On Wed, Aug 24, 2016 at 09:13:51PM -0400, David Malcolm wrote:
> This version removes edit_context::apply_changes and related
> functionality, retaining the ability to generate diffs.
> 
> It also improves error-handling (adding a selftest for this).
> 
> gcc/ChangeLog:
>       * Makefile.in (OBJS-libcommon): Add edit-context.o.
>       * diagnostic-color.c (color_dict): Add "diff-filename",
>       "diff-hunk", "diff-delete", and "diff-insert".
>       (parse_gcc_colors): Update default value of GCC_COLORS in comment
>       to reflect above changes.
>       * edit-context.c: New file.
>       * edit-context.h: New file.
>       * selftest-run-tests.c (selftest::run_tests): Call
>       edit_context_c_tests.
>       * selftest.h (edit_context_c_tests): New decl.
> ---
>  gcc/Makefile.in          |    1 +
>  gcc/diagnostic-color.c   |    8 +-
>  gcc/edit-context.c       | 1347 
> ++++++++++++++++++++++++++++++++++++++++++++++
>  gcc/edit-context.h       |   65 +++
>  gcc/selftest-run-tests.c |    1 +
>  gcc/selftest.h           |    1 +
>  6 files changed, 1422 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/edit-context.c
>  create mode 100644 gcc/edit-context.h
> 
> diff --git a/gcc/Makefile.in b/gcc/Makefile.in
> index f5f3339..506f0d4 100644
> --- a/gcc/Makefile.in
> +++ b/gcc/Makefile.in
> @@ -1561,6 +1561,7 @@ OBJS = \
>  # Objects in libcommon.a, potentially used by all host binaries and with
>  # no target dependencies.
>  OBJS-libcommon = diagnostic.o diagnostic-color.o diagnostic-show-locus.o \
> +     edit-context.o \
>       pretty-print.o intl.o \
>       vec.o input.o version.o hash-table.o ggc-none.o memory-block.o \
>       selftest.o
> diff --git a/gcc/diagnostic-color.c b/gcc/diagnostic-color.c
> index f76c87b..decbe84 100644
> --- a/gcc/diagnostic-color.c
> +++ b/gcc/diagnostic-color.c
> @@ -168,6 +168,10 @@ static struct color_cap color_dict[] =
>    { "range2", SGR_SEQ (COLOR_FG_BLUE), 6, false },
>    { "locus", SGR_SEQ (COLOR_BOLD), 5, false },
>    { "quote", SGR_SEQ (COLOR_BOLD), 5, false },
> +  { "diff-filename", SGR_SEQ (COLOR_BOLD), 13, false },
> +  { "diff-hunk", SGR_SEQ (COLOR_FG_CYAN), 9, false },
> +  { "diff-delete", SGR_SEQ (COLOR_FG_RED), 11, false },
> +  { "diff-insert", SGR_SEQ (COLOR_FG_GREEN), 11, false },
>    { NULL, NULL, 0, false }
>  };
>  
> @@ -196,7 +200,9 @@ colorize_stop (bool show_color)
>  }
>  
>  /* Parse GCC_COLORS.  The default would look like:
> -   
> GCC_COLORS='error=01;31:warning=01;35:note=01;36:range1=32:range2=34;locus=01:quote=01'
> +   GCC_COLORS='error=01;31:warning=01;35:note=01;36:\
> +   range1=32:range2=34:locus=01:quote=01:\
> +   diff-filename=01:diff-hunk=32:diff-delete=31:diff-insert=32'
>     No character escaping is needed or supported.  */
>  static bool
>  parse_gcc_colors (void)
> diff --git a/gcc/edit-context.c b/gcc/edit-context.c
> new file mode 100644
> index 0000000..6b79b45
> --- /dev/null
> +++ b/gcc/edit-context.c
> @@ -0,0 +1,1347 @@
> +/* Determining the results of applying fix-its.
> +   Copyright (C) 2016 Free Software Foundation, Inc.
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify it under
> +the terms of the GNU General Public License as published by the Free
> +Software Foundation; either version 3, or (at your option) any later
> +version.
> +
> +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with GCC; see the file COPYING3.  If not see
> +<http://www.gnu.org/licenses/>.  */
> +
> +#include "config.h"
> +#include "system.h"
> +#include "coretypes.h"
> +#include "line-map.h"
> +#include "edit-context.h"
> +#include "pretty-print.h"
> +#include "diagnostic-color.h"
> +#include "selftest.h"
> +
> +/* This file implements a way to track the effect of fix-its,
> +   via a class edit_context; the other classes are support classes for
> +   edit_context.
> +
> +   A complication here is that fix-its are expressed relative to coordinates
> +   in the file when it was parsed, before any changes have been made, and
> +   so if there's more that one fix-it to be applied, we have to adjust
> +   later fix-its to allow for the changes made by earlier ones.  This
> +   is done by the various "get_effective_column" methods.
> +
> +   The "filename" params are required to outlive the edit_context (no
> +   copy of the underlying str is taken, just the ptr).  */
> +
> +/* Forward decls.  class edit_context is declared within edit-context.h.
> +   The other types are declared here.  */
> +class edit_context;
> +class edited_file;
> +class line_state;
> +class line_event;
> +  class insert_event;
> +  class replace_event;
> +
> +/* A struct to hold the params of a print_diff call.  */
> +
> +struct diff
> +{
> +  diff (pretty_printer *pp, bool show_filenames)
> +  : m_pp (pp), m_show_filenames (show_filenames) {}
> +
> +  pretty_printer *m_pp;
> +  bool m_show_filenames;
> +};
> +
> +/* The state of one named file within an edit_context: the filename,
> +   the current content of the file after applying all changes so far, and
> +   a record of the changes, so that further changes can be applied in
> +   the correct place.  */
> +
> +class edited_file
> +{
> + public:
> +  edited_file (const char *filename);
> +  bool read_from_file ();
> +  ~edited_file ();

nit picking, but I think it would be nice to have the ctor and dtor next
to each other.

> +  static void delete_cb (edited_file *file);
> +
> +  const char *get_filename () const { return m_filename; }
> +  const char *get_content () const { return m_content; }
> +
> +  bool apply_insert (int line, int column, const char *str, int len);
> +  bool apply_replace (int line, int start_column,
> +                   int finish_column,
> +                   const char *replacement_str,
> +                   int replacement_len);
> +  int get_effective_column (int line, int column);
> +
> +  static int call_print_diff (const char *, edited_file *file,
> +                           void *user_data)
> +  {
> +    diff *d = (diff *)user_data;
> +    file->print_diff (d->m_pp, d->m_show_filenames);
> +    return 0;
> +  }
> +
> + private:
> +  void print_diff (pretty_printer *pp, bool show_filenames);
> +  void print_line_in_diff (pretty_printer *pp, int line_num);
> +  line_state *get_line (int line);
> +  line_state &get_or_insert_line (int line);
> +  void ensure_capacity (size_t len);
> +  void ensure_terminated ();
> +  char *get_line_start (int line_num);
> +  void ensure_line_start_index ();
> +  void evict_line_start_index ();
> +  int get_num_lines ();
> +
> +  const char *m_filename;
> +  char *m_content;
> +  size_t m_len;
> +  size_t m_alloc_sz;
> +  typed_splay_tree<int, line_state *> m_edited_lines;
> +  auto_vec<int> m_line_start_index;

have you considered parsing lines when you read the file, and then
storing a vec<char *> where element I is line I in the file?  Its more
allocations, but when you need to edit a line you'll only need to copy
around that line instead of the whole rest of the file.

> +};
> +
> +/* A mapping from pre-edit columns to post-edit columns
> +   within one line of one file.  */
> +
> +class line_state
> +{
> + public:
> +  line_state (int line_num) : m_line_num (line_num), m_line_events () {}
> +  ~line_state ();
> +  static void delete_cb (line_state *ls);
> +
> +  int get_line_num () const { return m_line_num; }
> +
> +  int get_effective_column (int orig_column) const;
> +  void apply_insert (int column, int len);
> +  void apply_replace (int start, int finish, int len);
> +
> + private:
> +  int m_line_num;
> +  auto_vec <line_event *> m_line_events;
> +};
> +
> +/* Abstract base class for representing events that have occurred
> +   on one line of one file.  */
> +
> +class line_event
> +{
> + public:
> +  virtual ~line_event () {}
> +  virtual int get_effective_column (int orig_column) const = 0;
> +};
> +
> +/* Concrete subclass of line_event: an insertion of some text
> +   at some column on the line.
> +
> +   Subsequent events will need their columns adjusting if they're
> +   are on this line and their column is >= the insertion point.  */
> +
> +class insert_event : public line_event
> +{
> + public:
> +  insert_event (int column, int len) : m_column (column), m_len (len) {}
> +  int get_effective_column (int orig_column) const FINAL OVERRIDE
> +  {
> +    if (orig_column >= m_column)
> +      return orig_column + m_len;
> +    else
> +      return orig_column;
> +  }
> +
> + private:
> +  int m_column;
> +  int m_len;
> +};
> +
> +/* Concrete subclass of line_event: the replacement of some text
> +   betweeen some columns on the line.
> +
> +   Subsequent events will need their columns adjusting if they're
> +   are on this line and their column is >= the finish point.  */
> +
> +class replace_event : public line_event
> +{
> + public:
> +  replace_event (int start, int finish, int len) : m_start (start),
> +    m_finish (finish), m_delta (len - (finish + 1 - start)) {}
> +
> +  int get_effective_column (int orig_column) const FINAL OVERRIDE
> +  {
> +    if (orig_column >= m_start)
> +      return orig_column += m_delta;
> +    else
> +      return orig_column;

What happens when orig_column is within the text being replaced?

> +  }
> +
> + private:
> +  int m_start;
> +  int m_finish;
> +  int m_delta;
> +};

It seems like it would greatly simplify things to merge fixit_insert and
fixit_replace so that an insertion is just a replacement where the start
and end of the replaced text are the same.  That would also have the
nice effect of making fixit_replace smaller since you wouldn't need the
vtable any more.

> +change_line (edit_context &edit, int line_num)

I guess this is test only, put I'm not a fan of non const references.

Trev

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