Named Digraphs: Implement ListNamedDigraphs as search function

digraphs · Feb 24, 2021 · ed0249b · ed0249b
1 parent b6cea6c
commit ed0249b
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diff --git a/gap/examples.gd b/gap/examples.gd
@@ -48,3 +48,5 @@ DeclareOperation("PetersenGraph", [IsFunction]);
 DeclareConstructor("GeneralisedPetersenGraphCons", [IsDigraph, IsInt, IsInt]);
 DeclareOperation("GeneralisedPetersenGraph", [IsInt, IsInt]);
 DeclareOperation("GeneralisedPetersenGraph", [IsFunction, IsInt, IsInt]);
+
+DeclareOperation("ListNamedDigraphs", [IsString]);
diff --git a/gap/examples.gi b/gap/examples.gi
@@ -370,3 +370,31 @@ GeneralisedPetersenGraphCons);
 
 InstallMethod(GeneralisedPetersenGraph, "for integer, integer", [IsInt, IsInt],
 {n, k} -> GeneralisedPetersenGraphCons(IsImmutableDigraph, n, k));
+
+InstallMethod(ListNamedDigraphs, "for a partially completed string",
+[IsString],
+function(s)
+  local l, cands, out, c;
+  # standardise request
+  s := LowercaseString(s);
+  RemoveCharacters(s, " \n\t\r");
+  l := Length(s);
+
+  # load database if not already done
+  DIGRAPHS_LoadNamedGraph6Strings();
+
+  # retrieve candidates
+  cands := RecNames(DIGRAPHS_NamedGraph6String);
+  if l = 0 then
+    return cands;
+  fi;
+
+  # add to out-list all valid completions of the request s
+  out := [];
+  for c in cands do
+    if c{[1..l]} = s then
+      Add(out, c);
+    fi;
+  od;
+  return out;
+end);