1 files changed, 261 insertions, 0 deletions
diff --git a/plumbing/format/config/merged.go b/plumbing/format/config/merged.go
new file mode 100644
index 0000000..a44f3b8
--- /dev/null
+++ b/plumbing/format/config/merged.go
@@ -0,0 +1,261 @@
+package config
+
+// Scope defines which configuration we're reading / writing. Git uses
+// a local config file in each repo (./.git/config) which corresponds
+// with LocalScope here. It's values have the highest priority (i.e. they
+// override those in the other two scopes). Next is the global config which
+// could also be described as a user config since it lives in the
+// ~/.gitconfig file. Last and lowest priority is the system config which
+// resides in the /etc/gitconfig file.
+type Scope int
+const (
+	LocalScope Scope = iota
+	GlobalScope
+	SystemScope
+)
+
+type ScopedConfigs map[Scope]*Config
+
+// Merged defines a read-only view of the priority-merged config params
+// so that you can access the effective settings in the same way git does.
+// For example, if a user has defined a user.name value in ~/.gitconfig but
+// a different one in the current repo's ./.git/config file, this code:
+// config.Merged.Section("user").Option("name") will give you the value
+// from ./.git/config.
+type Merged struct {
+	scopedConfigs ScopedConfigs
+}
+
+// MergedSection is a read-only Section for merged config views.
+type MergedSection struct {
+	backingSection *Section
+}
+
+// MergedSubsection is a read-only Subsection for merged config views.
+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()
+}
+
+// ScopedConfig allows accessing specific backing *Config instances.
+func (m *Merged) ScopedConfig(scope Scope) *Config {
+	return m.scopedConfigs[scope]
+}
+
+// LocalConfig allows accessing the local (i.e. ./.git/config) backing
+// *Config instance.
+func (m *Merged) LocalConfig() *Config {
+	return m.ScopedConfig(LocalScope)
+}
+
+// GlobalConfig allows accessing the global (i.e. ~/.gitconfig) backing
+// *Config instance.
+func (m *Merged) GlobalConfig() *Config {
+	return m.ScopedConfig(GlobalScope)
+}
+
+// SystemConfig allows accessing the system (i.e. /etc/gitconfig) backing
+// *Config instance.
+func (m *Merged) SystemConfig() *Config {
+	return m.ScopedConfig(SystemScope)
+}
+
+// SetLocalConfig allows updating the local (i.e. ./.git/config) config. If you
+// call config.SetConfig(...) on the containing top-level config instance after
+// this, your new local config params will be written to ./.git/config.
+func (m *Merged) SetLocalConfig(c *Config) {
+	m.scopedConfigs[LocalScope] = c
+}
+
+// SetGlobalConfig allows updating the global (i.e. ~/.gitconfig) config. If you
+// call config.SetConfig(...) on the containing top-level config instance after
+// this, your new global config params will be written to ~/.gitconfig.
+func (m *Merged) SetGlobalConfig(c *Config) {
+	m.scopedConfigs[GlobalScope] = c
+}
+
+// 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
+}
+
+// Section returns a read-only *MergedSection view of the config in which
+// params are merged in the same order as git itself:
+// Local overrides global overrides system.
+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
+}
+
+// AddOption works just like config.AddOption except that it takes a Scope as its first argument.
+// This defines which config scope (local, global, or system) this option should be added to.
+func (m *Merged) AddOption(scope Scope, section string, subsection string, key string, value string) *Config {
+	return m.ScopedConfig(scope).AddOption(section, subsection, key, value)
+}
+
+// SetOption works just like config.SetOption except that it takes a Scope as its first argument.
+// This defines which config scope (local, global, or system) this option should be set in.
+func (m *Merged) SetOption(scope Scope, section string, subsection string, key string, value string) *Config {
+	return m.ScopedConfig(scope).SetOption(section, subsection, key, value)
+}
+
+// RemoveSection works just like config.RemoveSection except that it takes a Scope as its first argument.
+// This defines which config scope (local, global, or system) the section should be removed from.
+func (m *Merged) RemoveSection(scope Scope, name string) *Config {
+	return m.ScopedConfig(scope).RemoveSection(name)
+}
+
+// RemoveSubsection works just like config.RemoveSubsection except that it takes a Scope as its first argument.
+// This defines which config scope (local, global, or system) the subsection should be removed from.
+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)
+}
+