[builtins/ysh] Add first pass of formatDebugFrame()

Add debug_frame.MainEntry(), for symmetry.

We might only use 'Call' and 'Source'.  Because each of those will have
a token, and then the first one may be in one of:

    main file
    [ -c flag ]
    [ stdin ]

builtin/func_reflect.py

@@ -4,8 +4,8 @@
 """
 from __future__ import print_function
 
-from _devbuild.gen.runtime_asdl import (scope_e)
-from _devbuild.gen.syntax_asdl import source
+from _devbuild.gen.runtime_asdl import scope_e
+from _devbuild.gen.syntax_asdl import (source, debug_frame, debug_frame_e)
 from _devbuild.gen.value_asdl import (value, value_e, value_t, cmd_frag)
 
 from core import alloc
@@ -20,7 +20,7 @@
 from mycpp import mops
 from mycpp.mylib import log, tagswitch
 
-from typing import List, TYPE_CHECKING
+from typing import List, cast, TYPE_CHECKING
 if TYPE_CHECKING:
     from frontend import parse_lib
     from display import ui
@@ -120,6 +120,37 @@ def Call(self, rd):
         return value.List(debug_frames)
 
 
+class FormatDebugFrame(vm._Callable):
+
+    def __init__(self):
+        # type: () -> None
+        vm._Callable.__init__(self)
+
+    def Call(self, rd):
+        # type: (typed_args.Reader) -> value_t
+        frame = rd.PosDebugFrame()
+        rd.Done()
+
+        UP_frame = frame
+        result = ''
+        with tagswitch(frame) as case:
+            if case(debug_frame_e.MainEntry):
+                frame = cast(debug_frame.MainEntry, UP_frame)
+                result = 'main entry %s' % frame.description
+            elif case(debug_frame_e.MainFile):
+                frame = cast(debug_frame.MainFile, UP_frame)
+                result = 'main file %s' % frame.main_filename
+            elif case(debug_frame_e.Call):
+                frame = cast(debug_frame.Call, UP_frame)
+                result = 'call'
+            elif case(debug_frame_e.Source):
+                frame = cast(debug_frame.Source, UP_frame)
+                result = 'source'
+            else:
+                raise AssertionError()
+        return value.Str(result)
+
+
 class Shvar_get(vm._Callable):
     """Look up with dynamic scope."""
 

core/shell.py

@@ -287,19 +287,20 @@ def Main(
                 status = 1
         return status
 
-    debug_stack = []  # type: List[debug_frame_t]
-    if arg_r.AtEnd():  # -c input, or stdin
+    script_name = arg_r.Peek()  # type: Optional[str]
+    arg_r.Next()
+
+    if script_name is None:
         dollar0 = argv0
+        if flag.c is None:
+            frame0 = debug_frame.MainEntry('[ stdin ]')  # type: debug_frame_t
+        else:
+            frame0 = debug_frame.MainEntry('[ -c flag ]')
     else:
-        dollar0 = arg_r.Peek()  # the script name
-
-        frame0 = debug_frame.Main(dollar0)
-        debug_stack.append(frame0)
+        dollar0 = script_name
+        frame0 = debug_frame.MainFile(script_name)
 
-    #log('STACK %s', debug_stack)
-
-    script_name = arg_r.Peek()  # type: Optional[str]
-    arg_r.Next()
+    debug_stack = [frame0]
 
     env_dict = NewDict()  # type: Dict[str, value_t]
     defaults = NewDict()  # type: Dict[str, value_t]
@@ -943,6 +944,8 @@ def Main(
     _AddBuiltinFunc(mem, 'fromJson8', func_misc.FromJson8(True))
     _AddBuiltinFunc(mem, 'fromJson', func_misc.FromJson8(False))
 
+    _AddBuiltinFunc(mem, 'formatDebugFrame', func_reflect.FormatDebugFrame())
+
     # Demos
     _AddBuiltinFunc(mem, '_a2sp', func_misc.BashArrayToSparse())
     _AddBuiltinFunc(mem, '_opsp', func_misc.SparseOp())

core/state.py

@@ -1314,7 +1314,7 @@ def Dump(self):
         # Reuse these immutable objects
         t_call = value.Str('Call')
         t_source = value.Str('Source')
-        t_main = value.Str('Main')
+        t_main = value.Str('MainFile')
 
         for frame in reversed(self.debug_stack):
             UP_frame = frame
@@ -1337,9 +1337,12 @@ def Dump(self):
                     }
                     _AddCallToken(d, frame.call_tok)
 
-                elif case(debug_frame_e.Main):
-                    frame = cast(debug_frame.Main, UP_frame)
-                    d = {'type': t_main, 'dollar0': value.Str(frame.dollar0)}
+                elif case(debug_frame_e.MainFile):
+                    frame = cast(debug_frame.MainFile, UP_frame)
+                    d = {
+                        'type': t_main,
+                        'filename': value.Str(frame.main_filename)
+                    }
 
             debug_stack.append(value.Dict(d))
         return var_stack, argv_stack, debug_stack
@@ -2140,9 +2143,12 @@ def GetValue(self, name, which_scopes=scope_e.Shopt):
                             # bash doesn't tell you the filename sourced
                             strs.append('source')
 
-                        elif case2(debug_frame_e.Main):
+                        elif case2(debug_frame_e.MainFile):
                             strs.append('main')  # also bash behavior
 
+                        else:  # ignore
+                            pass
+
                 return value.BashArray(strs)  # TODO: Reuse this object too?
 
             # $BASH_SOURCE and $BASH_LINENO have OFF BY ONE design bugs:
@@ -2172,9 +2178,12 @@ def GetValue(self, name, which_scopes=scope_e.Shopt):
                             # Is this right?
                             strs.append(frame.source_name)
 
-                        elif case2(debug_frame_e.Main):
-                            frame = cast(debug_frame.Main, UP_frame)
-                            strs.append(frame.dollar0)
+                        elif case2(debug_frame_e.MainFile):
+                            frame = cast(debug_frame.MainFile, UP_frame)
+                            strs.append(frame.main_filename)
+
+                        else:  # ignore
+                            pass
 
                 return value.BashArray(strs)  # TODO: Reuse this object too?
 
@@ -2191,10 +2200,13 @@ def GetValue(self, name, which_scopes=scope_e.Shopt):
                             frame = cast(debug_frame.Source, UP_frame)
                             strs.append(_LineNumber(frame.call_tok))
 
-                        elif case2(debug_frame_e.Main):
+                        elif case2(debug_frame_e.MainFile):
                             # Bash does this to line up with 'main'
                             strs.append('0')
 
+                        else:  # ignore
+                            pass
+
                 return value.BashArray(strs)  # TODO: Reuse this object too?
 
             elif case('LINENO'):

frontend/syntax.asdl

@@ -116,7 +116,8 @@ module syntax
     # 
     # bash won't print those
 
-    Main(str dollar0)
+    MainEntry(str description)  # -c or stdin
+  | MainFile(str main_filename)
     # call_tok => BASH_LINENO
     # call_tok may be None with new --source flag?
   | Source(Token? call_tok, str source_name)

frontend/typed_args.py

@@ -2,7 +2,8 @@
 from __future__ import print_function
 
 from _devbuild.gen.runtime_asdl import cmd_value, ProcArgs, Cell
-from _devbuild.gen.syntax_asdl import (loc, loc_t, ArgList, command_t, Token)
+from _devbuild.gen.syntax_asdl import (loc, loc_t, ArgList, command_t, Token,
+                                       debug_frame_t)
 from _devbuild.gen.value_asdl import (value, value_e, value_t, RegexMatch, Obj,
                                       cmd_frag, cmd_frag_e, cmd_frag_str,
                                       LiteralBlock)
@@ -368,6 +369,15 @@ def _ToFrame(self, val):
                             'Arg %d should be a Frame' % self.pos_consumed,
                             self.BlamePos())
 
+    def _ToDebugFrame(self, val):
+        # type: (value_t) -> debug_frame_t
+        if val.tag() == value_e.DebugFrame:
+            return cast(value.DebugFrame, val).frame
+
+        raise error.TypeErr(
+            val, 'Arg %d should be a DebugFrame' % self.pos_consumed,
+            self.BlamePos())
+
     def _ToCommandFrag(self, val):
         # type: (value_t) -> command_t
         if val.tag() == value_e.CommandFrag:
@@ -491,6 +501,11 @@ def PosFrame(self):
         val = self.PosValue()
         return self._ToFrame(val)
 
+    def PosDebugFrame(self):
+        # type: () -> debug_frame_t
+        val = self.PosValue()
+        return self._ToDebugFrame(val)
+
     def PosCommandFrag(self):
         # type: () -> command_t
         val = self.PosValue()

spec/testdata/debug-frame-lib.ysh

@@ -0,0 +1,14 @@
+
+proc p {
+  for fr in (vm.getDebugStack()) {
+    echo $[formatDebugFrame(fr)]
+  }
+}
+
+proc p2 {
+  p
+}
+
+p
+echo
+p2

spec/testdata/debug-frame-main.ysh

@@ -0,0 +1,2 @@
+
+source $_this_dir/debug-frame-lib.ysh

spec/ysh-func-builtin.test.sh

@@ -1,4 +1,4 @@
-## oils_failures_allowed: 2
+## oils_failures_allowed: 3
 ## our_shell: ysh
 
 #### join()
@@ -266,3 +266,22 @@ p2
 1
 2
 ## END
+
+#### formatDebugFrame()
+
+$[ENV.SH] $[ENV.REPO_ROOT]/spec/testdata/debug-frame-main.ysh
+
+echo
+
+# -c
+$[ENV.SH] -c 'source $[ENV.REPO_ROOT]/spec/testdata/debug-frame-lib.ysh'
+
+echo
+
+# stdin
+echo 'source $[ENV.REPO_ROOT]/spec/testdata/debug-frame-lib.ysh' | $[ENV.SH]
+
+## STDOUT:
+z
+## END
+