1 files changed, 215 insertions, 0 deletions
diff --git a/plumbing/format/config/merged.go b/plumbing/format/config/merged.go
new file mode 100644
index 0000000..3afb063
--- /dev/null
+++ b/plumbing/format/config/merged.go
@@ -0,0 +1,215 @@
+package config
+
+type Scope int
+
+const (
+	LocalScope Scope = iota
+	GlobalScope
+	SystemScope
+)
+
+type ScopedConfigs map[Scope]*Config
+
+type Merged struct {
+	scopedConfigs ScopedConfigs
+}
+
+type MergedSection struct {
+	backingSection *Section
+}
+
+type MergedSubsection struct {
+	backingSubsection *Subsection
+}
+
+type MergedSubsections []*MergedSubsection
+
+func NewMerged() *Merged {
+	cfg := &Merged{
+		scopedConfigs: make(ScopedConfigs),
+	}
+	for s := LocalScope; s <= SystemScope; s++ {
+		cfg.scopedConfigs[s] = New()
+	}
+
+	return cfg
+}
+
+func (m *Merged) ResetScopedConfig(scope Scope) {
+	m.scopedConfigs[scope] = New()
+}
+
+func (m *Merged) ScopedConfig(scope Scope) *Config {
+	return m.scopedConfigs[scope]
+}
+
+func (m *Merged) LocalConfig() *Config {
+	return m.ScopedConfig(LocalScope)
+}
+
+func (m *Merged) GlobalConfig() *Config {
+	return m.ScopedConfig(GlobalScope)
+}
+
+func (m *Merged) SystemConfig() *Config {
+	return m.ScopedConfig(SystemScope)
+}
+
+// Config.Section creates the section if it doesn't exist, which is not
+// what we want in here.
+func (c *Config) hasSection(name string) bool {
+	sections := c.Sections
+	var found bool
+
+	for _, s := range sections {
+		if s.IsName(name) {
+			found = true
+			break
+		}
+	}
+
+	return found
+}
+
+func (m *Merged) Section(name string) *MergedSection {
+	var mergedSection *MergedSection
+
+	for s := SystemScope; s >= LocalScope; s-- {
+		if m.scopedConfigs[s].hasSection(name) {
+			sec := m.scopedConfigs[s].Section(name)
+			if mergedSection == nil {
+				mergedSection = NewMergedSection(sec)
+			}
+
+			if mergedSection.Options() == nil {
+				mergedSection.backingSection.Options = sec.Options
+			} else {
+				for _, o := range sec.Options {
+					mergedSection.backingSection.SetOption(o.Key, o.Value)
+				}
+			}
+
+			if mergedSection.Subsections() == nil {
+				mergedSection.backingSection.Subsections = sec.Subsections
+			} else {
+				for _, ss := range sec.Subsections {
+					if mergedSection.HasSubsection(ss.Name) {
+						for _, o := range ss.Options {
+							mergedSection.backingSection.Subsection(ss.Name).SetOption(o.Key, o.Value)
+						}
+					} else {
+						mergedSection.backingSection.Subsections = append(mergedSection.backingSection.Subsections, ss)
+					}
+				}
+			}
+		}
+	}
+
+	if mergedSection != nil {
+		mergedSection.backingSection.Name = name
+	}
+
+	return mergedSection
+}
+
+func (m *Merged) AddOption(scope Scope, section string, subsection string, key string, value string) *Config {
+	return m.ScopedConfig(scope).AddOption(section, subsection, key, value)
+}
+
+func (m *Merged) SetOption(scope Scope, section string, subsection string, key string, value string) *Config {
+	return m.ScopedConfig(scope).SetOption(section, subsection, key, value)
+}
+
+func (m *Merged) RemoveSection(scope Scope, name string) *Config {
+	return m.ScopedConfig(scope).RemoveSection(name)
+}
+
+func (m *Merged) RemoveSubsection(scope Scope, section string, subsection string) *Config {
+	return m.ScopedConfig(scope).RemoveSubsection(section, subsection)
+}
+
+func copyOptions(os Options) Options {
+	copiedOptions := make(Options, 0)
+
+	for _, o := range os {
+		copiedOptions = append(copiedOptions, o)
+	}
+
+	return copiedOptions
+}
+
+func copySubsections(ss Subsections) Subsections {
+	copiedSubsections := make(Subsections, 0)
+
+	for _, ss := range ss {
+		copiedSubsections = append(copiedSubsections, &Subsection{
+			Name:    ss.Name,
+			Options: copyOptions(ss.Options),
+		})
+	}
+
+	return copiedSubsections
+}
+
+func NewMergedSection(backing *Section) *MergedSection {
+	return &MergedSection{
+		backingSection: &Section{
+			Name: backing.Name,
+			Options: copyOptions(backing.Options),
+			Subsections: copySubsections(backing.Subsections),
+		},
+	}
+}
+
+func (ms *MergedSection) Name() string {
+	return ms.backingSection.Name
+}
+
+func (ms *MergedSection) IsName(name string) bool {
+	return ms.backingSection.IsName(name)
+}
+
+func (ms *MergedSection) Options() []*Option {
+	return ms.backingSection.Options
+}
+
+func (ms *MergedSection) Option(key string) string {
+	return ms.backingSection.Option(key)
+}
+
+func (ms *MergedSection) Subsections() MergedSubsections {
+	mss := make(MergedSubsections, 0)
+	for _, ss := range ms.backingSection.Subsections {
+		mss = append(mss, NewMergedSubsection(ss))
+	}
+	return mss
+}
+
+func (ms *MergedSection) Subsection(name string) *MergedSubsection {
+	return NewMergedSubsection(ms.backingSection.Subsection(name))
+}
+
+func (ms *MergedSection) HasSubsection(name string) bool {
+	return ms.backingSection.HasSubsection(name)
+}
+
+func NewMergedSubsection(backing *Subsection) *MergedSubsection {
+	return &MergedSubsection{backingSubsection: backing}
+}
+
+func (mss *MergedSubsection) Name() string {
+	return mss.backingSubsection.Name
+}
+
+func (mss *MergedSubsection) IsName(name string) bool {
+	return mss.backingSubsection.IsName(name)
+}
+
+func (mss *MergedSubsection) Options() []*Option {
+	return mss.backingSubsection.Options
+}
+
+func (mss *MergedSubsection) Option(key string) string {
+	return mss.backingSubsection.Option(key)
+}
+