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Add writing support #46

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9ad8e3c
Add writing support
TonyLianLong Mar 10, 2019
1bbaef1
Add libreadstat into readstat_begin_row and readstat_end_row, pass po…
TonyLianLong Mar 20, 2019
150e1cd
Add handle_write and fix several syntax errors
TonyLianLong Mar 20, 2019
fcfc6fe
Update writing
TonyLianLong Mar 24, 2019
9f5c76e
Change functions for writing and export write functions
TonyLianLong Mar 24, 2019
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28 changes: 28 additions & 0 deletions src/C_interface.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -69,4 +69,32 @@ end

function readstat_parse(filename::String, type::Val{:sas7bdat}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
return ccall((:readstat_parse_sas7bdat, libreadstat), Int, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
end

function readstat_begin_row(writer)
return ccall((:readstat_begin_row), Int, (Ptr{Nothing},), writer)
end

function readstat_end_row(writer)
return ccall((:readstat_end_row), Int, (Ptr{Nothing},), writer)
end

function readstat_begin_writing(writer, filetype::Val{:dta}, io, row_count)
return ccall((:readstat_begin_writing_dta, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}, Cint), writer, io, Cint(row_count))
end

function readstat_begin_writing(writer, filetype::Val{:sav}, io, row_count)
return ccall((:readstat_begin_writing_sav, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}, Cint), writer, io, Cint(row_count))
end

function readstat_begin_writing(writer, filetype::Val{:por}, io, row_count)
return ccall((:readstat_begin_writing_por, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}, Cint), writer, io, Cint(row_count))
end

function readstat_begin_writing(writer, filetype::Val{:sas7bdat}, io, row_count)
return ccall((:readstat_begin_writing_sas7bdat, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}, Cint), writer, io, Cint(row_count))
end

function readstat_insert_double_value(writer, variable, item)
return ccall((:readstat_insert_double_value, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}, Any), writer, variable, item)
end
55 changes: 54 additions & 1 deletion src/ReadStat.jl
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Expand Up @@ -248,17 +248,70 @@ function Parser()
ccall((:readstat_set_value_handler, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}), parser, val_fxn)
ccall((:readstat_set_value_label_handler, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}), parser, label_fxn)
return parser
end
end

function parse_data_file!(ds::ReadStatDataFrame, parser::Ptr{Nothing}, filename::AbstractString, filetype::Val)
retval = readstat_parse(filename, filetype, parser, ds)
readstat_parser_free(parser)
retval == 0 || error("Error parsing $filename: $retval")
end


function handle_write!()

end
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Function probably has to look something like:

 function handle_!(data::Ptr, len::Int, ctx::Ptr)
          io = unsafe_pointer_to_objref(ctx)
          actual_data = unsafe_wrap(data, len)
          write(io, actual_data)
       end


function Writer(source; file_label="File Label")
writer = ccall((:readstat_writer_init, libreadstat), Ptr{Nothing}, ())
write_bytes = @cfunction(handle_write!, Cint, (Cint, Cint, Ptr{ReadStatDataFrame}))
ccall((:readstat_set_data_writer, libreadstat), Int, (Ptr{Nothing}, ), parser, write_bytes)
ccall((:readstat_writer_set_file_label, libreadstat, Cvoid, (Ptr{Nothing}, Cstring), writer, file_label)
return writer
end

function write_data_file(filename::AbstractString, filetype::Val, io::IO, source)
writer = Writer(source)
fields = fieldnames(eltype(source))
variables_array = []

for field in fields:
variable = ccall((:readstat_add_variable, libreadstat), Ptr{Nothing}, (Ptr{Nothing}, Cstring, Cint, Cint), writer, String(field), READSTAT_TYPE_DOUBLE, 0); # TODO: know width
readstat_variable_set_label(variable, String(field))
variables_array.push!(variable)

variables = NamedTuple{(fields...,)}((variables...,)) # generate a NamedTuple for variables


if Base.IteratorSize(source) == Base.HasLength(): # TODO: what about HasShape
row_count = length(q)
else: #fallback
row_count = 0
for _ in source
row_count += 1
end

readstat_begin_writing(writer, filetype, io, row_count)

for row in source
readstat_begin_row(writer)
for field in fields
readstat_insert_double_value(writer, variables[field], row[field]) # TODO: more than double
end
readstat_end_row(writer);
end

ccall((:readstat_end_writing, libreadstat), Int, (Ptr{Nothing}), writer)
ccall((:readstat_writer_free, libreadstat), Cvoid, (Ptr{Nothing}), writer)
end

read_dta(filename::AbstractString) = read_data_file(filename, Val(:dta))
read_sav(filename::AbstractString) = read_data_file(filename, Val(:sav))
read_por(filename::AbstractString) = read_data_file(filename, Val(:por))
read_sas7bdat(filename::AbstractString) = read_data_file(filename, Val(:sas7bdat))

write_dta(filename::AbstractString, io::IO, source) = write_data_file(filename, Val(:dta), io, source)
write_sav(filename::AbstractString, io::IO, source) = write_data_file(filename, Val(:sav), io, source)
write_por(filename::AbstractString, io::IO, source) = write_data_file(filename, Val(:por), io, source)
write_sas7bdat(filename::AbstractString, io::IO, source) = write_data_file(filename, Val(:sas7bdat), io, source)

end #module ReadStat