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add FunctionCallInfo, SortSupport, StringInfo #35

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add FunctionCallInfo, SortSupport, StringInfo #35

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e1db075
add access/hash.h to C includes
angaz Mar 24, 2024
752cc1f
add libpq/pqformat.h to C includes
angaz Mar 24, 2024
21f88fb
add FunctionCallInfo, SortSupport, StringInfo
angaz Mar 23, 2024
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2 changes: 2 additions & 0 deletions src/pgzx/c.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ const includes = @cImport({
@cInclude("postgres.h");
@cInclude("postgres_ext.h");

@cInclude("access/hash.h");
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I can't tell how this file is sorted, so I just put the new import at the top.

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I might have put it after varatt.h :). But feel free to keep it here.

@cInclude("fmgr.h");
@cInclude("miscadmin.h");
@cInclude("varatt.h");
Expand Down Expand Up @@ -40,6 +41,7 @@ const includes = @cImport({
// libpq support
@cInclude("libpq-fe.h");
@cInclude("libpq/libpq-be.h");
@cInclude("libpq/pqformat.h");
@cInclude("libpqsrv.h");
});

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41 changes: 37 additions & 4 deletions src/pgzx/datum.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -9,12 +9,14 @@ const varatt = @import("varatt.zig");
pub fn Conv(comptime T: type, comptime from: anytype, comptime to: anytype) type {
return struct {
pub const Type = T;

pub fn fromNullableDatum(d: c.NullableDatum) !Type {
if (d.isnull) {
return err.PGError.UnexpectedNullValue;
}
return try from(d.value);
}

pub fn toNullableDatum(v: Type) !c.NullableDatum {
return .{
.value = try to(v),
Expand All @@ -27,12 +29,14 @@ pub fn Conv(comptime T: type, comptime from: anytype, comptime to: anytype) type
pub fn ConvNoFail(comptime T: type, comptime from: anytype, comptime to: anytype) type {
return struct {
pub const Type = T;

pub fn fromNullableDatum(d: c.NullableDatum) !T {
if (d.isnull) {
return err.PGError.UnexpectedNullValue;
}
return from(d.value);
}

pub fn toNullableDatum(v: T) !c.NullableDatum {
return .{
.value = to(v),
Expand All @@ -46,12 +50,14 @@ pub fn ConvNoFail(comptime T: type, comptime from: anytype, comptime to: anytype
pub fn OptConv(comptime C: anytype) type {
return struct {
pub const Type = ?C.Type;

pub fn fromNullableDatum(d: c.NullableDatum) !Type {
if (d.isnull) {
return null;
}
return try C.fromNullableDatum(d);
}

pub fn toNullableDatum(v: Type) !c.NullableDatum {
if (v) |value| {
return try C.toNullableDatum(value);
Expand All @@ -70,7 +76,10 @@ pub fn OptConv(comptime C: anytype) type {
/// reflection only.
var directMappings = .{
.{ c.Datum, PGDatum },
.{ c.FunctionCallInfo, PGFunctionCallInfo },
.{ c.NullableDatum, PGNullableDatum },
.{ c.SortSupport, PGSortSupport },
.{ c.StringInfo, PGStringInfo },
};

pub fn fromNullableDatum(comptime T: type, d: c.NullableDatum) !T {
Expand Down Expand Up @@ -154,7 +163,7 @@ inline fn isConv(comptime T: type) bool {
return @hasDecl(T, "Type") and @hasDecl(T, "fromNullableDatum") and @hasDecl(T, "toNullableDatum");
}

pub const Void = ConvNoFail(void, idDatum, toVoid);
pub const Void = ConvNoFail(void, makeID(c.Datum), toVoid);
pub const Bool = ConvNoFail(bool, c.DatumGetBool, c.BoolGetDatum);
pub const Int8 = ConvNoFail(i8, datumGetInt8, c.Int8GetDatum);
pub const Int16 = ConvNoFail(i16, c.DatumGetInt16, c.Int16GetDatum);
Expand All @@ -170,12 +179,18 @@ pub const Float64 = ConvNoFail(f64, c.DatumGetFloat8, c.Float8GetDatum);
pub const SliceU8 = Conv([]const u8, getDatumTextSlice, sliceToDatumText);
pub const SliceU8Z = Conv([:0]const u8, getDatumTextSliceZ, sliceToDatumText);

pub const PGDatum = ConvNoFail(c.Datum, idDatum, idDatum);
pub const PGFunctionCallInfo = ConvID(c.FunctionCallInfo);
pub const PGSortSupport = ConvID(c.SortSupport);
pub const PGStringInfo = Conv(c.StringInfo, datumGetStringInfo, c.PointerGetDatum);
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I see why we want these types. But I don't think we should add them to datum conversions 🤔

We already have support to capture FunctionCallInfo via pgzx.fmgr.args module. Maybe that would be a better place for these argument types?

This and the other PRs also make me wonder if we rather want to introduce different function types. Right now we have PG_FUNCTION_V1, which can be any function. But maybe it would make sense to also introduce PG_OUT_FUNCTION or PG_SORT_FUNCTION exporters. These function types would ensure the correct number of argument and pass SortSupport or StringInfo right away.

For SortSupport one needs to functions like:

static int
btfloat8fastcmp(Datum x, Datum y, SortSupport ssup)
{
	float8		arg1 = DatumGetFloat8(x);
	float8		arg2 = DatumGetFloat8(y);

	return float8_cmp_internal(arg1, arg2);
}

Datum
btfloat8sortsupport(PG_FUNCTION_ARGS)
{
	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);

	ssup->comparator = btfloat8fastcmp;
	PG_RETURN_VOID();
}

Using an "abstraction" in Zig this might become:

comptime {
  pgzx.PG_SORT_SUPPORT("btfloat8sortsupport", .{
    .comparator = btfloat8fastcmp,
  })
}

Maybe it is worth to open an issue to discuss functionality that you are missing for the kind of work you are planning. Then we can discuss what needs to be adapted where, or if it makes sense to introduce abstractions. WDYT?

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Ok. I didn't know about the fmgr.args module. I'll have to check it out. I like the idea of different types of functions. It would simplify the definition boilerplate.


pub const PGDatum = ConvID(c.Datum);
const PGNullableDatum = struct {
pub const Type = c.NullableDatum;

pub fn fromNullableDatum(d: c.NullableDatum) !Type {
return d;
}

pub fn toNullableDatum(v: Type) !c.NullableDatum {
return v;
}
Expand All @@ -185,8 +200,26 @@ const PGNullableDatum = struct {

// TODO: conversion decorator for jsonb decoding/encoding types

fn idDatum(d: c.Datum) c.Datum {
return d;
fn ConvID(comptime T: type) type {
const idFn = makeID(T);

return ConvNoFail(T, idFn, idFn);
}

fn makeID(comptime T: type) fn (T) T {
return struct {
fn id(t: T) T {
return t;
}
}.id;
}

fn datumGetStringInfo(datum: c.Datum) !c.StringInfo {
return datumGetPointer(c.StringInfo, datum);
}

inline fn datumGetPointer(comptime T: type, datum: c.Datum) T {
return @ptrCast(@alignCast(c.DatumGetPointer(datum)));
}

fn toVoid(d: void) c.Datum {
Expand Down