-- (c) Copyright - See License.txt

--

namespace serialize

--****

-- == Serialization of Euphoria Objects

--

-- <>

include std/convert.e

include std/machine.e

-- Serialized format of Euphoria objects

--

-- First byte:

-- 0..248 -- immediate small integer, -9 to 239

-- since small negative integers -9..-1 might be common

atom mem0, mem1, mem2, mem3

-- read 4-byte value at current position in database file

end function

-- read a serialized Euphoria object from disk

sequence s

atom len

end if

end if

case I2B then

#100 * getc(fh) +

MIN2B

case I3B then

#100 * getc(fh) +

#10000 * getc(fh) +

MIN3B

case I4B then

case F4B then

getc(fh), getc(fh)})

case F8B then

getc(fh), getc(fh),

getc(fh), getc(fh),

getc(fh), getc(fh)})

case else

-- sequence

else

end if

end if

-- in-line small integer for greater speed on strings

else

end if

end switch

end function

end function

-- read a serialized Euphoria object from a sequence

sequence s

integer len

end if

end if

case I2B then

#100 * sdata[pos+1] +

MIN2B, pos + 2}

case I3B then

#100 * sdata[pos+1] +

#10000 * sdata[pos+2] +

MIN3B, pos + 3}

case I4B then

case F4B then

sdata[pos+2], sdata[pos+3]}), pos + 4}

case F8B then

sdata[pos+2], sdata[pos+3],

sdata[pos+4], sdata[pos+5],

sdata[pos+6], sdata[pos+7]}), pos + 8}

case else

-- sequence

else

end if

-- in-line small integer for greater speed on strings

else

end if

end switch

end function

--****

-- === Routines

--**

-- Convert a serialized object in to a standard Euphoria object.

--

-- Parameters:

-- # ##sdata## : either a sequence containing one or more concatenated serialized objects or

-- an open file handle. If this is a file handle, the current position in the

-- file is assumed to be at a serialized object in the file.

-- # ##pos## : optional index into ##sdata##. If omitted 1 is assumed. The index must

-- point to the start of a serialized object.

--

-- Returns:

-- The return **value**, depends on the input type.

-- * If ##sdata## is a file handle then

-- this function returns a Euphoria object that had been stored in the file, and

-- moves the current file to the first byte after the stored object.

-- * If ##sdata## is a sequence then this returns a two-element sequence.

-- The //first// element is the Euphoria object that corresponds to the serialized

-- object that begins at index ##pos##, and the //second// element is the index

-- position in the input parameter just after the serialized object.

--

--

-- Comments:

-- A serialized object is one that has been returned from the [[:serialize]] function.

--

-- Example 1:

--

-- sequence objcache

-- objcache = serialize(FirstName) &

-- serialize(LastName) &

-- serialize(PhoneNumber) &

-- serialize(Address)

--

-- sequence res

-- integer pos = 1

-- res = deserialize( objcache , pos)

-- FirstName = res[1] pos = res[2]

-- res = deserialize( objcache , pos)

-- LastName = res[1] pos = res[2]

-- res = deserialize( objcache , pos)

-- PhoneNumber = res[1] pos = res[2]

-- res = deserialize( objcache , pos)

-- Address = res[1] pos = res[2]

--

--

-- Example 2:

--

-- sequence objcache

-- objcache = serialize({FirstName,

-- LastName,

-- PhoneNumber,

-- Address})

--

-- sequence res

-- res = deserialize( objcache )

-- FirstName = res[1][1]

-- LastName = res[1][2]

-- PhoneNumber = res[1][3]

-- Address = res[1][4]

--

--

-- Example 3:

--

-- integer fh

-- fh = open("cust.dat", "wb")

-- puts(fh, serialize(FirstName))

-- puts(fh, serialize(LastName))

-- puts(fh, serialize(PhoneNumber))

-- puts(fh, serialize(Address))

-- close(fh)

--

-- fh = open("cust.dat", "rb")

-- FirstName = deserialize(fh)

-- LastName = deserialize(fh)

-- PhoneNumber = deserialize(fh)

-- Address = deserialize(fh)

-- close(fh)

--

--

-- Example 4:

--

-- integer fh

-- fh = open("cust.dat", "wb")

-- puts(fh, serialize({FirstName,

-- LastName,

-- PhoneNumber,

-- Address}))

-- close(fh)

--

-- sequence res

-- fh = open("cust.dat", "rb")

-- res = deserialize(fh)

-- close(fh)

-- FirstName = res[1]

-- LastName = res[2]

-- PhoneNumber = res[3]

-- Address = res[4]

--

--

-- read a serialized Euphoria object

end if

end if

end function

--**

-- Convert a standard Euphoria object in to a serialized version of it.

--

-- Parameters:

-- # ##euobj## : any Euphoria object.

--

-- Returns:

-- A **sequence**, this is the serialized version of the input object.

--

-- Comments:

-- A serialized object is one that has been converted to a set of byte values. This

-- can then by written directly out to a file for storage.

--

-- You can use the [[:deserialize]] function to convert it back into a standard

-- Euphoria object.

--

-- Example 1:

--

-- integer fh

-- fh = open("cust.dat", "wb")

-- puts(fh, serialize(FirstName))

-- puts(fh, serialize(LastName))

-- puts(fh, serialize(PhoneNumber))

-- puts(fh, serialize(Address))

-- close(fh)

--

-- fh = open("cust.dat", "rb")

-- FirstName = deserialize(fh)

-- LastName = deserialize(fh)

-- PhoneNumber = deserialize(fh)

-- Address = deserialize(fh)

-- close(fh)

--

--

-- Example 2:

--

-- integer fh

-- fh = open("cust.dat", "wb")

-- puts(fh, serialize({FirstName,

-- LastName,

-- PhoneNumber,

-- Address}))

-- close(fh)

--

-- sequence res

-- fh = open("cust.dat", "rb")

-- res = deserialize(fh)

-- close(fh)

-- FirstName = res[1]

-- LastName = res[2]

-- PhoneNumber = res[3]

-- Address = res[4]

--

--

-- return the serialized representation of a Euphoria object

-- as a sequence of bytes

sequence x4, s

else

end if

-- floating point

-- can represent as 4-byte float

else

end if

else

-- sequence

else

end if

end if

end function

--**

-- Saves a Euphoria object to disk in a binary format.

--

-- Parameters:

-- # ##data## : any Euphoria object.

-- # ##filename## : the name of the file to save it to.

--

-- Returns:

-- An **integer**, 0 if the function fails, otherwise the number of bytes in the

-- created file.

--

-- Comments:

-- If the named file doesn't exist it is created, otherwise it is overwritten.

--

-- You can use the [[:load]] function to recover the data from the file.

--

-- Example :

--

-- include std/serialize.e

-- integer size = dump(myData, theFileName)

-- if size = 0 then

-- puts(1, "Failed to save data to file\n")

-- else

-- printf(1, "Saved file is %d bytes long\n", size)

-- end if

--

--

integer fh

sequence sdata

end if

end function

--**

-- Restores a Euphoria object that has been saved to disk by [[:dump]].

--

-- Parameters:

-- # ##filename## : the name of the file to restore it from.

--

-- Returns:

-- A **sequence**, the first element is the result code. If the result code is 0

-- then it means that the function failed, otherwise the restored data is in the

-- second element.

--

-- Comments:

-- This is used to load back data from a file created by the [[:dump]]

-- function.

--

-- Example :

--

-- include std/serialize.e

-- sequence mydata = load(theFileName)

-- if mydata[1] = 0 then

-- puts(1, "Failed to load data from file\n")

-- else

-- mydata = mydata[2] -- Restored data is in second element.

-- end if

--

--

integer fh

sequence sdata

end if

end function