Struct ZIO 

pub struct ZIO { /* private fields */ }

Buffered input stream wrapping an external chunk-reader callback.

Corresponds to struct Zio / ZIO in lzio.h. The C struct stored a lua_State *L back-pointer and a void *data opaque pointer alongside a raw lua_Reader function pointer. In Rust:

• lua_State *L is removed from the struct; callers hold &mut LuaState directly and pass it to fallible methods.
• void *data is folded into the reader closure.
• const char *p (raw pointer into the reader’s internal buffer) becomes a usize index into the owned current_chunk field.

Implementations

impl ZIO

pub fn new(reader: ChunkReader) -> Self

Initialise a ZIO with the given reentrant reader callback.

Corresponds to luaZ_init in lzio.c. The C parameters reader and data are combined into a single closure; L is threaded through the fallible methods rather than stored on the struct.

pub fn from_bytes(bytes: Vec<u8>) -> Self

Construct a ZIO that yields the supplied bytes once and then EOZ.

Used for in-memory sources (a string chunk, or the lexer’s own unit tests) where there is no reader to call back into Lua. The state passed to getc/fill is ignored by this reader.

pub fn take(&mut self) -> ZIO

Move this stream out, leaving an exhausted (empty) ZIO in its place.

The parser owns the lexer’s LexState, which owns its ZIO; the loader only holds a &mut ZIO. This hands the live stream — its reader and any bytes already buffered by [getc] — to the parser by value so the lexer can keep pulling from the same reader (and the same &mut LuaState) on demand. The original slot becomes an immediately-EOZ stream.

pub fn getc(&mut self, state: &mut LuaState) -> Result<i32, LuaError>

Return the next byte from the stream as an i32, or [EOZ] at end-of-stream.

This is the hot-path inline method corresponding to the zgetc macro. When bytes remain in the current chunk no allocation occurs.

C’s macro uses (z)->n-- > 0, which reads n, tests it, then decrements; when n == 0 the test is false (0 > 0) so fill is called without decrementing. This preserves that: if self.n > 0 followed by an explicit self.n -= 1.