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	## Summary Garbage collect ASTs once we are done checking a given file. Queries with a cross-file dependency on the AST will reparse the file on demand. This reduces ty's peak memory usage by ~20-30%. The primary change of this PR is adding a `node_index` field to every AST node, that is assigned by the parser. `ParsedModule` can use this to create a flat index of AST nodes any time the file is parsed (or reparsed). This allows `AstNodeRef` to simply index into the current instance of the `ParsedModule`, instead of storing a pointer directly. The indices are somewhat hackily (using an atomic integer) assigned by the `parsed_module` query instead of by the parser directly. Assigning the indices in source-order in the (recursive) parser turns out to be difficult, and collecting the nodes during semantic indexing is impossible as `SemanticIndex` does not hold onto a specific `ParsedModuleRef`, which the pointers in the flat AST are tied to. This means that we have to do an extra AST traversal to assign and collect the nodes into a flat index, but the small performance impact (~3% on cold runs) seems worth it for the memory savings. Part of https://github.com/astral-sh/ty/issues/214.
		
			
				
	
	
		
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			45 lines
		
	
	
	
		
			1.4 KiB
		
	
	
	
		
			Text
		
	
	
	
	
	
---
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source: crates/ruff_python_parser/tests/fixtures.rs
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input_file: crates/ruff_python_parser/resources/inline/ok/walrus_py38.py
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---
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## AST
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```
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Module(
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    ModModule {
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        node_index: AtomicNodeIndex(..),
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        range: 0..54,
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        body: [
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            Expr(
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                StmtExpr {
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                    node_index: AtomicNodeIndex(..),
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                    range: 45..53,
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                    value: Named(
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                        ExprNamed {
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                            node_index: AtomicNodeIndex(..),
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                            range: 46..52,
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                            target: Name(
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                                ExprName {
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                                    node_index: AtomicNodeIndex(..),
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                                    range: 46..47,
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                                    id: Name("x"),
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                                    ctx: Store,
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                                },
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                            ),
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                            value: NumberLiteral(
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                                ExprNumberLiteral {
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                                    node_index: AtomicNodeIndex(..),
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                                    range: 51..52,
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                                    value: Int(
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                                        1,
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                                    ),
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                                },
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                            ),
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                        },
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                    ),
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                },
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            ),
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        ],
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    },
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)
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```
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