[pkg/ottl] Add BoolGetter and IsBool converter (open-telemetry#27900)

**Description:**
This PR focuses on adding a new feature to the pkg/ottl package—namely,
the `IsBool` converter, along with its prerequisites, `BoolGetter` and
`BoolLikeGetter`. The series of commits implement the core logic, unit
tests, and documentation to ensure that the `IsBool` converter is
seamlessly integrated into the OTTL framework. By using this feature,
users can conveniently determine whether a given value is a boolean or
not.

**Link to tracking Issue:** 
open-telemetry#27897

**Testing:**

- A comprehensive set of unit tests were added to validate the
functionality of the `IsBool` converter. The tests cover native boolean
values, `pcommon.ValueTypeBool` objects, and incorrect types such as
integers and slices.
- Tests for `BoolGetter` and `BoolLikeGetter` were also included to
verify their behavior and error handling mechanisms. Detailed test
implementations can be found in
[pkg/ottl/expression_test.go](https://github.com/Dennis40816/opentelemetry-collector-contrib/blob/0d1c2c0216f5647404573a6cfe66ebc0081a4167/pkg/ottl/expression_test.go#L1452).

**Documentation:**
- Updated README.md in the `pkg/ottl/ottlfuncs` directory to include
detailed descriptions, usage guidelines, and examples for the `IsBool`
converter.
- The README file also reflects the addition of `BoolGetter` and
`BoolLikeGetter` to the list of supported types for single-value
parameters in OTTL functions.

Author: Dennis40816

.chloggen/issue-27897-IsBool-Converter.yaml

@@ -0,0 +1,27 @@
+# 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 IsBool function into OTTL
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [27897]
+
+# (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:
+
+# 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/README.md

@@ -77,6 +77,8 @@ The following types are supported for single-value parameters in OTTL functions:
 - `StringLikeGetter`
 - `IntGetter`
 - `IntLikeGetter`
+- `BoolGetter`
+- `BoolLikeGetter`
 - `Enum`
 - `string`
 - `float64`

pkg/ottl/expression.go

@@ -247,6 +247,41 @@ func (g StandardFloatGetter[K]) Get(ctx context.Context, tCtx K) (float64, error
 	}
 }
 
+// BoolGetter is a Getter that must return a bool.
+type BoolGetter[K any] interface {
+	// Get retrieves a bool value.
+	Get(ctx context.Context, tCtx K) (bool, error)
+}
+
+// StandardBoolGetter is a basic implementation of BoolGetter
+type StandardBoolGetter[K any] struct {
+	Getter func(ctx context.Context, tCtx K) (any, error)
+}
+
+// Get retrieves a bool value.
+// If the value is not a bool a new TypeError is returned.
+// If there is an error getting the value it will be returned.
+func (g StandardBoolGetter[K]) Get(ctx context.Context, tCtx K) (bool, error) {
+	val, err := g.Getter(ctx, tCtx)
+	if err != nil {
+		return false, fmt.Errorf("error getting value in %T: %w", g, err)
+	}
+	if val == nil {
+		return false, TypeError("expected bool but got nil")
+	}
+	switch v := val.(type) {
+	case bool:
+		return v, nil
+	case pcommon.Value:
+		if v.Type() == pcommon.ValueTypeBool {
+			return v.Bool(), nil
+		}
+		return false, TypeError(fmt.Sprintf("expected bool but got %v", v.Type()))
+	default:
+		return false, TypeError(fmt.Sprintf("expected bool but got %T", val))
+	}
+}
+
 // FunctionGetter uses a function factory to return an instantiated function as an Expr.
 type FunctionGetter[K any] interface {
 	Get(args Arguments) (Expr[K], error)
@@ -507,6 +542,64 @@ func (g StandardIntLikeGetter[K]) Get(ctx context.Context, tCtx K) (*int64, erro
 	return &result, nil
 }
 
+// BoolLikeGetter is a Getter that returns a bool by converting the underlying value to a bool if necessary.
+type BoolLikeGetter[K any] interface {
+	// Get retrieves a bool value.
+	// Unlike `BoolGetter`, the expectation is that the underlying value is converted to a bool if possible.
+	// If the value cannot be converted to a bool, nil and an error are returned.
+	// If the value is nil, nil is returned without an error.
+	Get(ctx context.Context, tCtx K) (*bool, error)
+}
+
+type StandardBoolLikeGetter[K any] struct {
+	Getter func(ctx context.Context, tCtx K) (any, error)
+}
+
+func (g StandardBoolLikeGetter[K]) Get(ctx context.Context, tCtx K) (*bool, error) {
+	val, err := g.Getter(ctx, tCtx)
+	if err != nil {
+		return nil, fmt.Errorf("error getting value in %T: %w", g, err)
+	}
+	if val == nil {
+		return nil, nil
+	}
+	var result bool
+	switch v := val.(type) {
+	case bool:
+		result = v
+	case int:
+		result = v != 0
+	case int64:
+		result = v != 0
+	case string:
+		result, err = strconv.ParseBool(v)
+		if err != nil {
+			return nil, err
+		}
+	case float64:
+		result = v != 0.0
+	case pcommon.Value:
+		switch v.Type() {
+		case pcommon.ValueTypeBool:
+			result = v.Bool()
+		case pcommon.ValueTypeInt:
+			result = v.Int() != 0
+		case pcommon.ValueTypeStr:
+			result, err = strconv.ParseBool(v.Str())
+			if err != nil {
+				return nil, err
+			}
+		case pcommon.ValueTypeDouble:
+			result = v.Double() != 0.0
+		default:
+			return nil, TypeError(fmt.Sprintf("unsupported value type: %v", v.Type()))
+		}
+	default:
+		return nil, TypeError(fmt.Sprintf("unsupported type: %T", val))
+	}
+	return &result, nil
+}
+
 func (p *Parser[K]) newGetter(val value) (Getter[K], error) {
 	if val.IsNil != nil && *val.IsNil {
 		return &literal[K]{value: nil}, nil

pkg/ottl/expression_test.go

@@ -1449,6 +1449,239 @@ func Test_StandardIntLikeGetter_WrappedError(t *testing.T) {
 	assert.False(t, ok)
 }
 
+func Test_StandardBoolGetter(t *testing.T) {
+	tests := []struct {
+		name             string
+		getter           StandardBoolGetter[any]
+		want             bool
+		valid            bool
+		expectedErrorMsg string
+	}{
+		{
+			name: "primitive bool type",
+			getter: StandardBoolGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return true, nil
+				},
+			},
+			want:  true,
+			valid: true,
+		},
+		{
+			name: "ValueTypeBool type",
+			getter: StandardBoolGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return pcommon.NewValueBool(true), nil
+				},
+			},
+			want:  true,
+			valid: true,
+		},
+		{
+			name: "Incorrect type",
+			getter: StandardBoolGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return 1, nil
+				},
+			},
+			valid:            false,
+			expectedErrorMsg: "expected bool but got int",
+		},
+		{
+			name: "nil",
+			getter: StandardBoolGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return nil, nil
+				},
+			},
+			valid:            false,
+			expectedErrorMsg: "expected bool but got nil",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			val, err := tt.getter.Get(context.Background(), nil)
+			if tt.valid {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.want, val)
+			} else {
+				assert.IsType(t, TypeError(""), err)
+				assert.EqualError(t, err, tt.expectedErrorMsg)
+			}
+		})
+	}
+}
+
+// nolint:errorlint
+func Test_StandardBoolGetter_WrappedError(t *testing.T) {
+	getter := StandardBoolGetter[any]{
+		Getter: func(ctx context.Context, tCtx any) (any, error) {
+			return nil, TypeError("")
+		},
+	}
+	_, err := getter.Get(context.Background(), nil)
+	assert.Error(t, err)
+	_, ok := err.(TypeError)
+	assert.False(t, ok)
+}
+
+func Test_StandardBoolLikeGetter(t *testing.T) {
+	tests := []struct {
+		name             string
+		getter           BoolLikeGetter[any]
+		want             any
+		valid            bool
+		expectedErrorMsg string
+	}{
+		{
+			name: "string type true",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return "true", nil
+				},
+			},
+			want:  true,
+			valid: true,
+		},
+		{
+			name: "string type false",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return "false", nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "int type",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return 0, nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "float64 type",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return float64(0.0), nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "pcommon.value type int",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					v := pcommon.NewValueInt(int64(0))
+					return v, nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "pcommon.value type string",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					v := pcommon.NewValueStr("false")
+					return v, nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "pcommon.value type bool",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					v := pcommon.NewValueBool(true)
+					return v, nil
+				},
+			},
+			want:  true,
+			valid: true,
+		},
+		{
+			name: "pcommon.value type double",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					v := pcommon.NewValueDouble(float64(0.0))
+					return v, nil
+				},
+			},
+			want:  false,
+			valid: true,
+		},
+		{
+			name: "nil",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return nil, nil
+				},
+			},
+			want:  nil,
+			valid: true,
+		},
+		{
+			name: "invalid type",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					return []byte{}, nil
+				},
+			},
+			valid:            false,
+			expectedErrorMsg: "unsupported type: []uint8",
+		},
+		{
+			name: "invalid pcommon.value type",
+			getter: StandardBoolLikeGetter[any]{
+				Getter: func(ctx context.Context, tCtx any) (any, error) {
+					v := pcommon.NewValueMap()
+					return v, nil
+				},
+			},
+			valid:            false,
+			expectedErrorMsg: "unsupported value type: Map",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			val, err := tt.getter.Get(context.Background(), nil)
+			if tt.valid {
+				assert.NoError(t, err)
+				if tt.want == nil {
+					assert.Nil(t, val)
+				} else {
+					assert.Equal(t, tt.want, *val)
+				}
+			} else {
+				assert.IsType(t, TypeError(""), err)
+				assert.EqualError(t, err, tt.expectedErrorMsg)
+			}
+		})
+	}
+}
+
+// nolint:errorlint
+func Test_StandardBoolLikeGetter_WrappedError(t *testing.T) {
+	getter := StandardBoolLikeGetter[any]{
+		Getter: func(ctx context.Context, tCtx any) (any, error) {
+			return nil, TypeError("")
+		},
+	}
+	_, err := getter.Get(context.Background(), nil)
+	assert.Error(t, err)
+	_, ok := err.(TypeError)
+	assert.False(t, ok)
+}
+
 func Test_StandardPMapGetter(t *testing.T) {
 	tests := []struct {
 		name             string