Can now execute user defined commands

2 files changed, 80 insertions, 3 deletions

diff --git a/cmd/grv/config.go b/cmd/grv/config.go
index c5df0ff..1712966 100644
--- a/cmd/grv/config.go
+++ b/cmd/grv/config.go
@@ -315,14 +315,16 @@ type Configuration struct {
 	grvConfigDir    string
 	channels        Channels
 	variables       GRVVariableGetter
+	customCommands  map[string]string
 }
 
 // NewConfiguration creates a Configuration instance with default values
 func NewConfiguration(keyBindings KeyBindings, channels Channels, variables GRVVariableGetter) *Configuration {
 	config := &Configuration{
-		keyBindings: keyBindings,
-		channels:    channels,
-		variables:   variables,
+		keyBindings:    keyBindings,
+		channels:       channels,
+		variables:      variables,
+		customCommands: map[string]string{},
 		themes: map[string]MutableTheme{
 			cfClassicThemeName:   NewClassicTheme(),
 			cfColdThemeName:      NewColdTheme(),
@@ -515,6 +517,10 @@ func (config *Configuration) processCommand(command ConfigCommand, inputSource s
 		config.processHelpCommand()
 	case *ShellCommand:
 		err = config.processShellCommand(command, inputSource)
+	case *DefCommand:
+		err = config.processDefCommand(command)
+	case *CustomCommand:
+		err = config.processCustomCommand(command)
 	default:
 		log.Errorf("Unknown command type %T", command)
 	}
@@ -833,6 +839,29 @@ func (config *Configuration) processShellCommand(shellCommand *ShellCommand, inp
 	return
 }
 
+func (config *Configuration) processDefCommand(defCommand *DefCommand) (err error) {
+	if err = DefineCustomCommand(defCommand.commandName); err != nil {
+		return
+	}
+
+	config.customCommands[defCommand.commandName] = defCommand.functionBody
+	return
+}
+
+func (config *Configuration) processCustomCommand(customCommand *CustomCommand) (err error) {
+	commandBody, ok := config.customCommands[customCommand.commandName]
+	if !ok {
+		return fmt.Errorf("No command with name %v exists", customCommand.commandName)
+	}
+
+	if errs := config.Evaluate(commandBody); len(errs) > 0 {
+		config.channels.ReportErrors(errs)
+		err = fmt.Errorf("Command %v generated errors", customCommand.commandName)
+	}
+
+	return
+}
+
 func (config *Configuration) runCommand(command string, outputType ShellCommandOutputType) {
 	NewShellCommandProcessor(config.channels, config.variables, command, outputType).Execute()
 }
diff --git a/cmd/grv/config_parse.go b/cmd/grv/config_parse.go
index f71e1aa..1aec5d8 100644
--- a/cmd/grv/config_parse.go
+++ b/cmd/grv/config_parse.go
@@ -141,6 +141,14 @@ type DefCommand struct {
 
 func (defCommand *DefCommand) configCommand() {}
 
+// CustomCommand represents an invocation of a user defined command
+type CustomCommand struct {
+	commandName string
+	args        []string
+}
+
+func (customCommand *CustomCommand) configCommand() {}
+
 type commandHelpGenerator func(config Config) []*HelpSection
 type commandCustomParser func(parser *ConfigParser) (tokens []*ConfigToken, err error)
 
@@ -149,6 +157,33 @@ type commandDescriptor struct {
 	constructor          commandConstructor
 	commandHelpGenerator commandHelpGenerator
 	customParser         commandCustomParser
+	userDefined          bool
+}
+
+// DefineCustomCommand allows a custom command to be parsed
+func DefineCustomCommand(commandName string) (err error) {
+	if existingDescriptor, ok := commandDescriptors[commandName]; ok && !existingDescriptor.userDefined {
+		return fmt.Errorf("Cannot override built in command %v", commandName)
+	}
+
+	commandDescriptors[commandName] = &commandDescriptor{
+		customParser: parseVarArgsCommand,
+		constructor:  customCommandConstructor,
+		userDefined:  true,
+	}
+
+	return
+}
+
+// UndefineCustomCommand invalidates a custom command
+func UndefineCustomCommand(commandName string) (err error) {
+	if existingDescriptor, ok := commandDescriptors[commandName]; ok && !existingDescriptor.userDefined {
+		return fmt.Errorf("Cannot undefine built in command %v", commandName)
+	}
+
+	delete(commandDescriptors, commandName)
+
+	return
 }
 
 var commandDescriptors = map[string]*commandDescriptor{
@@ -633,3 +668,16 @@ func defCommandConstructor(parser *ConfigParser, commandToken *ConfigToken, toke
 
 	return
 }
+
+func customCommandConstructor(parser *ConfigParser, commandToken *ConfigToken, tokens []*ConfigToken) (configCommand ConfigCommand, err error) {
+	var args []string
+
+	for _, token := range tokens {
+		args = append(args, token.value)
+	}
+
+	return &CustomCommand{
+		commandName: commandToken.value,
+		args:        args,
+	}, nil
+}