runtime: command: add an arg to begin_processing() to indicate pipeline position

bshell.runtime/command/command.c

@@ -57,6 +57,11 @@ static const fx_value *command_get_arg(
 	return &cmd->cmd_args[index];
 }
 
+static size_t command_get_arg_count(struct bshell_command_p *cmd)
+{
+	return cmd->cmd_nr_args;
+}
+
 static fx_status get_command_type(
 	const fx_value *cmd_v,
 	const fx_property *prop,
@@ -236,14 +241,25 @@ const fx_value *bshell_command_get_arg(bshell_command *cmd, size_t index)
 		index);
 }
 
-enum bshell_status bshell_command_begin_processing(bshell_command *command)
+size_t bshell_command_get_arg_count(const bshell_command *cmd)
 {
-	FX_CLASS_DISPATCH_VIRTUAL_0(
+	FX_CLASS_DISPATCH_STATIC_0(
+		BSHELL_TYPE_COMMAND,
+		command_get_arg_count,
+		cmd);
+}
+
+enum bshell_status bshell_command_begin_processing(
+	bshell_command *command,
+	enum bshell_command_position position)
+{
+	FX_CLASS_DISPATCH_VIRTUAL(
 		bshell_command,
 		BSHELL_TYPE_COMMAND,
 		BSHELL_ERR_NOT_SUPPORTED,
 		c_begin_processing,
-		command);
+		command,
+		position);
 }
 
 enum bshell_status bshell_command_process_record(

bshell.runtime/command/function.c

@@ -43,7 +43,9 @@ static enum bshell_status get_callable_name(
 	return BSHELL_SUCCESS;
 }
 
-static enum bshell_status begin_processing(bshell_command *cmd)
+static enum bshell_status begin_processing(
+	bshell_command *cmd,
+	enum bshell_command_position position)
 {
 	return BSHELL_SUCCESS;
 }

bshell.runtime/include/bshell/command/command.h

@@ -8,6 +8,13 @@
 
 FX_DECLS_BEGIN;
 
+enum bshell_command_position {
+	BSHELL_COMMAND_POSITION_SINGLE = 0,
+	BSHELL_COMMAND_POSITION_BEGINNING,
+	BSHELL_COMMAND_POSITION_MIDDLE,
+	BSHELL_COMMAND_POSITION_END,
+};
+
 struct bshell_runtime;
 
 #define BSHELL_TYPE_COMMAND (bshell_command_get_type())
@@ -24,7 +31,9 @@ FX_TYPE_CLASS_DECLARATION_BEGIN(bshell_command)
 		*c_get_description)(const bshell_command *, fx_string *);
 	enum bshell_status (
 		*c_get_description_static)(const fx_type *, fx_string *);
-	enum bshell_status (*c_begin_processing)(bshell_command *);
+	enum bshell_status (*c_begin_processing)(
+		bshell_command *,
+		enum bshell_command_position);
 	enum bshell_status (*c_process_record)(
 		bshell_command *,
 		FX_TYPE_FWDREF(bshell_pipeline) * pipeline,
@@ -47,9 +56,11 @@ extern void bshell_command_set_args_reverse(
 extern const fx_value *bshell_command_get_arg(
 	bshell_command *cmd,
 	size_t index);
+extern size_t bshell_command_get_arg_count(const bshell_command *cmd);
 
 extern enum bshell_status bshell_command_begin_processing(
-	bshell_command *command);
+	bshell_command *command,
+	enum bshell_command_position position);
 extern enum bshell_status bshell_command_process_record(
 	bshell_command *command,
 	FX_TYPE_FWDREF(bshell_pipeline) * pipeline,

bshell.runtime/include/bshell/runtime/cmdcall.h

@@ -8,6 +8,8 @@ FX_DECLS_BEGIN;
 
 struct bshell_runtime;
 
+enum bshell_command_position;
+
 #define BSHELL_TYPE_CMDCALL (bshell_cmdcall_get_type())
 
 FX_DECLARE_TYPE(bshell_cmdcall);
@@ -29,7 +31,8 @@ extern enum bshell_status bshell_cmdcall_resolve(
 extern enum bshell_status bshell_cmdcall_process_record(
 	bshell_cmdcall *cmdcall,
 	FX_TYPE_FWDREF(bshell_pipeline) * pipeline,
-	struct bshell_runtime *rt);
+	struct bshell_runtime *rt,
+	enum bshell_command_position position);
 
 FX_DECLS_END;
 

bshell.runtime/runtime/cmdcall.c

@@ -195,14 +195,15 @@ static enum bshell_status cmdcall_execute(struct bshell_cmdcall_p *cmdcall)
 static enum bshell_status cmdcall_process_record(
 	struct bshell_cmdcall_p *cmdcall,
 	bshell_pipeline *pipeline,
-	struct bshell_runtime *rt)
+	struct bshell_runtime *rt,
+	enum bshell_command_position position)
 {
 	if (!cmdcall->cmd_target) {
 		return BSHELL_ERR_NOT_SUPPORTED;
 	}
 
 	if (!cmdcall->cmd_initialised) {
-		bshell_command_begin_processing(cmdcall->cmd_target);
+		bshell_command_begin_processing(cmdcall->cmd_target, position);
 		cmdcall->cmd_initialised = true;
 	}
 
@@ -231,25 +232,19 @@ enum bshell_status bshell_cmdcall_resolve(
 		rt);
 }
 
-enum bshell_status bshell_cmdcall_execute(bshell_cmdcall *cmdcall)
-{
-	FX_CLASS_DISPATCH_STATIC_0(
-		BSHELL_TYPE_CMDCALL,
-		cmdcall_execute,
-		cmdcall);
-}
-
 enum bshell_status bshell_cmdcall_process_record(
 	bshell_cmdcall *cmdcall,
 	bshell_pipeline *pipeline,
-	struct bshell_runtime *rt)
+	struct bshell_runtime *rt,
+	enum bshell_command_position position)
 {
 	FX_CLASS_DISPATCH_STATIC(
 		BSHELL_TYPE_CMDCALL,
 		cmdcall_process_record,
 		cmdcall,
 		pipeline,
-		rt);
+		rt,
+		position);
 }
 
 FX_TYPE_CLASS_BEGIN(bshell_cmdcall)

bshell.runtime/runtime/pipeline.c

@@ -7,6 +7,7 @@
 #include <fx/vector.h>
 
 struct bshell_pipeline_p {
+	bool p_input_values_provided;
 	bshell_pipeline *p_self;
 	fx_array *p_in, *p_out;
 	FX_VECTOR_DECLARE(bshell_cmdcall *, p_cmds);
@@ -72,6 +73,7 @@ static enum bshell_status pipeline_add_input_value(
 	fx_value value,
 	bool enumerate)
 {
+	pipeline->p_input_values_provided = true;
 	return write_value(pipeline, pipeline->p_in, value, enumerate);
 }
 
@@ -118,10 +120,26 @@ static enum bshell_status pipeline_pump_record(
 
 	size_t i = 0;
 	for (i = 0; i < pipeline->p_cmds.count;) {
+		enum bshell_command_position position;
+		if (pipeline->p_cmds.count == 1) {
+			position = pipeline->p_input_values_provided
+			                 ? BSHELL_COMMAND_POSITION_END
+			                 : BSHELL_COMMAND_POSITION_SINGLE;
+		} else if (i == 0) {
+			position = pipeline->p_input_values_provided
+			                 ? BSHELL_COMMAND_POSITION_END
+			                 : BSHELL_COMMAND_POSITION_BEGINNING;
+		} else if (i == pipeline->p_cmds.count - 1) {
+			position = BSHELL_COMMAND_POSITION_END;
+		} else {
+			position = BSHELL_COMMAND_POSITION_MIDDLE;
+		}
+
 		status = bshell_cmdcall_process_record(
 			pipeline->p_cmds.items[i],
 			pipeline->p_self,
-			rt);
+			rt,
+			position);
 
 		if (status != BSHELL_SUCCESS) {
 			break;