Merged revisions 72487-72488,72879 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r72487 | jeffrey.yasskin | 2009-05-08 17:51:06 -0400 (Fri, 08 May 2009) | 7 lines

  PyCode_NewEmpty:
  Most uses of PyCode_New found by http://www.google.com/codesearch?q=PyCode_New
  are trying to build an empty code object, usually to put it in a dummy frame
  object. This patch adds a PyCode_NewEmpty wrapper which lets the user specify
  just the filename, function name, and first line number, instead of also
  requiring lots of code internals.
........
  r72488 | jeffrey.yasskin | 2009-05-08 18:23:21 -0400 (Fri, 08 May 2009) | 13 lines

  Issue 5954, PyFrame_GetLineNumber:
  Most uses of PyCode_Addr2Line
  (http://www.google.com/codesearch?q=PyCode_Addr2Line) are just trying to get
  the line number of a specified frame, but there's no way to do that directly.
  Forcing people to go through the code object makes them know more about the
  guts of the interpreter than they should need.

  The remaining uses of PyCode_Addr2Line seem to be getting the line from a
  traceback (for example,
  http://www.google.com/codesearch/p?hl=en#u_9_nDrchrw/pygame-1.7.1release/src/base.c&q=PyCode_Addr2Line),
  which is replaced by the tb_lineno field.  So we may be able to deprecate
  PyCode_Addr2Line entirely for external use.
........
  r72879 | jeffrey.yasskin | 2009-05-23 19:23:01 -0400 (Sat, 23 May 2009) | 14 lines

  Issue #6042:
  lnotab-based tracing is very complicated and isn't documented very well.  There
  were at least 3 comment blocks purporting to document co_lnotab, and none did a
  very good job. This patch unifies them into Objects/lnotab_notes.txt which
  tries to completely capture the current state of affairs.

  I also discovered that we've attached 2 layers of patches to the basic tracing
  scheme. The first layer avoids jumping to instructions that don't start a line,
  to avoid problems in if statements and while loops.  The second layer
  discovered that jumps backward do need to trace at instructions that don't
  start a line, so it added extra lnotab entries for 'while' and 'for' loops, and
  added a special case for backward jumps within the same line. I replaced these
  patches by just treating forward and backward jumps differently.
........

2 files changed, 22 insertions, 11 deletions

diff --git a/Include/code.h b/Include/code.h
index efaf3c4..c93d861 100644
--- a/Include/code.h
+++ b/Include/code.h
@@ -24,7 +24,8 @@ typedef struct {
     PyObject *co_filename;	/* unicode (where it was loaded from) */
     PyObject *co_name;		/* unicode (name, for reference) */
     int co_firstlineno;		/* first source line number */
-    PyObject *co_lnotab;	/* string (encoding addr<->lineno mapping) */
+    PyObject *co_lnotab;	/* string (encoding addr<->lineno mapping) See
+				   Objects/lnotab_notes.txt for details. */
     void *co_zombieframe;     /* for optimization only (see frameobject.c) */
 } PyCodeObject;
 
@@ -72,6 +73,14 @@ PyAPI_FUNC(PyCodeObject *) PyCode_New(
 	PyObject *, PyObject *, PyObject *, PyObject *,
 	PyObject *, PyObject *, int, PyObject *); 
         /* same as struct above */
+
+/* Creates a new empty code object with the specified source location. */
+PyAPI_FUNC(PyCodeObject *)
+PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno);
+
+/* Return the line number associated with the specified bytecode index
+   in this code object.  If you just need the line number of a frame,
+   use PyFrame_GetLineNumber() instead. */
 PyAPI_FUNC(int) PyCode_Addr2Line(PyCodeObject *, int);
 
 /* for internal use only */
@@ -80,15 +89,11 @@ typedef struct _addr_pair {
         int ap_upper;
 } PyAddrPair;
 
-/* Check whether lasti (an instruction offset) falls outside bounds
-   and whether it is a line number that should be traced.  Returns
-   a line number if it should be traced or -1 if the line should not.
-
-   If lasti is not within bounds, updates bounds.
+/* Update *bounds to describe the first and one-past-the-last instructions in the
+   same line as lasti.  Return the number of that line.
 */
-
-PyAPI_FUNC(int) PyCode_CheckLineNumber(PyCodeObject* co,
-                                       int lasti, PyAddrPair *bounds);
+PyAPI_FUNC(int) _PyCode_CheckLineNumber(PyCodeObject* co,
+                                        int lasti, PyAddrPair *bounds);
 
 PyAPI_FUNC(PyObject*) PyCode_Optimize(PyObject *code, PyObject* consts,
                                       PyObject *names, PyObject *lineno_obj);
diff --git a/Include/frameobject.h b/Include/frameobject.h
index 65ebd2a..9440973 100644
--- a/Include/frameobject.h
+++ b/Include/frameobject.h
@@ -38,8 +38,11 @@ typedef struct _frame {
 
     PyThreadState *f_tstate;
     int f_lasti;		/* Last instruction if called */
-    /* As of 2.3 f_lineno is only valid when tracing is active (i.e. when
-       f_trace is set) -- at other times use PyCode_Addr2Line instead. */
+    /* Call PyFrame_GetLineNumber() instead of reading this field
+       directly.  As of 2.3 f_lineno is only valid when tracing is
+       active (i.e. when f_trace is set).  At other times we use
+       PyCode_Addr2Line to calculate the line from the current
+       bytecode index. */
     int f_lineno;		/* Current line number */
     int f_iblock;		/* index in f_blockstack */
     PyTryBlock f_blockstack[CO_MAXBLOCKS]; /* for try and loop blocks */
@@ -75,6 +78,9 @@ PyAPI_FUNC(void) PyFrame_FastToLocals(PyFrameObject *);
 
 PyAPI_FUNC(int) PyFrame_ClearFreeList(void);
 
+/* Return the line of code the frame is currently executing. */
+PyAPI_FUNC(int) PyFrame_GetLineNumber(PyFrameObject *);
+
 #ifdef __cplusplus
 }
 #endif