Mojo package

string

Provides comprehensive Unicode string functionality.

Core features:

Unicode support with UTF-8 encoding
Efficient string slicing and views
String formatting and interpolation
Memory-safe string operations
Unicode case conversion
Unicode property lookups and validation

Key components:

String: Mutable and owning string
- Uses a smart three-mode allocation strategy: static memory references for string literals, small string optimization (SSO) for strings ≤23 bytes (stored directly within the String object with zero allocation cost), and reference-counted heap allocation for larger strings. This design makes the vast majority of real-world strings extremely fast.
- Owns its data and manages memory automatically when heap-allocated.
- Mutable and grows dynamically as needed.
StringSlice: Non-owning string view
- Performs zero heap allocations: stores only a pointer and length that reference existing string data owned by another object.
- Does not own the data pointed to, so it can't outlive the data it references.
StaticString: Compile-time constant (immutable) string reference
- Performs zero heap allocations: stores a pointer and length to a compile-time constant or static program memory.
- References data with a static lifetime that exists for the entire program duration, unlike StringSlice which can reference temporary data.
Codepoint: Unicode codepoint representation and operations
- Represents a single Unicode codepoint as a 32-bit value.
- Enables iteration over string contents at the Unicode codepoint level rather than byte level for proper Unicode text processing.
format: Built-in string formatting and interpolation utilities.

Note

String stores data using UTF-8, and all operations (unless clearly noted) are intended to be fully Unicode compliant and maintain correct UTF-8 encoded data. A handful of operations are known to not be Unicode / UTF-8 compliant yet, but will be fixed as time permits.

Modules

codepoint: Unicode codepoint handling.
format: String formatting utilities for Mojo.
string: Implements the core String type and related utilities.
string_slice: Implements the StringSlice type and related utilities for efficient string operations.

Modules​

Modules