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pgparser - Pure Go PostgreSQL Parser

Project Overview

pgparser is a pure Go implementation of PostgreSQL's SQL parser, providing 100% compatible parse tree representation. It translates PostgreSQL's gram.y (Bison grammar) into Go using goyacc.

Target PostgreSQL Version: 17.7 (REL_17_STABLE)

Key Directories

  • parser/ - SQL parser (goyacc-based, translated from PostgreSQL gram.y)
  • nodes/ - Node type definitions (parse tree types, enums, serialization)
  • cmd/pgsema-gen/ - Code generator for keywords and node types

PostgreSQL Source References

All translations are based on ~/Github/postgres (REL_17_STABLE branch):

  • Grammar: src/backend/parser/gram.y
  • Lexer: src/backend/parser/scan.l
  • Keywords: src/include/parser/kwlist.h
  • Parse nodes: src/include/nodes/parsenodes.h
  • Primitive nodes: src/include/nodes/primnodes.h

Development Workflow

Build

go build ./...

Run Tests

go test ./...

Regenerate Parser

make generate-parser

Regenerate Node Types

make generate-nodes

Translation Guidelines

goyacc Translation (from Bison)

  1. %locations - Not supported; add location fields to %union manually
  2. %parse-param / %lex-param - Embed state in Lexer struct
  3. makeNode(X) -> &nodes.X{}
  4. list_make1(x) -> []nodes.Node{x}
  5. lappend(list, x) -> append(list, x)
  6. $1, $2 -> Need explicit type assertions: $1.(*nodes.SelectStmt)

Node Serialization

Output format must match PostgreSQL's nodeToString() exactly:

{QUERY :commandType 1 :querySource 0 :canSetTag true ...}

Field order must match PostgreSQL's output order.