Module traversal

Expand description

Tree traversal utilities for SQL expression ASTs.

This module provides read-only traversal, search, and transformation utilities for the Expression tree produced by the parser. Because Rust’s ownership model does not allow parent pointers inside the AST, parent information is tracked externally via TreeContext (built on demand).

§Traversal

Two iterator types are provided:

DfsIter – depth-first (pre-order) traversal using a stack. Visits a node before its children. Good for top-down analysis and early termination.
BfsIter – breadth-first (level-order) traversal using a queue. Visits all nodes at depth N before any node at depth N+1. Good for level-aware analysis.

Both are available through the ExpressionWalk trait methods dfs and bfs.

§Searching

The ExpressionWalk trait also provides convenience methods for finding expressions: find, find_all, contains, and count. Common predicates are available as free functions: is_column, is_literal, is_function, is_aggregate, is_window_function, is_subquery, and is_select.

§Transformation

The transform and transform_map functions perform bottom-up (post-order) tree rewrites, delegating to transform_recursive. The ExpressionWalk::transform_owned method provides the same capability as an owned method on Expression.

Based on traversal patterns from sqlglot/expressions.py.

Structs§

BfsIter: Level-order breadth-first iterator over an expression tree.
DfsIter: Pre-order depth-first iterator over an expression tree.
ParentInfo: Information about a node’s parent relationship
TreeContext: External parent-tracking context for an expression tree.

Traits§

ExpressionWalk: Extension trait that adds traversal and search methods to Expression.

Functions§

contains_aggregate: Returns true if the expression tree contains any aggregate function calls.
contains_subquery: Returns true if the expression tree contains any subquery nodes.
contains_window_function: Returns true if the expression tree contains any window function calls.
find_ancestor: Find the first ancestor of target matching predicate, walking from parent toward root.
find_parent: Find the parent of target within the tree rooted at root.
get_columns: Collects all column references (Expression::Column) from the expression tree.
get_tables: Collects all table references (Expression::Table) from the expression tree.
is_add: Returns true if expr matches the expected AST variant(s).
is_aggregate: Returns true if expr is an aggregate function (Expression::AggregateFunction).
is_alias: Returns true if expr matches the expected AST variant(s).
is_alter_table: Returns true if expr matches the expected AST variant(s).
is_and: Returns true if expr matches the expected AST variant(s).
is_arithmetic: Returns true if expr is an arithmetic operator.
is_avg: Returns true if expr matches the expected AST variant(s).
is_between: Returns true if expr matches the expected AST variant(s).
is_boolean: Returns true if expr matches the expected AST variant(s).
is_case: Returns true if expr matches the expected AST variant(s).
is_cast: Returns true if expr matches the expected AST variant(s).
is_coalesce: Returns true if expr matches the expected AST variant(s).
is_column: Returns true if expr is a column reference (Expression::Column).
is_comparison: Returns true if expr is a comparison operator.
is_concat: Returns true if expr matches the expected AST variant(s).
is_count: Returns true if expr matches the expected AST variant(s).
is_create_index: Returns true if expr matches the expected AST variant(s).
is_create_table: Returns true if expr matches the expected AST variant(s).
is_create_view: Returns true if expr matches the expected AST variant(s).
is_cte: Returns true if expr matches the expected AST variant(s).
is_ddl: Returns true if expr is a DDL statement.
is_delete: Returns true if expr matches the expected AST variant(s).
is_div: Returns true if expr matches the expected AST variant(s).
is_drop_index: Returns true if expr matches the expected AST variant(s).
is_drop_table: Returns true if expr matches the expected AST variant(s).
is_drop_view: Returns true if expr matches the expected AST variant(s).
is_eq: Returns true if expr matches the expected AST variant(s).
is_except: Returns true if expr matches the expected AST variant(s).
is_exists: Returns true if expr matches the expected AST variant(s).
is_from: Returns true if expr matches the expected AST variant(s).
is_function: Returns true if expr is a function call (regular or aggregate).
is_group_by: Returns true if expr matches the expected AST variant(s).
is_gt: Returns true if expr matches the expected AST variant(s).
is_gte: Returns true if expr matches the expected AST variant(s).
is_having: Returns true if expr matches the expected AST variant(s).
is_identifier: Returns true if expr matches the expected AST variant(s).
is_ilike: Returns true if expr matches the expected AST variant(s).
is_in: Returns true if expr matches the expected AST variant(s).
is_insert: Returns true if expr matches the expected AST variant(s).
is_intersect: Returns true if expr matches the expected AST variant(s).
is_is_null: Returns true if expr matches the expected AST variant(s).
is_join: Returns true if expr matches the expected AST variant(s).
is_like: Returns true if expr matches the expected AST variant(s).
is_limit: Returns true if expr matches the expected AST variant(s).
is_literal: Returns true if expr is a literal value (number, string, boolean, or NULL).
is_logical: Returns true if expr is a logical operator (AND, OR, NOT).
is_lt: Returns true if expr matches the expected AST variant(s).
is_lte: Returns true if expr matches the expected AST variant(s).
is_max_func: Returns true if expr matches the expected AST variant(s).
is_min_func: Returns true if expr matches the expected AST variant(s).
is_mod: Returns true if expr matches the expected AST variant(s).
is_mul: Returns true if expr matches the expected AST variant(s).
is_neq: Returns true if expr matches the expected AST variant(s).
is_not: Returns true if expr matches the expected AST variant(s).
is_null_if: Returns true if expr matches the expected AST variant(s).
is_null_literal: Returns true if expr matches the expected AST variant(s).
is_offset: Returns true if expr matches the expected AST variant(s).
is_or: Returns true if expr matches the expected AST variant(s).
is_order_by: Returns true if expr matches the expected AST variant(s).
is_ordered: Returns true if expr matches the expected AST variant(s).
is_paren: Returns true if expr matches the expected AST variant(s).
is_query: Returns true if expr is a query statement (SELECT, INSERT, UPDATE, or DELETE).
is_safe_cast: Returns true if expr matches the expected AST variant(s).
is_select: Returns true if expr is a SELECT statement (Expression::Select).
is_set_operation: Returns true if expr is a set operation (UNION, INTERSECT, or EXCEPT).
is_star: Returns true if expr matches the expected AST variant(s).
is_sub: Returns true if expr matches the expected AST variant(s).
is_subquery: Returns true if expr is a subquery (Expression::Subquery).
is_sum: Returns true if expr matches the expected AST variant(s).
is_table: Returns true if expr matches the expected AST variant(s).
is_try_cast: Returns true if expr matches the expected AST variant(s).
is_union: Returns true if expr matches the expected AST variant(s).
is_update: Returns true if expr matches the expected AST variant(s).
is_where: Returns true if expr matches the expected AST variant(s).
is_window_function: Returns true if expr is a window function (Expression::WindowFunction).
is_with: Returns true if expr matches the expected AST variant(s).
transform: Transforms an expression tree bottom-up, with optional node removal.
transform_map: Transforms an expression tree bottom-up without node removal.

Type Aliases§

NodeId: Unique identifier for expression nodes during traversal

Module traversal

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§Traversal

§Searching

§Transformation

Structs§

Traits§

Functions§

Type Aliases§

Module traversal