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-rw-r--r--libbuild2/in/init.cxx16
-rw-r--r--libbuild2/in/rule.cxx47
-rw-r--r--libbuild2/in/rule.hxx5
3 files changed, 59 insertions, 9 deletions
diff --git a/libbuild2/in/init.cxx b/libbuild2/in/init.cxx
index 6743e31..8bd5909 100644
--- a/libbuild2/in/init.cxx
+++ b/libbuild2/in/init.cxx
@@ -64,6 +64,22 @@ namespace build2
//
vp.insert_alias (im, "in.substitution");
+ // Substitution map. Substitutions can be specified as key-value pairs
+ // rather than buildfile variables. This map is checked before the
+ // variables. An absent value in key-value has the NULL semantics.
+ //
+ // This mechanism has two primary uses: Firstly, it allows us to have
+ // substitution names that cannot be specified as buildfile variables.
+ // For example, a name may start with an underscore and thus be
+ // reserved or it may refer to one of the predefined variables such a
+ // `include` or `extension` that may have a wrong visibility and/or
+ // type.
+ //
+ // Secondly, this mechanism allows us to encapsulate a group of
+ // substitutions and pass this group around as a single value.
+ //
+ vp.insert<map<string, optional<string>>> ("in.substitutions");
+
// Fallback value to use for NULL value substitutions. If unspecified,
// NULL substitutions are an error.
//
diff --git a/libbuild2/in/rule.cxx b/libbuild2/in/rule.cxx
index 3aa92a2..d07adfc 100644
--- a/libbuild2/in/rule.cxx
+++ b/libbuild2/in/rule.cxx
@@ -116,6 +116,11 @@ namespace build2
fail << "invalid substitution mode '" << *s << "'";
}
+ // Substitution map.
+ //
+ const substitution_map* smap (
+ cast_null<map<string, optional<string>>> (t["in.substitutions"]));
+
// NULL substitutions.
//
optional<string> null;
@@ -251,7 +256,7 @@ namespace build2
substitute (location (ip, ln),
a, t,
name, flags,
- strict, null));
+ strict, smap, null));
assert (v); // Rule semantics change without version increment?
@@ -379,7 +384,7 @@ namespace build2
a, t,
dd, dd_skip,
s, 0,
- nl, sym, strict, null);
+ nl, sym, strict, smap, null);
ofs << s;
}
@@ -445,6 +450,7 @@ namespace build2
const char* nl,
char sym,
bool strict,
+ const substitution_map* smap,
const optional<string>& null) const
{
// Scan the line looking for substiutions in the $<name>$ form. In the
@@ -500,8 +506,7 @@ namespace build2
dd, dd_skip,
string (s, b + 1, e - b -1),
nullopt /* flags */,
- strict,
- null))
+ strict, smap, null))
{
replace_newlines (*val, nl);
@@ -522,9 +527,10 @@ namespace build2
const string& n,
optional<uint64_t> flags,
bool strict,
+ const substitution_map* smap,
const optional<string>& null) const
{
- optional<string> val (substitute (l, a, t, n, flags, strict, null));
+ optional<string> val (substitute (l, a, t, n, flags, strict, smap, null));
if (val)
{
@@ -561,6 +567,7 @@ namespace build2
const string& n,
optional<uint64_t> flags,
bool strict,
+ const substitution_map* smap,
const optional<string>& null) const
{
// In the lax mode scan the fragment to make sure it is a variable name
@@ -585,7 +592,7 @@ namespace build2
}
}
- return lookup (l, a, t, n, flags, null);
+ return lookup (l, a, t, n, flags, smap, null);
}
string rule::
@@ -593,10 +600,32 @@ namespace build2
action, const target& t,
const string& n,
optional<uint64_t> flags,
+ const substitution_map* smap,
const optional<string>& null) const
{
assert (!flags);
+ // First look in the substitution map.
+ //
+ if (smap != nullptr)
+ {
+ auto i (smap->find (n));
+
+ if (i != smap->end ())
+ {
+ if (i->second)
+ return *i->second;
+
+ if (null)
+ return *null;
+
+ fail (loc) << "null value in substitution map entry '" << n << "'" <<
+ info << "use in.null to specify null value substiution string";
+ }
+ }
+
+ // Next look for the buildfile variable.
+ //
auto l (t[n]);
if (l.defined ())
@@ -607,9 +636,9 @@ namespace build2
{
if (null)
return *null;
- else
- fail (loc) << "null value in variable '" << n << "'" <<
- info << "use in.null to specify null value substiution string";
+
+ fail (loc) << "null value in variable '" << n << "'" <<
+ info << "use in.null to specify null value substiution string";
}
// For typed values call string() for conversion.
diff --git a/libbuild2/in/rule.hxx b/libbuild2/in/rule.hxx
index bd0d15a..369fd93 100644
--- a/libbuild2/in/rule.hxx
+++ b/libbuild2/in/rule.hxx
@@ -54,6 +54,7 @@ namespace build2
// Customization hooks and helpers.
//
+ using substitution_map = map<string, optional<string>>;
// Perform prerequisite search.
//
@@ -89,6 +90,7 @@ namespace build2
action, const target&,
const string& name,
optional<uint64_t> flags,
+ const substitution_map*,
const optional<string>& null) const;
// Perform variable substitution. Return nullopt if it should be
@@ -100,6 +102,7 @@ namespace build2
const string& name,
optional<uint64_t> flags,
bool strict,
+ const substitution_map*,
const optional<string>& null) const;
// Call the above version and do any necessary depdb saving.
@@ -111,6 +114,7 @@ namespace build2
const string& name,
optional<uint64_t> flags,
bool strict,
+ const substitution_map*,
const optional<string>& null) const;
// Process a line of input from the specified position performing any
@@ -124,6 +128,7 @@ namespace build2
const char* newline,
char sym,
bool strict,
+ const substitution_map*,
const optional<string>& null) const;
// Replace newlines in a multi-line value with the given newline