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authorBoris Kolpackov <boris@codesynthesis.com>2019-03-14 17:19:01 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2019-03-14 17:19:01 +0200
commitd1b3ad7b302d037c8154bab9c4810d499c0bf1e4 (patch)
tree8c6ce63cb0a71bc670c3c5d46c2c1a06366956ad
parent8d8d7784d5fe0dc3cd8d7fbd4196c2337d389fd1 (diff)
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Change variable::override list order, make doubly-linked
-rw-r--r--build2/context.cxx36
-rw-r--r--build2/scope.cxx15
-rw-r--r--build2/variable.hxx14
3 files changed, 48 insertions, 17 deletions
diff --git a/build2/context.cxx b/build2/context.cxx
index 7b473e2..633f3ff 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -682,27 +682,45 @@ namespace build2
c == '%' ? variable_visibility::project :
variable_visibility::normal);
- const variable& var (vp.insert (n, true)); // Allow overrides.
+ variable& var (const_cast<variable&> (
+ vp.insert (n, true /* overridable */)));
const char* k (tt == token_type::assign ? ".__override" :
tt == token_type::append ? ".__suffix" : ".__prefix");
// We might already have a variable for this kind of override.
//
- const variable* o (&var); // Step behind.
- for (; o->override != nullptr; o = o->override.get ())
+ const variable* o (var.override.get ());
+ for (; o != nullptr; o = o->override.get ())
{
- if (o->override->visibility == v &&
- o->override->name.rfind (k) != string::npos)
+ if (o->visibility == v && o->name.rfind (k) != string::npos)
break;
}
// Add it if not found.
//
- if (o->override == nullptr)
- const_cast<variable*> (o)->override.reset (
- new variable {n + k, nullptr , nullptr, nullptr, v});
+ if (o == nullptr)
+ {
+ unique_ptr<variable> p (
+ new variable {
+ n + k,
+ nullptr /* alias */,
+ nullptr /* type */,
+ nullptr /* override */,
+ v});
+
+ // Back link.
+ //
+ p->alias = p.get ();
+ if (var.override != nullptr)
+ swap (p->alias, const_cast<variable*> (var.override.get ())->alias);
- o = o->override.get ();
+ // Forward link.
+ //
+ p->override = move (var.override);
+ var.override = move (p);
+
+ o = var.override.get ();
+ }
// Currently we expand project overrides in the global scope to keep
// things simple. Pass original variable for diagnostics. Use current
diff --git a/build2/scope.cxx b/build2/scope.cxx
index 69ab4b6..4dd475d 100644
--- a/build2/scope.cxx
+++ b/build2/scope.cxx
@@ -397,6 +397,9 @@ namespace build2
// Then look for an __override that applies.
//
+ // Note that the override list is in the reverse order of appearance and
+ // so we will naturally see the most recent override first.
+ //
for (const variable* o (var.override.get ());
o != nullptr;
o = o->override.get ())
@@ -488,14 +491,18 @@ namespace build2
{
++ovr_depth;
- // Skip any append/prepend overrides that appear before __override,
- // provided it is from this scope.
+ // The override list is in the reverse order of appearance so we need to
+ // iterate backwards in order to apply things in the correct order.
+ //
+ // We also need to skip any append/prepend overrides that appear before
+ // __override (in the command line order), provided it is from this
+ // scope.
//
bool skip (stem_ovr != nullptr && stem_depth == ovr_depth);
- for (const variable* o (var.override.get ());
+ for (const variable* o (var.override->alias); // Last override.
o != nullptr;
- o = o->override.get ())
+ o = (o->alias != var.override->alias ? o->alias : nullptr))
{
if (skip)
{
diff --git a/build2/variable.hxx b/build2/variable.hxx
index 51e6eed..2bdfe30 100644
--- a/build2/variable.hxx
+++ b/build2/variable.hxx
@@ -149,10 +149,16 @@ namespace build2
// variable itself).
//
// If the variable is overridden on the command line, then override is the
- // chain of the special override variables. Their names are derived from the
- // main variable name as <name>.{__override,__prefix,__suffix} and they are
- // not entered into the var_pool. The override variables only vary in their
- // names and visibility. Their alias pointer is always NULL.
+ // linked list of the special override variables. Their names are derived
+ // from the main variable name as <name>.{__override,__prefix,__suffix} and
+ // they are not entered into the var_pool. The override variables only vary
+ // in their names and visibility. Their alias pointer is re-purposed to make
+ // the list doubly-linked with the first override's alias pointing to the
+ // last element (or itself).
+ //
+ // Note that the override list is in the reverse order of the overrides
+ // appearing on the command line, which is important when deciding whether
+ // and in what order they apply (see find_override() for details).
//
// Note also that we don't propagate the variable type to override variables
// and we keep override values as untyped names. They get "typed" when they