tests/test-diff-indent-heuristic.t

obsolete: explicitly track folds inside the markers

We now record information to be able to recognize "fold" event from
obsolescence markers. To do so, we track the following pieces of information:

a) a fold ID. Unique to that fold (per successor),
b) the number of predecessors,
c) the index of the predecessor in that fold.

We will now be able to create an algorithm able to find "predecessorssets".

We now store this data in the generic "metadata" field of the markers.
Updating the format to have a more compact storage for this would be useful.

This way of tracking a fold through multiple markers could be applied to split
too. This would have two advantages:

1) We get a simpler format, since number of successors is limited to [0-1].
2) We can better deal with situations where only some of the split successors
   are pushed to a remote repository.

We should look into the relevance of such a change before updating the on-disk
format.

note: unlike splits, folds do not have to deal with cases where only some of
the markers have been synchronized. As they all share the same successor
changesets, they are all relevant to the same nodes.

#testcases bdiff xdiff

#if xdiff
#require xdiff
  $ cat >> $HGRCPATH <<EOF
  > [experimental]
  > xdiff = true
  > EOF
#endif

  $ hg init

  $ cat > a.c <<'EOF'
  > /*
  >  * This function returns 1.
  >  */
  > int f() {
  >   return 1;
  > }
  > /*
  >  * This function returns 2.
  >  */
  > int g() {
  >   return 2;
  > }
  > /*
  >  * This function returns 3.
  >  */
  > int h() {
  >   return 3;
  > }
  > EOF

  $ cat > b.c <<'EOF'
  > if (x) {
  >    do_something();
  > }
  > 
  > if (y) {
  >    do_something_else();
  > }
  > EOF

  $ cat > c.rb <<'EOF'
  > #!ruby
  > ["foo", "bar", "baz"].map do |i|
  >   i.upcase
  > end
  > EOF

  $ cat > d.py <<'EOF'
  > try:
  >     import foo
  > except ImportError:
  >     pass
  > try:
  >     import bar
  > except ImportError:
  >     pass
  > EOF

The below two files are taken from git: t/t4061-diff-indent.sh

  $ cat > spaces.txt <<'EOF'
  > 1
  > 2
  > a
  > 
  > b
  > 3
  > 4
  > EOF

  $ cat > functions.c <<'EOF'
  > 1
  > 2
  > /* function */
  > foo() {
  >     foo
  > }
  > 
  > 3
  > 4
  > EOF

  $ hg commit -m 1 -A . -q

  $ cat > a.c <<'EOF'
  > /*
  >  * This function returns 1.
  >  */
  > int f() {
  >   return 1;
  > }
  > /*
  >  * This function returns 3.
  >  */
  > int h() {
  >   return 3;
  > }
  > EOF

  $ cat > b.c <<'EOF'
  > if (x) {
  >    do_something();
  > }
  > 
  > if (y) {
  >    do_another_thing();
  > }
  > 
  > if (y) {
  >    do_something_else();
  > }
  > EOF

  $ cat > c.rb <<'EOF'
  > #!ruby
  > ["foo", "bar", "baz"].map do |i|
  >   i
  > end
  > ["foo", "bar", "baz"].map do |i|
  >   i.upcase
  > end
  > EOF

  $ cat > d.py <<'EOF'
  > try:
  >     import foo
  > except ImportError:
  >     pass
  > try:
  >     import baz
  > except ImportError:
  >     pass
  > try:
  >     import bar
  > except ImportError:
  >     pass
  > EOF

  $ cat > spaces.txt <<'EOF'
  > 1
  > 2
  > a
  > 
  > b
  > a
  > 
  > b
  > 3
  > 4
  > EOF

  $ cat > functions.c <<'EOF'
  > 1
  > 2
  > /* function */
  > bar() {
  >     foo
  > }
  > 
  > /* function */
  > foo() {
  >     foo
  > }
  > 
  > 3
  > 4
  > EOF

#if xdiff
  $ hg diff --git
  diff --git a/a.c b/a.c
  --- a/a.c
  +++ b/a.c
  @@ -4,12 +4,6 @@
   int f() {
     return 1;
   }
  -/*
  - * This function returns 2.
  - */
  -int g() {
  -  return 2;
  -}
   /*
    * This function returns 3.
    */
  diff --git a/b.c b/b.c
  --- a/b.c
  +++ b/b.c
  @@ -2,6 +2,10 @@
      do_something();
   }
   
  +if (y) {
  +   do_another_thing();
  +}
  +
   if (y) {
      do_something_else();
   }
  diff --git a/c.rb b/c.rb
  --- a/c.rb
  +++ b/c.rb
  @@ -1,4 +1,7 @@
   #!ruby
  +["foo", "bar", "baz"].map do |i|
  +  i
  +end
   ["foo", "bar", "baz"].map do |i|
     i.upcase
   end
  diff --git a/d.py b/d.py
  --- a/d.py
  +++ b/d.py
  @@ -2,6 +2,10 @@
       import foo
   except ImportError:
       pass
  +try:
  +    import baz
  +except ImportError:
  +    pass
   try:
       import bar
   except ImportError:
  diff --git a/functions.c b/functions.c
  --- a/functions.c
  +++ b/functions.c
  @@ -1,5 +1,10 @@
   1
   2
  +/* function */
  +bar() {
  +    foo
  +}
  +
   /* function */
   foo() {
       foo
  diff --git a/spaces.txt b/spaces.txt
  --- a/spaces.txt
  +++ b/spaces.txt
  @@ -2,6 +2,9 @@
   2
   a
   
  +b
  +a
  +
   b
   3
   4
#else
  $ hg diff --git
  diff --git a/a.c b/a.c
  --- a/a.c
  +++ b/a.c
  @@ -5,12 +5,6 @@
     return 1;
   }
   /*
  - * This function returns 2.
  - */
  -int g() {
  -  return 2;
  -}
  -/*
    * This function returns 3.
    */
   int h() {
  diff --git a/b.c b/b.c
  --- a/b.c
  +++ b/b.c
  @@ -3,5 +3,9 @@
   }
   
   if (y) {
  +   do_another_thing();
  +}
  +
  +if (y) {
      do_something_else();
   }
  diff --git a/c.rb b/c.rb
  --- a/c.rb
  +++ b/c.rb
  @@ -1,4 +1,7 @@
   #!ruby
   ["foo", "bar", "baz"].map do |i|
  +  i
  +end
  +["foo", "bar", "baz"].map do |i|
     i.upcase
   end
  diff --git a/d.py b/d.py
  --- a/d.py
  +++ b/d.py
  @@ -3,6 +3,10 @@
   except ImportError:
       pass
   try:
  +    import baz
  +except ImportError:
  +    pass
  +try:
       import bar
   except ImportError:
       pass
  diff --git a/functions.c b/functions.c
  --- a/functions.c
  +++ b/functions.c
  @@ -1,6 +1,11 @@
   1
   2
   /* function */
  +bar() {
  +    foo
  +}
  +
  +/* function */
   foo() {
       foo
   }
  diff --git a/spaces.txt b/spaces.txt
  --- a/spaces.txt
  +++ b/spaces.txt
  @@ -3,5 +3,8 @@
   a
   
   b
  +a
  +
  +b
   3
   4
#endif