org.teiid.translator.jdbc
Class ConvertModifier

java.lang.Object
  org.teiid.translator.jdbc.FunctionModifier
      org.teiid.translator.jdbc.ConvertModifier

public class ConvertModifier
extends FunctionModifier

Base class for handling the convert function.

Convert is by far the most complicated pushdown function since it actually represents a matrix of possible functions. Additionally not every source supports the same semantics as our conversions.

Each instance of this class makes a best effort at handling converts for for a given source - compensating for differing string representation, the lack a time type etc.

The choice of conversion logic is as follows:

• Provide specific conversion between the source and target - addConvert(int, int, FunctionModifier) mostly one do not need to provide any conversion if the default is cast(srcType AS targetType), however if the source database requires different specific format for example to cast(srctype, targetType FORMAT 'more-info') this conversion needs to be added
• Filter common implicit conversions
• Look for a general source conversion - addSourceConversion(FunctionModifier, int...)
• Look for a general target conversion - addTypeConversion(FunctionModifier, int...). If the source database provides a specific function for converting *any* source datatype to this target datatype then use this to define it. Like in oracle "to_char" function will convert any other data type to string. Use this to define those kind of conversions convert any data type to string. so you can use this for purpose.
• Type maps from database data type to Teiid runtime types. - addTypeMapping(String, int...) define mappings for every datatype available in database. The cast operation will replace the target type (teiid type) with the given native type in the cast operation generated. Do not need to really look at implicit/explicit conversions that are supported by the source database, because when a cast is defined on the sql it is up to the source database to apply it as implicit or explicit operation. Teiid generates cast always when needed
• Drop the conversion

Nested Class Summary

static class

ConvertModifier.FormatModifier

Field Summary

Fields inherited from class org.teiid.translator.jdbc.FunctionModifier

BIGDECIMAL, BIGINTEGER, BLOB, BOOLEAN, BYTE, CHAR, CLOB, DATE, DOUBLE, FLOAT, INTEGER, LONG, NULL, OBJECT, SHORT, STRING, TIME, TIMESTAMP, XML

Constructor Summary

ConvertModifier()

Method Summary

void	addConvert(int sourceType, int targetType, FunctionModifier convert)
void	addNumericBooleanConversions()
void	addSourceConversion(FunctionModifier convert, int... sourceType)
void	addTypeConversion(FunctionModifier convert, int... targetType)
void	addTypeMapping(String nativeType, int... targetType)
static Function	createConvertFunction(LanguageFactory langFactory, Expression expr, String typeName)
void	setBooleanNullable(boolean booleanNullable)
void	setWideningNumericImplicit(boolean wideningNumericImplicit)
List<?>	translate(Function function) Return a List of translated parts (LanguageObjects and Objects), or null if this FunctionModifier wishes to rely on the default translation of the conversion visitor.

Methods inherited from class org.teiid.translator.jdbc.FunctionModifier

getCode

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ConvertModifier

public ConvertModifier()

Method Detail

addTypeConversion

public void addTypeConversion(FunctionModifier convert,
                              int... targetType)

addSourceConversion

public void addSourceConversion(FunctionModifier convert,
                                int... sourceType)

addTypeMapping

public void addTypeMapping(String nativeType,
                           int... targetType)

setWideningNumericImplicit

public void setWideningNumericImplicit(boolean wideningNumericImplicit)

addConvert

public void addConvert(int sourceType,
                       int targetType,
                       FunctionModifier convert)

translate

public List<?> translate(Function function)

Description copied from class: FunctionModifier

Return a List of translated parts (LanguageObjects and Objects), or null if this FunctionModifier wishes to rely on the default translation of the conversion visitor.

Specified by:

translate in class FunctionModifier

Parameters:

function - IFunction to be translated

Returns:

List of translated parts, or null

createConvertFunction

public static Function createConvertFunction(LanguageFactory langFactory,
                                             Expression expr,
                                             String typeName)

addNumericBooleanConversions

public void addNumericBooleanConversions()

setBooleanNullable

public void setBooleanNullable(boolean booleanNullable)