gistfile1.java

    public List<?> translate(LanguageObject obj, ExecutionContext context) {
		List<?> parts = null;
    	if (obj instanceof Function) {
    		Function function = (Function)obj;
    		if (functionModifiers != null) {
    			String name = function.getName();
    			while (true) {
	    			FunctionModifier modifier = functionModifiers.get(name);
	    			if (modifier != null) {
	    				parts = modifier.translate(function);
	    				break;
	    			}
	    			int index = name.indexOf('.');
	    			if (index < 0 || index == name.length() - 1) {
	    				break;
	    			}
    				name = name.substring(index + 1);
    			}
    		}
    	} else if (obj instanceof Command) {
    		parts = translateCommand((Command)obj, context);
    	} else if (obj instanceof Limit) {
    		parts = translateLimit((Limit)obj, context);
    	} else if (obj instanceof ColumnReference) {
    		ColumnReference elem = (ColumnReference)obj;
			if (isTrimStrings() && elem.getType() == TypeFacility.RUNTIME_TYPES.STRING && elem.getMetadataObject() != null 
					&& ("char".equalsIgnoreCase(elem.getMetadataObject().getNativeType()) || "nchar".equalsIgnoreCase(elem.getMetadataObject().getNativeType()))) { //$NON-NLS-1$ //$NON-NLS-2$
				return Arrays.asList(getLanguageFactory().createFunction(SourceSystemFunctions.RTRIM, new Expression[] {elem}, TypeFacility.RUNTIME_TYPES.STRING));
			}
    	} else if (obj instanceof DerivedColumn) {
            DerivedColumn dc = (DerivedColumn) obj;
            Expression expr = dc.getExpression();
            // For GEOMETRY SELECT expressions: force source to do
            // conversion from proprietary format to SRID + WKB blob.
            if (expr.getType() == TypeFacility.RUNTIME_TYPES.GEOMETRY) {
                return translateGeometrySelect(dc);
            }
        } else if (obj instanceof Literal) {
            Literal l = (Literal) obj;
            // For GEOMETRY literals: force source to do conversion
            // from WKB blob + SRID to proprietary format.
            if (l.getType() == TypeFacility.RUNTIME_TYPES.GEOMETRY) {
                return translateGeometryLiteral(l);
            }
        }
    	return parts;
    }

    public List<?> translateGeometryLiteral(Literal l) {
        GeometryType geom = (GeometryType) l.getValue();
        return Arrays.asList(
                getLanguageFactory().createFunction(SourceSystemFunctions.ST_GEOMFROMWKB,
                        new Expression[] {
                            new Literal(geom, TypeFacility.RUNTIME_TYPES.BLOB),
                            new Literal(geom.getSrid(), TypeFacility.RUNTIME_TYPES.INTEGER)
                        },
                        TypeFacility.RUNTIME_TYPES.GEOMETRY
                ));
    }

    public List<?> translateGeometrySelect(DerivedColumn dc) {
        return Arrays.asList(
                new DerivedColumn(
                        dc.getAlias(),
                        getLanguageFactory().createFunction(SourceSystemFunctions.ST_ASTEIIDFORMAT,
                                new Expression[] {
                                    dc.getExpression()
                                },
                                TypeFacility.RUNTIME_TYPES.GEOMETRY
                        )
                ));
    }

    public GeometryType retrieveGeometryValue(Object value) {
        return null;
    }

RetrieveGeometryValue could be overridden in one of the sub-translators if a special strategy is required (like reading EWKB or doing some reflection magic with vendor classes).