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authorBoris Kolpackov <boris@codesynthesis.com>2019-07-08 14:55:35 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2019-07-24 13:53:25 +0200
commit83bb02cada0b894d9134cc5489999e0f0fe8bd7c (patch)
tree1dedff27ce2b7d54bd6b0875c9125f4dafde2e80 /libbuild2/in
parent1ba934bb973c234b68751ee5866365c14da4e795 (diff)
Move in build system module to separate library
Diffstat (limited to 'libbuild2/in')
-rw-r--r--libbuild2/in/buildfile62
-rw-r--r--libbuild2/in/export.hxx34
-rw-r--r--libbuild2/in/init.cxx126
-rw-r--r--libbuild2/in/init.hxx30
-rw-r--r--libbuild2/in/rule.cxx485
-rw-r--r--libbuild2/in/rule.hxx90
-rw-r--r--libbuild2/in/target.cxx62
-rw-r--r--libbuild2/in/target.hxx48
8 files changed, 937 insertions, 0 deletions
diff --git a/libbuild2/in/buildfile b/libbuild2/in/buildfile
new file mode 100644
index 0000000..ae07e27
--- /dev/null
+++ b/libbuild2/in/buildfile
@@ -0,0 +1,62 @@
+# file : libbuild2/in/buildfile
+# copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+# license : MIT; see accompanying LICENSE file
+
+import int_libs = libbutl%lib{butl}
+
+include ../
+int_libs += ../lib{build2}
+
+./: lib{build2-in}: libul{build2-in}: {hxx ixx txx cxx}{** -**.test...} \
+ $int_libs
+
+# Unit tests.
+#
+exe{*.test}:
+{
+ test = true
+ install = false
+}
+
+for t: cxx{**.test...}
+{
+ d = $directory($t)
+ n = $name($t)...
+
+ ./: $d/exe{$n}: $t $d/{hxx ixx txx}{+$n} $d/testscript{+$n}
+ $d/exe{$n}: libul{build2-in}: bin.whole = false
+}
+
+# Build options.
+#
+obja{*}: cxx.poptions += -DLIBBUILD2_IN_STATIC_BUILD
+objs{*}: cxx.poptions += -DLIBBUILD2_IN_SHARED_BUILD
+
+# Export options.
+#
+lib{build2-in}:
+{
+ cxx.export.poptions = "-I$out_root" "-I$src_root"
+ cxx.export.libs = $int_libs
+}
+
+liba{build2-in}: cxx.export.poptions += -DLIBBUILD2_IN_STATIC
+libs{build2-in}: cxx.export.poptions += -DLIBBUILD2_IN_SHARED
+
+# For pre-releases use the complete version to make sure they cannot be used
+# in place of another pre-release or the final version. See the version module
+# for details on the version.* variable values.
+#
+if $version.pre_release
+ lib{build2-in}: bin.lib.version = @"-$version.project_id"
+else
+ lib{build2-in}: bin.lib.version = @"-$version.major.$version.minor"
+
+# Install into the libbuild2/in/ subdirectory of, say, /usr/include/
+# recreating subdirectories.
+#
+{hxx ixx txx}{*}:
+{
+ install = include/libbuild2/in/
+ install.subdirs = true
+}
diff --git a/libbuild2/in/export.hxx b/libbuild2/in/export.hxx
new file mode 100644
index 0000000..47909e7
--- /dev/null
+++ b/libbuild2/in/export.hxx
@@ -0,0 +1,34 @@
+#pragma once
+
+// Normally we don't export class templates (but do complete specializations),
+// inline functions, and classes with only inline member functions. Exporting
+// classes that inherit from non-exported/imported bases (e.g., std::string)
+// will end up badly. The only known workarounds are to not inherit or to not
+// export. Also, MinGW GCC doesn't like seeing non-exported functions being
+// used before their inline definition. The workaround is to reorder code. In
+// the end it's all trial and error.
+
+#if defined(LIBBUILD2_IN_STATIC) // Using static.
+# define LIBBUILD2_IN_SYMEXPORT
+#elif defined(LIBBUILD2_IN_STATIC_BUILD) // Building static.
+# define LIBBUILD2_IN_SYMEXPORT
+#elif defined(LIBBUILD2_IN_SHARED) // Using shared.
+# ifdef _WIN32
+# define LIBBUILD2_IN_SYMEXPORT __declspec(dllimport)
+# else
+# define LIBBUILD2_IN_SYMEXPORT
+# endif
+#elif defined(LIBBUILD2_IN_SHARED_BUILD) // Building shared.
+# ifdef _WIN32
+# define LIBBUILD2_IN_SYMEXPORT __declspec(dllexport)
+# else
+# define LIBBUILD2_IN_SYMEXPORT
+# endif
+#else
+// If none of the above macros are defined, then we assume we are being used
+// by some third-party build system that cannot/doesn't signal the library
+// type. Note that this fallback works for both static and shared but in case
+// of shared will be sub-optimal compared to having dllimport.
+//
+# define LIBBUILD2_IN_SYMEXPORT // Using static or shared.
+#endif
diff --git a/libbuild2/in/init.cxx b/libbuild2/in/init.cxx
new file mode 100644
index 0000000..6ef996b
--- /dev/null
+++ b/libbuild2/in/init.cxx
@@ -0,0 +1,126 @@
+// file : libbuild2/in/init.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#include <libbuild2/in/init.hxx>
+
+#include <libbuild2/scope.hxx>
+#include <libbuild2/context.hxx>
+#include <libbuild2/variable.hxx>
+#include <libbuild2/diagnostics.hxx>
+
+#include <libbuild2/in/rule.hxx>
+#include <libbuild2/in/target.hxx>
+
+using namespace std;
+
+namespace build2
+{
+ namespace in
+ {
+ static const rule rule_ ("in", "in");
+
+ bool
+ base_init (scope& rs,
+ scope&,
+ const location&,
+ unique_ptr<module_base>&,
+ bool first,
+ bool,
+ const variable_map&)
+ {
+ tracer trace ("in::base_init");
+ l5 ([&]{trace << "for " << rs;});
+
+ assert (first);
+
+ // Enter variables.
+ //
+ {
+ auto& vp (var_pool.rw (rs));
+
+ // Alternative variable substitution symbol with '$' being the
+ // default.
+ //
+ vp.insert<string> ("in.symbol");
+
+ // Substitution mode. Valid values are 'strict' (default) and 'lax'.
+ // In the strict mode every substitution symbol is expected to start a
+ // substitution with the double symbol (e.g., $$) serving as an escape
+ // sequence.
+ //
+ // In the lax mode a pair of substitution symbols is only treated as a
+ // substitution if what's between them looks like a build2 variable
+ // name (i.e., doesn't contain spaces, etc). Everything else,
+ // including unterminated substitution symbols, is copied as is. Note
+ // also that in this mode the double symbol is not treated as an
+ // escape sequence.
+ //
+ // The lax mode is mostly useful when trying to reuse existing .in
+ // files, for example, from autoconf. Note, however, that the lax mode
+ // is still stricter than the autoconf's semantics which also leaves
+ // unknown substitutions as is.
+ //
+ vp.insert<string> ("in.substitution");
+ }
+
+ // Register target types.
+ //
+ rs.target_types.insert<in> ();
+
+ return true;
+ }
+
+ bool
+ init (scope& rs,
+ scope& bs,
+ const location& loc,
+ unique_ptr<module_base>&,
+ bool,
+ bool,
+ const variable_map&)
+ {
+ tracer trace ("in::init");
+ l5 ([&]{trace << "for " << bs;});
+
+ // Load in.base.
+ //
+ if (!cast_false<bool> (rs["in.base.loaded"]))
+ load_module (rs, rs, "in.base", loc);
+
+ // Register rules.
+ //
+ {
+ auto& r (bs.rules);
+
+ // There are rules that are "derived" from this generic in rule in
+ // order to provide extended preprocessing functionality (see the
+ // version module for an example). To make sure they are tried first
+ // we register for path_target, not file, but in rule::match() we only
+ // match if the target is a file. A bit of a hack.
+ //
+ r.insert<path_target> (perform_update_id, "in", rule_);
+ r.insert<path_target> (perform_clean_id, "in", rule_);
+ r.insert<path_target> (configure_update_id, "in", rule_);
+ }
+
+ return true;
+ }
+
+ static const module_functions mod_functions[] =
+ {
+ // NOTE: don't forget to also update the documentation in init.hxx if
+ // changing anything here.
+
+ {"in.base", nullptr, base_init},
+ {"in", nullptr, init},
+ {nullptr, nullptr, nullptr}
+ };
+
+ const module_functions*
+ build2_in_load ()
+ {
+ return mod_functions;
+ }
+ }
+}
diff --git a/libbuild2/in/init.hxx b/libbuild2/in/init.hxx
new file mode 100644
index 0000000..b82c77e
--- /dev/null
+++ b/libbuild2/in/init.hxx
@@ -0,0 +1,30 @@
+// file : libbuild2/in/init.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_IN_INIT_HXX
+#define LIBBUILD2_IN_INIT_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/module.hxx>
+
+#include <libbuild2/in/export.hxx>
+
+namespace build2
+{
+ namespace in
+ {
+ // Module `in` does not require bootstrapping.
+ //
+ // Submodules:
+ //
+ // `in.base` -- only variables and target types.
+ //
+ extern "C" LIBBUILD2_IN_SYMEXPORT const module_functions*
+ build2_in_load ();
+ }
+}
+
+#endif // LIBBUILD2_IN_INIT_HXX
diff --git a/libbuild2/in/rule.cxx b/libbuild2/in/rule.cxx
new file mode 100644
index 0000000..bdc9b24
--- /dev/null
+++ b/libbuild2/in/rule.cxx
@@ -0,0 +1,485 @@
+// file : libbuild2/in/rule.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#include <libbuild2/in/rule.hxx>
+
+#include <cstdlib> // strtoull()
+
+#include <libbuild2/depdb.hxx>
+#include <libbuild2/scope.hxx>
+#include <libbuild2/target.hxx>
+#include <libbuild2/function.hxx>
+#include <libbuild2/algorithm.hxx>
+#include <libbuild2/filesystem.hxx>
+#include <libbuild2/diagnostics.hxx>
+
+#include <libbuild2/in/target.hxx>
+
+using namespace std;
+using namespace butl;
+
+namespace build2
+{
+ namespace in
+ {
+ bool rule::
+ match (action a, target& xt, const string&) const
+ {
+ tracer trace ("in::rule::match");
+
+ if (!xt.is_a<file> ()) // See module init() for details.
+ return false;
+
+ file& t (static_cast<file&> (xt));
+
+ bool fi (false); // Found in.
+ for (prerequisite_member p: group_prerequisite_members (a, t))
+ {
+ if (include (a, t, p) != include_type::normal) // Excluded/ad hoc.
+ continue;
+
+ fi = fi || p.is_a<in> ();
+ }
+
+ // Note that while normally we print these at verbosity level 4, this
+ // one gets quite noisy since we try this rule for any file target.
+ //
+ if (!fi)
+ l5 ([&]{trace << "no in file prerequisite for target " << t;});
+
+ return fi;
+ }
+
+ recipe rule::
+ apply (action a, target& xt) const
+ {
+ file& t (static_cast<file&> (xt));
+
+ // Derive the file name.
+ //
+ t.derive_path ();
+
+ // Inject dependency on the output directory.
+ //
+ inject_fsdir (a, t);
+
+ // Match prerequisite members.
+ //
+ match_prerequisite_members (a,
+ t,
+ [this] (action a,
+ const target& t,
+ const prerequisite_member& p,
+ include_type i)
+ {
+ return search (a, t, p, i);
+ });
+
+ switch (a)
+ {
+ case perform_update_id: return [this] (action a, const target& t)
+ {
+ return perform_update (a, t);
+ };
+ case perform_clean_id: return &perform_clean_depdb; // Standard clean.
+ default: return noop_recipe; // Configure update.
+ }
+ }
+
+ target_state rule::
+ perform_update (action a, const target& xt) const
+ {
+ tracer trace ("in::rule::perform_update");
+
+ const file& t (xt.as<const file&> ());
+ const path& tp (t.path ());
+
+ // Substitution symbol.
+ //
+ char sym (symbol_);
+ if (const string* s = cast_null<string> (t["in.symbol"]))
+ {
+ if (s->size () == 1)
+ sym = s->front ();
+ else
+ fail << "invalid substitution symbol '" << *s << "'";
+ }
+
+ // Substitution mode.
+ //
+ bool strict (strict_);
+ if (const string* s = cast_null<string> (t["in.substitution"]))
+ {
+ if (*s == "lax")
+ strict = false;
+ else if (*s != "strict")
+ fail << "invalid substitution mode '" << *s << "'";
+ }
+
+ // Determine if anything needs to be updated.
+ //
+ timestamp mt (t.load_mtime ());
+ auto pr (execute_prerequisites<in> (a, t, mt));
+
+ bool update (!pr.first);
+ target_state ts (update ? target_state::changed : *pr.first);
+
+ const in& i (pr.second);
+ const path& ip (i.path ());
+
+ // We use depdb to track changes to the .in file name, symbol/mode, and
+ // variable values that have been substituted.
+ //
+ depdb dd (tp + ".d");
+
+ // First should come the rule name/version.
+ //
+ if (dd.expect (rule_id_ + " 1") != nullptr)
+ l4 ([&]{trace << "rule mismatch forcing update of " << t;});
+
+ // Then the substitution symbol.
+ //
+ if (dd.expect (string (1, sym)) != nullptr)
+ l4 ([&]{trace << "substitution symbol mismatch forcing update of"
+ << t;});
+
+ // Then the substitution mode.
+ //
+ if (dd.expect (strict ? "strict" : "lax") != nullptr)
+ l4 ([&]{trace << "substitution mode mismatch forcing update of"
+ << t;});
+
+ // Then the .in file.
+ //
+ if (dd.expect (i.path ()) != nullptr)
+ l4 ([&]{trace << "in file mismatch forcing update of " << t;});
+
+ // Update if any mismatch or depdb is newer that the output.
+ //
+ if (dd.writing () || dd.mtime > mt)
+ update = true;
+
+ // Substituted variable values.
+ //
+ // The plan is to save each substituted variable name and the hash of
+ // its value one entry per line. Plus the line location of its expansion
+ // for diagnostics.
+ //
+ // If update is true (i.e., the .in file has changes), then we simply
+ // overwrite the whole list.
+ //
+ // If update is false, then we need to read each name/hash, query and
+ // hash its current value, and compare. If hashes differ, then we need
+ // to start overwriting from this variable (the prefix of variables
+ // couldn't have changed since the .in file hasn't changed).
+ //
+ // Note that if the .in file substitutes the same variable multiple
+ // times, then we will end up with multiple entries for such a variable.
+ // For now we assume this is ok since this is probably not very common
+ // and it makes the overall logic simpler.
+ //
+ // Note also that because updating the depdb essentially requires
+ // performing the substitutions, this rule ignored the dry-run mode.
+ //
+ size_t dd_skip (0); // Number of "good" variable lines.
+
+ if (update)
+ {
+ // If we are still reading, mark the next line for overwriting.
+ //
+ if (dd.reading ())
+ {
+ dd.read (); // Read the first variable line, if any.
+ dd.write (); // Mark it for overwriting.
+ }
+ }
+ else
+ {
+ while (dd.more ())
+ {
+ if (string* s = dd.read ())
+ {
+ // The line format is:
+ //
+ // <ln> <name> <hash>
+ //
+ // Note that <name> can contain spaces (see the constraint check
+ // expressions in the version module).
+ //
+ char* e (nullptr);
+ uint64_t ln (strtoull (s->c_str (), &e, 10));
+
+ size_t p1 (*e == ' ' ? e - s->c_str () : string::npos);
+ size_t p2 (s->rfind (' '));
+
+ if (p1 != string::npos && p2 != string::npos && p2 - p1 > 1)
+ {
+ string n (*s, p1 + 1, p2 - p1 - 1);
+
+ // Note that we have to call substitute(), not lookup() since it
+ // can be overriden with custom substitution semantics.
+ //
+ optional<string> v (
+ substitute (location (&ip, ln), a, t, n, strict));
+
+ assert (v); // Rule semantics change without version increment?
+
+ if (s->compare (p2 + 1,
+ string::npos,
+ sha256 (*v).string ()) == 0)
+ {
+ dd_skip++;
+ continue;
+ }
+ else
+ l4 ([&]{trace << n << " variable value mismatch forcing "
+ << "update of " << t;});
+ // Fall through.
+ }
+
+ dd.write (); // Mark this line for overwriting.
+
+ // Fall through.
+ }
+
+ break;
+ }
+ }
+
+ if (dd.writing ()) // Recheck.
+ update = true;
+
+ // If nothing changed, then we are done.
+ //
+ if (!update)
+ {
+ dd.close ();
+ return ts;
+ }
+
+ if (verb >= 2)
+ text << program_ << ' ' << ip << " >" << tp;
+ else if (verb)
+ text << program_ << ' ' << ip;
+
+ // Read and process the file, one line at a time, while updating depdb.
+ //
+ const char* what;
+ const path* whom;
+ try
+ {
+ what = "open"; whom = &ip;
+ ifdstream ifs (ip, fdopen_mode::in, ifdstream::badbit);
+
+ // See fdopen() for details (umask, etc).
+ //
+ permissions prm (permissions::ru | permissions::wu |
+ permissions::rg | permissions::wg |
+ permissions::ro | permissions::wo);
+
+ if (t.is_a<exe> ())
+ prm |= permissions::xu | permissions::xg | permissions::xo;
+
+ // Remove the existing file to make sure permissions take effect. If
+ // this fails then presumable writing to it will fail as well and we
+ // will complain there.
+ //
+ try_rmfile (tp, true /* ignore_error */);
+
+ what = "open"; whom = &tp;
+ ofdstream ofs (fdopen (tp,
+ fdopen_mode::out | fdopen_mode::create,
+ prm));
+ auto_rmfile arm (tp);
+
+ string s; // Reuse the buffer.
+ for (size_t ln (1);; ++ln)
+ {
+ what = "read"; whom = &ip;
+ if (!getline (ifs, s))
+ break; // Could not read anything, not even newline.
+
+ // Not tracking column for now (see also depdb above).
+ //
+ const location l (&ip, ln);
+
+ // Scan the line looking for substiutions in the $<name>$ form. In
+ // the strict mode treat $$ as an escape sequence.
+ //
+ for (size_t b (0), n, d; b != (n = s.size ()); b += d)
+ {
+ d = 1;
+
+ if (s[b] != sym)
+ continue;
+
+ // Note that in the lax mode these should still be substitutions:
+ //
+ // @project@@
+ // @@project@
+
+ // Find the other end.
+ //
+ size_t e (b + 1);
+ for (; e != (n = s.size ()); ++e)
+ {
+ if (s[e] == sym)
+ {
+ if (strict && e + 1 != n && s[e + 1] == sym) // Escape.
+ s.erase (e, 1); // Keep one, erase the other.
+ else
+ break;
+ }
+ }
+
+ if (e == n)
+ {
+ if (strict)
+ fail (l) << "unterminated '" << sym << "'" << endf;
+
+ break;
+ }
+
+ if (e - b == 1) // Escape (or just double symbol in the lax mode).
+ {
+ if (strict)
+ s.erase (b, 1); // Keep one, erase the other.
+
+ continue;
+ }
+
+ // We have a (potential, in the lax mode) substition with b
+ // pointing to the opening symbol and e -- to the closing.
+ //
+ string name (s, b + 1, e - b -1);
+ if (optional<string> val = substitute (l, a, t, name, strict))
+ {
+ // Save in depdb.
+ //
+ if (dd_skip == 0)
+ {
+ // The line format is:
+ //
+ // <ln> <name> <hash>
+ //
+ string s (to_string (ln));
+ s += ' ';
+ s += name;
+ s += ' ';
+ s += sha256 (*val).string ();
+ dd.write (s);
+ }
+ else
+ --dd_skip;
+
+ // Patch the result in and adjust the delta.
+ //
+ s.replace (b, e - b + 1, *val);
+ d = val->size ();
+ }
+ else
+ d = e - b + 1; // Ignore this substitution.
+ }
+
+ what = "write"; whom = &tp;
+ if (ln != 1)
+ ofs << '\n'; // See below.
+ ofs << s;
+ }
+
+ // Close depdb before closing the output file so its mtime is not
+ // newer than of the output.
+ //
+ dd.close ();
+
+ what = "close"; whom = &tp;
+ ofs << '\n'; // Last write to make sure our mtime is older than dd.
+ ofs.close ();
+ arm.cancel ();
+
+ what = "close"; whom = &ip;
+ ifs.close ();
+ }
+ catch (const io_error& e)
+ {
+ fail << "unable to " << what << ' ' << *whom << ": " << e;
+ }
+
+ dd.check_mtime (tp);
+
+ t.mtime (system_clock::now ());
+ return target_state::changed;
+ }
+
+ prerequisite_target rule::
+ search (action,
+ const target& t,
+ const prerequisite_member& p,
+ include_type i) const
+ {
+ return prerequisite_target (&build2::search (t, p), i);
+ }
+
+ string rule::
+ lookup (const location& l, action, const target& t, const string& n) const
+ {
+ if (auto x = t[n])
+ {
+ value v (*x);
+
+ // For typed values call string() for conversion.
+ //
+ try
+ {
+ return convert<string> (
+ v.type == nullptr
+ ? move (v)
+ : functions.call (&t.base_scope (),
+ "string",
+ vector_view<value> (&v, 1),
+ l));
+ }
+ catch (const invalid_argument& e)
+ {
+ fail (l) << e <<
+ info << "while substituting '" << n << "'" << endf;
+ }
+ }
+ else
+ fail (l) << "undefined variable '" << n << "'" << endf;
+ }
+
+ optional<string> rule::
+ substitute (const location& l,
+ action a,
+ const target& t,
+ const string& n,
+ bool strict) const
+ {
+ // In the lax mode scan the fragment to make sure it is a variable name
+ // (that is, it can be expanded in a buildfile as just $<name>; see
+ // lexer's variable mode for details).
+ //
+ if (!strict)
+ {
+ for (size_t i (0), e (n.size ()); i != e; )
+ {
+ bool f (i == 0); // First.
+ char c (n[i++]);
+ bool l (i == e); // Last.
+
+ if (c == '_' || (f ? alpha (c) : alnum (c)))
+ continue;
+
+ if (c == '.' && !l)
+ continue;
+
+ return nullopt; // Ignore this substitution.
+ }
+ }
+
+ return lookup (l, a, t, n);
+ }
+ }
+}
diff --git a/libbuild2/in/rule.hxx b/libbuild2/in/rule.hxx
new file mode 100644
index 0000000..0daf6c0
--- /dev/null
+++ b/libbuild2/in/rule.hxx
@@ -0,0 +1,90 @@
+// file : libbuild2/in/rule.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_IN_RULE_HXX
+#define LIBBUILD2_IN_RULE_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/rule.hxx>
+
+#include <libbuild2/in/export.hxx>
+
+namespace build2
+{
+ namespace in
+ {
+ // Preprocess an .in file.
+ //
+ // Note that a derived rule can use the target data pad to cache data
+ // (e.g., in match()) to be used in substitute/lookup() calls.
+ //
+ // Note also that currently this rule ignores the dry-run mode (see
+ // perform_update() for the rationale).
+ //
+ class LIBBUILD2_IN_SYMEXPORT rule: public build2::rule
+ {
+ public:
+ // The rule id is used to form the rule name/version entry in depdb. The
+ // program argument is the pseudo-program name to use in the command
+ // line diagnostics.
+ //
+ rule (string rule_id,
+ string program,
+ char symbol = '$',
+ bool strict = true)
+ : rule_id_ (move (rule_id)),
+ program_ (move (program)),
+ symbol_ (symbol),
+ strict_ (strict) {}
+
+ virtual bool
+ match (action, target&, const string&) const override;
+
+ virtual recipe
+ apply (action, target&) const override;
+
+ virtual target_state
+ perform_update (action, const target&) const;
+
+ // Customization hooks.
+ //
+
+ // Perform prerequisite search.
+ //
+ virtual prerequisite_target
+ search (action,
+ const target&,
+ const prerequisite_member&,
+ include_type) const;
+
+ // Perform variable lookup.
+ //
+ virtual string
+ lookup (const location&,
+ action,
+ const target&,
+ const string& name) const;
+
+ // Perform variable substitution. Return nullopt if it should be
+ // ignored.
+ //
+ virtual optional<string>
+ substitute (const location&,
+ action,
+ const target&,
+ const string& name,
+ bool strict) const;
+
+ protected:
+ const string rule_id_;
+ const string program_;
+ char symbol_;
+ bool strict_;
+ };
+ }
+}
+
+#endif // LIBBUILD2_IN_RULE_HXX
diff --git a/libbuild2/in/target.cxx b/libbuild2/in/target.cxx
new file mode 100644
index 0000000..490ab10
--- /dev/null
+++ b/libbuild2/in/target.cxx
@@ -0,0 +1,62 @@
+// file : libbuild2/in/target.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#include <libbuild2/in/target.hxx>
+
+using namespace std;
+
+namespace build2
+{
+ namespace in
+ {
+ static const target*
+ in_search (const target& xt, const prerequisite_key& cpk)
+ {
+ // If we have no extension then derive it from our target. Then delegate
+ // to file_search().
+ //
+ prerequisite_key pk (cpk);
+ optional<string>& e (pk.tk.ext);
+
+ if (!e)
+ {
+ if (const file* t = xt.is_a<file> ())
+ {
+ const string& te (t->derive_extension ());
+ e = te + (te.empty () ? "" : ".") + "in";
+ }
+ else
+ fail << "prerequisite " << pk << " for a non-file target " << xt;
+ }
+
+ return file_search (xt, pk);
+ }
+
+ static bool
+ in_pattern (const target_type&,
+ const scope&,
+ string&,
+ optional<string>&,
+ const location& l,
+ bool)
+ {
+ fail (l) << "pattern in in{} prerequisite" << endf;
+ }
+
+ extern const char in_ext_def[] = ""; // No extension by default.
+
+ const target_type in::static_type
+ {
+ "in",
+ &file::static_type,
+ &target_factory<in>,
+ &target_extension_fix<in_ext_def>,
+ nullptr, /* default_extension */ // Taken care of by search.
+ &in_pattern,
+ &target_print_1_ext_verb, // Same as file.
+ &in_search,
+ false
+ };
+ }
+}
diff --git a/libbuild2/in/target.hxx b/libbuild2/in/target.hxx
new file mode 100644
index 0000000..5e3438d
--- /dev/null
+++ b/libbuild2/in/target.hxx
@@ -0,0 +1,48 @@
+// file : libbuild2/in/target.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_IN_TARGET_HXX
+#define LIBBUILD2_IN_TARGET_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/target.hxx>
+
+#include <libbuild2/in/export.hxx>
+
+namespace build2
+{
+ namespace in
+ {
+ // This is the venerable .in ("input") file that needs some kind of
+ // preprocessing.
+ //
+ // One interesting aspect of this target type is that the prerequisite
+ // search is target-dependent. Consider:
+ //
+ // hxx{version}: in{version.hxx} // version.hxx.in -> version.hxx
+ //
+ // Having to specify the header extension explicitly is inelegant. Instead
+ // what we really want to write is this:
+ //
+ // hxx{version}: in{version}
+ //
+ // But how do we know that in{version} means version.hxx.in? That's where
+ // the target-dependent search comes in: we take into account the target
+ // we are a prerequisite of.
+ //
+ class LIBBUILD2_IN_SYMEXPORT in: public file
+ {
+ public:
+ using file::file;
+
+ public:
+ static const target_type static_type;
+ virtual const target_type& dynamic_type () const {return static_type;}
+ };
+ }
+}
+
+#endif // LIBBUILD2_IN_TARGET_HXX