report: build only required figures

Introduces a intermediate derivation that can be imported into the
report derivation, which contains a string cmd that expands the fig
variable as needed.

garlic/report.nix

@@ -5,6 +5,7 @@
 , busybox
 , jq
 , texlive
+, sedReport
 }:
 let
   # TODO: We can select only which elements we need from fig by using:
@@ -13,15 +14,15 @@ let
 
   # By now, we require all plots
   figJSON = writeText "fig.json" (builtins.toJSON fig);
+  sedCmd = (import sedReport) fig;
 in
   stdenv.mkDerivation {
     name = "report";
     src = ./.;
     buildInputs = [ jq texlive.combined.scheme-basic ];
     buildPhase = ''
-      ls -l
-      sed -i -e "s:@fig\.nbody\.test@:$(jq -r .nbody.test ${figJSON}):g" report.tex
-      jq . ${figJSON}
+      ${sedCmd}
+      cat report.tex
       pdflatex report.tex -o report.pdf
       # Run again to fix figure references
       pdflatex report.tex -o report.pdf

garlic/report.tex

@@ -14,8 +14,8 @@ time $t$ is measured, as shown in the figure \ref{fig:nbody.test}.
 %
 \begin{figure}[h]
     \centering
-		\includegraphics[width=0.45\textwidth]{@fig.nbody.test@/scatter.png}
-		\includegraphics[width=0.45\textwidth]{@fig.nbody.test@/box.png}
+		\includegraphics[width=0.45\textwidth]{@fig.nbody.baseline@/scatter.png}
+		\includegraphics[width=0.45\textwidth]{@fig.nbody.baseline@/box.png}
 		\caption{Nbody times with varying block size}
 		\label{fig:nbody.test}
 \end{figure}

garlic/sedReport.nix

@@ -0,0 +1,19 @@
+{
+  stdenv
+, fig
+}:
+  stdenv.mkDerivation {
+    name = "report";
+    src = ./.;
+    buildPhase = ''
+      grep -o '@[^ @]*@' report.tex | sed 's/@//g' | sort -u > list
+
+      echo "fig:" > fun.nix
+      echo "'''" >> fun.nix
+      sed 's:\(^.*\)$:sed -i "s;@\1@;''${\1};g" report.tex:g' list >> fun.nix
+      echo "'''" >> fun.nix
+    '';
+    installPhase = ''
+      cp fun.nix $out
+    '';
+  }

overlay.nix

@@ -181,6 +181,9 @@ let
       report = callPackage ./garlic/report.nix {
         fig = self.bsc.garlic.fig;
       };
+      sedReport = callPackage ./garlic/sedReport.nix {
+        fig = self.bsc.garlic.fig;
+      };
 
       # Use the configuration for the following target machine
       targetMachine = self.garlic.machines.mn4;