functions can be used in any implementation of the Telemetry Query
 
 Factory Functions
 - [IsMatch](#ismatch)
+- [Int](#int)
 
 Functions
 - [set](#set)
@@ -27,6 +28,22 @@ Examples:
 
 - `IsMatch("string", ".*ring")`
 
+## Int
+
+`Int(value)`
+
+The `Int` factory function converts a float, bool and string data to the int type.
+
+`value` is either a path expression to a telemetry field to retrieve or a literal.
+If `value` is another type or parsing failed nil is always returned.
+
+Examples:
+
+- `Int(attributes["http.status_code"])`
+
+
+- `Int("2.0")`
+
 ## set
 
 `set(target, value)`

pkg/telemetryquerylanguage/functions/tqlcommon/func_int.go

@@ -0,0 +1,48 @@
+// 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 tqlcommon // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/functions/tqlcommon"
+
+import (
+	"strconv"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/telemetryquerylanguage/tql"
+)
+
+func Int(target tql.Getter) (tql.ExprFunc, error) {
+	return func(ctx tql.TransformContext) interface{} {
+		value := target.Get(ctx)
+		switch value := value.(type) {
+		case int64:
+			return value
+		case string:
+			intValue, err := strconv.ParseInt(value, 10, 64)
+			if err != nil {
+				return nil
+			}
+
+			return intValue
+		case float64:
+			return (int64)(value)
+		case bool:
+			if value {
+				return int64(1)
+			}
+
+			return int64(0)
+		default:
+			return nil
+		}
+	}, nil
+}

pkg/telemetryquerylanguage/functions/tqlcommon/func_int_test.go

@@ -0,0 +1,92 @@
+// 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 tqlcommon
+
+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_Int(t *testing.T) {
+	tests := []struct {
+		name     string
+		value    interface{}
+		expected interface{}
+	}{
+		{
+			name:     "string",
+			value:    "50",
+			expected: int64(50),
+		},
+		{
+			name:     "empty string",
+			value:    "",
+			expected: nil,
+		},
+		{
+			name:     "not a number string",
+			value:    "test",
+			expected: nil,
+		},
+		{
+			name:     "int64",
+			value:    int64(333),
+			expected: int64(333),
+		},
+		{
+			name:     "float64",
+			value:    float64(2.7),
+			expected: int64(2),
+		},
+		{
+			name:     "true",
+			value:    true,
+			expected: int64(1),
+		},
+		{
+			name:     "false",
+			value:    false,
+			expected: int64(0),
+		},
+		{
+			name:     "nil",
+			value:    nil,
+			expected: nil,
+		},
+		{
+			name:     "some struct",
+			value:    struct{}{},
+			expected: nil,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := tqltest.TestTransformContext{}
+
+			exprFunc, _ := Int(&tql.StandardGetSetter{
+				Getter: func(_ tql.TransformContext) interface{} {
+					return tt.value
+				},
+			})
+			actual := exprFunc(ctx)
+
+			assert.Equal(t, tt.expected, actual)
+		})
+	}
+}