using Printf, DataStructures

function funcfreqs(expr::Expr)
    cnt = counter(Symbol)
    expr.head == :call &&
        push!(cnt, expr.args[1])
    for e in expr.args
        e isa Expr && merge!(cnt, funcfreqs(e))
    end
    return cnt
end

function parseall(str::AbstractString)
    exs = Any[]
    pos = start(str)
    while !done(str, pos)
        ex, pos = parse(str, pos) # returns next starting point as well as expr
        ex.head == :toplevel ? append!(exs, ex.args) : push!(exs, ex)
    end
    if isempty(exs)
        throw(ParseError("end of input"))
    elseif length(exs) == 1
        return exs[1]
    else
        return Expr(:block, exs...)
    end
end

freqs = readstring("src/Function_frequency.jl") |> parseall |> funcfreqs

for (v, f) in freqs
    @printf("%10s → %i\n", v, f)
end