Crate spg_sql 

SPG SQL front-end. v0.2 ships only the lexer + a minimal recursive-descent parser for the SELECT [..] FROM [..] WHERE [..] subset.

Layers (each in its own module):

• lexer — byte stream → tokens
• ast — abstract syntax tree types + Display (pretty-print)
• parser — tokens → AST (Pratt parser for expression precedence)

Modules

ast

AST for the PG-dialect subset SPG accepts in v0.2.

lexer

Lexer for the PG-dialect subset that SPG accepts.

parser

Recursive-descent parser with a Pratt (precedence-climbing) sub-parser for expressions.