adding dynamic width and precision to printf

[johanmon]

So this is a second attempt to add dynamic width and precision to printf.

In order to handle dynamic width and precision I've added two fields to the Spec data structure. These indicate if the specification uses dynamic width and/or precision. I've also added a field to the Format data structure that tells us how many arguments a format string requires (this is no longer simply the number of specifications).

I've tried to keep as much of the existing code intact so fmt(buf, pos, arg, spec) is unchanged. We have a function fmt(buf, pos, args, argp, spec) and depending on if the specification uses dynamic width and/or precision call fmt(buf, pos, args[argp], spec). If the specification was dynamic the actual values are taken from the args and the specification is updated (we need to patch the zero flag for Ints since we now know the precision.

The plength(f, args) is handled in the same way so we first check if we have a dynamic specification and if so update it. The function now also returns the next argument position since it could be that we use one or two for dynamic values.

For the tests I've added a few explicit test but then only checked that the version with dynamic width an precision return the same string as the static versions.

Closes #40654

The previous pull request was: #33278 but since I rewrote everything and the Printf moved I thought it was better to do a new.

[musm]

Anything left to be done here or can we merge this?
Note this closes: #40654

[stevengj]

Looks like a botched merge/rebase?

[johanmon]

@stevengj Yes, complete fubar, how do I get out of this?

[stevengj]

I put together a cleaned-up branch that contains all your changes to stdlib/Printf (which I think is everything in this PR?). You should be able to do:

git fetch https://github.com/stevengj/julia jmon/dynamic2
git checkout jmon/dynamic2
git push --force https://github.com/johanmon/julia jmon/dynamic2:jmon/dynamic

[giordano]

Bump. Would be nice to eventually get this in, but the PR is still in a bad state. @johanmon are you still willing to push this through?

[stevengj]

I force-pushed the rebase.

[stevengj]

Good to merge?

[johanmon]

As far as I know yes.

[johanmon]

hmm.... just compiled everything and there is a duplication of code in Printf.jl

 rmdynamic(Printf.Spec{T}, Any, Any) where {T} 

occures twice?

[stevengj]

@johanmon, good catch — looks like a manual-rebase snafu. Should be fixed now.

[timholy]

From a JET report I'm seeing this:

rmdynamic(spec::Printf.Spec{T}, args, argp) where T @ Printf ~/.julia/juliaup/julia-1.11.0-rc1+0.x64.linux.gnu/share/julia/stdlib/v1.11/Printf/src/Printf.jl:297
297 function rmdynamic(spec::Printf.Spec{Val{'s'}}::Spec{T}, args::NTuple{5, String}, argp::Int64) where {T}
298     zero::Bool, width::Int64, precision::Int64 = spec::Printf.Spec{Val{'s'}}.zero::Bool, spec::Printf.Spec{Val{'s'}}.width::Int64, spec::Printf.Spec{Val{'s'}}.precision::Int64
299     if spec::Printf.Spec{Val{'s'}}.dynamic_width::Bool
300         width::String = args::NTuple{5, String}[argp::Int64]::String
301         (argp::Int64 += 1)::Int64
302     end
303     if spec::Printf.Spec{Val{'s'}}.dynamic_precision::Bool
304         precision::String = args::NTuple{5, String}[argp::Int64]::String
305         if zero::Bool && T <: Ints::Type{Union{Val{'d'}, Val{'i'}, Val{'u'}, Val{'x'}, Val{'X'}, Val{'o'}}}::Bool && precision > 0
306             zero = false
307         end
308         (argp::Int64 += 1)::Int64
309     end
310     (Spec::Type{Printf.Spec}{T}::Type{Printf.Spec{Val{'s'}}}(spec::Printf.Spec{Val{'s'}}.leftalign::Bool, spec::Printf.Spec{Val{'s'}}.plus::Bool, spec::Printf.Spec{Val{'s'}}.space::Bool, zero::Bool, spec::Printf.Spec{Val{'s'}}.hash::Bool, width::Union{Int64, String}, precision::Union{Int64, String}, false, false)::Printf.Spec{Val{'s'}}, argp::Int64)::Tuple{Printf.Spec{Val{'s'}}, Int64}
311 end

It seems to think that args::NTuple{5, String} and hence width and precision might be String. That seems problematic? Spec can only take Ints:

julia/stdlib/Printf/src/Printf.jl

Lines 33 to 43 in 0945b9d

	struct Spec{T} # T => %type => Val{'type'}
	leftalign::Bool
	plus::Bool
	space::Bool
	zero::Bool
	hash::Bool
	width::Int
	precision::Int
	dynamic_width::Bool
	dynamic_precision::Bool
	end

The call chain is as follows:

       Printf.Spec{Val{'s'}}(::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::String, ::Int64, ::Bool, ::Bool)
         rmdynamic(::Printf.Spec{Val{'s'}}, ::NTuple{5, String}, ::Int64)
           plength(::Printf.Spec{Val{'s'}}, ::NTuple{5, String}, ::Int64)
             computelen(::Vector{UnitRange{Int64}}, ::NTuple{5, Printf.Spec{Val{'s'}}}, ::NTuple{5, String})
               format(::IO, ::Printf.Format{Base.CodeUnits{UInt8, String}, NTuple{5, Printf.Spec{Val{'s'}}}}, ::String, ::String, ::String, ::String, ::Stri
                 nmf_skeleton!(::NMF.ProjectedALSUpd{Float64}, ::Matrix{Float64}, ::Matrix{Float64}, ::Matrix{Float64}, ::Int64, ::Bool, ::Float64)

nmf_skeleton! comes from NMF.jl