Introduce find pattern [Feature #16828]

10 files changed, 449 insertions, 10 deletions

diff --git a/NEWS.md b/NEWS.md
index 6856a29517..8b92aa45b0 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -38,6 +38,18 @@ sufficient information, see the ChangeLog file or Redmine
   instead of a warning. yield in a class definition outside of a method
   is now a SyntaxError instead of a LocalJumpError.  [[Feature #15575]]
 
+* Find pattern is added. [[Feature #16828]]
+
+    ```ruby
+    case ["a", 1, "b", "c", 2, "d", "e", "f", 3]
+    in [*pre, String => x, String => y, *post]
+      p pre  #=> ["a", 1]
+      p x    #=> "b"
+      p y    #=> "c"
+      p post #=> [2, "d", "e", "f", 3]
+    end
+    ```
+
 * Rightward assignment statement is added.  [EXPERIMENTAL]
   [[Feature #15921]]
 
diff --git a/ast.c b/ast.c
index 18a97239ff..44fec1645c 100644
--- a/ast.c
+++ b/ast.c
@@ -599,6 +599,19 @@ node_children(rb_ast_t *ast, NODE *node)
                                         rest,
                                         NEW_CHILD(ast, apinfo->post_args));
         }
+      case NODE_FNDPTN:
+        {
+            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
+            VALUE pre_rest = NODE_NAMED_REST_P(fpinfo->pre_rest_arg) ? NEW_CHILD(ast, fpinfo->pre_rest_arg) :
+                                                                       ID2SYM(rb_intern("NODE_SPECIAL_NO_NAME_REST"));
+            VALUE post_rest = NODE_NAMED_REST_P(fpinfo->post_rest_arg) ? NEW_CHILD(ast, fpinfo->post_rest_arg) :
+                                                                         ID2SYM(rb_intern("NODE_SPECIAL_NO_NAME_REST"));
+            return rb_ary_new_from_args(4,
+                                        NEW_CHILD(ast, node->nd_pconst),
+                                        pre_rest,
+                                        NEW_CHILD(ast, fpinfo->args),
+                                        post_rest);
+        }
       case NODE_HSHPTN:
         {
             VALUE kwrest = node->nd_pkwrestarg == NODE_SPECIAL_NO_REST_KEYWORD ? ID2SYM(rb_intern("NODE_SPECIAL_NO_REST_KEYWORD")) :
diff --git a/compile.c b/compile.c
index 5a7a088f61..9fba24f0fa 100644
--- a/compile.c
+++ b/compile.c
@@ -5752,6 +5752,173 @@ iseq_compile_pattern_each(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *c
 
         break;
       }
+      case NODE_FNDPTN: {
+        /*
+         *   if pattern.has_constant_node?
+         *     unless pattern.constant === obj
+         *       goto match_failed
+         *     end
+         *   end
+         *   unless obj.respond_to?(:deconstruct)
+         *     goto match_failed
+         *   end
+         *   d = obj.deconstruct
+         *   unless Array === d
+         *     goto type_error
+         *   end
+         *   unless d.length >= pattern.args_num
+         *     goto match_failed
+         *   end
+         *
+         *   begin
+         *     len = d.length
+         *     limit = d.length - pattern.args_num
+         *     i = 0
+         *     while i <= limit
+         *       if pattern.args_num.times.all? {|j| pattern.args[j].match?(d[i+j]) }
+         *         if pattern.has_pre_rest_arg_id
+         *           unless pattern.pre_rest_arg.match?(d[0, i])
+         *             goto find_failed
+         *           end
+         *         end
+         *         if pattern.has_post_rest_arg_id
+         *           unless pattern.post_rest_arg.match?(d[i+pattern.args_num, len])
+         *             goto find_failed
+         *           end
+         *         end
+         *         goto find_succeeded
+         *       end
+         *       i+=1
+         *     end
+         *   find_failed:
+         *     goto match_failed
+         *   find_succeeded:
+         *   end
+         *
+         *   goto matched
+         * type_error:
+         *   FrozenCore.raise TypeError
+         * match_failed:
+         *   goto unmatched
+         */
+        struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
+        const NODE *args = fpinfo->args;
+        const int args_num = fpinfo->args ? rb_long2int(fpinfo->args->nd_alen) : 0;
+
+        LABEL *match_failed, *type_error;
+        match_failed = NEW_LABEL(line);
+        type_error = NEW_LABEL(line);
+
+        if (node->nd_pconst) {
+            ADD_INSN(ret, line, dup);
+            CHECK(COMPILE(ret, "constant", node->nd_pconst));
+            ADD_INSN1(ret, line, checkmatch, INT2FIX(VM_CHECKMATCH_TYPE_CASE));
+            ADD_INSNL(ret, line, branchunless, match_failed);
+        }
+
+        ADD_INSN(ret, line, dup);
+        ADD_INSN1(ret, line, putobject, ID2SYM(rb_intern("deconstruct")));
+        ADD_SEND(ret, line, idRespond_to, INT2FIX(1));
+        ADD_INSNL(ret, line, branchunless, match_failed);
+
+        ADD_SEND(ret, line, rb_intern("deconstruct"), INT2FIX(0));
+
+        ADD_INSN(ret, line, dup);
+        ADD_INSN1(ret, line, checktype, INT2FIX(T_ARRAY));
+        ADD_INSNL(ret, line, branchunless, type_error);
+
+        ADD_INSN(ret, line, dup);
+        ADD_SEND(ret, line, idLength, INT2FIX(0));
+        ADD_INSN1(ret, line, putobject, INT2FIX(args_num));
+        ADD_SEND(ret, line, idGE, INT2FIX(1));
+        ADD_INSNL(ret, line, branchunless, match_failed);
+
+        {
+            LABEL *while_begin = NEW_LABEL(nd_line(node));
+            LABEL *next_loop = NEW_LABEL(nd_line(node));
+            LABEL *find_succeeded = NEW_LABEL(line);
+            LABEL *find_failed = NEW_LABEL(nd_line(node));
+            int j;
+
+            ADD_INSN(ret, line, dup); /* allocate stack for len */
+            ADD_SEND(ret, line, idLength, INT2FIX(0));
+
+            ADD_INSN(ret, line, dup); /* allocate stack for limit */
+            ADD_INSN1(ret, line, putobject, INT2FIX(args_num));
+            ADD_SEND(ret, line, idMINUS, INT2FIX(1));
+
+            ADD_INSN1(ret, line, putobject, INT2FIX(0)); /* allocate stack for i */
+
+            ADD_LABEL(ret, while_begin);
+
+            ADD_INSN(ret, line, dup);
+            ADD_INSN1(ret, line, topn, INT2FIX(2));
+            ADD_SEND(ret, line, idLE, INT2FIX(1));
+            ADD_INSNL(ret, line, branchunless, find_failed);
+
+            for (j = 0; j < args_num; j++) {
+                ADD_INSN1(ret, line, topn, INT2FIX(3));
+                ADD_INSN1(ret, line, topn, INT2FIX(1));
+                if (j != 0) {
+                    ADD_INSN1(ret, line, putobject, INT2FIX(j));
+                    ADD_SEND(ret, line, idPLUS, INT2FIX(1));
+                }
+                ADD_SEND(ret, line, idAREF, INT2FIX(1));
+
+                CHECK(iseq_compile_pattern_match(iseq, ret, args->nd_head, next_loop, in_alt_pattern));
+                args = args->nd_next;
+            }
+
+            if (NODE_NAMED_REST_P(fpinfo->pre_rest_arg)) {
+                ADD_INSN1(ret, line, topn, INT2FIX(3));
+                ADD_INSN1(ret, line, putobject, INT2FIX(0));
+                ADD_INSN1(ret, line, topn, INT2FIX(2));
+                ADD_SEND(ret, line, idAREF, INT2FIX(2));
+                CHECK(iseq_compile_pattern_match(iseq, ret, fpinfo->pre_rest_arg, find_failed, in_alt_pattern));
+            }
+            if (NODE_NAMED_REST_P(fpinfo->post_rest_arg)) {
+                ADD_INSN1(ret, line, topn, INT2FIX(3));
+                ADD_INSN1(ret, line, topn, INT2FIX(1));
+                ADD_INSN1(ret, line, putobject, INT2FIX(args_num));
+                ADD_SEND(ret, line, idPLUS, INT2FIX(1));
+                ADD_INSN1(ret, line, topn, INT2FIX(3));
+                ADD_SEND(ret, line, idAREF, INT2FIX(2));
+                CHECK(iseq_compile_pattern_match(iseq, ret, fpinfo->post_rest_arg, find_failed, in_alt_pattern));
+            }
+            ADD_INSNL(ret, line, jump, find_succeeded);
+
+            ADD_LABEL(ret, next_loop);
+            ADD_INSN1(ret, line, putobject, INT2FIX(1));
+            ADD_SEND(ret, line, idPLUS, INT2FIX(1));
+            ADD_INSNL(ret, line, jump, while_begin);
+
+            ADD_LABEL(ret, find_failed);
+            ADD_INSN(ret, line, pop);
+            ADD_INSN(ret, line, pop);
+            ADD_INSN(ret, line, pop);
+            ADD_INSNL(ret, line, jump, match_failed);
+
+            ADD_LABEL(ret, find_succeeded);
+            ADD_INSN(ret, line, pop);
+            ADD_INSN(ret, line, pop);
+            ADD_INSN(ret, line, pop);
+        }
+
+        ADD_INSN(ret, line, pop);
+        ADD_INSNL(ret, line, jump, matched);
+
+        ADD_LABEL(ret, type_error);
+        ADD_INSN1(ret, line, putspecialobject, INT2FIX(VM_SPECIAL_OBJECT_VMCORE));
+        ADD_INSN1(ret, line, putobject, rb_eTypeError);
+        ADD_INSN1(ret, line, putobject, rb_fstring_lit("deconstruct must return Array"));
+        ADD_SEND(ret, line, id_core_raise, INT2FIX(2));
+
+        ADD_LABEL(ret, match_failed);
+        ADD_INSN(ret, line, pop);
+        ADD_INSNL(ret, line, jump, unmatched);
+
+        break;
+      }
       case NODE_HSHPTN: {
         /*
          *   keys = nil
diff --git a/ext/objspace/objspace.c b/ext/objspace/objspace.c
index 0799944a5b..a3f3ef4845 100644
--- a/ext/objspace/objspace.c
+++ b/ext/objspace/objspace.c
@@ -479,6 +479,7 @@ count_nodes(int argc, VALUE *argv, VALUE os)
 		COUNT_NODE(NODE_ATTRASGN);
 		COUNT_NODE(NODE_LAMBDA);
 		COUNT_NODE(NODE_ARYPTN);
+		COUNT_NODE(NODE_FNDPTN);
 		COUNT_NODE(NODE_HSHPTN);
 #undef COUNT_NODE
 	      case NODE_LAST: break;
diff --git a/node.c b/node.c
index 9decd803ce..4ef18db544 100644
--- a/node.c
+++ b/node.c
@@ -1053,6 +1053,27 @@ dump_node(VALUE buf, VALUE indent, int comment, const NODE * node)
         F_NODE(nd_apinfo->post_args, "post arguments");
         return;
 
+      case NODE_FNDPTN:
+        ANN("find pattern");
+        ANN("format: [nd_pconst](*[pre_rest_arg], args, ..., *[post_rest_arg])");
+        F_NODE(nd_pconst, "constant");
+        if (NODE_NAMED_REST_P(node->nd_fpinfo->pre_rest_arg)) {
+            F_NODE(nd_fpinfo->pre_rest_arg, "pre rest argument");
+        }
+        else {
+            F_MSG(nd_fpinfo->pre_rest_arg, "pre rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
+        }
+        F_NODE(nd_fpinfo->args, "arguments");
+
+        LAST_NODE;
+        if (NODE_NAMED_REST_P(node->nd_fpinfo->post_rest_arg)) {
+            F_NODE(nd_fpinfo->post_rest_arg, "post rest argument");
+        }
+        else {
+            F_MSG(nd_fpinfo->post_rest_arg, "post rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
+        }
+        return;
+
       case NODE_HSHPTN:
         ANN("hash pattern");
         ANN("format: [nd_pconst]([nd_pkwargs], ..., **[nd_pkwrestarg])");
@@ -1204,6 +1225,7 @@ rb_ast_newnode(rb_ast_t *ast, enum node_type type)
       case NODE_ARGS:
       case NODE_SCOPE:
       case NODE_ARYPTN:
+      case NODE_FNDPTN:
         return ast_newnode_in_bucket(&nb->markable);
       default:
         return ast_newnode_in_bucket(&nb->unmarkable);
@@ -1271,6 +1293,12 @@ mark_ast_value(void *ctx, NODE * node)
             rb_gc_mark_movable(apinfo->imemo);
             break;
         }
+      case NODE_FNDPTN:
+        {
+            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
+            rb_gc_mark_movable(fpinfo->imemo);
+            break;
+        }
       case NODE_ARGS:
         {
             struct rb_args_info *args = node->nd_ainfo;
@@ -1311,6 +1339,12 @@ update_ast_value(void *ctx, NODE * node)
             apinfo->imemo = rb_gc_location(apinfo->imemo);
             break;
         }
+      case NODE_FNDPTN:
+        {
+            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
+            fpinfo->imemo = rb_gc_location(fpinfo->imemo);
+            break;
+        }
       case NODE_ARGS:
         {
             struct rb_args_info *args = node->nd_ainfo;
diff --git a/node.h b/node.h
index 805491b87e..60e9604f46 100644
--- a/node.h
+++ b/node.h
@@ -123,6 +123,7 @@ enum node_type {
     NODE_LAMBDA,
     NODE_ARYPTN,
     NODE_HSHPTN,
+    NODE_FNDPTN,
     NODE_LAST
 };
 
@@ -166,6 +167,7 @@ typedef struct RNode {
 	struct rb_global_entry *entry;
 	struct rb_args_info *args;
 	struct rb_ary_pattern_info *apinfo;
+	struct rb_fnd_pattern_info *fpinfo;
 	VALUE value;
     } u3;
     rb_code_location_t nd_loc;
@@ -278,6 +280,8 @@ typedef struct RNode {
 
 #define nd_apinfo u3.apinfo
 
+#define nd_fpinfo u3.fpinfo
+
 #define NEW_NODE(t,a0,a1,a2,loc) rb_node_newnode((t),(VALUE)(a0),(VALUE)(a1),(VALUE)(a2),loc)
 #define NEW_NODE_WITH_LOCALS(t,a1,a2,loc) node_newnode_with_locals(p, (t),(VALUE)(a1),(VALUE)(a2),loc)
 
@@ -456,6 +460,13 @@ struct rb_ary_pattern_info {
     VALUE imemo;
 };
 
+struct rb_fnd_pattern_info {
+    NODE *pre_rest_arg;
+    NODE *args;
+    NODE *post_rest_arg;
+    VALUE imemo;
+};
+
 struct parser_params;
 void *rb_parser_malloc(struct parser_params *, size_t);
 void *rb_parser_realloc(struct parser_params *, void *, size_t);
diff --git a/parse.y b/parse.y
index 38640664d0..2c8b1ab97a 100644
--- a/parse.y
+++ b/parse.y
@@ -496,6 +496,8 @@ static NODE *new_args(struct parser_params*,NODE*,NODE*,ID,NODE*,NODE*,const YYL
 static NODE *new_args_tail(struct parser_params*,NODE*,ID,ID,const YYLTYPE*);
 static NODE *new_array_pattern(struct parser_params *p, NODE *constant, NODE *pre_arg, NODE *aryptn, const YYLTYPE *loc);
 static NODE *new_array_pattern_tail(struct parser_params *p, NODE *pre_args, int has_rest, ID rest_arg, NODE *post_args, const YYLTYPE *loc);
+static NODE *new_find_pattern(struct parser_params *p, NODE *constant, NODE *fndptn, const YYLTYPE *loc);
+static NODE *new_find_pattern_tail(struct parser_params *p, ID pre_rest_arg, NODE *args, ID post_rest_arg, const YYLTYPE *loc);
 static NODE *new_hash_pattern(struct parser_params *p, NODE *constant, NODE *hshptn, const YYLTYPE *loc);
 static NODE *new_hash_pattern_tail(struct parser_params *p, NODE *kw_args, ID kw_rest_arg, const YYLTYPE *loc);
 static NODE *new_case3(struct parser_params *p, NODE *val, NODE *pat, const YYLTYPE *loc);
@@ -871,6 +873,42 @@ new_array_pattern_tail(struct parser_params *p, VALUE pre_args, VALUE has_rest,
     return (VALUE)t;
 }
 
+static VALUE
+new_find_pattern(struct parser_params *p, VALUE constant, VALUE fndptn, const YYLTYPE *loc)
+{
+    NODE *t = (NODE *)fndptn;
+    struct rb_fnd_pattern_info *fpinfo = t->nd_fpinfo;
+    VALUE pre_rest_arg = Qnil, args = Qnil, post_rest_arg = Qnil;
+
+    if (fpinfo) {
+        pre_rest_arg = rb_ary_entry(fpinfo->imemo, 0);
+        args = rb_ary_entry(fpinfo->imemo, 1);
+        post_rest_arg = rb_ary_entry(fpinfo->imemo, 2);
+    }
+
+    return dispatch4(fndptn, constant, pre_rest_arg, args, post_rest_arg);
+}
+
+static VALUE
+new_find_pattern_tail(struct parser_params *p, VALUE pre_rest_arg, VALUE args, VALUE post_rest_arg, const YYLTYPE *loc)
+{
+    NODE *t;
+    struct rb_fnd_pattern_info *fpinfo;
+
+    pre_rest_arg = dispatch1(var_field, pre_rest_arg ? pre_rest_arg : Qnil);
+    post_rest_arg = dispatch1(var_field, post_rest_arg ? post_rest_arg : Qnil);
+
+    VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
+    fpinfo = ZALLOC(struct rb_fnd_pattern_info);
+    rb_imemo_tmpbuf_set_ptr(tmpbuf, fpinfo);
+    fpinfo->imemo = rb_ary_new_from_args(4, pre_rest_arg, args, post_rest_arg, tmpbuf);
+
+    t = rb_node_newnode(NODE_FNDPTN, Qnil, Qnil, (VALUE)fpinfo, &NULL_LOC);
+    RB_OBJ_WRITTEN(p->ast, Qnil, fpinfo->imemo);
+
+    return (VALUE)t;
+}
+
 #define new_hash(p,h,l) rb_ary_new_from_args(0)
 
 static VALUE
@@ -1139,14 +1177,14 @@ static int looking_at_eol_p(struct parser_params *p);
 %type <node> brace_block cmd_brace_block do_block lhs none fitem
 %type <node> mlhs mlhs_head mlhs_basic mlhs_item mlhs_node mlhs_post mlhs_inner
 %type <node> p_case_body p_cases p_top_expr p_top_expr_body
-%type <node> p_expr p_as p_alt p_expr_basic
+%type <node> p_expr p_as p_alt p_expr_basic p_find
 %type <node> p_args p_args_head p_args_tail p_args_post p_arg
 %type <node> p_value p_primitive p_variable p_var_ref p_const
 %type <node> p_kwargs p_kwarg p_kw
 %type <id>   keyword_variable user_variable sym operation operation2 operation3
 %type <id>   cname fname op f_rest_arg f_block_arg opt_f_block_arg f_norm_arg f_bad_arg
 %type <id>   f_kwrest f_label f_arg_asgn call_op call_op2 reswords relop dot_or_colon
-%type <id>   p_kwrest p_kwnorest p_any_kwrest p_kw_label
+%type <id>   p_rest p_kwrest p_kwnorest p_any_kwrest p_kw_label
 %type <id>   f_no_kwarg f_any_kwrest args_forward excessed_comma
 %token END_OF_INPUT 0	"end-of-input"
 %token <id> '.'
@@ -3963,6 +4001,10 @@ p_top_expr_body : p_expr
 		    /*%
 		    %*/
 		    }
+		| p_find
+		    {
+			$$ = new_find_pattern(p, Qnone, $1, &@$);
+		    }
 		| p_args_tail
 		    {
 			$$ = new_array_pattern(p, Qnone, Qnone, $1, &@$);
@@ -4011,6 +4053,15 @@ p_expr_basic	: p_value
 		    /*%
 		    %*/
 		    }
+		| p_const p_lparen p_find rparen
+		    {
+			pop_pktbl(p, $<tbl>2);
+			$$ = new_find_pattern(p, $1, $3, &@$);
+		    /*%%%*/
+			nd_set_first_loc($$, @1.beg_pos);
+		    /*%
+		    %*/
+		    }
 		| p_const p_lparen p_kwargs rparen
 		    {
 			pop_pktbl(p, $<tbl>2);
@@ -4034,6 +4085,15 @@ p_expr_basic	: p_value
 		    /*%
 		    %*/
 		    }
+		| p_const p_lbracket p_find rbracket
+		    {
+			pop_pktbl(p, $<tbl>2);
+			$$ = new_find_pattern(p, $1, $3, &@$);
+		    /*%%%*/
+			nd_set_first_loc($$, @1.beg_pos);
+		    /*%
+		    %*/
+		    }
 		| p_const p_lbracket p_kwargs rbracket
 		    {
 			pop_pktbl(p, $<tbl>2);
@@ -4052,6 +4112,10 @@ p_expr_basic	: p_value
 		    {
 			$$ = new_array_pattern(p, Qnone, Qnone, $2, &@$);
 		    }
+		| tLBRACK p_find rbracket
+		    {
+			$$ = new_find_pattern(p, Qnone, $2, &@$);
+		    }
 		| tLBRACK rbracket
 		    {
 			$$ = new_array_pattern_tail(p, Qnone, 0, 0, Qnone, &@$);
@@ -4135,21 +4199,30 @@ p_args_head	: p_arg ','
 		    }
 		;
 
-p_args_tail	: tSTAR tIDENTIFIER
+p_args_tail	: p_rest
 		    {
-			$$ = new_array_pattern_tail(p, Qnone, 1, $2, Qnone, &@$);
+			$$ = new_array_pattern_tail(p, Qnone, 1, $1, Qnone, &@$);
 		    }
-		| tSTAR tIDENTIFIER ',' p_args_post
+		| p_rest ',' p_args_post
 		    {
-			$$ = new_array_pattern_tail(p, Qnone, 1, $2, $4, &@$);
+			$$ = new_array_pattern_tail(p, Qnone, 1, $1, $3, &@$);
 		    }
-		| tSTAR
+		;
+
+p_find		: p_rest ',' p_args_post ',' p_rest
 		    {
-			$$ = new_array_pattern_tail(p, Qnone, 1, 0, Qnone, &@$);
+			$$ = new_find_pattern_tail(p, $1, $3, $5, &@$);
+		    }
+		;
+
+
+p_rest		: tSTAR tIDENTIFIER
+		    {
+			$$ = $2;
 		    }
-		| tSTAR ',' p_args_post
+		| tSTAR
 		    {
-			$$ = new_array_pattern_tail(p, Qnone, 1, 0, $3, &@$);
+			$$ = 0;
 		    }
 		;
 
@@ -11537,6 +11610,34 @@ new_array_pattern_tail(struct parser_params *p, NODE *pre_args, int has_rest, ID
 }
 
 static NODE*
+new_find_pattern(struct parser_params *p, NODE *constant, NODE *fndptn, const YYLTYPE *loc)
+{
+    fndptn->nd_pconst = constant;
+
+    return fndptn;
+}
+
+static NODE*
+new_find_pattern_tail(struct parser_params *p, ID pre_rest_arg, NODE *args, ID post_rest_arg, const YYLTYPE *loc)
+{
+    int saved_line = p->ruby_sourceline;
+    NODE *node;
+    VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
+    struct rb_fnd_pattern_info *fpinfo = ZALLOC(struct rb_fnd_pattern_info);
+    rb_imemo_tmpbuf_set_ptr(tmpbuf, fpinfo);
+    node = NEW_NODE(NODE_FNDPTN, 0, 0, fpinfo, loc);
+    fpinfo->imemo = tmpbuf;
+    RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
+
+    fpinfo->pre_rest_arg = pre_rest_arg ? assignable(p, pre_rest_arg, 0, loc) : NODE_SPECIAL_NO_NAME_REST;
+    fpinfo->args = args;
+    fpinfo->post_rest_arg = post_rest_arg ? assignable(p, post_rest_arg, 0, loc) : NODE_SPECIAL_NO_NAME_REST;
+
+    p->ruby_sourceline = saved_line;
+    return node;
+}
+
+static NODE*
 new_hash_pattern(struct parser_params *p, NODE *constant, NODE *hshptn, const YYLTYPE *loc)
 {
     hshptn->nd_pconst = constant;
diff --git a/test/ripper/test_parser_events.rb b/test/ripper/test_parser_events.rb
index 544896b15f..d61dba340d 100644
--- a/test/ripper/test_parser_events.rb
+++ b/test/ripper/test_parser_events.rb
@@ -1548,6 +1548,12 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
     assert_equal true, thru_aryptn
   end
 
+  def test_fndptn
+    thru_fndptn = false
+    parse('case 0; in [*,0,*]; end', :on_fndptn) {thru_fndptn = true}
+    assert_equal true, thru_fndptn
+  end
+
   def test_hshptn
     thru_hshptn = false
     parse('case 0; in {a:}; end', :on_hshptn) {thru_hshptn = true}
diff --git a/test/ripper/test_sexp.rb b/test/ripper/test_sexp.rb
index 89b45941a3..47339ba496 100644
--- a/test/ripper/test_sexp.rb
+++ b/test/ripper/test_sexp.rb
@@ -412,6 +412,43 @@ eot
       [:@int, "0", [1, 5]],
       [:in, [:aryptn, nil, nil, nil, nil], [[:void_stmt]], nil]],
 
+    [__LINE__, %q{ 0 in [*, a, *] }] =>
+    [:case,
+      [:@int, "0", [1, 0]],
+      [:in,
+        [:fndptn,
+          nil,
+          [:var_field, nil],
+          [[:var_field, [:@ident, "a", [1, 9]]]],
+          [:var_field, nil]],
+        nil,
+        nil]],
+
+    [__LINE__, %q{ 0 in [*a, b, *c] }] =>
+    [:case,
+      [:@int, "0", [1, 0]],
+      [:in,
+        [:fndptn,
+          nil,
+          [:var_field, [:@ident, "a", [1, 7]]],
+          [[:var_field, [:@ident, "b", [1, 10]]]],
+          [:var_field, [:@ident, "c", [1, 14]]]],
+        nil,
+        nil]],
+
+    [__LINE__, %q{ 0 in A(*a, b, c, *d) }] =>
+    [:case,
+      [:@int, "0", [1, 0]],
+      [:in,
+        [:fndptn,
+          [:var_ref, [:@const, "A", [1, 5]]],
+          [:var_field, [:@ident, "a", [1, 8]]],
+          [[:var_field, [:@ident, "b", [1, 11]]],
+            [:var_field, [:@ident, "c", [1, 14]]]],
+          [:var_field, [:@ident, "d", [1, 18]]]],
+        nil,
+        nil]],
+
     [__LINE__, %q{ case 0; in {a: 0}; end }] =>
     [:case,
       [:@int, "0", [1, 5]],
diff --git a/test/ruby/test_pattern_matching.rb b/test/ruby/test_pattern_matching.rb
index 2afa823d53..de8515b397 100644
--- a/test/ruby/test_pattern_matching.rb
+++ b/test/ruby/test_pattern_matching.rb
@@ -736,6 +736,63 @@ END
     end
   end
 
+  def test_find_pattern
+    [0, 1, 2] in [*, 1 => a, *]
+    assert_equal(1, a)
+
+    [0, 1, 2] in [*a, 1 => b, *c]
+    assert_equal([0], a)
+    assert_equal(1, b)
+    assert_equal([2], c)
+
+    assert_block do
+      case [0, 1, 2]
+      in [*, 9, *]
+        false
+      else
+        true
+      end
+    end
+
+    assert_block do
+      case [0, 1, 2]
+      in [*, Integer, String, *]
+        false
+      else
+        true
+      end
+    end
+
+    [0, 1, 2] in [*a, 1 => b, 2 => c, *d]
+    assert_equal([0], a)
+    assert_equal(1, b)
+    assert_equal(2, c)
+    assert_equal([], d)
+
+    case [0, 1, 2]
+    in *, 1 => a, *;
+        assert_equal(1, a)
+    end
+
+    assert_block do
+      case [0, 1, 2]
+      in String(*, 1, *)
+        false
+      in Array(*, 1, *)
+        true
+      end
+    end
+
+    assert_block do
+      case [0, 1, 2]
+      in String[*, 1, *]
+        false
+      in Array[*, 1, *]
+        true
+      end
+    end
+  end
+
   def test_hash_pattern
     assert_block do
       [{}, C.new({})].all? do |i|