pgsys module #67
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pgsys module #67
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tsg
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Jun 22, 2024
urso
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Requires #67 Closes #66 Postgres sources use tagging and the `Node` (and `NodeTag`) types for many internal types. Unfortunately the macros did not translate well to Zig, which makes it annoying to work with the low level types. We introduce the `pgzx.node` module that provides a list of helper functions like `pgzx.node.make`, `pgzx.node.create`, `pgzx.node.tag`, or `pgzx.node.isA`. We also wrap the constants into our own `pgzx.node.Tag` enum, so you can use `pgzx.node.isA(node, .Query)` in code. Postgres uses code generation to collect the node tags and supported types into `nodetags.h`. We also use code generation to produce the list of tags and type mappings. The generated module is then imported by `pgzx.node`. The `tools/gennodetags` tool imports the `nodes/nodes.h` header file at compile time and uses comptime to collect all known tags into an `ArrayList` which is then used to produce the sources for the anonymous module imported into `pgzx`.
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Requires: #65
With this change we split the C include and the
pgzxinto 2 modules:pgzx_pgsys: C includes and some custom C helperspgzx: High level Zig utilities and abstractions.The split is to prepare for code generation support. When generating Zig code on the fly the generated code is imported as a module into
pgzx, but we also want the generated code to depend on the C includes. By splitting out the C support we can have the generated module importpgsysas a module dependency itself.The change follows the pattern in https://github.com/ziglang/zig/blob/master/test/standalone/dep_triangle/build.zig
We still re-export
pgsysunderpgzx.c.Within
pgzxwe replaceconst c = @import(...)withconst pg = @import("pgzx_pgsys");. Now Postgres API usage is always prefixed withpg.*instead ofc.*, which is also more consistent on how we use the namespaces ourselves and in the example extensions.Follow ups (not handled in this PR):
pgsysfolderpgzx.ctopgzx.pg