feat: support expression index

[leiysky]

No description provided.

[Copilot]

Pull request overview

This pull request adds support for expression indexes to the PostgreSQL query builder. Expression indexes allow creating indexes on computed expressions (like lower(email)) rather than just simple columns. The implementation changes the internal representation of index columns from Vec<Iden> to Vec<Expr> and adds a new expr() method to the CreateIndex builder.

Changes:

• Modified the CreateIndex struct to use Vec<Expr> instead of Vec<Iden> for columns, enabling support for both simple column references and complex expressions
• Added new expr() method for adding expression-based index entries
• Updated write_index_columns() to use write_tuple() for rendering, and made write_tuple() publicly accessible within the crate

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
pqb/src/index/create.rs	Modified column type from Vec to Vec, added expr() method, updated write_index_columns to use write_tuple
pqb/src/expr.rs	Changed write_tuple visibility from private to pub(crate) to enable use in index module
pqb/tests/index.rs	Updated all existing test expectations to reflect new SQL output format and added two new tests for expression indexes
pqb/tests/create_table.rs	Updated PRIMARY KEY test expectation to match new rendering behavior

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

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