EB initialization with Parser (#1980)

If `warpx.eb_implicit_function = ...` is present in input parameters, Parser
will be used to initialize EB.  For example,
```
warpx.eb_implicit_function = "max(max(max(x-0.5,-0.5-x), max(y-0.5,-0.5-y)), max(z-0.5,-0.5-z))"
```
specifies a box with boundaries at x=+-0.5, y=+-0.5 and z=+-0.5 and regular
domain inside the box.
```
warpx.eb_implicit_function = "-(x**2+y**2+z**2-0.2**2)"
```
specifies a solid sphere at (0,0,0) with a radius of 0.2.

1 files changed, 3 insertions, 0 deletions

diff --git a/Source/WarpX.H b/Source/WarpX.H
index 82a3e1483..9141df0e9 100644
--- a/Source/WarpX.H
+++ b/Source/WarpX.H
@@ -1099,6 +1099,9 @@ private:
     amrex::EBFArrayBoxFactory const& fieldEBFactory (int lev) const noexcept {
         return static_cast<amrex::EBFArrayBoxFactory const&>(*m_field_factory[lev]);
     }
+
+    // EB implicit funciton
+    std::unique_ptr<ParserWrapper<3> > m_eb_if_parser;
 #endif
 
     void InitEB ();