Module expansion 

Word expansion.

The word expansion involves many kinds of operations described below. The expand_word_multiple function performs all of them and produces any number of fields depending on the expanded word. The expand_word_attr and expand_word functions omit some of them to ensure that the result is a single field. Other functions in this module are provided for convenience in specific situations.

Initial expansion

The initial expansion is the first step of the word expansion that evaluates a Word to a Phrase. It is performed by recursively calling Expand implementors’ methods. Notable (sub)expansions that may occur in the initial expansion include the tilde expansion, parameter expansion, command substitution, and arithmetic expansion.

A successful initial expansion of a word usually results in a single-field phrase. Still, it may yield any number of fields if the word contains a parameter expansion of $@ or $*.

Multi-field expansion

The multi-field expansion is a group of operation steps performed after the initial expansion to render final multi-field results.

Brace expansion

The brace expansion produces copies of a field containing a pair of braces. (TODO: This feature is not yet implemented.)

Field splitting

The field splitting divides a field into smaller parts delimited by a character contained in $IFS. Consequently, this operation removes empty fields from the results of the previous steps.

Pathname expansion

The pathname expansion performs pattern matching on the name of existing files to produce pathnames. This operation is also known as “globbing.”

Quote removal and attribute stripping

The quote removal drops characters quoting other characters, and the attribute stripping converts AttrFields into bare Fields. In expand_word_multiple, the quote removal is performed between the field splitting and pathname expansion, and the attribute stripping is part of the pathname expansion. In expand_word, they are carried out as the last step of the whole expansion.

Re-exports

pub use yash_env::semantics::Field;

pub use yash_env::semantics::expansion::attr;

pub use yash_env::semantics::expansion::attr_strip;

pub use yash_env::semantics::expansion::quote_removal;

pub use yash_env::semantics::expansion::split;

Modules

glob

Pathname expansion

initial

Initial expansion

phrase

Array of fields as an intermediate expansion result

Structs

AssignReadOnlyError

Error returned on assigning to a read-only variable

Error

Explanation of an expansion failure.

Enums

ErrorCause

Types of errors that may occur in the word expansion.

Functions

expand_text

Expands a text to a string.

expand_value

Expands an assignment value.

expand_word

Expands a word to a field.

expand_word_attr

Expands a word to an attributed field.

expand_word_multiple

Expands a word to fields.

expand_word_with_mode

Expands a word to fields.

expand_words

Expands words to fields.

Type Aliases

Result

Result of word expansion.