class Sequel::Postgres::PGRow::Parser

The Parser is responsible for taking the input string from PostgreSQL, and returning an appropriate ruby object that the type represents, such as an ArrayRow or HashRow.

Attributes

column_converters[R]

Converters for each member in the composite type. If not present, no conversion will be done, so values will remain strings. If present, should be an array of callable objects.

column_oids[R]

The OIDs for each member in the composite type. Not currently used, but made available for user code.

columns[R]

The columns for the parser, if any. If the parser has no columns, it will treat the input as an array. If it has columns, it will treat the input as a hash. If present, should be an array of strings.

converter[R]

A converter for the object as a whole. Used to wrap the returned array/hash in another object, such as an ArrayRow or HashRow. If present, should be callable.

oid[R]

The oid for the composite type itself.

typecaster[R]

A callable object used for typecasting the object. This is similar to the converter, but it is called by the typecasting code, which has different assumptions than the converter. For instance, the converter should be called with all of the member values already typecast, but the typecaster may not be.

Public Class Methods

new(h=OPTS) click to toggle source

Sets each of the parser's attributes, using options with the same name (e.g. :columns sets the columns attribute).

    # File lib/sequel/extensions/pg_row.rb
286 def initialize(h=OPTS)
287   @columns = h[:columns]
288   @column_converters = h[:column_converters]
289   @column_oids = h[:column_oids]
290   @converter = h[:converter]
291   @typecaster = h[:typecaster]
292   @oid = h[:oid]
293 end

Public Instance Methods

call(s) click to toggle source

Convert the PostgreSQL composite type input format into an appropriate ruby object.

    # File lib/sequel/extensions/pg_row.rb
297 def call(s)
298   convert(convert_format(convert_columns(Splitter.new(s).parse)))
299 end
typecast(obj) click to toggle source

Typecast the given object to the appropriate type using the typecaster. Note that this does not conversion for the members of the composite type, since those conversion expect strings and strings may not be provided.

    # File lib/sequel/extensions/pg_row.rb
305 def typecast(obj)
306   case obj 
307   when Array
308     _typecast(convert_format(obj))
309   when Hash
310     unless @columns
311       raise Error, 'PGRow::Parser without columns cannot typecast from a hash'
312     end
313     _typecast(obj)
314   else
315     raise Error, 'PGRow::Parser can only typecast arrays and hashes'
316   end
317 end

Private Instance Methods

_typecast(obj) click to toggle source

If the parser has a typecaster, call it with the object, otherwise return the object as is.

    # File lib/sequel/extensions/pg_row.rb
323 def _typecast(obj)
324   if t = @typecaster
325     t.call(obj)
326   else
327     obj
328   end
329 end
convert(obj) click to toggle source

If the parser has a converter, call it with the object, otherwise return the object as is.

    # File lib/sequel/extensions/pg_row.rb
356 def convert(obj)
357   if c = @converter
358     c.call(obj)
359   else
360     obj
361   end
362 end
convert_columns(arr) click to toggle source

If the parser has column converters, map the array of strings input to a array of appropriate ruby objects, one for each converter.

    # File lib/sequel/extensions/pg_row.rb
334 def convert_columns(arr)
335   if ccs = @column_converters
336     arr.zip(ccs).map{|v, pr| (v && pr) ? pr.call(v) : v}
337   else
338     arr 
339   end
340 end
convert_format(arr) click to toggle source

If the parser has columns, return a hash assuming that the array is ordered by the columns.

    # File lib/sequel/extensions/pg_row.rb
344 def convert_format(arr)
345   if cs = @columns
346     h = {}
347     arr.zip(cs).each{|v, c| h[c] = v}
348     h
349   else
350     arr
351   end
352 end