Create file for helper functions

src/HelperFunctions.jl

@@ -0,0 +1,71 @@
+using MacroTools
+
+"""
+Some variable names are interpreted as operators.
+Thus, we decompose expressions like :(a in b) in individual Symbols.
+"""
+function remove_expr(x::Expr)
+    if x.head == :call
+        return [x.args[2], x.args[1], x.args[3]]
+    else
+        error("Can not handle $x")
+    end
+end
+
+"""
+We expect an array of variable names; some however form an Expr instead of being individual Symbols.
+"""
+function remove_expr(x::Array)
+    # we need a deepcopy to avoid issues with recursive changes
+    untangled = deepcopy(x)
+    for i in eachindex(x)[end:begin]
+        if typeof(untangled[i]) == Expr
+            untangled = [
+                untangled[1:(i-1)];
+                remove_expr(untangled[i]);
+                untangled[(i+1):end]
+            ]
+        end
+    end
+    return untangled
+end
+
+remove_blocks(e::Any) = e
+
+"""
+Sometimes our equation input might have lines which are themselves blocks (with only a single line).
+This happens e.g. if we have two variables on the left hand side.
+In such a case we just want to convert this block into it's contents.
+"""
+function remove_blocks(expr::Expr)
+    for (i, arg) in enumerate(expr.args)
+        if typeof(arg) == Expr
+            if arg.head == :block
+                if (length(arg.args) == 1)
+                    expr.args[i] = remove_blocks(arg.args[1])
+                else
+                    error("Can not handle sub-blocks with multiple lines.")
+                end
+            else
+                expr.args[i] = remove_blocks(arg)
+            end
+        end
+    end
+    return expr
+end
+
+"""
+Find all symbols in an Expr aside from the math operators.
+"""
+function find_symbols(line::Expr)
+    found::Set{Symbol} = Set([])
+    args = line.args
+    for i in eachindex(args)
+        if typeof(args[i]) == Symbol
+            push!(found, args[i])
+        elseif typeof(args[i]) == Expr
+            union!(found, find_symbols(args[i]))
+        end
+    end
+    return setdiff(found, math_operators)
+end