org.aksw.sparqlify.core

Interface DatatypeSystemOld

All Known Implementing Classes:

DatatypeSystemDefault

public interface DatatypeSystemOld

A class with knowlegde about the type hierarchy. For instance, given two datatypes, it is possible to determine the most general datatype (int, float -> numeric), or the mightier of the two (float, double) -> double. Essentially, the dataypes form a tree,

Author:

raven

Method Summary

Methods

Modifier and Type	Method and Description
Object	cast(Object value, SqlDatatype target)
Factory1<SqlExpr>	cast(SqlDatatype from, SqlDatatype to) Return a factory for creating cast-expressions between the given datatypes Null if no such cast exists.
Integer	compare(SqlDatatype a, SqlDatatype b) Returns -1, 0, 1 if a is more specific, equal, more general the b.
SqlDatatype	getByClass(Class<?> clazz)
SqlDatatype	getByName(String name)
SqlDatatype	mostGenericDatatype(SqlDatatype from, SqlDatatype to) Returns the top-most node of the tree of compatible datatypes Hm, how to justify not returning object? so integer and string -> numeric string -> text The rationale is, that all numeric types have similar semantics in regard to comparison and arithmetic operations.
SqlDatatype	requireByName(String name)
Set<SqlDatatype>	supremumDatatypes(SqlDatatype from, SqlDatatype to)

Method Detail

getByName

SqlDatatype getByName(String name)

getByClass

SqlDatatype getByClass(Class<?> clazz)

requireByName

SqlDatatype requireByName(String name)

cast

Object cast(Object value,
          SqlDatatype target)

cast

Factory1<SqlExpr> cast(SqlDatatype from,
                     SqlDatatype to)

Return a factory for creating cast-expressions between the given datatypes Null if no such cast exists. Constant folding may be performed, but do not rely on it. So cast(string, int).create(NodeValue.makeString('666')) may return Cast((string, int), NodeValue('666')) rather than NodeValue.makeInteger(666)

mostGenericDatatype

SqlDatatype mostGenericDatatype(SqlDatatype from,
                              SqlDatatype to)

Returns the top-most node of the tree of compatible datatypes Hm, how to justify not returning object? so integer and string -> numeric string -> text The rationale is, that all numeric types have similar semantics in regard to comparison and arithmetic operations. However mixing string and numeric is invalid.

Parameters:

from -

to -

Returns:

supremumDatatypes

Set<SqlDatatype> supremumDatatypes(SqlDatatype from,
                                 SqlDatatype to)

compare

Integer compare(SqlDatatype a,
              SqlDatatype b)

Returns -1, 0, 1 if a is more specific, equal, more general the b. null if no subsumption relation exists

Parameters:

a -

b -

Returns: