* vm.c: refactoring backtrace related funcitons.

(1) unify similar functions (rb_backtrace_each() and
  backtrace_object()).  backtrace_each() is a unified function.
  variation:
  a) backtrace_object(): create backtrace object.
  b) vm_backtrace_str_ary(): create bt as an array of string.
  c) vm_backtrace_print(): print backtrace to specified file.
  d) rb_backtrace_print_as_bugreport(): print backtrace on
  bugreport style.
  (2) remove rb_backtrace_each().  Use backtrace_each() instead.
  (3) chang the type of lev parameter to size_t.
  a) lev == 0 means current frame (exception, etc use it).
  b) lev == 1 means upper frame (caller(0) use it).
* vm_core.h, vm_dump.c, vm_eval.c: ditto.
* vm.c (backtrace_object(), vm_backtrace_str_ary()): fix to return a
  correct size of caller(lev) array.
  Let n be a "caller(0).size" then ln as caller(lev).size should be
  (n - lev).  However, the previous implementation returns a wrong
  size array (ln > n - lev).  [ruby-dev:45673]
* test/ruby/test_backtrace.rb: add tests for backtrace.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35787 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_backtrace.rb

@@ -0,0 +1,57 @@
+
+require 'test/unit'
+
+class TestBacktrace < Test::Unit::TestCase
+  def test_exception
+    bt = Fiber.new{
+      begin
+        raise
+      rescue => e
+        e.backtrace
+      end
+    }.resume
+    assert_equal(1, bt.size)
+    assert_match(/.+:\d+:.+/, bt[0])
+  end
+
+  def test_caller_lev
+    cs = []
+    Fiber.new{
+      Proc.new{
+        cs << caller(0)
+        cs << caller(1)
+        cs << caller(2)
+        cs << caller(3)
+        cs << caller(4)
+        cs << caller(5)
+      }.call
+    }.resume
+    assert_equal(3, cs[0].size)
+    assert_equal(2, cs[1].size)
+    assert_equal(1, cs[2].size)
+    assert_equal(0, cs[3].size)
+    assert_equal(nil, cs[4])
+
+    #
+    max = 20
+    rec = lambda{|n|
+      if n > 0
+        1.times{
+          rec[n-1]
+        }
+      else
+        max.times{|i|
+          total_size = caller(0).size
+          c = caller(i)
+          if c
+            assert_equal(total_size - i, caller(i).size, "[ruby-dev:45673]")
+          end
+        }
+      end
+    }
+    bt = Fiber.new{
+      rec[max]
+    }.resume
+  end
+end
+