Added multi-type generics support.

5 files changed, 214 insertions, 49 deletions

diff --git a/src/ast/ast.h b/src/ast/ast.h
index e38453c..1b83a91 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -376,7 +376,8 @@ struct ASTNode
             char *name;
             ASTNode *fields;
             int is_template;
-            char *generic_param;
+            char **generic_params;   // Array of generic parameter names (for example, ["K", "V"])
+            int generic_param_count; // Number of generic parameters
             char *parent;
             int is_union;
             int is_packed;     // @packed attribute.
diff --git a/src/parser/parser.h b/src/parser/parser.h
index 1e047b4..ca8c447 100644
--- a/src/parser/parser.h
+++ b/src/parser/parser.h
@@ -321,6 +321,8 @@ void add_to_global_list(ParserContext *ctx, ASTNode *node);
 void register_builtins(ParserContext *ctx);
 void add_instantiated_func(ParserContext *ctx, ASTNode *fn);
 void instantiate_generic(ParserContext *ctx, const char *name, const char *concrete_type, Token t);
+void instantiate_generic_multi(ParserContext *ctx, const char *name, char **args, int arg_count,
+                               Token t);
 char *sanitize_mangled_name(const char *name);
 void register_type_alias(ParserContext *ctx, const char *alias, const char *original);
 const char *find_type_alias(ParserContext *ctx, const char *alias);
diff --git a/src/parser/parser_stmt.c b/src/parser/parser_stmt.c
index f391f97..ac2d622 100644
--- a/src/parser/parser_stmt.c
+++ b/src/parser/parser_stmt.c
@@ -3238,14 +3238,33 @@ ASTNode *parse_struct(ParserContext *ctx, Lexer *l, int is_union)
     Token n = lexer_next(l);
     char *name = token_strdup(n);
 
-    // Generic Param <T>
-    char *gp = NULL;
+    // Generic Params <T> or <K, V>
+    char **gps = NULL;
+    int gp_count = 0;
     if (lexer_peek(l).type == TOK_LANGLE)
     {
-        lexer_next(l);
-        Token g = lexer_next(l);
-        gp = token_strdup(g);
-        lexer_next(l);
+        lexer_next(l); // eat <
+        while (1)
+        {
+            Token g = lexer_next(l);
+            gps = realloc(gps, sizeof(char *) * (gp_count + 1));
+            gps[gp_count++] = token_strdup(g);
+
+            Token next = lexer_peek(l);
+            if (next.type == TOK_COMMA)
+            {
+                lexer_next(l); // eat ,
+            }
+            else if (next.type == TOK_RANGLE)
+            {
+                lexer_next(l); // eat >
+                break;
+            }
+            else
+            {
+                zpanic_at(next, "Expected ',' or '>' in generic parameter list");
+            }
+        }
         register_generic(ctx, name);
     }
 
@@ -3255,16 +3274,13 @@ ASTNode *parse_struct(ParserContext *ctx, Lexer *l, int is_union)
         lexer_next(l);
         ASTNode *n = ast_create(NODE_STRUCT);
         n->strct.name = name;
-        n->strct.is_template = (gp != NULL);
-        n->strct.generic_param = gp;
+        n->strct.is_template = (gp_count > 0);
+        n->strct.generic_params = gps;
+        n->strct.generic_param_count = gp_count;
         n->strct.is_union = is_union;
         n->strct.fields = NULL;
         n->strct.is_incomplete = 1;
 
-        if (!gp)
-        {
-            add_to_struct_list(ctx, n);
-        }
         return n;
     }
 
@@ -3390,7 +3406,7 @@ ASTNode *parse_struct(ParserContext *ctx, Lexer *l, int is_union)
     add_to_struct_list(ctx, node);
 
     // Auto-prefix struct name if in module context
-    if (ctx->current_module_prefix && !gp)
+    if (ctx->current_module_prefix && gp_count == 0)
     { // Don't prefix generic templates
         char *prefixed_name = xmalloc(strlen(ctx->current_module_prefix) + strlen(name) + 2);
         sprintf(prefixed_name, "%s_%s", ctx->current_module_prefix, name);
@@ -3403,24 +3419,25 @@ ASTNode *parse_struct(ParserContext *ctx, Lexer *l, int is_union)
     // Initialize Type Info so we can track traits (like Drop)
     node->type_info = type_new(TYPE_STRUCT);
     node->type_info->name = xstrdup(name);
-    if (gp)
+    if (gp_count > 0)
     {
         node->type_info->kind = TYPE_GENERIC;
         // TODO: track generic params
     }
 
     node->strct.fields = h;
-    node->strct.generic_param = gp;
+    node->strct.generic_params = gps;
+    node->strct.generic_param_count = gp_count;
     node->strct.is_union = is_union;
 
-    if (gp)
+    if (gp_count > 0)
     {
         node->strct.is_template = 1;
         register_template(ctx, name, node);
     }
 
     // Register definition for 'use' lookups and LSP
-    if (!gp)
+    if (gp_count == 0)
     {
         register_struct_def(ctx, name, node);
     }
@@ -3430,10 +3447,10 @@ ASTNode *parse_struct(ParserContext *ctx, Lexer *l, int is_union)
 
 Type *parse_type_obj(ParserContext *ctx, Lexer *l)
 {
-    // 1. Parse the base type (int, U32, MyStruct, etc.)
+    // Parse the base type (int, U32, MyStruct, etc.)
     Type *t = parse_type_base(ctx, l);
 
-    // 2. Handle Pointers (e.g. int***)
+    // Handle Pointers
     while (lexer_peek(l).type == TOK_OP && lexer_peek(l).start[0] == '*')
     {
         lexer_next(l); // eat *
@@ -3443,8 +3460,6 @@ Type *parse_type_obj(ParserContext *ctx, Lexer *l)
         t = ptr;
     }
 
-    // (Optional: You can add array parsing here later if needed)
-
     return t;
 }
 
diff --git a/src/parser/parser_type.c b/src/parser/parser_type.c
index 3b4abf3..7dded00 100644
--- a/src/parser/parser_type.c
+++ b/src/parser/parser_type.c
@@ -382,44 +382,99 @@ Type *parse_type_base(ParserContext *ctx, Lexer *l)
         Type *ty = type_new(TYPE_STRUCT);
         ty->name = name;
 
-        // Handle Generics <T>
+        // Handle Generics <T> or <K, V>
         if (lexer_peek(l).type == TOK_LANGLE)
         {
             lexer_next(l); // eat <
-            Type *arg = parse_type_formal(ctx, l);
+            Type *first_arg = parse_type_formal(ctx, l);
+            char *first_arg_str = type_to_string(first_arg);
 
-            // Handle nested generics like Vec<Vec<int>> where >> is tokenized as one
-            // op
+            // Check for multi-arg: <K, V>
             Token next_tok = lexer_peek(l);
-            if (next_tok.type == TOK_RANGLE)
-            {
-                lexer_next(l); // Consume >
-            }
-            else if (next_tok.type == TOK_OP && next_tok.len == 2 &&
-                     strncmp(next_tok.start, ">>", 2) == 0)
+            if (next_tok.type == TOK_COMMA)
             {
-                // Split >> into two > tokens
-                // Consume the first > by advancing lexer manually
-                l->pos += 1;
-                l->col += 1;
+                // Multi-arg case
+                char **args = xmalloc(sizeof(char *) * 8);
+                int arg_count = 0;
+                args[arg_count++] = xstrdup(first_arg_str);
+
+                while (lexer_peek(l).type == TOK_COMMA)
+                {
+                    lexer_next(l); // eat ,
+                    Type *arg = parse_type_formal(ctx, l);
+                    char *arg_str = type_to_string(arg);
+                    args = realloc(args, sizeof(char *) * (arg_count + 1));
+                    args[arg_count++] = xstrdup(arg_str);
+                    free(arg_str);
+                }
+
+                // Consume >
+                next_tok = lexer_peek(l);
+                if (next_tok.type == TOK_RANGLE)
+                {
+                    lexer_next(l);
+                }
+                else if (next_tok.type == TOK_OP && next_tok.len == 2 &&
+                         strncmp(next_tok.start, ">>", 2) == 0)
+                {
+                    l->pos += 1;
+                    l->col += 1;
+                }
+                else
+                {
+                    zpanic_at(t, "Expected > after generic");
+                }
+
+                // Call multi-arg instantiation
+                instantiate_generic_multi(ctx, name, args, arg_count, t);
+
+                // Build mangled name
+                char mangled[256];
+                strcpy(mangled, name);
+                for (int i = 0; i < arg_count; i++)
+                {
+                    char *clean = sanitize_mangled_name(args[i]);
+                    strcat(mangled, "_");
+                    strcat(mangled, clean);
+                    free(clean);
+                    free(args[i]);
+                }
+                free(args);
+
+                free(ty->name);
+                ty->name = xstrdup(mangled);
             }
             else
             {
-                zpanic_at(t, "Expected > after generic");
-            }
+                // Single-arg case - PRESERVE ORIGINAL FLOW EXACTLY
+                if (next_tok.type == TOK_RANGLE)
+                {
+                    lexer_next(l); // Consume >
+                }
+                else if (next_tok.type == TOK_OP && next_tok.len == 2 &&
+                         strncmp(next_tok.start, ">>", 2) == 0)
+                {
+                    // Split >> into two > tokens
+                    l->pos += 1;
+                    l->col += 1;
+                }
+                else
+                {
+                    zpanic_at(t, "Expected > after generic");
+                }
 
-            char *arg_str = type_to_string(arg);
-            instantiate_generic(ctx, name, arg_str, t);
+                instantiate_generic(ctx, name, first_arg_str, t);
 
-            char *clean_arg = sanitize_mangled_name(arg_str);
-            char mangled[256];
-            sprintf(mangled, "%s_%s", name, clean_arg);
-            free(clean_arg);
+                char *clean_arg = sanitize_mangled_name(first_arg_str);
+                char mangled[256];
+                sprintf(mangled, "%s_%s", name, clean_arg);
+                free(clean_arg);
 
-            free(ty->name);
-            ty->name = xstrdup(mangled);
-            free(arg_str);
+                free(ty->name);
+                ty->name = xstrdup(mangled);
+            }
 
+            free(first_arg_str);
             ty->kind = TYPE_STRUCT;
             ty->args = NULL;
             ty->arg_count = 0;
diff --git a/src/parser/parser_utils.c b/src/parser/parser_utils.c
index 6129990..51d89d7 100644
--- a/src/parser/parser_utils.c
+++ b/src/parser/parser_utils.c
@@ -1948,8 +1948,11 @@ void instantiate_generic(ParserContext *ctx, const char *tpl, const char *arg, T
         ASTNode *i = ast_create(NODE_STRUCT);
         i->strct.name = xstrdup(m);
         i->strct.is_template = 0;
-        i->strct.fields = copy_fields_replacing(ctx, t->struct_node->strct.fields,
-                                                t->struct_node->strct.generic_param, arg);
+        // Use first generic param for substitution (single-param backward compat)
+        const char *gp = (t->struct_node->strct.generic_param_count > 0)
+                             ? t->struct_node->strct.generic_params[0]
+                             : "T";
+        i->strct.fields = copy_fields_replacing(ctx, t->struct_node->strct.fields, gp, arg);
         struct_node_copy = i;
         register_struct_def(ctx, m, i);
     }
@@ -2004,6 +2007,95 @@ void instantiate_generic(ParserContext *ctx, const char *tpl, const char *arg, T
     }
 }
 
+void instantiate_generic_multi(ParserContext *ctx, const char *tpl, char **args, int arg_count,
+                               Token token)
+{
+    // Build mangled name from all args
+    char m[256];
+    strcpy(m, tpl);
+    for (int i = 0; i < arg_count; i++)
+    {
+        char *clean = sanitize_mangled_name(args[i]);
+        strcat(m, "_");
+        strcat(m, clean);
+        free(clean);
+    }
+
+    // Check if already instantiated
+    Instantiation *c = ctx->instantiations;
+    while (c)
+    {
+        if (strcmp(c->name, m) == 0)
+        {
+            return; // Already done
+        }
+        c = c->next;
+    }
+
+    // Find the template
+    GenericTemplate *t = ctx->templates;
+    while (t)
+    {
+        if (strcmp(t->name, tpl) == 0)
+        {
+            break;
+        }
+        t = t->next;
+    }
+    if (!t)
+    {
+        zpanic_at(token, "Unknown generic: %s", tpl);
+    }
+
+    // Register instantiation first (to break cycles)
+    Instantiation *ni = xmalloc(sizeof(Instantiation));
+    ni->name = xstrdup(m);
+    ni->template_name = xstrdup(tpl);
+    ni->concrete_arg = (arg_count > 0) ? xstrdup(args[0]) : xstrdup("T");
+    ni->struct_node = NULL;
+    ni->next = ctx->instantiations;
+    ctx->instantiations = ni;
+
+    if (t->struct_node->type == NODE_STRUCT)
+    {
+        ASTNode *i = ast_create(NODE_STRUCT);
+        i->strct.name = xstrdup(m);
+        i->strct.is_template = 0;
+
+        // Copy fields with sequential substitutions for each param
+        ASTNode *fields = t->struct_node->strct.fields;
+        int param_count = t->struct_node->strct.generic_param_count;
+
+        // Perform substitution for each param (simple approach: copy for first param, then replace
+        // in-place)
+        if (param_count > 0 && arg_count > 0)
+        {
+            // First substitution
+            i->strct.fields = copy_fields_replacing(
+                ctx, fields, t->struct_node->strct.generic_params[0], args[0]);
+
+            // Subsequent substitutions (for params B, C, etc.)
+            for (int j = 1; j < param_count && j < arg_count; j++)
+            {
+                ASTNode *tmp = copy_fields_replacing(
+                    ctx, i->strct.fields, t->struct_node->strct.generic_params[j], args[j]);
+                // This leaks prev fields, but that's acceptable for now, still, TODO.
+                i->strct.fields = tmp;
+            }
+        }
+        else
+        {
+            i->strct.fields = copy_fields_replacing(ctx, fields, "T", "int");
+        }
+
+        ni->struct_node = i;
+        register_struct_def(ctx, m, i);
+
+        i->next = ctx->instantiated_structs;
+        ctx->instantiated_structs = i;
+    }
+}
+
 int is_file_imported(ParserContext *ctx, const char *p)
 {
     ImportedFile *c = ctx->imported_files;