FEATURE/MINOR: add SectionAttributesGet to Parser interface to be able to list available / existing attributes in a section

fetch.go

@@ -103,6 +103,21 @@ func (p *configParser) SectionsGet(sectionType Section) ([]string, error) {
 	return result, nil
 }
 
+// SectionAttributesGet lists all attributes in the section of certain type and name
+func (p *configParser) SectionAttributesGet(sectionType Section, sectionName string, existingOnly bool) ([]string, error) {
+	p.lock()
+	defer p.unLock()
+	st, ok := p.Parsers[sectionType]
+	if !ok {
+		return nil, errors.ErrSectionMissing
+	}
+	section, ok := st[sectionName]
+	if !ok {
+		return nil, errors.ErrSectionMissing
+	}
+	return section.GetAttributes(existingOnly), nil
+}
+
 // SectionsDelete deletes one section of sectionType
 func (p *configParser) SectionsDelete(sectionType Section, sectionName string) error {
 	p.lock()

parser-type.go

@@ -19,6 +19,7 @@ package parser
 import (
 	"github.com/haproxytech/config-parser/v5/common"
 	"github.com/haproxytech/config-parser/v5/errors"
+	"github.com/haproxytech/config-parser/v5/parsers/extra"
 )
 
 type ParserInterface interface { //nolint:revive
@@ -44,6 +45,29 @@ type Parsers struct {
 	DefaultSectionName string
 }
 
+func (p *Parsers) GetAttributes(existingOnly bool) []string {
+	keys := make([]string, len(p.Parsers))
+	i := 0
+	for _, section := range p.ParserSequence {
+		attribute := string(section)
+		if attribute == "" {
+			continue
+		}
+		if _, ok := p.Parsers[attribute].(*extra.Section); ok {
+			continue
+		}
+		if existingOnly {
+			val, err := p.Parsers[attribute].Get(false)
+			if err != nil || val == nil {
+				continue
+			}
+		}
+		keys[i] = attribute
+		i++
+	}
+	return keys[:i]
+}
+
 func (p *Parsers) Get(attribute string, createIfNotExist ...bool) (common.ParserData, error) {
 	createNew := false
 	if len(createIfNotExist) > 0 && createIfNotExist[0] {

parser.go

@@ -69,6 +69,7 @@ type Parser interface {
 	GetPreComments(sectionType Section, sectionName string, attribute string) ([]string, error)
 	GetOne(sectionType Section, sectionName string, attribute string, index ...int) (common.ParserData, error)
 	SectionsGet(sectionType Section) ([]string, error)
+	SectionAttributesGet(sectionType Section, sectionName string, existingOnly bool) ([]string, error)
 	SectionsDelete(sectionType Section, sectionName string) error
 	SectionsCreate(sectionType Section, sectionName string) error
 	SectionsDefaultsFromGet(sectionType Section, sectionName string) (string, error)

tests/configs/parse_get_attributes_test.go

@@ -0,0 +1,73 @@
+/*
+Copyright 2019 HAProxy Technologies
+
+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 configs //nolint:testpackage
+
+import (
+	"slices"
+	"strings"
+	"testing"
+
+	parser "github.com/haproxytech/config-parser/v5"
+	"github.com/haproxytech/config-parser/v5/options"
+)
+
+func TestParseGetAttributesExistingOnly(t *testing.T) {
+	tests := []struct {
+		Name, Config string
+	}{
+		{"configBasic1", configBasic1},
+	}
+	for _, config := range tests {
+		t.Run(config.Name, func(t *testing.T) {
+			p, err := parser.New(options.String(config.Config))
+			if err != nil {
+				t.Fatalf(err.Error())
+			}
+			result, err := p.SectionAttributesGet(parser.Frontends, "http", true)
+			if err != nil {
+				t.Fatalf("err should be nil %v", err)
+			}
+			if 0 != slices.Compare(result, []string{
+				"mode", "bind", "default_backend",
+			}) {
+				t.Fatalf("retrieved attributes do not match %s", strings.Join(result, ", "))
+			}
+		})
+	}
+}
+
+func TestParseGetAttributesComplete(t *testing.T) {
+	tests := []struct {
+		Name, Config string
+	}{
+		{"configBasic1", configBasic1},
+	}
+	for _, config := range tests {
+		t.Run(config.Name, func(t *testing.T) {
+			p, err := parser.New(options.String(config.Config))
+			if err != nil {
+				t.Fatalf(err.Error())
+			}
+			result, err := p.SectionAttributesGet(parser.Backends, "default_backend", false)
+			if err != nil {
+				t.Fatalf("err should be nil %v", err)
+			}
+			if !slices.Contains(result, "option tcp-smart-connect") {
+				t.Fatalf("should contain registered attribute 'option tcp-smart-connect'")
+			}
+		})
+	}
+}