bugfix: optimization of complex constant string concatenations

tools/cmerge.nim

@@ -1,26 +1,35 @@
 # Simple tool to merge C projects into a single C file
 
-import os, strtabs, pegs
+import os, sets, pegs
 
-proc process(dir, infile: string, outfile: TFile, processed: PStringTable) =
-  if processed.hasKey(infile): return
-  processed[infile] = "True"
-  echo "adding: ", infile
-  for line in lines(dir / infile):
+type
+  TProcessResult = enum prSkipIncludeDir, prAddIncludeDir
+
+proc process(dir, infile: string, outfile: TFile, 
+             processed: var TSet[string]): TProcessResult =
+  if processed.containsOrIncl(infile): return prSkipIncludeDir
+  let toProcess = dir / infile
+  if not existsFile(toProcess):
+    echo "Warning: could not process: ", toProcess
+    return prAddIncludeDir
+  echo "adding: ", toProcess
+  for line in lines(toProcess):
     if line =~ peg"""s <- ig '#include' ig '"' {[^"]+} '"' ig
                      comment <- '/*' !'*/'* '*/' / '//' .*
                      ig <- (comment / \s+)* """:
       # follow the include file:
-      process(dir, matches[0], outfile, processed)
+      if process(dir, matches[0], outfile, processed) == prAddIncludeDir:
+        writeln(outfile, line)
     else:
       writeln(outfile, line)
 
 proc main(dir, outfile: string) =
   var o: TFile
   if open(o, outfile, fmWrite):
-    var processed = newStringTable([outfile, "True"])
+    var processed = initSet[string]()
+    processed.incl(outfile)
     for infile in walkfiles(dir / "*.c"):
-      process(dir, extractFilename(infile), o, processed)
+      discard process(dir, extractFilename(infile), o, processed)
     close(o)
   else:
     quit("Cannot open for writing: " & outfile)