otellogr: Implement Info, WithName, WithValues (#6111)

This PR implements a few methods for otellogr package
- Info
- WithName
- WithValues

Out of scope
- Enabled
- Init
- Error
- Level

Part of
#5192

bridges/otellogr/convert.go

@@ -0,0 +1,156 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package otellogr // import "go.opentelemetry.io/contrib/bridges/otellogr"
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"reflect"
+	"strconv"
+	"time"
+
+	"go.opentelemetry.io/otel/log"
+)
+
+// convertKVs converts a list of key-value pairs to a list of [log.KeyValue].
+// The last [context.Context] value is returned as the context.
+// If no context is found, the original context is returned.
+func convertKVs(ctx context.Context, keysAndValues ...any) (context.Context, []log.KeyValue) {
+	if len(keysAndValues) == 0 {
+		return ctx, nil
+	}
+	if len(keysAndValues)%2 != 0 {
+		// Ensure an odd number of items here does not corrupt the list.
+		keysAndValues = append(keysAndValues, nil)
+	}
+
+	kvs := make([]log.KeyValue, 0, len(keysAndValues)/2)
+	for i := 0; i < len(keysAndValues); i += 2 {
+		k, ok := keysAndValues[i].(string)
+		if !ok {
+			// Ensure that the key is a string.
+			k = fmt.Sprintf("%v", keysAndValues[i])
+		}
+
+		v := keysAndValues[i+1]
+		if vCtx, ok := v.(context.Context); ok {
+			// Special case when a field is of context.Context type.
+			ctx = vCtx
+			continue
+		}
+
+		kvs = append(kvs, log.KeyValue{
+			Key:   k,
+			Value: convertValue(v),
+		})
+	}
+
+	return ctx, kvs
+}
+
+func convertValue(v any) log.Value {
+	// Handling the most common types without reflect is a small perf win.
+	switch val := v.(type) {
+	case bool:
+		return log.BoolValue(val)
+	case string:
+		return log.StringValue(val)
+	case int:
+		return log.Int64Value(int64(val))
+	case int8:
+		return log.Int64Value(int64(val))
+	case int16:
+		return log.Int64Value(int64(val))
+	case int32:
+		return log.Int64Value(int64(val))
+	case int64:
+		return log.Int64Value(val)
+	case uint:
+		return convertUintValue(uint64(val))
+	case uint8:
+		return log.Int64Value(int64(val))
+	case uint16:
+		return log.Int64Value(int64(val))
+	case uint32:
+		return log.Int64Value(int64(val))
+	case uint64:
+		return convertUintValue(val)
+	case uintptr:
+		return convertUintValue(uint64(val))
+	case float32:
+		return log.Float64Value(float64(val))
+	case float64:
+		return log.Float64Value(val)
+	case time.Duration:
+		return log.Int64Value(val.Nanoseconds())
+	case complex64:
+		r := log.Float64("r", real(complex128(val)))
+		i := log.Float64("i", imag(complex128(val)))
+		return log.MapValue(r, i)
+	case complex128:
+		r := log.Float64("r", real(val))
+		i := log.Float64("i", imag(val))
+		return log.MapValue(r, i)
+	case time.Time:
+		return log.Int64Value(val.UnixNano())
+	case []byte:
+		return log.BytesValue(val)
+	case error:
+		return log.StringValue(val.Error())
+	}
+
+	t := reflect.TypeOf(v)
+	if t == nil {
+		return log.Value{}
+	}
+	val := reflect.ValueOf(v)
+	switch t.Kind() {
+	case reflect.Struct:
+		return log.StringValue(fmt.Sprintf("%+v", v))
+	case reflect.Slice, reflect.Array:
+		items := make([]log.Value, 0, val.Len())
+		for i := 0; i < val.Len(); i++ {
+			items = append(items, convertValue(val.Index(i).Interface()))
+		}
+		return log.SliceValue(items...)
+	case reflect.Map:
+		kvs := make([]log.KeyValue, 0, val.Len())
+		for _, k := range val.MapKeys() {
+			var key string
+			switch k.Kind() {
+			case reflect.String:
+				key = k.String()
+			default:
+				key = fmt.Sprintf("%+v", k.Interface())
+			}
+			kvs = append(kvs, log.KeyValue{
+				Key:   key,
+				Value: convertValue(val.MapIndex(k).Interface()),
+			})
+		}
+		return log.MapValue(kvs...)
+	case reflect.Ptr, reflect.Interface:
+		if val.IsNil() {
+			return log.Value{}
+		}
+		return convertValue(val.Elem().Interface())
+	}
+
+	// Try to handle this as gracefully as possible.
+	//
+	// Don't panic here. it is preferable to have user's open issue
+	// asking why their attributes have a "unhandled: " prefix than
+	// say that their code is panicking.
+	return log.StringValue(fmt.Sprintf("unhandled: (%s) %+v", t, v))
+}
+
+// convertUintValue converts a uint64 to a log.Value.
+// If the value is too large to fit in an int64, it is converted to a string.
+func convertUintValue(v uint64) log.Value {
+	if v > math.MaxInt64 {
+		return log.StringValue(strconv.FormatUint(v, 10))
+	}
+	return log.Int64Value(int64(v))
+}