efunc_tcontseq_tcontseq efunc_tcontseq_tcontseq_discont efunc_tcontseq_tdiscseq efunc_tcontseq_tinstant efunc_tdiscseq_tcontseq efunc_tdiscseq_tdiscseq efunc_tdiscseq_tinstant efunc_tdiscseq_tsequenceset efunc_temporal_temporal efunc_tinstant_tcontseq efunc_tinstant_tdiscseq efunc_tinstant_tinstant efunc_tinstant_tsequenceset efunc_tsequence_tsequenceset efunc_tsequenceset_tcontseq efunc_tsequenceset_tdiscseq efunc_tsequenceset_tinstant efunc_tsequenceset_tsequenceset lfinfo_invert tfunc_base tfunc_base_base tfunc_tcontseq_tcontseq tfunc_tcontseq_tcontseq_dispatch tfunc_tcontseq_tcontseq_multi tfunc_tcontseq_tcontseq_single tfunc_tcontseq_tdiscseq tfunc_tcontseq_tinstant tfunc_tcontseq_tsequenceset tfunc_tdiscseq_tcontseq tfunc_tdiscseq_tdiscseq tfunc_tdiscseq_tinstant tfunc_tdiscseq_tsequenceset tfunc_temporal tfunc_temporal_base tfunc_temporal_temporal tfunc_tinstant tfunc_tinstant_base tfunc_tinstant_tcontseq tfunc_tinstant_tdiscseq tfunc_tinstant_tinstant tfunc_tinstant_tsequenceset tfunc_tlinearseq_base tfunc_tlinearseq_base_discont tfunc_tlinearseq_base_turnpt tfunc_tsequence tfunc_tsequence_base tfunc_tsequenceset tfunc_tsequenceset_base tfunc_tsequenceset_tcontseq tfunc_tsequenceset_tdiscseq tfunc_tsequenceset_tinstant tfunc_tsequenceset_tsequenceset

tfunc_base() static Datum tfunc_base ( Datum  value, LiftedFunctionInfo *  lfinfo  ) static Generic functions for lifting functions and operators on temporal types. These functions are used for lifting arithmetic operators (+, -, *, /), Boolean operators (and, or, not), comparisons (<, <=, >, >=), distance (<->), spatial relationships (tcontains), etc. The lifting of functions and operators must take into account the following characteristic of the function to be lifted The number of arguments of the function unary functions, such as degrees for temporal floats or round for temporal points. binary functions and operators, such as arithmetic operators and comparisons (e.g., + or <) or spatial relationships functions (e.g.,tintersects). The type of the arguments for binary functions a temporal type and a base type. In this case the non-lifted function is applied to each instant of the temporal type. two temporal types. In this case the operands must be synchronized and the function is applied to each pair of synchronized instants. Whether the type of the arguments may vary. For example, temporal numbers can be of different base type (that is, integer and float). Therefore, the types of the arguments must be taken into account when computing binary operators (e.g., + or <) for temporal numbers. The number of optional parameters of the function no arguments, such as most spatial relationships functions (e.g., tintersects). one argument, such as spatial relationships functions that need an additional parameter (e.g., tdwithin). two arguments, e.g., when assembling a temporal point from two temporal floats, the SRID and a boolean flag stating whether the resulting temporal point is geometric or geographic are needed. Whether the function has instantaneous discontinuities at the crossings. Examples of such functions are temporal comparisons for temporal floats or temporal spatial relationships since the value of the result may change immediately before, at, or immediately after a crossing. Whether intermediate points between synchronized instants must be added to take into account the crossings or the turning points (or local minimum/maximum) of the function. For example, tfloat + tfloat only needs to synchronize the arguments while tfloat * tfloat requires in addition to add the turning point, which is the timestamp between the two consecutive synchronized instants in which the linear functions defined by the two segments are equal. Examples tfloat_degrees => tfunc_temporal applies the degrees function to each instant. tfloatseq + base => tfunc_tsequence_base applies the + operator to each instant and results in a tfloatseq. tfloatseq < base => tfunc_tlinearseq_base_discont applies the < operator to each instant, if the sequence is equal to the base value in the middle of two consecutive instants add an instantaneous sequence at the crossing. The result is a tfloatseqset. tfloatseq + tfloatseq => tfunc_tcontseq_tcontseq synchronizes the sequences and applies the + operator to each instant. tfloatseq * tfloatseq => tfunc_tcontseq_tcontseq synchronizes the sequences possibly adding the turning points between two consecutive instants and applies the * operator to each instant. The result is a tfloatseq. tfloatseq < tfloatseq => tfunc_tcontseq_tcontseq_multi synchronizes the sequences, applies the < operator to each instant, and if there is a crossing in the middle of two consecutive pairs of instants add an instant sequence at the crossing. The result is a tfloatseqset. A struct named LiftedFunctionInfo is used to describe the above characteristics of the function to be lifted. Such struct is filled by the calling function and is passed through the dispatch functions. To avoid code redundancy when coping with functions with 2, 3, and 4 arguments, variadic function pointers are used. The idea is sketched next. typedef Datum (*varfunc) (Datum, ...); TInstant * tfunc_tinstant(const TInstant *inst, LiftedFunctionInfo *lfinfo) { Datum resvalue; if (lfinfo->numparam == 1) resvalue = (*lfinfo->func)(temporalinst_value(inst)); else if (lfinfo->numparam == 2) resvalue = (*lfinfo->func)(temporalinst_value(inst), lfinfo->param[0]); resvalue = (*lfinfo->func)(temporalinst_value(inst), lfinfo->param[0]); else elog(ERROR, "Number of function parameters not supported: %u", lfinfo->numparam); TInstant *result = tinstant_make(resvalue, lfinfo->restype, inst->t); DATUM_FREE(resvalue, temptype_basetype(lfinfo->restype)); return result; } // Definitions for TSequence, TSequence, and TSequenceSet [...] // Dispatch function Temporal * tfunc_temporal(const Temporal *temp, LiftedFunctionInfo *lfinfo) { // Dispatch depending on the temporal type [...] } An example of use of the lifting functions is given next. // Transform the geometry to a geography PGDLLEXPORT Datum tgeompoint_tgeogpoint(PG_FUNCTION_ARGS) { Temporal *temp = PG_GETARG_TEMPORAL_P(0); LiftedFunctionInfo *lfinfo; memset(&lfinfo, 0, sizeof(LiftedFunctionInfo)); lfinfo->func = (varfunc) &geom_to_geog; lfinfo->numparam = 1; lfinfo->restype = T_TGEOGPOINT; lfinfo->tpfunc_base = NULL; lfinfo->tpfunc = NULL; Temporal *result = tfunc_temporal(temp, (Datum) NULL, lfinfo); PG_FREE_IF_COPY(temp, 0); PG_RETURN_POINTER(result); } Apply the variadic function with the optional arguments to the base value