Implemented #407 (variables in technology base path)

The implementation uses extrapolation of strings in the
"Expressions" framework.

There is how:
* $(tech_name) -> substituted by the technology name
* $(tech_dir) -> substituted by the directory the technology file is stored in
* $(tech_file) -> substituted by the absolute path to the tech file
* $(appdata_path) -> substituted by KLayout's home directory (e.g. ~/.klayout)
* $(env('X')) -> substituted by the environment variable $X

src/db/db/dbTechnology.cc

@@ -24,6 +24,7 @@
 #include "dbTechnology.h"
 #include "dbStream.h"
 #include "tlFileUtils.h"
+#include "tlExpression.h"
 
 #include <stdio.h>
 
@@ -408,13 +409,24 @@ Technology::set_component (TechnologyComponent *component)
   }
 }
 
+std::string
+Technology::base_path () const
+{
+  tl::Eval expr;
+  expr.set_var ("tech_dir", m_default_base_path);
+  expr.set_var ("tech_file", m_lyt_file);
+  expr.set_var ("tech_name", name ());
+  return expr.interpolate (m_explicit_base_path.empty () ? m_default_base_path : m_explicit_base_path);
+}
+
 std::string 
 Technology::correct_path (const std::string &fp) const
 {
-  if (base_path ().empty ()) {
+  std::string bp = base_path ();
+  if (bp.empty ()) {
     return fp;
   } else {
-    return tl::relative_path (base_path (), fp);
+    return tl::relative_path (bp, fp);
   }
 }
 
@@ -442,14 +454,15 @@ Technology::save (const std::string &fn) const
 std::string 
 Technology::build_effective_path (const std::string &p) const
 {
-  if (p.empty () || base_path ().empty ()) {
+  std::string bp = base_path ();
+  if (p.empty () || bp.empty ()) {
     return p;
   }
 
   if (tl::is_absolute (p)) {
     return p;
   } else {
-    return tl::combine_path (base_path (), p);
+    return tl::combine_path (bp, p);
   }
 }
 

src/db/db/dbTechnology.h

@@ -327,10 +327,7 @@ public:
    *  a technology file was imported. The explicit one is the one that is specified
    *  explicitly.
    */
-  const std::string &base_path () const
+  std::string base_path () const;
-  {
-    return m_explicit_base_path.empty () ? m_default_base_path : m_explicit_base_path;
-  }
 
   /**
    *  @brief Makes a file path relative to the base path if one is specified.

src/db/unit_tests/dbTechnologyTests.cc

@@ -0,0 +1,70 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2019 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+
+#include "dbTechnology.h"
+#include "tlUnitTest.h"
+#include "tlFileUtils.h"
+
+TEST(1_Basic)
+{
+  db::Technology tech ("name", "description");
+
+  EXPECT_EQ (tech.name (), "name");
+  EXPECT_EQ (tech.description (), "description");
+
+  tech.set_name ("x");
+  EXPECT_EQ (tech.name (), "x");
+
+  tech.set_description ("y");
+  EXPECT_EQ (tech.description (), "y");
+
+  tech.set_grain_name ("a");
+  EXPECT_EQ (tech.grain_name (), "a");
+
+  tech.set_grain_name ("a");
+  EXPECT_EQ (tech.grain_name (), "a");
+
+  tech.set_dbu (2.5);
+  EXPECT_EQ (tech.dbu (), 2.5);
+}
+
+TEST(2_BasePath)
+{
+  db::Technology tech ("x", "description");
+
+  tech.set_default_base_path ("def");
+  EXPECT_EQ (tech.default_base_path (), "def");
+
+  tech.set_explicit_base_path ("$(tech_name)_plus");
+  EXPECT_EQ (tech.explicit_base_path (), "$(tech_name)_plus");
+
+  EXPECT_EQ (tech.base_path (), "x_plus");
+  EXPECT_EQ (tech.correct_path (tl::combine_path ("x_plus", "z")), "z");
+
+  tech.set_tech_file_path ("lyt");
+  tech.set_explicit_base_path ("$(tech_file)_plus");
+  EXPECT_EQ (tech.base_path (), "lyt_plus");
+
+  tech.set_explicit_base_path ("$(tech_dir)_plus");
+  EXPECT_EQ (tech.base_path (), "def_plus");
+}

src/db/unit_tests/unit_tests.pro

@@ -72,7 +72,8 @@ SOURCES = \
     dbNetlistReaderTests.cc \
     dbLayoutVsSchematicTests.cc \
     dbLayoutQueryTests.cc \
-    dbPolygonToolsTests.cc
+    dbPolygonToolsTests.cc \
+    dbTechnologyTests.cc
 
 INCLUDEPATH += $$TL_INC $$DB_INC $$GSI_INC
 DEPENDPATH += $$TL_INC $$DB_INC $$GSI_INC