Add new specifiers/modifiers to format string of `mrb_vfromat()`

Format sequence syntax:

  %[modifier]specifier

Modifiers:

  ----------+------------------------------------------------------------
  Modifier  | Meaning
  ----------+------------------------------------------------------------
      !     | Convert to string by corresponding `inspect` instead of
            | corresponding `to_s`.
  ----------+------------------------------------------------------------

Specifiers:

  ----------+----------------+--------------------------------------------
  Specifier | Argument Type  | Note
  ----------+----------------+--------------------------------------------
      c     | char           |
     d,i    | mrb_int        |
      f     | mrb_float      |
      l     | char*, mrb_int | Arguments are string and length.
      n     | mrb_sym        |
      s     | char*          | Argument is NUL terminated string.
      t     | mrb_value      | Convert to type (class) of object.
     v,S    | mrb_value      |
      C     | struct RClass* |
      T     | mrb_value      | Convert to real type (class) of object.
      Y     | mrb_value      | Same as `!v` if argument is `true`, `false`
            |                | or `nil`, otherwise same as `T`.
      %     | -              | Convert to percent sign itself (no argument
            |                | taken).
  ----------+----------------+--------------------------------------------

This change will increase the binary size, but replacing all format strings
with new specifiers/modifiers will decrease the size because it reduces
inline expansion of `mrb_obj_value()`, etc. at the caller.

5 files changed, 404 insertions, 42 deletions

diff --git a/mrbgems/mruby-test/driver.c b/mrbgems/mruby-test/driver.c
index b6c9fab35..a5f723927 100644
--- a/mrbgems/mruby-test/driver.c
+++ b/mrbgems/mruby-test/driver.c
@@ -21,6 +21,7 @@
 extern const uint8_t mrbtest_assert_irep[];
 
 void mrbgemtest_init(mrb_state* mrb);
+void mrb_init_test_vformat(mrb_state* mrb);
 
 /* Print a short remark for the user */
 static void
@@ -231,6 +232,8 @@ mrb_init_test_driver(mrb_state *mrb, mrb_bool verbose)
 #endif
 #endif
 
+  mrb_init_test_vformat(mrb);
+
   if (verbose) {
     mrb_gv_set(mrb, mrb_intern_lit(mrb, "$mrbtest_verbose"), mrb_true_value());
   }
diff --git a/mrbgems/mruby-test/mrbgem.rake b/mrbgems/mruby-test/mrbgem.rake
index dcb7bb719..bf90e0791 100644
--- a/mrbgems/mruby-test/mrbgem.rake
+++ b/mrbgems/mruby-test/mrbgem.rake
@@ -15,8 +15,9 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
   mrbtest_lib = libfile("#{build_dir}/mrbtest")
   mrbtest_objs = []
 
-  driver_obj = objfile("#{build_dir}/driver")
-  # driver = "#{spec.dir}/driver.c"
+  driver_objs = Dir.glob("#{dir}/*.{c,cpp,cxx,cc,m,asm,s,S}").map do |f|
+    objfile(f.relative_path_from(dir).to_s.pathmap("#{build_dir}/%X"))
+  end
 
   assert_c = "#{build_dir}/assert.c"
   assert_rb = "#{MRUBY_ROOT}/test/assert.rb"
@@ -133,7 +134,7 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
   end
 
   unless build.build_mrbtest_lib_only?
-    file exec => [driver_obj, mlib, mrbtest_lib, build.libmruby_static] do |t|
+    file exec => [*driver_objs, mlib, mrbtest_lib, build.libmruby_static] do |t|
       gem_flags = build.gems.map { |g| g.linker.flags }
       gem_flags_before_libraries = build.gems.map { |g| g.linker.flags_before_libraries }
       gem_flags_after_libraries = build.gems.map { |g| g.linker.flags_after_libraries }
diff --git a/mrbgems/mruby-test/vformat.c b/mrbgems/mruby-test/vformat.c
new file mode 100644
index 000000000..a10e49b08
--- /dev/null
+++ b/mrbgems/mruby-test/vformat.c
@@ -0,0 +1,186 @@
+#include <string.h>
+#include <mruby.h>
+#include <mruby/class.h>
+#include <mruby/data.h>
+#include <mruby/string.h>
+
+#define NATIVE_TYPES                                                        \
+  char c;                                                                   \
+  mrb_float f;                                                              \
+  mrb_int i;                                                                \
+  mrb_sym n;                                                                \
+  char *s;                                                                  \
+  struct RClass *C
+
+typedef enum {
+  ARG_c,
+  ARG_f,
+  ARG_i,
+  ARG_n,
+  ARG_s,
+  ARG_C,
+  ARG_v,
+} VFArgumentType;
+
+typedef struct {
+  VFArgumentType type;
+  union { NATIVE_TYPES; };
+} VFNative;
+
+typedef struct {
+  VFArgumentType type;
+  union {
+    NATIVE_TYPES;
+    mrb_value v;
+  };
+} VFArgument;
+
+static void
+native_free(mrb_state *mrb, void *data)
+{
+  VFNative *native = (VFNative*)data;
+  if (native->type == ARG_s) mrb_free(mrb, native->s);
+  mrb_free(mrb, native);
+}
+
+static const struct mrb_data_type native_data_type = {
+  "TestVFormat::Native", native_free
+};
+
+static mrb_value
+native_initialize(mrb_state *mrb, mrb_value self)
+{
+  VFNative data, *datap;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+  switch (mrb_type(obj)) {
+    case MRB_TT_FLOAT:
+      data.f = mrb_float(obj);
+      data.type = ARG_f;
+      break;
+    case MRB_TT_FIXNUM:
+      data.i = mrb_fixnum(obj);
+      data.type = ARG_i;
+      break;
+    case MRB_TT_SYMBOL:
+      data.n = mrb_symbol(obj);
+      data.type = ARG_n;
+      break;
+    case MRB_TT_CLASS: case MRB_TT_SCLASS: case MRB_TT_MODULE:
+      data.C = mrb_class_ptr(obj);
+      data.type = ARG_C;
+      break;
+    case MRB_TT_STRING: {
+      mrb_int len = RSTRING_LEN(obj);
+      const char *s = RSTRING_PTR(obj);
+      if (len == 1) {
+        /* one byte string is considered char */
+        data.c = s[0];
+        data.type = ARG_c;
+      }
+      else {
+        data.s = (char*)mrb_malloc(mrb, len + 1);
+        memcpy(data.s, s, len);
+        data.s[len] = '\0';
+        data.type = ARG_s;
+      }
+      break;
+    }
+    default: {
+      mrb_value msg = mrb_str_new_cstr(mrb, "native type for ");
+      mrb_str_cat_cstr(mrb, msg, mrb_class_name(mrb, mrb_class(mrb, obj)));
+      mrb_str_cat_cstr(mrb, msg, " is unknown");
+      mrb_raise(mrb, E_ARGUMENT_ERROR, RSTRING_PTR(msg));
+    }
+  }
+
+  datap = (VFNative*)mrb_malloc(mrb, sizeof(VFNative));
+  *datap = data;
+  mrb_data_init(self, datap, &native_data_type);
+  return self;
+}
+
+static VFArgument*
+arg_from_obj(mrb_state *mrb, mrb_value obj, struct RClass *native_class,
+             VFArgument *vf_arg)
+{
+  if (mrb_obj_is_instance_of(mrb, obj, native_class)) {
+    const VFNative *native = (VFNative*)DATA_PTR(obj);
+    *(VFNative*)vf_arg = *native;
+  }
+  else {
+    vf_arg->v = obj;
+    vf_arg->type = ARG_v;
+  }
+  return vf_arg;
+}
+
+#define VF_FORMAT_INIT(klass)                                               \
+  struct RClass *vf_native_class =                                          \
+    mrb_class_get_under(mrb, mrb_class_ptr(klass), "Native");               \
+  VFArgument vf_args[2];
+
+#define VF_ARG(args, idx) \
+  arg_from_obj(mrb, args[idx], vf_native_class, &vf_args[idx])
+
+#define VF_FORMAT0(fmt) mrb_format(mrb, fmt);
+#define VF_FORMAT1(fmt, args) \
+  (VF_ARG(args, 0), VF_FORMAT_TYPED(fmt, 1, vf_args, NULL))
+#define VF_FORMAT2(fmt, args) (                                             \
+  VF_ARG(args, 0), VF_ARG(args, 1),                                         \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, c) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, f) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, i) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, n) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, s) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, C) :                        \
+  VF_FORMAT2_COND_EXPR(fmt, vf_args, vf_args+1, v) :                        \
+  mrb_nil_value()  /* not reached */                                        \
+)
+#define VF_FORMAT2_COND_EXPR(fmt, a1, a2, t) \
+  a1->type == ARG_##t ? VF_FORMAT_TYPED(fmt, 2, a2, (a1)->t)
+#define VF_FORMAT_TYPED(fmt, n_arg, type_a, v1)                             \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, c) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, f) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, i) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, n) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, s) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, C) :                    \
+  VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, v) :                    \
+  mrb_nil_value()  /* not reached */
+#define VF_FORMAT_TYPED_COND_EXPR(fmt, n_arg, type_a, v1, t)                \
+  (type_a)->type == ARG_##t ? n_arg == 1 ?                                  \
+    mrb_format(mrb, fmt, (type_a)->t) : mrb_format(mrb, fmt, v1, (type_a)->t)
+
+static mrb_value
+vf_s_format(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value fmt_str, args[2];
+  mrb_int argc = mrb_get_args(mrb, "S|oo", &fmt_str, args, args+1);
+  const char *fmt = mrb_string_value_cstr(mrb, &fmt_str);
+
+  VF_FORMAT_INIT(klass);
+
+  switch (argc) {
+    case 1: return VF_FORMAT0(fmt);
+    case 2: return VF_FORMAT1(fmt, args);
+    case 3: return VF_FORMAT2(fmt, args);
+    default: return mrb_nil_value();  /* not reached */
+  }
+}
+
+void
+mrb_init_test_vformat(mrb_state *mrb)
+{
+  struct RClass *vf, *n;
+
+  vf = mrb_define_module(mrb, "TestVFormat");
+  mrb_define_class_method(mrb, vf, "format", vf_s_format, MRB_ARGS_ARG(1,2));
+
+  n = mrb_define_class_under(mrb, vf, "Native", mrb->object_class);
+  MRB_SET_INSTANCE_TT(n, MRB_TT_DATA);
+  mrb_define_method(mrb, n, "initialize", native_initialize, MRB_ARGS_REQ(1));
+  mrb_singleton_class(mrb, mrb_obj_value(n));
+  mrb_define_alias(mrb, n->c, "[]", "new");
+}
diff --git a/src/error.c b/src/error.c
index 4c1b67c99..d8224622b 100644
--- a/src/error.c
+++ b/src/error.c
@@ -260,59 +260,143 @@ mrb_raise(mrb_state *mrb, struct RClass *c, const char *msg)
   mrb_exc_raise(mrb, mrb_exc_new_str(mrb, c, mrb_str_new_cstr(mrb, msg)));
 }
 
+/*
+ * <code>vsprintf</code> like formatting.
+ *
+ * The syntax of a format sequence is as follows.
+ *
+ *   %[modifier]specifier
+ *
+ * The modifiers are:
+ *
+ *   ----------+------------------------------------------------------------
+ *   Modifier  | Meaning
+ *   ----------+------------------------------------------------------------
+ *       !     | Convert to string by corresponding `inspect` instead of
+ *             | corresponding `to_s`.
+ *   ----------+------------------------------------------------------------
+ *
+ * The specifiers are:
+ *
+ *   ----------+----------------+--------------------------------------------
+ *   Specifier | Argument Type  | Note
+ *   ----------+----------------+--------------------------------------------
+ *       c     | char           |
+ *      d,i    | mrb_int        |
+ *       f     | mrb_float      |
+ *       l     | char*, mrb_int | Arguments are string and length.
+ *       n     | mrb_sym        |
+ *       s     | char*          | Argument is NUL terminated string.
+ *       t     | mrb_value      | Convert to type (class) of object.
+ *      v,S    | mrb_value      |
+ *       C     | struct RClass* |
+ *       T     | mrb_value      | Convert to real type (class) of object.
+ *       Y     | mrb_value      | Same as `!v` if argument is `true`, `false`
+ *             |                | or `nil`, otherwise same as `T`.
+ *       %     | -              | Convert to percent sign itself (no argument
+ *             |                | taken).
+ *   ----------+----------------+--------------------------------------------
+ */
 MRB_API mrb_value
 mrb_vformat(mrb_state *mrb, const char *format, va_list ap)
 {
-  const char *p = format;
-  const char *b = p;
-  ptrdiff_t size;
-  int ai0 = mrb_gc_arena_save(mrb);
-  mrb_value ary = mrb_ary_new_capa(mrb, 4);
+  const char *chars, *p = format, *b = format, *e;
+  char ch;
+  struct RClass *cls;
+  mrb_int len;
+  mrb_bool inspect = FALSE;
+  mrb_value result = mrb_str_new_capa(mrb, 128), obj, str;
   int ai = mrb_gc_arena_save(mrb);
 
   while (*p) {
     const char c = *p++;
-
+    e = p;
     if (c == '%') {
-      if (*p == 'S') {
-        mrb_value val;
-
-        size = p - b - 1;
-        mrb_ary_push(mrb, ary, mrb_str_new(mrb, b, size));
-        val = va_arg(ap, mrb_value);
-        mrb_ary_push(mrb, ary, mrb_obj_as_string(mrb, val));
-        b = p + 1;
+      if (*p == '!') {
+        inspect = TRUE;
+        ++p;
       }
-    }
-    else if (c == '\\') {
-      if (*p) {
-        size = p - b - 1;
-        mrb_ary_push(mrb, ary, mrb_str_new(mrb, b, size));
-        mrb_ary_push(mrb, ary, mrb_str_new(mrb, p, 1));
-        b = ++p;
-      }
-      else {
-        break;
+      if (!*p) break;
+      switch (*p) {
+        case 'c':
+          ch = (char)va_arg(ap, int);
+          chars = &ch;
+          len = 1;
+          goto L_cat;
+        case 'd': case 'i':
+          obj = mrb_fixnum_value(va_arg(ap, mrb_int));
+          goto L_cat_obj;
+        case 'f':
+          obj = mrb_float_value(mrb, va_arg(ap, mrb_float));
+          goto L_cat_obj;
+        case 'l':
+          chars = va_arg(ap, char*);
+          len = va_arg(ap, mrb_int);
+        L_cat:
+          if (inspect) {
+            obj = mrb_str_new(mrb, chars, len);
+            goto L_cat_obj;
+          }
+          mrb_str_cat(mrb, result, b,  e - b - 1);
+          mrb_str_cat(mrb, result, chars, len);
+          b = ++p;
+          mrb_gc_arena_restore(mrb, ai);
+          break;
+        case 'n':
+          obj = mrb_symbol_value(va_arg(ap, mrb_sym));
+          goto L_cat_obj;
+        case 's':
+          chars = va_arg(ap, char*);
+          len = strlen(chars);
+          goto L_cat;
+        case 't':
+          cls = mrb_class(mrb, va_arg(ap, mrb_value));
+          goto L_cat_class;
+        case 'v': case 'S':
+          obj = va_arg(ap, mrb_value);
+        L_cat_obj:
+          str = (inspect ? mrb_inspect : mrb_obj_as_string)(mrb, obj);
+          chars = RSTRING_PTR(str);
+          len = RSTRING_LEN(str);
+          inspect = FALSE;
+          goto L_cat;
+        case 'C':
+          cls = va_arg(ap, struct RClass*);
+        L_cat_class:
+          obj = mrb_obj_value(cls);
+          goto L_cat_obj;
+        case 'T':
+          obj = va_arg(ap, mrb_value);
+        L_cat_real_class_of:
+          cls = mrb_obj_class(mrb, obj);
+          goto L_cat_class;
+        case 'Y':
+          obj = va_arg(ap, mrb_value);
+          if (!mrb_test(obj) || mrb_true_p(obj)) {
+            inspect = TRUE;
+            goto L_cat_obj;
+          }
+          else {
+            goto L_cat_real_class_of;
+          }
+        case '%':
+        L_cat_current:
+          chars = p;
+          len = 1;
+          goto L_cat;
+        default:
+          mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed format string - %%%c", *p);
       }
     }
-    mrb_gc_arena_restore(mrb, ai);
-  }
-  if (b == format) {
-    mrb_gc_arena_restore(mrb, ai0);
-    return mrb_str_new_cstr(mrb, format);
-  }
-  else {
-    mrb_value val;
+    else if (c == '\\') {
+      if (!*p) break;
+      goto L_cat_current;
 
-    size = p - b;
-    if (size > 0) {
-      mrb_ary_push(mrb, ary, mrb_str_new(mrb, b, size));
     }
-    val = mrb_ary_join(mrb, ary, mrb_nil_value());
-    mrb_gc_arena_restore(mrb, ai0);
-    mrb_gc_protect(mrb, val);
-    return val;
   }
+
+  mrb_str_cat(mrb, result, b, p - b);
+  return result;
 }
 
 MRB_API mrb_value
diff --git a/test/t/vformat.rb b/test/t/vformat.rb
new file mode 100644
index 000000000..2270d6490
--- /dev/null
+++ b/test/t/vformat.rb
@@ -0,0 +1,88 @@
+def assert_format(exp, args)
+  assert_equal(exp, TestVFormat.format(*args))
+end
+
+def assert_format_pattern(exp_pattern, args)
+  assert_match(exp_pattern, TestVFormat.format(*args))
+end
+
+# Pass if ArgumentError is raised or return value is +exp+.
+def assert_implementation_dependent(exp, args)
+  begin
+    ret = TestVFormat.format(*args)
+  rescue ArgumentError
+    return pass
+  end
+  if ret == exp
+    pass
+  else
+    flunk "", "Expected ArgumentError is raised or #{ret.inspect} to be #{exp}."
+  end
+end
+
+def sclass(v)
+  class << v
+    self
+  end
+end
+
+assert('mrb_vformat') do
+  n = TestVFormat::Native
+  assert_format '', ['']
+  assert_format 'No specifier!', ['No specifier!']
+  assert_format '`c`: C', ['`c`: %c', n[?C]]
+  assert_format '`d`: 123', ['`d`: %d', n[123]]
+  assert_format '`i`: -83', ['`i`: %i', n[-83]]
+  assert_format '`f`: 0.0125', ['`f`: %f', n[0.0125]]
+  assert_format '`t`: NilClass', ['`t`: %t', nil]
+  assert_format '`t`: FalseClass', ['`t`: %t', false]
+  assert_format '`t`: TrueClass', ['`t`: %t', true]
+  assert_format '`t`: Fixnum', ['`t`: %t', 0]
+  assert_format '`t`: Hash', ['`t`: %t', k: "value"]
+  assert_format_pattern '#<Class:#<Class:#<Hash:0x*>>>', ['%t', sclass({})]
+  assert_format '-Infinity', ['%f', n[-Float::INFINITY]]
+  assert_format 'NaN: Not a Number', ['%f: Not a Number', n[Float::NAN]]
+  assert_format 'string and length', ['string %l length', n['andante'], n[3]]
+  assert_format '`n`: sym', ['`n`: %n', n[:sym]]
+  assert_format '%C文字列%', ['%s', n['%C文字列%']]
+  assert_format '`C`: Kernel module', ['`C`: %C module', n[Kernel]]
+  assert_format '`C`: NilClass', ['`C`: %C', n[nil.class]]
+  assert_format_pattern '#<Class:#<String:0x*>>', ['%C', n[sclass("")]]
+  assert_format '`T`: NilClass', ['`T`: %T', nil]
+  assert_format '`T`: FalseClass', ['`T`: %T', false]
+  assert_format '`T`: TrueClass', ['`T`: %T', true]
+  assert_format '`T`: Fixnum', ['`T`: %T', 0]
+  assert_format '`T`: Hash', ['`T`: %T', k: "value"]
+  assert_format_pattern 'Class', ['%T', sclass({})]
+  assert_format '`Y`: nil', ['`Y`: %Y', nil]
+  assert_format '`Y`: false', ['`Y`: %Y', false]
+  assert_format '`Y`: true', ['`Y`: %Y', true]
+  assert_format '`Y`: Fixnum', ['`Y`: %Y', 0]
+  assert_format '`Y`: Hash', ['`Y`: %Y', k: "value"]
+  assert_format 'Class', ['%Y', sclass({})]
+  assert_format_pattern '#<Class:#<String:0x*>>', ['%v', sclass("")]
+  assert_format '`v`: 1...3', ['`v`: %v', 1...3]
+  assert_format '`S`: {:a=>1, "b"=>"c"}', ['`S`: %S', a: 1, "b" => ?c]
+  assert_format 'percent: %', ['percent: %%']
+  assert_format '"I": inspect char', ['%!c: inspect char', n[?I]]
+  assert_format '709: inspect mrb_int', ['%!d: inspect mrb_int', n[709]]
+  assert_format '"a\x00b\xff"', ['%!l', n["a\000b\xFFc\000d"], n[4]]
+  assert_format ':"&.": inspect symbol', ['%!n: inspect symbol', n['&.'.to_sym]]
+  assert_format 'inspect "String"', ['inspect %!v', 'String']
+  assert_format 'inspect Array: [1, :x, {}]', ['inspect Array: %!v', [1,:x,{}]]
+  assert_format_pattern '`!C`: #<Class:0x*>', ['`!C`: %!C', n[Class.new]]
+  assert_format 'to_s -> to_s: ab,cd', ['to_s -> to_s: %n,%v', n[:ab], 'cd']
+  assert_format 'to_s -> inspect: x:y', ['to_s -> inspect: %v%!v', 'x', :y]
+  assert_format 'inspect -> to_s: "a"b', ['inspect -> to_s: %!v%n', 'a', n[:b]]
+  assert_format 'Y -> to_s: nile', ['Y -> to_s: %Y%v', nil, "e"]
+  assert_format '"abc":Z', ['%!s%!n', n['abc'], n[:Z]]
+  assert_format 'escape: \\%a,b,c,d', ['escape: \\\\\%a,b,\c%v', ',d']
+
+  assert_implementation_dependent 'unknown specifier: %^',
+                                  ['unknown specifier: %^']
+  assert_implementation_dependent 'unknown specifier with modifier: %!^',
+                                  ['unknown specifier with modifier: %!^']
+  assert_implementation_dependent 'termination is \\', ['termination is \\']
+  assert_implementation_dependent 'termination is %', ['termination is %']
+  assert_implementation_dependent 'termination is %!', ['termination is %!']
+end