[gnome-calculator/60-split-out-a-backend-library] gcalc: implemented tan() function

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 9d910054ecaf874ec1ac8aa224f489eb5f19ff42
Author: Daniel Espinosa Ortiz <esodan gmail com>
Date:   Fri Jan 4 16:18:45 2019 -0600

    gcalc: implemented tan() function

 gcalc/gcalc-function-tan.vala  | 54 ++++++++++++++++++++++++++++++++++++++++++
 gcalc/meson.build              |  1 +
 tests/gcalc-solving-basic.vala | 14 +++++++++++
 3 files changed, 69 insertions(+)
---
diff --git a/gcalc/gcalc-function-tan.vala b/gcalc/gcalc-function-tan.vala
new file mode 100644
index 00000000..914a1caf
--- /dev/null
+++ b/gcalc/gcalc-function-tan.vala
@@ -0,0 +1,54 @@
+/* gcalc-function-tan.vala
+ *
+ * Copyright (C) 2018  Daniel Espinosa <esodan gmail com>
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *      Daniel Espinosa <esodan gmail com>
+ */
+public class GCalc.GFunctionTan : GFunction {
+
+  public GFunctionTan () {
+    base ("sqrt", 1);
+    param_types.add (new GConstant ());
+  }
+
+  public override Expression call () throws GLib.Error
+  {
+    verify_params ();
+    GConstant c = null;
+    var exp = parameters.get_item (0) as Expression;
+    if (exp == null) {
+      throw new FunctionError.INVOCATION_ERROR ("Invalid parameter type. Expected %s", 
typeof(Expression).name ());
+    }
+    var ev = exp.solve ();
+    if (ev is ErrorResult) {
+       throw new FunctionError.INVOCATION_ERROR ("Invalid expression: %s", ((ErrorResult) ev).to_string ());
+    }
+    if (ev is Result) {
+      c = ((Result) ev).expression as GConstant;
+    }
+    if (c == null) {
+       throw new FunctionError.INVOCATION_ERROR ("Invalid expression in result");
+    }
+    var p1 = MPC.Complex (1000);
+    p1.set (c.get_complex ());
+    var res = MPC.Complex (1000);
+    res.tan (p1);
+    var nc = new GConstant.internal_complex (res);
+    return nc as Expression;
+  }
+}
+
diff --git a/gcalc/meson.build b/gcalc/meson.build
index 839d64d2..a980c384 100644
--- a/gcalc/meson.build
+++ b/gcalc/meson.build
@@ -51,6 +51,7 @@ sources = files([
        'gcalc-function-log.vala',
        'gcalc-function-sin.vala',
        'gcalc-function-sqrt.vala',
+       'gcalc-function-tan.vala',
        'gcalc-error-result.vala',
        'gcalc-gexpression.vala',
        'gcalc-gassign.vala',
diff --git a/tests/gcalc-solving-basic.vala b/tests/gcalc-solving-basic.vala
index 4eeb4299..08b2feee 100644
--- a/tests/gcalc-solving-basic.vala
+++ b/tests/gcalc-solving-basic.vala
@@ -536,6 +536,20 @@ class Tests {
         warning ("Error: %s", e.message);
       }
     });
+    Test.add_func ("/gcalc/solve/function/tan",
+    ()=>{
+      try {
+        var c1 = new GConstant.@double (0.0);
+        var f = new GFunctionTan ();
+        f.parameters.add (c1);
+        var c2 = f.call () as Constant;
+        assert (c2 != null);
+        message (c2.to_string ());
+        assert (c2.real () >= 0.0);
+      } catch (GLib.Error e) {
+        warning ("Error: %s", e.message);
+      }
+    });
     return Test.run ();
   }
 }