From b4401224612367bba465d15e1f940fcf00173142 Mon Sep 17 00:00:00 2001
From: Steve Bennett <steveb@workware.net.au>
Date: Thu, 22 Jun 2023 13:55:33 +1000
Subject: subcmd: minor improvements

Add support for modulo maxarg count.  If maxargs is (e.g.) -2, then a
multiple of 2 args is expected.

Also expose Jim_SubCmdArgError() to make it easy to add additional
arg validation but still have subcmd report the usage.

Signed-off-by: Steve Bennett <steveb@workware.net.au>
---
 jim-subcmd.c | 20 ++++++++++++++++----
 jim-subcmd.h | 12 ++++++++++++
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/jim-subcmd.c b/jim-subcmd.c
index 2063704..8a946ce 100644
--- a/jim-subcmd.c
+++ b/jim-subcmd.c
@@ -82,10 +82,10 @@ static void add_cmd_usage(Jim_Interp *interp, const jim_subcmd_type * ct, Jim_Ob
     }
 }
 
-static void set_wrong_args(Jim_Interp *interp, const jim_subcmd_type * command_table, Jim_Obj *subcmd)
+void Jim_SubCmdArgError(Jim_Interp *interp, const jim_subcmd_type * ct, Jim_Obj *subcmd)
 {
     Jim_SetResultString(interp, "wrong # args: should be \"", -1);
-    add_cmd_usage(interp, command_table, subcmd);
+    add_cmd_usage(interp, ct, subcmd);
     Jim_AppendStrings(interp, Jim_GetResult(interp), "\"", NULL);
 }
 
@@ -110,6 +110,7 @@ const jim_subcmd_type *Jim_ParseSubCmd(Jim_Interp *interp, const jim_subcmd_type
     Jim_Obj *cmd;
     const char *cmdstr;
     int help = 0;
+    int argsok = 1;
 
     if (argc < 2) {
         Jim_SetResultFormatted(interp, "wrong # args: should be \"%#s command ...\"\n"
@@ -200,7 +201,18 @@ const jim_subcmd_type *Jim_ParseSubCmd(Jim_Interp *interp, const jim_subcmd_type
 
 found:
     /* Check the number of args */
-    if (argc - 2 < ct->minargs || (ct->maxargs >= 0 && argc - 2 > ct->maxargs)) {
+
+    if (argc - 2 < ct->minargs) {
+        argsok = 0;
+    }
+    else if (ct->maxargs >= 0 && argc - 2 > ct->maxargs) {
+        argsok = 0;
+    }
+    else if (ct->maxargs < -1 && (argc - 2) % -ct->maxargs != 0) {
+        /* -2 means must have n * 2 args */
+        argsok = 0;
+    }
+    if (!argsok) {
         Jim_SetResultString(interp, "wrong # args: should be \"", -1);
         /* subcmd */
         add_cmd_usage(interp, ct, argv[0]);
@@ -225,7 +237,7 @@ int Jim_CallSubCmd(Jim_Interp *interp, const jim_subcmd_type * ct, int argc, Jim
             ret = ct->function(interp, argc - 2, argv + 2);
         }
         if (ret < 0) {
-            set_wrong_args(interp, ct, argv[0]);
+            Jim_SubCmdArgError(interp, ct, argv[0]);
             ret = JIM_ERR;
         }
     }
diff --git a/jim-subcmd.h b/jim-subcmd.h
index ab30f37..2d05821 100644
--- a/jim-subcmd.h
+++ b/jim-subcmd.h
@@ -31,6 +31,11 @@ typedef struct {
 	unsigned short flags;			/* JIM_MODFLAG_... plus custom flags */
 } jim_subcmd_type;
 
+/* This makes it easy to define a jim_subcmd_type array with function=NULL
+ * see jim-namespace.c for an example
+ */
+#define JIM_DEF_SUBCMD(name, args, minargs, maxargs) { name, args, NULL, minargs, maxargs }
+
 /**
  * Looks up the appropriate subcommand in the given command table and return
  * the command function which implements the subcommand.
@@ -70,6 +75,13 @@ int Jim_SubCmdProc(Jim_Interp *interp, int argc, Jim_Obj *const *argv);
  */
 int Jim_CallSubCmd(Jim_Interp *interp, const jim_subcmd_type *ct, int argc, Jim_Obj *const *argv);
 
+/**
+ * Sets an error result indicating the usage of the subcmd 'ct'.
+ * Typically this will be called with the result of Jim_ParseSubCmd() after
+ * additional checks if the args are wrong.
+ */
+void Jim_SubCmdArgError(Jim_Interp *interp, const jim_subcmd_type *ct, Jim_Obj *subcmd);
+
 #ifdef __cplusplus
 }
 #endif
-- 
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