codegen: Add support for feature test macros

This adds new CCode string attribute 'feature_test_macro = "VALUE"'. Such
values will be added before the headers section as '#define VALUE'.

https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html

https://bugzilla.gnome.org/show_bug.cgi?id=793444

3 files changed, 56 insertions, 0 deletions

diff --git a/ccode/Makefile.am b/ccode/Makefile.am
index 0f86b9646..3518c82fd 100644
--- a/ccode/Makefile.am
+++ b/ccode/Makefile.am
@@ -34,6 +34,7 @@ libvalaccode_la_VALASOURCES = \
 	valaccodeenumvalue.vala \
 	valaccodeexpression.vala \
 	valaccodeexpressionstatement.vala \
+	valaccodefeaturetestmacro.vala \
 	valaccodefile.vala \
 	valaccodeforstatement.vala \
 	valaccodefragment.vala \
diff --git a/ccode/valaccodefeaturetestmacro.vala b/ccode/valaccodefeaturetestmacro.vala
new file mode 100644
index 000000000..d18f28dcb
--- /dev/null
+++ b/ccode/valaccodefeaturetestmacro.vala
@@ -0,0 +1,44 @@
+/* valaccodefeaturetestmacro.vala
+ *
+ * Copyright (C) 2018  Dr. Michael 'Mickey' Lauer
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+
+ * This library 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
+ * Lesser General Public License for more details.
+
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+ *
+ * Author:
+ * 	Dr. Michael 'Mickey' Lauer <mickey@vanille-media.de>
+ */
+
+using GLib;
+
+/**
+ * Represents a feature test macro definition in the C code.
+ */
+public class Vala.CCodeFeatureTestMacro : CCodeNode {
+	/**
+	 * The name of this macro.
+	 */
+	public string name { get; set; }
+
+	public CCodeFeatureTestMacro (string name) {
+		this.name = name;
+	}
+
+	public override void write (CCodeWriter writer) {
+		writer.write_indent ();
+		writer.write_string ("#define ");
+		writer.write_string (name);
+		writer.write_newline ();
+	}
+}
diff --git a/ccode/valaccodefile.vala b/ccode/valaccodefile.vala
index 128cd3938..aa5be219e 100644
--- a/ccode/valaccodefile.vala
+++ b/ccode/valaccodefile.vala
@@ -24,9 +24,11 @@
 public class Vala.CCodeFile {
 	public bool is_header { get; set; }
 
+	Set<string> features = new HashSet<string> (str_hash, str_equal);
 	Set<string> declarations = new HashSet<string> (str_hash, str_equal);
 	Set<string> includes = new HashSet<string> (str_hash, str_equal);
 	CCodeFragment comments = new CCodeFragment ();
+	CCodeFragment feature_test_macros = new CCodeFragment ();
 	CCodeFragment include_directives = new CCodeFragment ();
 	CCodeFragment type_declaration = new CCodeFragment ();
 	CCodeFragment type_definition = new CCodeFragment ();
@@ -46,6 +48,13 @@ public class Vala.CCodeFile {
 		comments.append (comment);
 	}
 
+	public void add_feature_test_macro (string feature_test_macro) {
+		if (!(feature_test_macro in features)) {
+			feature_test_macros.append (new CCodeFeatureTestMacro (feature_test_macro));
+			features.add (feature_test_macro);
+		}
+	}
+
 	public void add_include (string filename, bool local = false) {
 		if (!(filename in includes)) {
 			include_directives.append (new CCodeIncludeDirective (filename, local));
@@ -133,6 +142,8 @@ public class Vala.CCodeFile {
 
 			comments.write (writer);
 			writer.write_newline ();
+			feature_test_macros.write (writer);
+			writer.write_newline ();
 			include_directives.write (writer);
 			writer.write_newline ();
 			type_declaration.write_combined (writer);