Module helper 

Helper utilities for SQL processing

This module provides various utility functions used throughout the codebase:

• Safe sequence access
• Collection normalization
• String manipulation
• Fixed-point transformation
• Topological sorting

Based on the Python implementation in sqlglot/helper.py.

Structs

SingleValuedMapping

A mapping where all keys return the same value.

Enums

TsortError

Error type for topological sort

Constants

DATE_UNITS

Interval units that operate on date components

Traits

EnsureList

Ensures that a value is wrapped in a Vec if it isn’t already a collection.

Functions

apply_index_offset

Applies an offset to a given integer literal expression for array indexing.

camel_to_snake_case

Converts a camelCase string to UPPER_SNAKE_CASE

csv

Formats any number of string arguments as CSV.

csv_default

Formats strings as CSV with default separator “, “

dict_depth

Get the nesting depth of a nested HashMap

ensure_list

Wrap a single value in a Vec

ensure_list_option

Wrap an Option in a Vec (empty if None)

find_new_name

Searches for a new name that doesn’t conflict with taken names.

first

Returns the first element from an iterator

flatten

Flattens a nested collection into a flat iterator

is_date_unit

Check if a unit is a date unit (operates on date components)

is_float

Check if a string can be parsed as a float

is_int

Check if a string can be parsed as an integer

is_iso_date

Check if a string is a valid ISO date (YYYY-MM-DD)

is_iso_datetime

Check if a string is a valid ISO datetime

merge_ranges

Merge overlapping ranges

name_sequence

Creates a name generator that produces sequential names.

seq_get

Returns the value in seq at position index, or None if index is out of bounds.

snake_to_camel_case

Converts a snake_case string to CamelCase

split_num_words

Perform a split on a value and return N words with None for missing parts.

to_bool

Convert a boolean-like string to an actual boolean.

tsort

Sorts a directed acyclic graph in topological order.

while_changing

Applies a transformation to a given expression until a fix point is reached.

while_changing_hash

Applies a transformation until a fix point, using a hash function for comparison.