NAME
    Data::Sah - Schema for data structures (Perl implementation)

VERSION
    version 0.08

SYNOPSIS
    Non-OO interface:

     use Data::Sah qw(
         normalize_schema
         gen_validator
     );

     # normalize a schema
     my $nschema = normalize_schema("int*"); # => ["int", {req=>1}, {}]

     # generate a validator for schema
     my $v = gen_validator(["int*", min=>1, max=>10]);

     # validate your data using the generated validator
     say "valid" if $v->(5);     # valid
     say "valid" if $->(11);     # invalid
     say "valid" if $v->(undef); # invalid
     say "valid" if $v->("x");   # invalid

     # generate validator which reports error message string, in Indonesian
     my $v = gen_validator(["int*", min=>1, max=>10],
                           {return_type=>'str', lang=>'id'});
     say $v->(5);  # ''
     say $v->(12); # 'Data tidak boleh lebih besar dari 10'
                   # (in English: 'Data must not be larger than 10')

    OO interface (more advanced usage):

     use Data::Sah;
     my $sah = Data::Sah->new;

     # get perl compiler
     my $pl = $sah->get_compiler("perl");

     # compile schema into Perl code
     my $cd = $pl->compile($schema, \%opts);

DESCRIPTION
    This module, Data::Sah, implements compilers for producing Perl and
    JavaScript validators, as well as human description text (English and
    Indonesian included) from Sah schemas. Compiler approach is used instead
    of interpreter for faster speed.

    The generated validator code can run without this module.

STATUS
    Early implementation, only Perl compiler implemented. Only a handful of
    types and attributes supported.

EXPORTS
    None exported by default.

  normalize_schema($schema) => ARRAY
    Normalize $schema.

    Can also be used as a method.

  gen_validator($schema, \%opts) => CODE
    Generate validator code for $schema. %opts are passed to the Perl schema
    compiler.

    Can also be used as a method.

ATTRIBUTES
  compilers => HASH
    A mapping of compiler name and compiler (Data::Sah::Compiler::*)
    objects.

VARIABLES
  $Log_Validator_Code (bool, default: 0)
ENVIRONMENT
    LOG_SAH_VALIDATOR_CODE

METHODS
  new() => OBJ
    Create a new Data::Sah instance.

  $sah->get_compiler($name) => OBJ
    Get compiler object. "Data::Sah::Compiler::$name" will be loaded first
    and instantiated if not already so. After that, the compiler object is
    cached.

    Example:

     my $plc = $sah->get_compiler("perl"); # loads Data::Sah::Compiler::perl

  $sah->normalize_schema($schema) => HASH
    Normalize a schema, e.g. change "int*" into "[int => {req=>1}]", as well
    as do some sanity checks on it. Returns the normalized schema if
    succeeds, or dies on error.

    Can also be used as a function.

  $sah->normalize_var($var) => STR
    Normalize a variable name in expression into its fully
    qualified/absolute form.

    Not yet implemented (pending specification).

    For example:

     [int => {min => 10, 'max=' => '2*$min'}]

    $min in the above expression will be normalized as "schema:clauses.min".

  $sah->gen_validator($schema, \%opts) => CODE
    Use the Perl compiler to generate validator code. %opts will be passed
    to the Perl compiler.

    Can also be used as a function.

MODULE ORGANIZATION
    Data::Sah::Type::* roles specify Sah types, e.g. Data::Sah::Type::bool
    specifies the bool type.

    Data::Sah::FuncSet::* roles specify bundles of functions, e.g.
    Data::Sah::FuncSet::Core specifies the core/standard functions.

    Data::Sah::Compiler::$LANG:: namespace is for compilers. Each compiler
    (if derived from BaseCompiler) might further contain ::TH::* and
    ::FSH::* to implement appropriate functionalities, e.g.
    Data::Sah::Compiler::perl::TH::bool is the 'bool' type handler for the
    Perl compiler and Data::Sah::Compiler::perl::FSH::Core is the funcset
    'Core' handler for Perl compiler.

    Data::Sah::Lang::$LANGCODE::* namespace is reserved for modules that
    contain translations. Language submodules follows the organization of
    other modules, e.g. Data::Sah::Lang::en_US::Type::int,
    Data::Sah::Lang::id_ID::FuncSet::Core, etc.

    Data::Sah::Schema:: namespace is reserved for modules that contain
    bundles of schemas. For example, Data::Sah::Schema::CPANMeta contains
    the schema to validate CPAN META.yml. Data::Sah::Schema::Sah contains
    the schema for Sah schema itself.

    Data::Sah::TypeX::$TYPENAME::$CLAUSENAME namespace can be used to name
    distributions that extend an existing Sah type by introducing a new
    clause for it. It must also contain, at the minimum: perl, js, and human
    compiler implementations for it, as well as English translations. For
    example, Data::Sah::TypeX::int::is_prime is a distribution that adds
    "is_prime" clause to the "int" type. It will contain the following
    packages inside: Data::Sah::Type::int,
    Data::Sah::Compiler::{perl,human,js}::TH::int. Other compilers'
    implementation can be packaged under
    Data::Sah::Compiler::$COMPILERNAME::TypeX::$TYPENAME::$CLAUSENAME, e.g.
    Data::Sah::Compiler::python::TypeX::int::is_prime distribution. Language
    can be put in Data::Sah::Lang::$LANGCODE::TypeX::int::is_prime.

FAQ
  Relation to Data::Schema?
    Data::Schema is the old incarnation of this module, deprecated since
    2011.

    There are enough incompatibilities between the two (some different
    syntaxes, renamed clauses). Also, some terminology have been changed,
    e.g. "attribute" become "clauses", "suffix" becomes "attributes". This
    warrants a new name.

    Compared to Data::Schema, Sah always compiles schemas and there is much
    greater flexibility in code generation (can generate data term, can
    generate code to validate multiple schemas, etc). There is no longer
    hash form, schema is either a string or an array. Some clauses have been
    renamed (mostly, commonly used clauses are abbreviated, Huffman encoding
    thingy), some removed (usually because they are replaced by a more
    general solution), and new ones have been added.

    If you use Data::Schema, I recommend you migrate to Data::Sah as I will
    not be developing Data::Schema anymore. Sorry, there's currently no tool
    to convert your Data::Schema schemas to Sah, but it should be relatively
    straightforward.

  Comparison to {JSON::Schema, Data::Rx, Data::FormValidator, ...}?
    See Sah::FAQ.

  Can I generate another schema dynamically from within the schema?
    For example:

     // if first element is an integer, require the array to contain only integers,
     // otherwise require the array to contain only strings.
     ["array", {"min_len": 1, "of=": "[is_int($_[0]) ? 'int':'str']"}]

    Currently no, Data::Sah does not support expression on clauses that
    contain other schemas. In other words, dynamically generated schemas are
    not supported. To support this, if the generated code needs to run
    independent of Data::Sah, it needs to contain the compiler code itself
    (or an interpreter) to compile or evaluate the generated schema.

    However, an "eval_schema()" Sah function which uses Data::Sah can be
    trivially declared and target the Perl compiler.

  How to display the Perl (JavaScript, ...) validator code being generated?
    If you compile using one of the compiler, e.g.:

     # generate perl code
     $cd = $plc->compile(schema=>..., ...);

    then the Perl code is in "$cd->{result}" and you can just print it.

    If you generate validator using "gen_validator()", you can set
    environment LOG_SAH_VALIDATOR_CODE or package variable
    $Log_Validator_Code to true and the generated code will be logged at
    trace level using Log::Any. The log can be displayed using, e.g.,
    Log::Any::App:

     % LOG_SAH_VALIDATOR_CODE=1 TRACE=1 \
       perl -MLog::Any::App -MData::Sah=gen_validator \
       -e '$sub = gen_validator([int => min=>1, max=>10])'

SEE ALSO
  Alternatives to Sah
    Moose has a type system. MooseX::Params::Validate, among others, can
    validate method parameters based on this.

    Some other data validation and data schema modules on CPAN:
    Data::FormValidator, Params::Validate, Data::Rx, Kwalify,
    Data::Verifier, Data::Validator, JSON::Schema, Validation::Class.

AUTHOR
    Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2012 by Steven Haryanto.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

