Add support for sub-interpreters

Includes support for aliases in sub-interp
These are not identical to Tcl interp, but are conceptually very similar

For example:

  set i [interp]
  $i alias localcmd parentcmd arg1
  $i eval { localcmd x }

Invokes: parentcmd arg1 x

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 178 insertions, 0 deletions

diff --git a/jim-interp.c b/jim-interp.c
new file mode 100644
index 0000000..dd80479
--- /dev/null
+++ b/jim-interp.c
@@ -0,0 +1,178 @@
+#include <assert.h>
+
+#include "jim.h"
+#include "jimautoconf.h"
+#include "jim-subcmd.h"
+
+static void JimInterpDelProc(Jim_Interp *interp, void *privData)
+{
+    Jim_FreeInterp((Jim_Interp *)privData);
+}
+
+/* Everything passing between interpreters must be converted to a string */
+static Jim_Obj *JimInterpCopyObj(Jim_Interp *target, Jim_Obj *obj)
+{
+    const char *rep;
+    int len;
+
+    rep = Jim_GetString(obj, &len);
+    return Jim_NewStringObj(target, rep, len);
+}
+
+#define JimInterpCopyResult(to, from) Jim_SetResult((to), JimInterpCopyObj((to), Jim_GetResult((from))))
+
+static int interp_cmd_eval(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    int ret;
+    Jim_Interp *child = Jim_CmdPrivData(interp);
+    Jim_Obj *scriptObj;
+    Jim_Obj *targetScriptObj;
+
+    scriptObj = Jim_ConcatObj(interp, argc, argv);
+    targetScriptObj = JimInterpCopyObj(child, scriptObj);
+    Jim_FreeNewObj(interp, scriptObj);
+
+    Jim_IncrRefCount(targetScriptObj);
+    ret = Jim_EvalObj(child, targetScriptObj);
+    Jim_DecrRefCount(child, targetScriptObj);
+
+    JimInterpCopyResult(interp, child);
+    return ret;
+}
+
+static int interp_cmd_delete(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    return Jim_DeleteCommand(interp, Jim_String(argv[0]));
+}
+
+static void JimInterpDelAlias(Jim_Interp *interp, void *privData)
+{
+    Jim_Interp *parent = Jim_GetAssocData(interp, "interp.parent");
+    Jim_DecrRefCount(parent, (Jim_Obj *)privData);
+}
+
+static int JimInterpAliasProc(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    int i, ret;
+    Jim_Interp *parent = Jim_GetAssocData(interp, "interp.parent");
+    Jim_Obj *targetPrefixObj = Jim_CmdPrivData(interp);
+    Jim_Obj *targetScriptObj;
+
+    assert(parent);
+
+    /* Build the complete command */
+    targetScriptObj = Jim_DuplicateObj(parent, targetPrefixObj);
+    for (i = 1; i < argc; i++) {
+        Jim_ListAppendElement(parent, targetScriptObj,
+            JimInterpCopyObj(parent, argv[i]));
+    }
+
+    Jim_IncrRefCount(targetScriptObj);
+    ret = Jim_EvalObj(parent, targetScriptObj);
+    Jim_DecrRefCount(parent, targetScriptObj);
+
+    JimInterpCopyResult(interp, parent);
+    return ret;
+}
+
+static int interp_cmd_alias(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    Jim_Interp *child = Jim_CmdPrivData(interp);
+    Jim_Obj *aliasPrefixList;
+
+    /* The prefix list will be held inside the child, but it still belongs
+     * to the parent!
+     */
+
+    aliasPrefixList = Jim_NewListObj(interp, argv + 1, argc - 1);
+    Jim_IncrRefCount(aliasPrefixList);
+
+    Jim_CreateCommand(child, Jim_String(argv[0]), JimInterpAliasProc, aliasPrefixList, JimInterpDelAlias);
+    return JIM_OK;
+}
+
+static const jim_subcmd_type interp_command_table[] = {
+    {   "eval",
+        "script ...",
+        interp_cmd_eval,
+        1,
+        -1,
+        /* Description: Concat the args and evaluate the script in the interpreter */
+    },
+    {   "delete",
+        NULL,
+        interp_cmd_delete,
+        0,
+        0,
+        JIM_MODFLAG_FULLARGV,
+        /* Description: Delete this interpreter */
+    },
+    {   "alias",
+        "childcmd parentcmd ?arg ...?",
+        interp_cmd_alias,
+        2,
+        -1,
+        /* Description: Create an alias which refers to a script in the parent interpreter */
+    },
+    { NULL }
+};
+
+static int JimInterpSubCmdProc(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    return Jim_CallSubCmd(interp, Jim_ParseSubCmd(interp, interp_command_table, argc, argv), argc, argv);
+}
+
+static void JimInterpCopyVariable(Jim_Interp *target, Jim_Interp *source, const char *var, const char *default_value)
+{
+    Jim_Obj *value = Jim_GetGlobalVariableStr(source, var, JIM_NONE);
+    const char *str;
+
+    str = value ? Jim_String(value) : default_value;
+    if (str) {
+        Jim_SetGlobalVariableStr(target, var, Jim_NewStringObj(target, str, -1));
+    }
+}
+
+/**
+ * [interp] creates a new interpreter.
+ */
+static int JimInterpCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
+{
+    Jim_Interp *child;
+    char buf[32];
+
+    if (argc != 1) {
+        Jim_WrongNumArgs(interp, 1, argv, "");
+        return JIM_ERR;
+    }
+
+    /* Create the interpreter command */
+    child = Jim_CreateInterp();
+    Jim_RegisterCoreCommands(child);
+    Jim_InitStaticExtensions(child);
+
+    /* Copy some core variables to the new interpreter */
+    JimInterpCopyVariable(child, interp, "argv", NULL);
+    JimInterpCopyVariable(child, interp, "argc", NULL);
+    JimInterpCopyVariable(child, interp, "argv0", NULL);
+    JimInterpCopyVariable(child, interp, "jim::argv0", NULL);
+    JimInterpCopyVariable(child, interp, "jim::exe", NULL);
+
+    /* Allow the child interpreter to find the parent */
+    Jim_SetAssocData(child, "interp.parent", NULL, interp);
+
+    snprintf(buf, sizeof(buf), "interp.handle%ld", Jim_GetId(interp));
+    Jim_CreateCommand(interp, buf, JimInterpSubCmdProc, child, JimInterpDelProc);
+    Jim_SetResultString(interp, buf, -1);
+    return JIM_OK;
+}
+
+int Jim_interpInit(Jim_Interp *interp)
+{
+    if (Jim_PackageProvide(interp, "interp", "1.0", JIM_ERRMSG))
+        return JIM_ERR;
+
+    Jim_CreateCommand(interp, "interp", JimInterpCommand, NULL, NULL);
+
+    return JIM_OK;
+}